Plastic surgery

PART VIII

HAND

CHAPTER 81  LIGAMENT INJURIES OF THE HAND AND WRIST

KARIM BAKRI, BRIAN T. CARLSEN, AND STEVEN L. MORAN

INTRODUCTION

Ligament injuries to the hand and wrist are common. In many cases, these injuries occur in the absence of concomitant fractures or gross radiographic abnormalities and therefore diagnosis is delayed. In addition to performing a history and physical examination, the plastic surgeon must have sufficient knowledge of joint anatomy and pathology to expediently make the correct diagnosis. In this chapter, the spectrum of major ligamentous injuries to the hand and wrist are reviewed with attention to pertinent anatomy, pathology, and treatment options.

PROXIMAL INTERPHALANGEAL JOINT

Ligament injuries around the proximal interphalangeal (PIP) joint are common. Immobility and improper splinting of the PIP joint can lead to permanent stiffness and contracture in as early as 2 weeks. It is imperative that these injuries be diagnosed and treated early. The most common injury patterns include ligament avulsions, dislocations, and fracture dislocations.

The PIP joint is a bicondylar hinge joint with 110° arc of motion in a single plane and has been called the functional locus of the hand because it produces 85% of intrinsic digital flexion and contributes 20% to the overall arc of finger motion. PIP joint stability is due to congruity of the articular surfaces and ligamentous anatomy including the proper and accessory collateral ligaments laterally and volar plate palmarly (Figure 81.1).

PIP dislocations occur in four major patterns: 1) dorsal dislocations, 2) fracture dislocations, 3) volar dislocations, and 4) lateral subluxation or dislocations. The extensor mechanism provides little support for the joint dorsally, and the bulk of dislocations occur dorsally as the middle phalanx is driven dorsally and proximally. Dislocations occurring laterally or volarly are less common and require a greater force for dislocation; these dislocation patterns often require operative intervention for successful management. A general treatment algorithm for all forms of PIP dislocation is 1) joint reduction, 2) verify the congruency of the joint surfaces throughout a normal arc of motion, 3) assess joint stability after reduction, and 4) institute early hand therapy to minimize stiffness. As a general rule, stable joints, following reduction, are treated nonoperatively, whereas unstable joints often require operative management to restore joint stability.

General Evaluation

A history is obtained to determine the mechanism of injury. Radiographs are obtained to assess concomitant fractures or evidence of ligament avulsion, which may present radiographically as small bone fragments near the site of ligament insertion. In partial injuries, with subluxation only, palpation over the volar plate and collateral ligaments can identify areas of injury. Dislocations are reduced with the aid of a digital block. If joint reduction does not occur easily, then further joint reduction maneuvers can be attempted with the aid of a portable fluoro-scanner. Multiple attempts at closed joint reduction should be avoided due to potential damage to the joint cartilage. In cases of irreducible dislocations, soft tissue interposition is usually preventing reduction and an open reduction in the operating room is indicated.

If the joint is amenable to closed reduction, the finger can then be assessed for tendon function and joint stability. Stability of the joint can be assessed passively by 1) laterally stressing the joint, 2) applying translational stress in a volar–dorsal direction, and 3) with active motion. Signs of subluxation or joint surface incongruity while the patient actively moves can be assessed in a fluoro-scanner. Joints that are stable throughout the full range of active motion are splinted or buddy taped for comfort for a few days, but can and should be mobilized early to prevent stiffness. Recurrent subluxation or dislocation with active motion necessitates splinting the joint in a position of stability to allow for ligament healing prior to mobilization.

Dorsal PIP Joint Dislocations

Dorsal dislocation or subluxation of the base of the middle phalanx is the most common PIP joint injury. The injury occurs as a result of hyperextension of the joint with axial loading. Dorsal PIP dislocations are classified into three types (Figure 81.2).1,2

Type 1(Hyperextension) injuries represent a hyperextension injury with an associated avulsion of the volar plate from the proximal phalanx. Although the degree of hyperextension may be dramatic, the articular surface of the middle phalanx remains in contact with the dorsal third of the proximal phalanx’s articular surface (Figure 81.2A).

Type 2 (Dorsal dislocation) injuries produce a complete longitudinal splitting of the collateral and accessory collateral ligaments and result in dorsal dislocation with incongruent joint surfaces and parallel phalanges in a bayonet configuration (Figure 81.2B).

Type 3 (Fracture dislocation) injuries result in an impaction fracture at the volar base of the middle phalanx, the fracture fragment remains attached to the volar plate, while the middle phalanx displaces dorsally. In acute injuries, deformity, swelling, and tenderness are frequently obvious; however, dedicated A-P and true lateral X-rays of the involved finger are essential and allow for the evaluation of subtle fractures or avulsed bone fragments. Fracture dislocations may either be stable or unstable based on the size and comminution of the fracture fragment. Stable fractures usually involve less than 30% to 40% of the volar articular surface of the middle phalanx. In cases of stable fracture dislocations, a portion of the proper collateral ligament remains attached to the middle phalanx, providing stability once the fracture is reduced. Unstable fractures usually involve more than 40% of volar articular surface of the middle phalanx. In these cases, the majority of the proper collateral ligament remains with the fracture fragment; thus, the middle phalanx has no remaining ligamentous support. Congruent reduction in such cases is unlikely and some means of fixation is required (Figure 81.2C).3

Treatment. Dorsal dislocations of the PIP joint are usually amenable to closed reduction by axial finger traction under digital block anesthesia. Hyperextension of the PIP and gentle pressure applied to the dorsal base of the middle phalanx facilitate reduction. Difficulty reducing a dorsal dislocation should always raise the suspicion of soft tissue interposition between the joint surfaces and may necessitate open reduction. The volar plate is most commonly interposed, although interposition of the profundus tendon or a portion of the extensor mechanism is also possible. After reduction, the joint should be assessed for stability, and X-rays should be obtained to confirm the reduction and further assess for fractures.

FIGURE 81.1. PIP joint anatomy. The soft tissue constraints include the proper and accessory collateral ligaments laterally and volar plate palmarly. The proper collateral ligaments attach to the bone of the middle phalanx while the accessory collateral ligaments attach to the volar plate.

Stable Joints

The majority of type 1 and type 2 injuries are stable after reduction and are treated nonoperatively with buddy-taping or extension block splinting. Simple hyperextension injuries, which are stable following reduction and without evidence of subluxation, can be splinted for comfort for 2 to 3 days and then patients may be started on active motion therapy protocols. Stable joints that have sustained more severe injuries (including congruent fracture dislocations that involve less than 40% of the articular surface of the middle phalanx) are placed in an extension block splint with the joint in 20° to 30° of flexion, which improves joint stability.2,4 Fluoroscopy is helpful in determining the angle to splint the joint to assure joint congruity in cases of fracture dislocations. The joint is allowed to flex within the splint. The splint is refashioned weekly to allow for gradual extension as the soft tissues heal. Alternatives to extension block splinting include extension block pinning which involves passing a K-wire into the head of the proximal phalanx to mechanically block PIP extension and prevent dorsal translation of the middle phalanx.5 Downsides of extension block pinning include the possibility of infection and the inability to gradually increase the amount of extension without removal of the pin. For stable dislocations, stiffness and swelling may persist for several months but long-term functional deficits are uncommon.

Unstable Joints and Fracture Dislocations

Intra-articular fractures and fracture dislocations that involve more than 30% to 40% of the articular surface leave little collateral ligament attached to the middle phalanx and are frequently unstable. These joints are much more prone to developing debilitating stiffness, contracture, and patient dissatisfaction. This type of injury is difficult to treat and complications may occur despite an optimally executed treatment regimen. The goals of treatment are to restore congruity at the articular surface and allow early active motion of the joint. There are several treatment options for unstable fracture dislocations and these include:

FIGURE 81.2. (AC) PIP dislocations are divided into three types as described by Eaton. In a type I hyperextension injury (A) there is an injury to the volar plate, in addition to an incomplete tear that occurs between the proper and accessory collateral ligaments. The joint surface remains congruent after the injury. In a type II dorsal dislocation injury (B) there is a complete disruption of the volar plate and a complete tear between the accessory and proper collateral ligament. The middle phalanx lies on the dorsum of the proximal phalanx in a bayonet fashion. In a type III hyperextension injury (C) there is a fracture and a dislocation. The volar plate, accessory collateral ligament, and proper collateral ligament are damaged. The volar margin of the middle phalanx fractures at the site of proper collateral ligament insertion and remains with the proximal phalanx while the middle phalanx moves dorsal and proximal. (Redrawn from Eaton RG, Lister JW. Joint injuries and their sequelae. Clin Plast Surg. 1976;3:85-98.)

1.  Dynamic skeletal traction—Longitudinal digital traction tightens the soft tissue envelope holding the bone fragments reduced (ligamentotaxis), and early range of motion can be initiated (Figure 81.3A–E).6

2.  ORIF—Open reduction internal fixation using a lag screw can be performed through a volar approach if there is a single large volar fragment.

3.  Trans-articular K-wire fixation—A single K-wire is passed proximally across the fracture site and into the head of the proximal phalanx with the joint in approximately 20° of flexion. The K-wire is removed after 3 weeks and the finger is mobilized,

4.  Extension block splintingUnstable PIP fracture dislocations tend to become more stable with an increasing degree of flexion. A dorsal splint can be used to block extension beyond the point of instability but allow for ongoing active flexion. The splint can be modified weekly to progressively decrease the degree of extension blocking. Extension blockade in greater than 30° of flexion for more than 3 weeks should be avoided, to minimize the risk of long-term PIP flexion contracture.4,7

5.  Volar plate arthroplasty—When the articular surface of the middle phalanx is severely comminuted, restoration of stable congruent bone surfaces is difficult. Soft-tissue interposition arthroplasty using the volar plate to resurface the base of the middle phalanx can be used to restore joint function.8

6.  Hemihamate osteochondral arthroplasty—For severe comminution of the middle phalanx, reconstruction of the volar portion of the middle phalanx is possible with the use of an osteochondral graft from the hamate. This procedure can be useful when there is >50% bone loss with instability. The dorsal central ridge of the hamate lies between the ring and small finger metacarpals and correlates nicely to the central ridge at the base of the middle phalanx. The graft is centered on this ridge and harvested slightly larger than the measured defect to allow for final contouring before inset. A volar approach to the PIP joint is used and the graft is secured with two or three bicortical screws. Early motion is begun at 1 week.9

FIGURE 81.3. Unstable type III dorsal fracture dislocation in a 32-year-old laborer. A. Radiograph of injury. BC. Following closed reduction the joint remained unstable; hence, dynamic traction pinning was used to restore articular alignment and allow the patient to begin immediate motion therapy. DE. At 6 weeks the pins were removed and at 6 months the patient has regained acceptable motion.

Volar PIP Dislocation

Volar dislocation of the base of the middle phalanx is a rare injury and is usually associated with either 1) rupture of the central slip of the extensor tendon with or without an avulsion fracture of the base of the middle phalanx or 2) a torsional force causing rotatory subluxation of the middle phalanx volarly. Pure volar dislocations cause injuries to the collateral ligaments, volar plate, and extensor mechanism; however, the joint is easily reducible with longitudinal traction and extension of the middle phalanx. Rotatory volar dislocations usually result in disruption of only one of the collateral ligaments. As the associated side of the base of the middle phalanx subluxes in a volar direction, the corresponding proximal phalangeal condyle may buttonhole in the interval between the central slip and the lateral band, making reduction challenging. In such a situation, attempting reduction by longitudinal traction tightens the lateral band further entrapping the condyle. For these dislocations, reduction should be performed by placing the joint in full flexion, which relaxes the volarly displaced lateral band, and gentle rotation of the base of the middle phalanx. Radiographs are obtained to confirm success, and active extension is tested to assess the central slip stability. Failure to achieve full extension requires splinting in extension for 6 weeks; otherwise, the joint can be mobilized after 2 weeks. Inability to achieve closed reduction necessitates open exploration to reduce the entrapped condyle and repair the extensor mechanism. Small dorsal avulsion fractures can be immobilized in extension for 6 weeks. Larger, intra-articular dorsal fragments that are not comminuted are rare; however, ORIF should be considered if there is significant displacement.10

PIP Collateral Ligament Injuries

Forced lateral deviation of the PIP joint puts significant stress on the associated collateral ligament, which may rupture at its proximal attachment causing lateral joint instability. With more severe injury, the volar plate is also avulsed causing disruption of two sides of the ligamentous “box”; the middle phalanx dislocates laterally and should be reduced by longitudinal traction. Joint stability can be assessed by stressing the injured collateral ligament following reduction. Isolated collateral ligament injuries usually heal after a course of protection and immobilization in extension for 7 to 10 days, followed by controlled active motion. Buddy taping can be used to allow motion while protecting from further lateral stress injuries. Operative collateral ligament repair may be appropriate if the joint is irreducible or persistently unstable. In these circumstances, the ligament should be reattached through a midaxial approach using suture anchors.11-13

Outcomes and Complications. Outcomes are predicated on appropriate reduction and early postoperative therapy. Type I injuries usually heal with few complications. Complete dorsal dislocations and fracture dislocations represent complete disruption of the volar plate and collateral ligaments and are associated with poorer outcomes. Collateral ligament fibrosis following dislocation is the most common complication, resulting in late joint stiffness and flexion contracture. For such cases, early therapy is the first-line treatment. If therapy fails to improve the stiff joint, consideration can be given to joint release, which can include total collateral ligament excision and volar plate release.

Other complications can include persistent volar plate laxity, which can lead to a hyperextension deformity (swan-neck) or early degenerative arthritis. In volar dislocations, extension lag can be troublesome even after repair of the central slip. Failure to identify central slip injuries in these patients will lead to chronic joint subluxation or a chronic boutonniere deformity.

DISTAL INTERPHALANGEAL JOINT

The distal interphalangeal (DIP) joint is also a uniaxial hinge joint and has an anatomic ligamentous structure similar to the PIP joint; however, additional volar support is provided by the profundus tendon insertion at the base of the distal phalanx. The checkrein ligaments are shorter and more laterally situated in comparison to the PIP joint which allows the joint to passively hyperextend by about 15°. The normal active motion arc is 0° to 60°, and restricted motion or fusion of the DIP joint is well tolerated. Dislocation of this joint is rare, and most cases are associated with concomitant flexor or extensor injury, and these will be discussed in greater detail in the section on extensor and flexor tendon injuries.

Dorsal DIP Dislocation

This is the most common DIP joint injury. Closed dislocations can be reduced by longitudinal traction and splinted for 2 to 3 weeks, with protected motion beginning at 1 week. The lack of soft tissue laxity often results in a dorsal skin laceration and an open joint, which should be irrigated, closed, and splinted. Rarely, DIP or thumb interphalangeal (IP) dislocations are irreducible due to interposition of the volar plate, flexor digitorum profundus (FDP) tendon, or even sesamoid bones and require open reduction. Hyperextension of the DIP joint can result in fracture of the volar lip of the distal phalanx. Small fragments proximal to the FDP insertion are usually inconsequential; fragments involving a large portion of the articular surface or the FDP insertion require operative fixation.14

METACARPOPHALANGEAL JOINT

Ligamentous injuries about the finger metacarpophalangeal (MP) joints are rare due to the significant amount of soft tissue stabilization around the metacarpal head. The MP joints are diarthrodial joints and are stabilized by a volar plate, as well as proper and accessory collateral ligaments. The MP joint has a complex articular geometry and extrinsic stabilizing structures that allow for stability in a multiplanar arc of motion. The metacarpal head is offset volarly from the shaft, which causes the collateral ligaments to tighten with increasing flexion. As such, the joint is lax in extension allowing for abduction and adduction when the hand is open. In flexion, the collateral ligaments are taut and joint stability is gained at the expense of lateral mobility. The volar plate is robust and cartilaginous distally, but thin and membranous proximally lacking checkrein ligaments and allowing for some hyperextension. Extrinsic stabilizers include the flexor tendons, the extensor mechanism, and the sagittal bands.15-17 Dislocations of the finger MP joints are usually dorsal or ulnar and occur most commonly in the index and small fingers. Volar dislocations and isolated collateral ligament injuries are rare.18

Dorsal MP Dislocation

Dorsal dislocation usually occurs as a result of forced MP hyperextension. Patients present with pain, deformity, and, usually, MP joint hyperextension. The diagnosis is confirmed radiographically. When the proximal phalanx is forced into hyperextension, the volar plate is torn proximally at its membranous portion. In a simple dorsal subluxation, there is often a marked hyperextension deformity of the finger; however by definition, the base of the proximal phalanx remains in contact with the metacarpal head; these injuries may be treated with closed reduction. In contrast, a complex dorsal dislocation occurs when the torn volar plate, which remains attached to the base of the proximal phalanx, becomes interposed in the joint. The finger assumes a bayonet position lying dorsally on the metacarpal head, and the deformity may be less impressive in appearance than a simple subluxation. The metacarpal head is forced into the palm and “buttonholes” between the lumbrical radially, and the FDP tendon ulnarly. The flexor tendon is pulled dorsally by the intact A1 pulley and the structures form a noose around the narrow metacarpal neck. Attempts at closed reduction by hyperextension or traction tighten this noose, preventing relocation of the interposed volar plate and proximal phalanx.19 This mechanism should be considered even when attempting reduction of a simple dislocation, as digital traction causing excessive MP joint distraction can inadvertently draw the torn volar plate dorsally, thus converting a simple dislocation into a complex one requiring operative intervention. Closed reduction of a simple dislocation requires the wrist and PIP joints to be in flexion to relax the flexor tendons, and pressure is then directed over the base of the proximal phalanx volarly, sliding it over the metacarpal head, keeping the joint surfaces in contact to prevent inadvertent volar plate interposition.

Complex, irreducible dislocations require open reduction. This can be approached through either a dorsal or volar incision.20 The dorsal approach carries a lower risk of injury to the neurovascular structures and allows direct visualization of the entrapped volar plate.21,22 The volar approach gives excellent access to the musculotendinous structures that entrap the metacarpal head, and reduction can be achieved by incising the A1 pulley, which allows the flexor tendon to return to its volar location by relaxing the noose around the metacarpal neck. In such cases, the neurovascular bundles will be placed on stretch and displaced superficially by the metacarpal head; the surgeon must be careful not to injure these structures during the skin incision and dissection to expose the joint.23 After reduction of simple or complex dislocations, a dorsal blocking splint should be applied to prevent recurrent hyperextension, and the reduction should be confirmed radiographically.

Volar MP Dislocation

Biomechanical studies in cadavers have shown that forced hyperflexion of the finger MP joints often results in a transverse proximal phalanx fracture rather than a volar MP dislocation; consequently, volar dislocation of the MP joint is an infrequent occurrence. Volar dislocations are usually irreducible due to interposition of the dorsal capsule, volar plate, juncturae tendinae, or collateral ligaments within the joint. Closed reduction may be attempted, but open reduction is usually required to remove the intervening structures prior to reduction.24

Isolated collateral ligament injuries at the MP joint are also rare, but may occur as a result of forced ulnar deviation at the MP joint and can be associated with a fracture of the base of the proximal phalanx. Injuries to the radial collateral ligament (RCL) of the index finger deserve special surgical consideration, as the integrity of this ligament is required to resist lateral deviation during pinch activities. If this injury is suspected, X-ray of the MP joint (Brewerton view) should be obtained to rule out avulsion fractures.25 Joint stability may be assessed by flexing the joint to 60° and placing a radial and ulnar lateral stress to the joint. Joints that are stable or have a firm endpoint on lateral stress testing can be splinted in 30° to 60° of flexion, and the patient may begin early active motion therapy. Such injuries may be expected to heal without surgical repair. Lack of a firm endpoint on lateral stress testing indicates a complete tear. Verification of such an injury can be performed with a magnetic resonance imaging (MRI). Unstable avulsion injuries are surgically repaired.26

LIGAMENT INJURIES OF THE THUMB

The thumb is capable of circumduction, opposition, flexion, extension, abduction, and adduction. The thumb contributes up to 40% of hand function, but due to its wide arc of motion, the thumb is at risk for hyperabduction and hyperextension injuries.27 The most common ligament injury occurring in the thumb is an acute tear of the MP ulnar collateral ligament (UCL), more commonly referred to as a “skier’s thumb.”

Thumb MP UCL Injury (Skier’s Thumb)

Acute tears of the UCL are 10 times more common than RCL injuries.28-30 The mechanism of injury is hyperabduction and forced radial deviation of the proximal phalanx during a fall. Patients will present with tenderness, swelling, and potentially bruising along the ulnar border of the thumb.

There are several important factors to determine when treating UCL injuries:

1.  Is the injury a partial or complete ligamentous tear?

2.  Is there a Stener lesion present?

3.  Is there an associated fracture?

4.  Is the injury acute or chronic?

Each of these factors will be discussed in greater detail below.

Physical Examination

The treatment of a UCL injury largely depends on whether the injury is a partial or complete ligament disruption. Partial tears (sprains) can be differentiated from complete tears on physical examination by assessing the degree of angulation on valgus stress testing, comparing this with the “normal” side, and evaluating for the presence of a “firm” endpoint. The differential attachment of the proper and accessory collateral ligaments normally allows the proper collateral ligaments to be taut in flexion and the accessory collateral ligaments to be taut in extension.

There is no consensus in the literature on how to clinically differentiate between partial and complete tears. However, if >35° of joint angulation is noted on valgus stress of the flexed MP joint, a complete tear of the proper collateral ligament is likely. In addition, if the degree of angulation with stress of the injured thumb exceeds that of the uninjured thumb by more than 15°, a complete tear is likely (Figure 81.4). Similarly, tears of the accessory collateral ligament can be identified when valgus stress testing of the extended MP joint results in more than 35° of radial deviation. Finally, the complete absence of resistance (“firm endpoint”) to lateral stress testing is also indicative of a complete UCL rupture. Pain and spasm of the injured adductor pollicis can confound the examination findings and a local anesthetic wrist block can be used to obtain a reliable examination. Partial tears are typically stable and can be treated by immobilizing the MP joint for a minimum of 4 weeks in a thumb spica or hand-based splint, leaving the IP joint free.16,31-33

FIGURE 81.4. Example of ulnar collateral ligament instability.

Complete rupture of the UCL should be repaired to prevent long-term laxity and instability. The ligament usually tears at its distal attachment, although proximal and intrasubstance tears have been reported. The surgical approach is through a lazy-S or chevron incision with the apex located at the volar, ulnar aspect of the MP joint. Mid-substance tears can be primarily repaired with nonabsorbable suture, and distal ligament avulsions should be securely fixed to the proximal phalanx using pullout sutures, bone anchors, or cerclage wire.34,35 In acute cases, the location of insertion on the proximal phalanx is apparent; however, in delayed cases, identifying the location of UCL attachment may be difficult. In these cases, the ligament should be reattached 3 mm distal to the articular surface and 3 mm dorsal to the volar cortex of the proximal phalanx to optimize MP range of motion.36

The Stener Lesion

Complete avulsion of the UCL from its distal attachment can result in interposition of the leading edge of the adductor aponeurosis between the ligament and its insertion (the Stener lesion).28,37,38 Without operative reduction and fixation, soft tissue interposition will prevent the ligament from healing and the thumb will be chronically unstable. Occasionally, a small bone fragment is avulsed with the ligament and can be seen proximal to the adductor hood on radiograph. In the absence of a bone fragment, the diagnosis is largely a clinical one based on findings of a complete UCL tear with a palpable mass proximal to the MP joint. MRI or ultrasound can confirm the diagnosis.39,40

UCL Avulsion Fractures

X-rays are always obtained because avulsion fractures of the proximal phalanx are common. The majority of these fractures do not have a Stener lesion present, and primary bony healing is possible in minimally displaced fractures with immobilization. Combination injuries (avulsion fracture and ligament injury) can occur, though much less frequently.41 Due to the possibility of these combined injuries, MRI is recommended for open reduction and fixation to verify that the ligament is not injured. Indications for open reduction and internal fixation of avulsion fractures include:

1.  Involvement of 20% or greater of the joint surface

2.  Significant fracture displacement (>2 mm)

3.  Significant instability with UCL testing

4.  Presence of a bony Stener lesion

5.  Combination injuries (avulsion fracture and ligament injury)

Minimally displaced fractures that are stable on stress testing can be immobilized in a thumb spica splint for 4 weeks, with a further 2 weeks of protected active motion.36

Chronic UCL Injuries (Gamekeeper’s Thumb)

The “gamekeeper’s thumb” refers to chronic symptomatic UCL laxity. It was originally described in a series of Scottish gamekeepers whose injury was a result of repetitively stressing the UCL as they fractured the necks of rabbits between the thumb and the index finger. This type of cyclical attenuation of the ligament can lead to symptomatic chronic UCL pain and laxity, although inadequate treatment of an acute tear or failure to recognize a Stener lesion are probably more common etiologies of chronic UCL symptoms.

Reconstruction of chronic UCL injuries can be achieved using either dynamic or static procedures. Dynamic procedures involve transferring the insertion of a musculotendinous unit (e.g., adductor pollicis or extensor pollicis brevis [EPB]) to the base of the proximal phalanx, stabilizing the MP joint by pulling the phalanx in an ulnar direction.42 Static procedures involve using free tendon grafts to reconstruct the proper and accessory collateral ligaments through bone tunnels.2,43 Satisfactory results have been reported with secondary ligament reconstruction; however, at the time of surgery the surgeon should still evaluate the mobility of the UCL because some surgeons have found that even after 2 years from the time of injury, the UCL can be dissected from the surrounding scar tissue and repaired to its original point of insertion.44 Contraindications to ligament repair or reconstruction includes evidence of MP joint arthritis, which can develop in cases of long-standing UCL instability. In such cases, MP fusion should be recommended.

Thumb MP Radial Collateral Ligament Injuries

Injuries to the RCL of the thumb occur as a result of forced ulnar deviation of the thumb and typically result from a fall on the radial side of the hand, or sporting injuries. They present much less frequently than UCL injuries; however, they deserve similar attention, as inadequate treatment leads to chronic pain, instability, and early degenerative arthritis necessitating secondary reconstruction.

The main stabilizer on the radial side is the proper collateral ligament, which functions as a static restraint when the joint is in flexion, and the accessory collateral ligament and volar plate, which provide stability in extension. The musculotendinous stabilizers (abductor pollicis brevis [APB] and flexor pollicis brevis) are less robust than their ulnar counterparts. In addition, the APB inserts more dorsally on the radial side and completely overlies the RCL preventing the development of a Stener-like lesion when the RCL ruptures. Also in contrast to the UCL, the RCL usually ruptures from its proximal insertion.

Patients present with pain and swelling on the radial side of the thumb, and initial assessment should include examination for joint instability. Radiographs are obtained to evaluate for avulsion fractures or other concomitant injuries. Rotatory or palmar subluxation around the axis of the intact UCL may be present as the collateral ligaments normally contribute to dorsal capsular support. Complete tear of the ligament is indicated by instability greater than 35° or 15° more than the contralateral side or palmar subluxation greater than 3 mm. Ultrasonography or MRI can confirm the diagnosis.2,45

Incomplete tears (stable on examination) are treated by splinting the MP joint in mild radial deviation, without IP joint immobilization. The treatment of acute complete tears is controversial. Due to the absence of a Stener lesion some surgeons have advocated cast immobilization only. Others have argued for operative repair, due to the distracting forces of the EPB and adductor pollicis. These muscles act to maintain ulnar deviation of the MP joint and prevent anatomic reduction of the joint with casting or splinting alone. In such cases, the ligament could heal in an elongated manner leading to chronic RCL laxity. This laxity may lead to persistent pain and instability and the development of arthritic changes. While prospective studies are not yet available, our indications for surgical repair of thumb MP RCL injuries are:

1.  Greater than 30° of laxity on physical examination.

2.  Greater than 3 mm of volar subluxation.

Acute, complete tears that present within 3 weeks of the injury can be repaired primarily. The joint is approached through a curved or lazy-S incision with the apex over the radial side of the MP joint. Care is taken to avoid injury to the dorsal sensory branches of the radial nerve. The joint is transfixed in 30° of flexion with K-wires to allow the RCL to be repaired under maximal tension as well as to protect the repair from the unopposed pull of the adductor pollicis. The thumb is immobilized in a thumb spica splint or cast for 6 weeks. Chronic injuries are best served by ligament reconstruction, which can be achieved using a free tendon graft, imbrication of the attenuated RCL and soft tissues, or RCL advancement with APB overlap.46,47

LIGAMENT INJURIES OF THE WRIST

Ligamentous injury about the carpus can disrupt the precise relationships between the carpal bones, leading to altered kinematics, instability, pain, and arthrosis. A basic understanding of wrist ligamentous anatomy and biomechanics is required to understand instability patterns within the wrist. Ligamentous injuries of the wrist include a wide spectrum of pathology and range from subtle tears to fracture dislocations. Treatment options vary depending on the chronicity of the injury and presence of osteoarthritis. The goals of treatment are to decrease pain and maintain motion.

Anatomy and Biomechanics

The wrist consists of 15 bones and multiple ligaments, allowing for tremendous mobility and stability. The distal radius and ulna, the proximal carpal row (scaphoid, lunate, triquetrum, and pisiform), distal carpal row (trapezium, trapezoid, capitate, and hamate), and the bases of the five metacarpals make up the osseous components of the wrist. Although there are more than 20 articulations in the wrist, there are three main joints: the radiocarpal joint, the midcarpal joint, and the carpometacarpal joint. The interface between the distal articular surface of the radius and proximal carpal row forms the radiocarpal joint, and the midcarpal joint consists of multiple articulations between the distal surface of the proximal carpal row and the proximal surface of the distal carpal row.

The ligaments of the wrist can be divided into two categories—the intrinsic ligaments and the extrinsic wrist ligaments (Figure 81.5A–C). The intrinsic, or interosseous, ligaments run between carpal bones and as such are oriented transversely. These include the scapholunate and lunotriquetral interosseous ligaments (SLIL and LTIL), which are the major stabilizers of the proximal carpal row (Figure 81.5A). The extrinsic wrist ligaments typically connect the forearm bones to the carpal bones and serve as secondary stabilizers of carpal motion. They consist of palmar and dorsal extrinsic wrist ligaments. The palmar extrinsic ligaments form a configuration of two V-shaped bands with a space between the bands. This gap has minimal ligamentous support and is an inherent point of weakness (the space of Poirier) and plays an important role in the mechanism of perilunate dislocations. The dorsal carpal ligaments include the dorsal intercarpal and dorsal radiocarpal ligaments. These extrinsic ligaments are thinner and weaker than the palmar ligaments, and also provide structural support to the carpus (Figure 81.5B, C).48-52

There is little interosseous motion between the bones in the distal carpal row and these bones can be thought of as a single bone for biomechanical purposes. In contrast, the proximal carpal row has a moderate amount of movement between individual bones with wrist motion. Because there are no muscular attachments to the proximal carpal row, its motion is in passive response to the motion of the distal carpal row or the radius; it is therefore termed the intercalated segment of the wrist, because it is not capable of any independent motion. During wrist radial deviation or flexion, the scaphoid is pushed into flexion by the distal carpal row; as this occurs the scaphoid pulls the lunate into flexion through the stout attachments of the SLIL, and the lunate pulls the triquetrum into flexion through the stout attachment of the LTIL. During ulnar deviation or wrist extension, the distal carpal row pushes the triquetrum into extension; thus, the triquetrum pulls the rest of the proximal carpal row into extension through an intact LTIL and SLIL. With disruption of either the SLIL or LTIL the bones of the proximal carpal row become unlinked and will move abnormally; this is referred to as a type ofcarpal instability. Over time abnormal motion will stretch the surrounding ligaments leading to further instability and wear down the articular cartilage within the wrist leading to arthritis (Figure 81.6A,B).52-56

CARPAL INSTABILITY

The term carpal instability is given to a broad spectrum of wrist injuries, resulting from injury to the extrinsic ligaments, intrinsic ligaments, or carpal bones.

Dyssynchronous motion from dissociation between bones within the same carpal row (e.g., dissociation within the proximal carpal row from an SLIL disruption) is termed carpal instability dissociative (CID), while dyssynchronous motion without intrinsic ligament disruption is described as carpal instability nondissociative. Proximal CIDs are the most common and result from a variety of conditions. The two major forms of CID include scapholunate (SL) and lunotriquetral (LT) dissociations.57-59

SCAPHOLUNATE LIGAMENT INJURY

SL dissociation results from injury to the SLIL and is the most common form of carpal instability. Injury to the SLIL typically results from a fall onto an extended wrist and may present as an isolated injury, in association with distal radius fracture, scaphoid fracture, or perilunate dislocation. SLIL disruption usually occurs first in the palmar component of the SLIL and progresses dorsally. Rupture of the SLIL dissociates the scaphoid from the lunate; consequently, there is an unopposed extension force exerted on the lunate by the triquetrum through the intact LTIL. With time, the lunate will be pulled into an extended position, termed a dorsal intercalated segment instability or a DISI deformity. The scaphoid, without the extension moment asserted through the lunate and the intact SLIL, will flex further. These changes occur chronically, resulting in abnormal radiographic findings, which include an increase in the SL angle and radioscaphoid angle (Figure 81.7). In advanced stages of SLIL injury, ongoing scaphoid flexion results in dorsal subluxation of the scaphoid from the radial fossa significantly altering carpal dynamics and load bearing across the radioscaphoid joint. This leads to articular damage and a progressive pattern of wrist arthritis termed scapholunate advanced collapse or SLAC wrist (Figure 81.8).58-60

When performing a history and physical examination, the surgeon needs to remember that SLIL tears may be partial or complete and form a spectrum of clinical entities as follows61:

1.  Predynamic instability—This is the mildest form of injury and results from a stretched or partially torn SLIL. Patients complain of dorsal wrist pain following heavy exertion or lifting, but have normal radiographs. Abnormalities within the SLIL may be seen arthroscopically.

2.  Dynamic instability—The extrinsic wrist ligaments and portions of the SLIL may still be preserved; however, abnormalities can be seen on radiographs when the wrist is loaded (e.g., in a clenched fist radiograph) or placed into the extremes of motion under fluoroscopy. The intact secondary stabilizers of scaphoid motion are able to maintain normal carpal alignment when the wrist is not being subjected to loading conditions.

3.  Static SL dissociation—The term static here refers to the fact that radiographic abnormalities are seen in the wrist at rest and do not require loading or some other dynamic maneuver to produce them. These findings on posteroanterior (PA) and lateral wrist radiographs indicate that there is usually a complete SLIL disruption with attrition of the supporting wrist ligaments, resulting in a fixed carpal deformity (Figure 81.7A, B).

4.  SLAC arthritis—With long-standing carpal malalignment, cartilaginous degeneration within the radioscaphoid articulation and midcarpal joint leads to osteoarthritis, and the wrist instability progresses to SLAC arthritis. These changes are visible on plain radiographs (Figure 81.8).62,63

FIGURE 81.5. Ligaments of the wrist. A. Intrinsic ligaments are those ligaments that both originate and insert on the carpal bones. They tend to be more stout than extrinsic ligaments. A schematic of the dorsal aspect of the wrist shows the scapholunate (SL), lunotriquetral (LT), trapezium–trapezoid (TT), the capitotrapeziod (CT), and capitohamate (CH) intrinsic ligaments. B. The extrinsic ligaments of the wrist are shown from the volar side. Extrinsic ligaments originate outside the carpal bones and insert onto the carpal bones. These ligaments include the radioscaphocapitate (RSC), long radiolunate (LRL), short radiolunate (SRL), ulnolunate (UL), ulnocapitate (UC), and ulnotriquetral (UT). (R, radius; U, ulna; RA, radial artery; AIA, anterior interosseous artery; PRU, palmar radioulnar ligament; S, scaphoid; P, pisiform; T, triquetrum; Tm, trapezium; Td, trapezoid; C, capitate; and H, hamate.) C. The dorsal extrinsic ligaments that include the radiotriquetral or dorsal radiocarpal (DRC) ligament. The scaphotriquetral or dorsal intercarpal (DIC) ligament is by definition an intrinsic ligament, but is easier to illustrate in this view. (Copyright Mayo Clinic, reproduced with permission of the Mayo Foundation.)

Diagnosis

Patients presenting with SL instability usually have a history of a fall on the outstretched hand or of a sudden load to the wrist. Physical examination and plain radiographs may be enough to diagnose static SL dissociation; however, MRI or arthroscopy may be necessary for partial injuries. Computed tomography (CT) is not a sensitive modality for assessing ligamentous pathology.

In acute injuries, findings include swelling in the anatomic snuffbox and dorsoradial tenderness over the SL interval (1 cm distal to Lister tubercle). Weakness and pain with loading activities such as push-ups can occur. The scaphoid shift test is a provocative test, which can help diagnose SLIL injuries. The wrist is moved from ulnar to radial deviation with the examiner’s thumb pressing against the scaphoid tubercle. Patients with partial tears will have an increase in pain dorsally over the SL articulation. An audible clunk signifies a complete tear, as the scaphoid is actively subluxed with dorsal pressure and spontaneously reduces into the radial fossa when the thumb is removed. The contralateral wrist should be examined for comparison, as the scaphoid shift test may be falsely positive in up to one-third of individuals due to ligamentous laxity without injury. Progressive loss of grip strength with repetitive gripping maneuver may also signify an SLIL injury.60,64

The following findings can be found on PA radiographs of the wrist in cases of static S-L dissociation (Figure 81.7)65:

1.  The “Terry Thomas” sign—diastasis between the scaphoid and lunate with a gap greater than 3 mm

2.  The “scaphoid ring sign” —due to projection of the distal pole from abnormal scaphoid flexion

3.  Disruption of Gilula’s lines of the carpus

On lateral view, a DISI deformity may be visible with a widened SL angle > 60° (normal is 45°) or an increased radiolunate angle > 15° (Figure 81.7A, B).65 Dynamic instability and predynamic instability can still be missed with radiographs and MRI. In cases when one is suspicious but there are no abnormalities visible on imaging studies, wrist arthroscopy is considered. Wrist arthroscopy is the gold standard for diagnosis of any dynamic instability as it allows direct inspection of the SLIL and surrounding supporting extrinsic ligaments. Both radiocarpal and midcarpal arthroscopy should be performed to diagnose interosseous ligamentous instability; however, midcarpal arthroscopy is the key to assessing the stability of the SL joint.

FIGURE 81.6. Carpal mechanics. A. Effects of radial and ulnar deviation. B. Effects of flexion and extension. The scaphoid is pushed into flexion with radial deviation (A) and with wrist flexion (B). With ulnar deviation (A) and extension (B) the triquetrum is pushed into dorsal extension. The forces acting on the scaphoid and the triquetrum may be transferred to the lunate through an intact SLIL and LTIL. A break in these ligaments can have a profound impact on carpal motion by unlinking the proximal carpal row.

Treatment

Treatment of SL dissociation is dependent upon the severity of the instability (predynamic, dynamic, or static), chronicity of the injury, and the presence of any degenerative changes to the carpus.

Acute Injuries. In acute injuries, arthroscopy can used to delineate the grade of SLIL disruption, and partial tears may be treated by percutaneous pinning of the scaphoid and lunate allowing for the possibility of primary healing or fibrosis . Open repair of acute, complete SLIL tears has been shown to maintain grip strength and wrist motion and presumably halts the progression to degenerative changes and the development of an SLAC wrist.65,66

Chronic Injuries. Treatment options for chronic SLIL injuries are dependent on the presence of degenerative arthritis. If arthritis is present around the scaphoid, then attempts at reconstruction of the SLIL are discouraged and some type of wrist salvage procedure is performed, most commonly a scaphoidectomy and four-corner fusion or proximal row carpectomy. In the absence of arthritis, treatment is directed at reconstructing the SLIL and if this is not possible then some other means must be used to stabilize the scaphoid and restore the SL relationship. Several methods have been described and these include capsulodesis procedures, tenodesis procedures, and limited intercarpal fusion.

Scapholunate Ligament Repair

Direct ligament repair is performed for acute SLIL injuries and can be considered in cases of chronic ligament injury if

1.  there is satisfactory ligament present for repair,

2.  the scaphoid and lunate are still easily reducible, and

3.  there is no evidence of arthritis within the carpus.

Ligament repair may be performed with the use of suture anchors, interosseous sutures, or interosseous wires. Recent reports have also noted the augmentation of the ligament with different types of biologic tendon replacements. Following repair, the joint is pinned and immobilized in a cast for 6 to 8 weeks.65,67

FIGURE 81.7. (A and B) AP and lateral radiographs of a wrist showing an SLIL injury. The AP radiograph (A) shows a widening between the scaphoid and the lunate. The lateral radiograph (B) shows a lunate which is tilted dorsally representing dorsal intercalated segmental instability (DISI). The angle between the scaphoid and the lunate is also increased and is approaching 90°. Intercarpal angles may be determined by drawing lines tangential to the contour of the carpal bones, or axially through the bones. A normal range for the scapholunate angle can vary between 30° and 60°. Anything greater than 70° is abnormal.

FIGURE 81.8. AP radiograph demonstrating SLAC arthritis. SLAC arthritis progresses over three stages. In the first stage, arthritis is confined to the radial styloid. In stage II, arthritis is seen throughout the radioscaphoid fossa. In stage III, arthritis is visible within the midcarpal joint. This radiograph depicts stage III SLAC changes with arthritis changes throughout the radioscaphoid fossa and in the midcarpal joint between the capitate scaphoid and lunate.

Capsulodesis and Tenodesis

When primary repair is not possible due to attrition of the SLIL, unopposed flexion of the scaphoid can be controlled with the use of a capsulodesis. Capsulodesis utilizes a portion of the dorsal wrist capsule to tether the scaphoid, and prevents it from flexing. A variety of forms of capsulodesis procedures have been described, but none has been shown to be superior to the other.68,69 This technique is useful in conjunction with ligament repair for chronic instability or may also be used alone for cases of dynamic instability.

Tenodesis procedures utilize tendons to either tether carpal bone motion or to replace/reconstruct the SLIL. A variety of tenodesis procedures have been described. The most common form of tenodesis is the Brunelli tenodesis, which utilizes half of the flexor carpi radialis tendon passed through a bone tunnel in the scaphoid and secured dorsally to the distal radius or lunate. The problem with all tenodesis procedures is that the elastic moduli of tendon and ligament are not equivalent. Restriction of scaphoid motion using a tendon usually requires a great deal of tension, which can restrict overall wrist motion.70-72

Intercarpal Fusion

In cases of chronic instability when the SL malalignment is not reducible and there is not yet any evidence of cartilage degeneration, limited intercarpal fusions can be performed, either scaphotrapezial–trapezoidal (STT) or scaphocapitate (SC) arthrodesis, to restrict scaphoid motion. Intercarpal fusion stabilizes the scaphoid and restores its alignment with the distal radius. Unfortunately, STT and SC fusions alter carpal kinematics, leading to an increased load across the radioscaphoid fossa. Over time these fusions have been shown to result in the development of degenerative arthritis within the wrist.73-75

LUNOTRIQUETRAL LIGAMENT INJURIES

LTIL injuries are much less common than SLIL injury. Acute LTIL injury usually results from a fall on the outstretched hand positioned in pronation, extension, and radial deviation, or in association with a perilunate injury. Chronic attritional degeneration of the LTIL can occur in conditions such as inflammatory arthritis and ulnar impaction syndrome. Physical findings in cases of LTIL injury include point tenderness over the LT joint and painful crepitus with ulnar deviation.

Similar to SLIL instability, LTIL injuries can present within a spectrum of severity, with dynamic and static instability patterns. Patients presenting with a dynamic instability, and thus no appreciable radiographic abnormalities, are classified as having LTIL tears, while those who present with a static instability, with abnormalities visible on plain radiographs, are classified as having LTILdissociation. Radiographs in cases of LTIL tears are often normal, and unlike SL dissociation, LT gapping is unusual. In LTIL dissociation, the triquetrum, no longer tethered to the lunate, will extend and the scaphoid and lunate will flex. This divergent motion produces a volar intercalated segment instability (VISI) deformity of the proximal row. Radiographically, this can be visualized in a lateral radiograph if the lunate is tilted volarly greater than 15° in relation to the radius. Static VISI deformity implies disruption of the secondary ligamentous restraints of the wrist with a complete LTIL dissociation. LT dissociation also results in disruption of Gilula’s arcs with a step off between the lunate and triquetrum on PA x-rays. The severity of instability, along with the chronicity of injury, determines the appropriate treatment option. Options include immobilization, corticosteroid injection, ligament repair, ligament reconstruction, limited arthrodesis, and ulnar shortening.76,77

PERILUNATE DISLOCATIONS

Perilunate dislocations are severe carpal disruptions usually resulting from high-velocity trauma, such as a motor vehicle accident, a fall from a height, or a sports-related injury, that causes forceful wrist hyperextension. These injuries include pure carpal dislocations as well as fracture dislocations, and the term perilunate refers to the fact that all fractures or ligamentous disruptions occur around or through the bones and ligaments immediately surrounding the lunate. Recognition of these injury patterns may be difficult to the untrained eye, which may result in treatment delays; however, early diagnosis is important as progression of carpal instability and traumatic arthritis will result if treatment is delayed.

Perilunate injuries are also considered within a spectrum of severity, which includes SLIL injuries as the first stage of severity. The injury pattern travels around the lunate (hence the term perilunate) with sequential ligament disruption leading to increased instability throughout the carpus. This injury pattern was originally described by Mayfield (Mayfield classification) and describes the stages of perilunate instability as follows (Figure 81.9)78,79:

1.  Stage I—disruption of the SL ligament resulting in SL dissociation.

2.  Stage II—a stage I injury in addition to a disruption of the lunocapitate ligaments as the force transmits through the space of Poirier.

3.  Stage III—a stage I and II injury in addition to a disruption of the LTIL. The lunate is now attached only to the radius. The capitate and attached carpus often will sublux or completely dislocate dorsally, resulting in a dorsal perilunate dislocation.

4.  Stage IV—a dislocation of the lunate, either in a volar or in a dorsal direction. Most commonly the lunate dislocates volarly into the carpal tunnel and is attached only to the short radiolunate ligament, but may be disrupted from all ligamentous attachments (Figure 81.10A,B).

Examination reveals a diffusely swollen and painful wrist. The digits are often held in a semiflexed position, and passive extension produces severe pain. Severe soft tissue swelling may obscure bony landmarks and examination can be difficult. Median neuropathy is common; particularly with stage IV injuries an urgent carpal tunnel release may be required. Plain radiographic are essential for making the diagnosis. On the lateral radiograph, the normal collinear alignment between the radius, lunate, and capitate is disturbed (Figure 81.10A,B).

Perilunate injuries may also occur with associated fractures of the radial styloid, scaphoid, capitate, triquetrum, or ulnar styloid. When fractures are present with a perilunate dislocation, the injury is called a perilunate fracture dislocation. The most commonly fractured bone in these injuries is the scaphoid.

All perilunate injuries should be treated with open operative repair of all injured structures. If there is any delay in getting the patient to the operating room, an attempt at closed reduction is made in the emergency room to restore the anatomy, to control pain, and to alleviate median nerve compression. Perilunate fracture dislocations are also managed operatively by initially reducing the fracture fragments to provide a stable platform upon which one may perform carpal bone reduction followed by ligament repair. Early treatment and anatomic reduction is the mainstay of treatment and has been shown to produce better outcomes than delayed treatment or casting alone; however, even anatomic reduction may not prevent patients from developing progressive arthrosis at the midcarpal and radiocarpal joints, which can be seen in up to 50% of treated individuals.80,81

FIGURE 81.9. Order of injury in a progressive periulnate injury as described by Mayfield and colleagues. The description of each stage is elaborated in the text.

FIGURE 81.10. (A and B) AP and lateral radiograph of a Mayfield IV perilunate dislocation. The AP radiograph (A) shows a disruption of Gilula’s lines. The lateral radiograph (B) shows the lunate dislocated and resting within the carpal tunnel.

Distal Radial Ulnar Joint Injuries

The final group of ligamentous injuries that can occur in the hand and wrist are those affecting the ulnar aspect of the wrist in the area of the distal radial ulnar joint (DRUJ) and triangular fibrocartilage complex (TFCC). The DRUJ is stabilized by the TFCC. The TFCC is a complex or group of ligaments which link the radius to the ulna during forearm rotation and assist in forearm stability. The other major components of forearm stability include the ligaments around the proximal radioulnar joint (PRUJ) and the interosseous membrane (IOM). The ulna comprises the fixed unit of the forearm joint. The ulna is capable of flexion and extension at the elbow, but it is the radius that rotates around the ulna allowing for pronation and supination of the hand. Rotation of the radius occurs at both the DRUJ and PRUJ at the elbow. During rotation, the radius also moves axially from distal to proximal as the radius rotates from supination into pronation. This results in a relative lengthening and shortening of the radius as it rotates about the ulnar head. In addition, there is dorsal and palmar translation of the radius with reference to the fixed ulnar head during forearm rotation.82

DRUJ stability is provided through a combination of bony architecture (the sigmoid notch and ulnar head) and soft tissue constraints, which include the ligaments found in the TFCC, the pronator quadratus, and the IOM (Figure 81.11).83-85 The primary stabilizer of the DRUJ is the TFCC. The TFCC is composed of several structures, including the triangular fibrocartilage, the ulnocarpal meniscus (meniscus homologue), the UCL, the dorsal radioulnar ligament, the palmar radioulnar ligament, and the subsheath of the extensor carpi ulnaris (ECU).86 The dorsal and palmar radioulnar ligaments are thought to be responsible for the majority of the stability at the DRUJ, while the bony architecture of the DRUJ accounts for only 20% of the joint’s stability.87 Individual variation in the bony configuration of the DRUJ may also affect stability. Tolat et al.88 defined the shape of the sigmoid notch in the transverse plain in four different configurations: flat face (42% incidence), ski slope (14%), “C”-type (30%), and “S”-type (14%). Flat faced or shallow sigmoid notches may provide less bony stability, causing the TFCC to play an even larger role in stabilizing the DRUJ.

Dislocations and instability at the DRUJ can result from injury to any of the soft tissue structures mentioned above when there is significant disruption of the bony anatomy, such as a comminuted ulnar head fracture or a fracture through the sigmoid notch; however, most commonly, injuries occur within the TFCC. Injuries can be acute or chronic and like all injuries within the hand, DRUJ injuries and TFCC injuries can occur within a spectrum of severity.

Palmer classified TFCC injuries based on location and chronicity (acute versus degenerative) (Figure 81.12).89,90 Injury to the TFCC can occur in the central portion of the disk itself, at its radial attachment to the radius, at the foveal attachment to the ulna, or at its periphery. Peripheral lesions and injuries to the foveal insertion tend to produce pain and instability, while those occurring in the central portion of the disk or at its radial insertion tend to produce pain alone. TFCC lesions may be repaired arthroscopically or with open techniques.91

Acute DRUJ Injuries

Isolated acute dislocations of the DRUJ (with or without ulnar styloid fracture) are less common than dislocation associated with a fracture of the radius or distal ulna. Although the ulna is the fixed unit of the forearm, dislocation and instability are conventionally described in terms of the ulna’s relationship to the radius, as in a dorsal dislocation of the ulna (ulna dorsal to the radius). Dorsal dislocation is more common than volar dislocations. Dorsal dislocations are believed to result from a hyperpronation force and volar dislocations from a hypersupination force.

An acute dislocation of the DRUJ may not cause complete disruption of the TFCC, and in many cases, the DRUJ may be stable after reduction of the dislocation. In a dorsal dislocation, there is typically a history of hyperpronation force usually as a result of a fall on the outstretched hand. In this situation, the hand is typically fixed by gravity to the ground while the body, together with the ulna, rotates around the hand, wrist, and radius unit. The patient presents with the hand fixed in pronation with the inability to supinate and a dorsal prominence of the ulnar head. In a volar dislocation, there is typically a history of hypersupination and the patient is unable to pronate. The ulnar head is usually not visibly prominent on the volar wrist because of the overlying soft tissues. However, there can be a “hollow” dorsally where the ulnar head is normally visible. The wrist can appear narrow due to the now compressive pull of the pronator quadratus muscle, resulting in a diminished transverse dimension. Examination findings can be obscured by ecchymosis and swelling.92-94

FIGURE 81.11. Primary and secondary stabilizers of the distal radioulnar joint. ECU, extensor carpi ulnaris; DL, ulnolunate ligament; DT, ulnotriquetral ligament. (Redrawn from Kleinman WB. Stability of the distal radioulnar joint: biomechanics, pathophysiology, physical diagnosis, and restoration of function what we have learned in 25 years. J Hand Surg Am. 2007;32(7):1086-1106.)

Imaging

Plain two-view radiographs that include the wrist, forearm, and elbow are critical for the evaluation of suspected DRUJ dislocation. The anteroposterior (AP) view in a dorsal dislocation will typically show a widened DRUJ with divergence of the radius and ulna when compared with the contralateral normal DRUJ. A volar dislocation will show an overlap of the radius and ulna on AP view due to the convergent pull of the pronator quadratus. In an anatomically reduced DRUJ in neutral rotation, the ulnar styloid will be located at the most ulnar aspect of the ulnar head. A standard PA view of the wrist may not be possible in the setting of acute DRUJ dislocation because of mechanical blockage due to the dislocation, pain, or splint immobilization and unfortunately, oblique films are obtained more often than true orthogonal radiographs. One must be careful in the interpretation of these radiographs: an obliquely malaligned view of a dislocation, by as little as 10°, may not reveal the dislocation and be falsely interpreted as negative. An axial CT scan may be helpful in the acute setting to determine joint reduction and congruity and should be obtained if there is any question about the plain radiographs.95

FIGURE 81.12. Common triangular fibrocartilage tears. As described by Palmer, injuries to the TFCC can occur in the central portion of the disc itself (A), at the foveal attachment to the ulna (B), at the volar attachment to the ulnocarpal ligaments (C) or at its radial attachment to the radius (D).

Treatment

Treatment of an acute dislocation without fracture begins with closed reduction under local, regional, or general anesthesia. With dorsal dislocation of the ulna, reduction is accomplished with gentle traction, dorsal pressure (translational force) over the ulnar head, and supination. The joint must be assessed for instability and typically is most stable in supination. With volar dislocation, reduction is usually more difficult due to the pull of the pronator quadratus muscle, and regional or general anesthesia may be necessary. Closed treatment is frequently successful in restoration of a stable construct.

Complex DRUJ dislocations occur when there is interposed soft tissue that blocks closed reduction; such dislocations require operative intervention to remove the interposed structures and reduce the joint. Following reduction of a complex dislocation stability of the DRUJ must be checked within the operating room. If the joint is unstable and has a tendency to dislocate or sublux, the stabilizing structures of the DRUJ must be repaired. Direct repair of the TFCC to the foveal insertion is preferred using suture anchors or heavy suture through bone tunnels. Following TFCC repair, the forearm is immobilized in a long-arm or Munster-type cast with or without transcutaneous radioulnar pinning, with two 0.062 in. K-wires just proximal to the DRUJ. These wires are left slightly prominent on both the radial and ulnar superficial cortices allowing for easy removal should one or both pins break between the radius and ulna. Although we prefer immobilization in neutral rotation to facilitate recovery of both pronation and supination, others have advocated immobilization in the position of maximal stability (supination for dorsal dislocations and pronation for volar dislocations). After 6 weeks, a removable splint is provided and a range of motion program is begun.92-94

Chronic DRUJ Instability

Chronic instability of the DRUJ results from an acute traumatic injury that is unrecognized at the time of injury, inadequately treated, or recurrent after ineffective treatment. Injury to the TFCC is common with distal radius fractures and likely contributes to the long-term poor outcomes seen in some patients after this injury.96,97 Malunion after distal radius fracture or significant ulnar head fractures can be associated with DRUJ instability. In particular, loss of the volar tilt of the distal radius following reduction of fractures (with final dorsal tilt of greater than 10°) is associated with altered DRUJ kinematics. Chronic DRUJ instability may also be found after Galeazzi or Essex-Lopresti injury patterns.92 If left untreated, instability of the DRUJ leads to chronic functional impairment and disability secondary to marked pain, decreased grip strength, and arthritis.

Evaluation

Chronic DRUJ injuries can present with pain alone or pain and instability. Frequently, there is a history of a fall on the outstretched hand with the wrist in the extended and pronated position. Patients may complain of a painful clunking sensation that is exacerbated with forearm rotation due to subluxation of the ulnar head. Instability on examination is a subjective assessment on the part of the examiner and it is essential that the contralateral extremity be assessed for comparison. Passive laxity of the DRUJ should be assessed with the forearm in neutral, pronation, and supination and compared with the uninjured side. Compression across the DRUJ with forearm rotation may cause pain or accentuate a clunk as the ulna head subluxates and reduces within the notch. The “press test” is performed by asking the patient to press both hands on a flat table with the forearms pronated and placed in front of him or her. With DRUJ instability, the ulna is more prominent dorsally and appears to sublux volar with pressure and creates a dorsal hollow.98

Ulnar-sided wrist pain is not always a result of DRUJ instability and other diagnoses must be considered and ruled out, such as ulnar styloid nonunion, ECU tenosynovitis or subluxation, ulnocarpal impaction, LT ligament injury, non-destabilizing TFCC tears, dorsal ulna sensory nerve injury, and inflammatory arthritides. With DRUJ pathology tenderness may be noted within the foveal region of the ulna head which corresponds to the site of insertion of the TFCC. The “fovea region” can be found on examination between the flexor carpi ulnaris tendon and ulna styloid.99 To differentiate DRUJ instability from other ulnar-sided pathology, one may use selectively placed injections of local anesthetic to differentiate between the tendonitis, synovitis, and true DRUJ pathology.

Imaging

Chronic DRUJ injuries are best assessed with MRI as these maladies are often due to soft tissue pathology; however, plain wrist radiographs (AP and lateral) may demonstrate a widened DRUJ and displacement of the ulna head, either volarly or dorsally relative to the radius. Radiographs should also be examined for any evidence of malunion of the radius or ulna and to rule out any evidence of DRUJ arthritis. An axial CT scan of the wrist is helpful to evaluate for degeneration, sigmoid notch incongruity, and instability. Reference measurements exist that define the relationship of the ulnar head to the sigmoid notch of the radius. Instability of the DRUJ is determined based on these measurements in comparison to the contralateral DRUJ.100

MRI has a sensitivity and specificity which is far superior to CT when looking at TFCC injuries and is the imaging tool of choice. In addition, MRI can identify LT injuries, tendonitis, and signs of arthritis. The injuries to the foveal attachment of the TFCC is best seen on coronal imaging.95

Wrist Arthroscopy. Wrist arthroscopy remains the gold standard for diagnosing TFCC injuries. Once the arthroscope is placed into the wrist, tears within the four palmar zones of the TFCC can be visualized. Other diagnosis such as ulnar impaction and SL and LT injury can also be diagnosed and allow the surgeon to proceed with the proper surgical procedure. Many TFCC injuries can be repaired in a minimally invasive fashion, with the aid of the arthroscope. Arthroscopic repair has been shown to be as effective as open repair.91

Treatment

Nonoperative treatment of chronic DRUJ instability may diminish the symptoms associated with instability and serve as initial therapy to treat coexistent conditions, such as ECU tendinitis. Functional bracing may reduce DRUJ mobility without compromising the elbow, wrist, or forearm motion. The brace is worn about the forearm without crossing the elbow or wrist and is felt to stabilize the radius and ulna through hydrostatic forces. A wrist strengthening program directed at dynamic stabilizers of the DRUJ, in particular the pronator quadratus and ECU, may also prove beneficial.

Surgery is indicated for patients who do not respond to conservative therapy, or who present with pain and gross instability. Peripheral tears and volar tears (palmar class IB and IC) of the TFCC may be repaired arthroscopically or with open repair. In those chronic cases where the TFCC cannot be repaired primarily, DRUJ reconstruction must be undertaken. Given the complexity of the TFCC, no reconstruction has been described that recreates all of the components. Newer techniques have focused on repair of the dorsal and volar radioulnar ligaments as these play a major role in stabilizing the DRUJ.

Adams and Berger described a technique that reconstructs the anatomic origin and insertion of the palmar and dorsal radioulnar ligaments. This procedure utilizes tendon graft (palmaris longus or plantaris tendon autograft versus allograft) passed through a dorsal/volar bone tunnel in the ulnar aspect of the distal radius approximating the origin of the dorsal and volar radioulnar ligaments. The two tails of the graft are then passed through a bone tunnel at the fovea of the ulnar head and the tails are secured with maximal tension with the forearm in neutral rotation.101 It is important to consider the shape of the sigmoid notch prior to proceeding to ligament reconstruction, as a flat notch may be associated with persistent instability. This can be corrected with an osteotomy and out-fracture of the dorsal lip of the sigmoid notch improving bony stabilization of the DRUJ at the time of soft tissue reconstruction. The forearm is immobilized with a Munster or long-arm cast for 6 weeks followed by a protective motion protocol. Strengthening is begun after full range of motion has been obtained at about 3 months. Published outcomes of treatments in which this method of reconstruction was followed are favorable with most patients experiencing improved pain and grip strength.

Other causes of DRUJ pain and instability include distal radius malunion. These cases should be treated with corrective osteotomy of the radius prior to any attempts at DRUJ reconstruction. Patients with instability and ulnar impaction are best treated with ulnar shortening. Patients presenting with instability and DRUJ arthritis are not appropriate candidates for DRUJ reconstruction. Instead these patients are best managed with DRUJ salvage procedures such as Sauve-Kapandji, Darrach procedure, and DRUJ arthroplasty. Attempts at soft tissue reconstruction in the presence of arthritis will not relieve the patient’s pain.98

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