AAOS Comprehensive Orthopaedic Review

Section 6 - Trauma

Chapter 51. Hand and Wrist Fractures and Dislocations, Including Carpal Instability

I. Fractures of the Hand

A. General principles of fixation


1. Compression screws are stronger than Kirschner-wires (K-wires), which provide no compression.


2. Plates are stronger than screws alone. Screws have resistance to bending only in the plane of the screw and little resistance to rotational or shear stress.


a. Compression plates resist bending and rotational forces better than neutralization or buttress plates.


b. Dorsal plates are best at resisting dorsally applied bending forces.


c. Plate bending strength is directly proportional to the thickness cubed and inversely proportional to the length cubed.


3. Lag screws


a. Lag screws are indicated when fracture length is at least twice the bone diameter.


b. Screws provide maximal compression when placed perpendicular to the fracture.


c. Screws should be placed two screw head diameters apart.


B. Determinants of fracture stability (all fractures)


1. Fracture pattern (transverse-stable, oblique, and spiral-unstable)


2. Integrity of periosteal envelope


3. Muscle forces


4. External forces


C. Treatment goals (all fractures)


1. Stabilizing the fracture


2. Repairing injured soft tissue


3. Mobilizing adjacent joints and soft tissues, particularly tendons


4. Restoring articular congruity


D. Incidence of hand fractures by location


1. Distal phalanx: 45% to 50%


2. Metacarpal: 30% to 35%


3. Proximal phalanx: 15% to 20%


4. Middle phalanx: 8%


E. Predictors of poorer outcome following fracture fixation


1. Open fractures


2. Intra-articular fractures


3. Associated nerve injury


4. Associated tendon injury


5. Crush injury

II. Fractures of the Metacarpals

A. Anatomy and biomechanics


1. Most metacarpal diaphyseal fractures are apex dorsal as a result of the pull of the interossei, which results in flexion of the distal fragment.


2. The hand can adjust dorsal angulation by compensating with metacarpophalangeal (MCP) hyperextension and carpometacarpal (CMC) motion. CMC motion is greatest at the little finger (30°), followed by the ring finger (20°). The long and index fingers have minimal CMC motion and thus can tolerate less angular deformity.


3. Rotational deformity is poorly tolerated; >5° can lead to finger scissoring.



Figure 1. PA view of the hand demonstrates a base of the fifth metacarpal fracture, or "reverse Bennett" fracture. Note the subluxation of the base of the little finger metacarpal on the ulnar aspect of the hamate.]

4. Normal physiologic rotation during digital flexion is 10° to 15° of pronation in the index and long fingers and 10° to 15° of supination in the ring and little fingers.


5. Shortening of 3 to 4 mm is tolerated. There is 7° of extensor lag per 2 mm of metacarpal shortening. MCP hyperextension usually can compensate for up to 4 mm of shortening.


6. Metacarpal shortening or angulation >30° can result in shortening of the intrinsics, which can lead to decrease in extensor excursion.


B. Fractures of the metacarpal diaphysis


1. Radiographic evaluation


a. PA and lateral views are indicated.


b. Acceptable angulation in metacarpal diaphyseal fractures:


i. 20° at the index and long fingers


ii. 40° at the ring and little fingers


iii. More displacement is tolerable at the ring and little fingers because of the motion of the CMC joints at these fingers. The second and third CMC joints are relatively fixed.


2. Treatment


a. Most metacarpal diaphyseal fractures can be treated nonsurgically.


b. Surgical treatment of these fractures is variable and may include percutaneous K-wire(s) placed longitudinally or transversely into the adjacent metacarpal, plate fixation, or intramedullary rods.


i. K-wire fixation minimizes soft-tissue injury.


ii. Plate fixation is usually performed dorsally.


iii. Early mobilization is required to reduce the incidence of tendon adhesions.


c. Treatment of metacarpal diaphysis bone loss


i. Distraction-fixation is used to restore length and alignment.


ii. Soft-tissue coverage is crucial.


iii. Secondary iliac crest bone graft can be used in fractures that are significantly contaminated.


iv. An intramedullary wire or polymethylmethacrylate spacer can be used with secondary bone graft.


d. Malunion may be treated with opening or closing wedge osteotomies or derotational osteotomies in conjunction with internal fixation.


C. Fractures of the metacarpal base


1. Mechanism of injury/pathoanatomy


a. Fractures of the metacarpal base can represent CMC fracture-dislocations.


b. Fracture-dislocations are often associated with high-energy trauma, which may produce axial carpal injuries.


c. Fracture-dislocations of the CMC joint of the little finger are sometimes called a "Tenneb" (Bennett spelled backward), "reverse Bennett," or "baby Bennett" fracture. The metacarpal diaphysis is displaced proximally and ulnarly as a result of the pull of the extensor carpi ulnaris (ECU) tendon (Figure 1).


2. Evaluation


a. Oblique radiographs must be obtained to assess displacement.


b. Sagittal CT also is helpful.


3. Treatment


a. Congruent joint reduction is important to maintain mobility of the fourth and fifth CMC joints.


b. Treatment of these fractures may be accomplished through closed reduction by longitudinal traction and K-wire fixation.


c. More comminuted fractures may require external fixation.


d. In patients with posttraumatic arthritis, arthrodesis or hemi-arthroplasty can be considered.


D. Fractures of the metacarpal neck (boxer's fracture)


1. Acceptable angulation is similar to metacarpal diaphyseal fractures.


2. Excessive palmar displacement of the metacarpal head can lead to claw deformity, palmar mass, and extensor tendon lag.


E. Fractures of the metacarpal head


1. Evaluation—A Brewerton view (20° of MCP flexion) is needed for adequate visualization.


2. Surgical treatment—A dorsal approach is preferred.

III. Metacarpophalangeal Dislocations

A. Dorsal MCP dislocations


1. The most frequently involved digit is the index finger.


2. The thumb is also commonly involved.


B. Simple dislocation (subluxation)


1. Simple dislocations can be inadvertently converted to complete dislocation if improperly reduced.


2. Simple traction and hyperextension should not be used to reduce these dislocations. Instead, the finger should be flexed to take tension off the flexor tendons, and the base of the proximal phalanx should be pushed volarly and distally to slide the displaced volar plate over the metacarpal head.


C. Complex dislocation (complete dislocation)


1. Evaluation—The patient presents with the digit held in slight extension and a prominence in the palm.


2. Pathoanatomy—The metacarpal head is caught between the volar plate, flexor tendon, lumbrical, and A1 pulley.


3. Treatment


a. These dislocations are irreducible by closed means.


b. A volar approach puts digital nerves at risk of injury.


c. Dorsal approach—A longitudinal incision is made to split the volar plate. A freer elevator is used to push the volar plate in the palmar direction.



Figure 2. PA view of the hand demonstrates a Bennett fracture.]

D. Fractures of the thumb metacarpal


1. Epidemiology and mechanism of injury


a. >80% of these fractures involve the base of the metacarpal.


b. These fractures are caused by an axially directed force through a partially flexed metacarpal.


2. Extra-articular fractures


a. Up to 30° of angulation is acceptable because of the mobility of the saddle joint.


b. Treatment is with a thumb spica cast and percutaneous K-wires as needed.


3. Bennett fracture—Base of the first metacarpal fracture (Figure 2)


a. Epidemiology—The Bennett fracture is the most common thumb fracture.


b. Mechanism of injury—The volar oblique ligament is attached to the volar ulnar fragment of the base; the abductor pollicis longus displaces the distal metacarpal proximally, and the adductor pollicis displaces the metacarpal into adduction. The metacarpal base is displaced dorsally and into supination.


c. Evaluation—The fracture is best visualized on the true lateral and hyperpronated AP (Robert) views.


d. Treatment


i. Closed reduction can be obtained with longitudinal traction with extension/abduction/pronation of the metacarpal as well as ulnarly based pressure over the base of the metacarpal. Percutaneous K-wire fixation may be used from the thumb metacarpal into the trapezium or into the index metacarpal.


ii. Open reduction is indicated if there is more than 2 to 3 mm of joint surface displacement or central impaction and a large fragment are present.


4. Rolando fracture


a. Rolando fractures are three-part Y or T intraarticular fractures.


b. Treatment


i. Open reduction and internal fixation (ORIF) (eg, interfragmentary screw, L- or T-plate)


ii. Alternative treatment includes external fixator and external traction device.

IV. Fractures of the Proximal and Middle Phalanx

A. Fractures of the proximal phalanx


1. Anatomy and biomechanics


a. Most transverse proximal phalanx fractures are apex palmar.


b. The central extensor tendon pulls the distal fragment dorsal, and the interossei insertion flexes the proximal fragment.


c. The proximal phalanx dorsal cortex is denser than the palmar cortex.


d. Proximal phalangeal fractures have less stability than metacarpal fractures because of multiple tendon forces acting on fragments.


e. Shortening of the proximal phalanx produces an extensor lag at the proximal interphalangeal (PIP) joint, with each millimeter of bone loss equaling 12° of extensor lag.


B. Fractures of the middle phalanx


1. Anatomy and biomechanics



Angulation depends on fracture position.


Proximal middle phalanx fractures are apex dorsal because of the pull of the central slip.


Distal middle phalanx fractures displace palmarly as a result of the pull of the superficialis insertion.



Table 1. Treatment for Fractures of the Proximal and Middle Phalanges]


Middle phalanx fractures may take longer to heal than fractures of the proximal phalanx and metacarpal because there is proportionately less cancellous bone in the diaphysis of the middle phalanx.


2. Complications—Shortening of the middle phalanx following fracture may result in distal interphalangeal joint extension lag.


C. Fractures of the proximal phalanx base—Extra-articular base fracture


1. Closed reduction and cast immobilization can be attempted with stable fractures, and the MCP joint should be flexed >60°.


2. Multiple tendon forces act on these fractures, so percutaneous K-wire fixation may provide more reliable fixation.


3. With complex trauma, including flexor tendon laceration, internal fixation with a minicondylar plate can allow early mobilization.


D. Fractures of the diaphysis of the proximal and middle phalanges


1. Angulation is usually volar apex as a result of the pull of the central slip and lateral bands.


2. Treatment—The type of fracture determines treatment (Table 1).


E. Fractures of the neck of the proximal and middle phalanges


1. Epidemiology and pathoanatomy


a. These fractures are uncommon in adults.


b. In children, phalangeal neck fractures may displace and rotate 90° (apex dorsally).


c. With complete displacement, the volar plate may become entrapped in the fracture.


2. Treatment


a. Treat with closed reduction and percutaneous K-wire.


b. Obtain lateral radiograph to verify reduction.


F. Condylar fractures of the proximal and middle phalanx


1. Evaluation—Evaluate angulation and malrotation with flexion fluoroscopy.


2. Treatment


a. Displaced condylar fractures require surgical reduction.


b. Internal fixation requires two screws, two wires, or a combination of both.


c. The PIP joint can be exposed by incising between the lateral band and the central tendon.

V. PIP Joint Dislocations and Fracture-Dislocations

A. Epidemiology


1. Dorsal—These PIP joint dislocations are common. They are often associated with volar plate avulsion or fracture of the volar base of the middle phalanx.


2. Lateral—These dislocations are uncommon.


3. Volar—These are rare.


B. Dorsal PIP joint dislocations and fracture-dislocations


1. Mechanism of injury: hyperextension and axial compression


2. Anatomy


a. The accessory collateral ligaments insert onto the volar plate.


b. The proper collateral ligaments insert onto the condyles.


c. Fracture-dislocations involving >40% of the volar base of the joint surface often disrupt both accessory and proper collateral ligaments, leading to an unstable fracture-dislocation.


3. Treatment of dorsal fracture-dislocations


a. Stable—Dorsal extension block splint with joint in 60° to 70° of flexion, decreasing flexion 15° to 20° weekly.


b. Unstable—The usual options are:




ii. Agee force couple or other dynamic skeletal traction


iii. Closed reduction and percutaneous K-wire fixation of the PIP joint in the reduced position


iv. Volar plate arthroplasty


4. Complications—Dorsal PIP joint dislocations may lead to pseudoboutonniere deformity.


C. Volar PIP joint fracture-dislocations


1. These injuries often involve a rotatory mechanism that disrupts the extensor mechanism and one central slip. The condyle can be trapped by the lateral band, preventing reduction.


2. If the central slip is disrupted, treatment must include initial immobilization of the finger in extension (in contradistinction to dorsal dislocations).


3. Volar PIP joint dislocations can lead to boutonniere deformity.

VI. Thumb MCP dislocations

A. Ulnar collateral ligament disruption (gamekeeper thumb)


1. Mechanism of injury and pathoanatomy


a. This injury results from a hyperabduction injury at the thumb MCP joint.


b. The adductor aponeurosis lies directly above the ulnar collateral ligament insertion on the ulnar aspect of the thumb. In many patients the avulsed ligament, with or without a bony fragment, may become displaced above the adductor aponeurosis, preventing reduction (Stener lesion).


2. Treatment


a. Partial tears without instability may be treated with immobilization for 4 to 6 weeks.


b. Complete tears and injuries associated with significant instability should be treated with surgical repair.


c. Chronic injuries may be treated with ligament reconstruction using tendon graft, MCP fusion, or adductor advancement.

VII. Fractures of the Distal Phalanx

A. Types of fractures


1. Tuft


2. Diaphyseal


3. Volar (mallet profundus tendon avulsion)


4. Dorsal (finger)


5. Epiphyseal injury (Seymour fracture)


B. Tuft fractures


1. Closed tuft fractures may be treated with a protective splint.


2. Open tuft fractures may require debridement and soft-tissue repair.


3. Widely displaced fractures require open reduction and possible internal fixation with K-wires.


4. Hypersensitivity may be present because of crushing of digital nerve terminal branches.


5. Fibrous unions of comminuted distal tuft fractures are often asymptomatic.


6. Subungual hematomas are commonly associated with tuft fractures.


a. The hematoma should be decompressed for pain relief.


b. Open repair of the nail plate will result in fewer nail deformities.


c. Consider prophylactic antibiotics, as subungual hematomas can represent "open" fractures.


C. Fractures of the diaphysis of the distal phalanx


1. These fractures are usually stable and can be treated with a splint.


2. Longitudinal K-wires are used as needed.


D. Fractures of the base of the distal phalanx


1. These fractures are unstable as a result of the pull of the extensor and flexor tendons.


2. Dorsal apex angulation is typical.


3. The fracture fragment is avulsed from the extensor tendon insertion.


4. Mild deformity is well tolerated.


5. Treatment for most patients is splinting for 6 to 8 weeks.


E. Epiphyseal fractures (Seymour fracture)


1. Open epiphyseal fractures occur in children (typical mechanism: finger caught in car door).


2. The fracture results in nail matrix disruption. The plate may be avulsed lying dorsal to the proximal nail fold. The nail bed also may become interposed in fracture, resulting in nonunion or osteomyelitis.


F. Traumatic mallet finger


1. Indications for ORIF of traumatic mallet fingers


a. Subluxation of the distal phalanx (volar subluxation seen with dorsal articular fracture fragment)


b. Incongruity of the articular surface


2. Relative indications


a. Articular fragment >40%


b. Gap in articular surface >2 mm

VIII. Carpal Fractures

A. Scaphoid fractures


1. Epidemiology—The scaphoid is the most frequently fractured carpal bone.


2. Anatomy


a. Half of the bone is covered by articular cartilage.


b. Blood supply is through the palmar and dorsal vessels. The dorsal vessels supply the proximal pole and are at risk of injury with proximal pole fractures.


3. Mechanism of injury: Axial load across a hyperextended wrist


4. Evaluation


a. Physical examination—The following findings are suggestive of a scaphoid fracture:


i. Pain over the anatomic snuffbox


ii. Pain with axial compression of first metacarpal


iii. Tenderness at the scaphoid tuberosity


b. Imaging


i. Radiographs may initially appear normal.


ii. When initial radiographs are normal, the patient can be casted and undergo one of the following: MRI within 24 hours (MRI allows for immediate identification of fractures and ligamentous injuries in addition to assessment of vascular status of the bone); bone scanning in 72 hours (bone scans obtained at 72 hours have an 85% to 93% positive predictive value); or repeat plain radiographs in 14 to 21 days.



Figure 3. Radiograph of a patient with scapholunate advanced collapse (SLAC).]

5. Treatment


a. Nonsurgical


i. Nondisplaced scaphoid waist fractures, as verified by CT, can be treated with cast immobilization. A long arm-thumb spica cast has been shown to produce the smallest amount of internal scaphoid motion.


ii. Distal pole scaphoid fractures, which occur commonly in children, almost always heal with nonsurgical treatment.


b. Surgical


i. Indications for surgery include displacement, evidence of a dorsal intercalated segment instability (DISI) deformity (radiolunate angle >15°), associated perilunate ligamentous injuries, and proximal pole fractures.


ii. Procedures—Internal fixation with a compression screw has been found to produce results superior to K-wires alone. Proximal pole fractures can be treated successfully with immediate internal fixation. Avascularity and displacement result in the highest risk factor for nonunion. Treatment of nonunions has been reported with the use of vascularized bone grafts (1,2 intercompart-mental recurrent branch of the radial artery) and internal fixation of the scaphoid. Vascularized pedicle grafts may be taken from either the dorsal or volar portion of the distal radius.


6. Complications


a. Delay in acute fracture treatment beyond 28 days significantly increases risk of nonunion.


b. Untreated scaphoid nonunions have the propensity to degenerate into a collapse or humpback deformity. Over time, this results in an increase in the radiolunate angle with degenerative changes occurring first at the radial styloid, radioscaphoid fossa, and eventually within the midcarpal joint. This degenerative pattern has been referred to as SNAC (scaphoid nonunion advanced collapse)(Figure 3) and is treated in a manner similar to scapholunate advanced collapse (SLAC).



Table 2. Stages of Kienbock Disease]

B. Lunate injuries and Kienbock disease


1. Injuries


a. Traumatic dislocation of the lunate is more common than fracture.


b. Large fracture fragments may be successfully treated with screw fixation (surgical approach is either volar through the carpal tunnel or dorsal).


c. Volar avulsion fractures should raise suspicion of volar ligament disruption.


2. Kienbock disease


a. Definition—Kienbock disease is idiopathic osteonecrosis of the lunate.


b. Etiology


i. The etiology is unclear, but the shape of the lunate as well as the ulnar variance have been implicated. Positive ulnar variance has been linked to ulnar impaction, whereas ulnar negative variance has been linked to the development of Kienbock disease.


ii. In cadaveric studies, 20% of lunates have been found to have a single artery supplying most of the bone. In patients with comparable anatomy, trauma may predispose them to progressive avascularity and collapse.


c. Course of the disease—Kienbock disease follows a predictable course of lunate collapse with progressive arthritis (Table 2).


d. Treatment—Treatment depends on the stage of the disease and the surgeon's preference.


i. Stage 2 or 3a—Historically, for ulnar negative variance and stage 2 or 3a disease, a radial shortening osteotomy has provided good pain relief. Other options include capitate shortening and open and closing wedge osteotomies of the radius. Scaphotrapezial-trapezoid or scaphocapitate fusion may also be used for stage 3a disease. More recent options have included vascularized bone grafting from the dorsal distal radius, which has also shown good success with the possibility of revascularizing the lunate.


ii. Stage 3b disease is treated with proximal row carpectomy, wrist fusion, or total wrist arthroplasty.


iii. Stage 4 disease is treated with wrist fusion or total wrist arthroplasty.


C. Triquetrum fractures


1. Dorsal ridge fractures


a. Dorsal ridge fractures are not uncommon and can be associated with avulsions of the dorsal intercarpal ligaments, which insert on the triquetral ridge.


b. These fractures may often be treated with casting or splinting.


2. Volar fractures


a. Volar fractures of the triquetrum are more concerning.


b. These fractures can lead to lunotriquetral (LT) instability.


3. Body fractures


a. Fractures of the body of the triquetrum often can be treated with cast immobilization.


b. Volar body fractures may be associated with perilunate injuries.


D. Capitate fractures


1. Like the scaphoid, the capitate is covered mainly by cartilage, and the blood supply to the proximal pole can be compromised during transverse fractures. In such cases the proximal pole may develop osteonecrosis, requiring salvage with grafting or resection.


2. Scaphocapitate syndrome refers to a greater arc injury pattern where force passes from the scaphoid to the capitate neck, resulting in both scaphoid and capitate fractures. In this syndrome, the capitate head may be displaced 180°, requiring ORIF through a dorsal approach.


E. Hamate fractures


1. The most common presentation is a fracture of the hook of the hamate, which usually results from a golf club, baseball bat, or racket sport injury.


2. Fractures may be treated with screw reduction or excision of the fragment, which avoids the possible complication of nonunion with reduction and closed casting.

IX. Wrist Instability and Dislocations

A. Anatomy and biomechanics


1. Radial wrist and scaphoid stabilizers


a. The scapholunate interosseous ligament (SLIL) is perceived as the primary stabilizer of the scapholunate joint. It is composed of three distinct portions:


i. The proximal or membranous portion, which has no significant strength


ii. The dorsal portion, which is the strongest portion and prevents translation


iii. The palmar portion, which acts as a rotational constraint


b. Distal scaphoid stabilizers include the scaphotrapezial interosseous ligaments (STIL).


c. The radioscapholunate ligament (ligament of Testut) is a volar intra-articular neurovascular structure and provides little mechanical stability.


d. The palmar stabilizers include the radioscaphocapitate ligament, long radiolunate ligament, and short radiolunate ligament. These ligaments are all thought to be secondary stabilizers of the scaphoid.


e. The dorsal stabilizers are the dorsal radiotriquetral ligament and the dorsal intercarpal ligament.


B. Pathomechanics


1. Mayfield described the four classic stages of progressive perilunate instability of the wrist (

Table 3).


2. Reverse perilunate injury/dislocation also has been described and suggested by several authors as a mechanism of isolated LT ligament injury (Table 3).


C. Evaluation


1. Imaging




i. Carpal instability can be described by abnormalities seen on radiographs.


ii. Standard views: PA, lateral, ulnar deviation PA, and supinated clenched-fist


[Table 3. Stages of Progressive Perilunar Instability and Reverse Perilunar Instability]



i. Historically, arthrography was the gold standard for the diagnosis of ligamentous injuries, but for the most part it has been replaced by diagnostic arthroscopy.


ii. With arthrography, contrast medium is injected into the midcarpal, radiocarpal, and radioulnar joints. If dye flows between any of the compartments, an intercarpal ligament tear is indicated. Attritional changes seen with advancing age may lead to spurious findings.


2. Direction—Description of the abnormal stance of the carpus regardless of etiology.


a. DISI: lunate extension


b. (VISI) (volar intercalated segmental instability): lunate flexion


c. Ulnar translocation means the carpus is displaced ulnarward (>50% of lunate lies ulnar to lunate fossa).


d. Dorsal translocation refers to the carpus that unnaturally displaced dorsally (ie, malunited and dorsally angulated distal radius fracture).


3. History—Determining the time from injury helps determine treatment options.


a. Acute: within 1 week of injury


b. Subacute: 1 to 6 weeks after injury


c. Chronic: more than 6 weeks after injury



Figure 4. Carpal arcs of Gilula. I = smooth arc outlining the proximal surfaces of the scaphoid, lunate, and triquetrum; II = smooth arc outlining the distal surfaces of the scaphoid, lunate, and triquetrum; III = arc outlining the proximal surfaces of the capitate and hamate.]

4. Constancy


a. Predynamic instability—No malalignment, only sporadic symptomatic dysfunction, normal radiographs.


b. Dynamic instability—Malalignment demonstrated on stress radiographs.


c. Static instability—Permanent alteration in carpal alignment, abnormal plain radiographs.


5. Radiographic parameters—The following measurements can be used to assess ligamentous stability using plain radiographs and fluoroscopy.



Carpal arcs of Gilula—Gilula described three parallel arcs observed on PA radiographs: the first arc corresponds to the proximal articular surface of the proximal row, the second corresponds to the distal articular surface of the proximal row, and the final arc represents the proximal articular surface of the distal carpal row. Disruption of one of these arcs suggests a carpal fracture or ligamentous injury (Figure 4).



Table 4. Intercarpal Angles and Distances]


Figure 5. Radiograph of a patient with scaphoid nonunion advanced collapse (SNAC).]


Carpal height ratio—This ratio is calculated by dividing the carpal height by the length of the third metacarpal. The normal ratio is 0.54 ± 0.03. In disease processes such as scapholunate dissociation, SLAC wrist, and Kienbock disease, collapse of the midcarpal joint produces a decrease in this ratio.


Intercarpal angles and distances—Significant deviation from normal values can indicate a disruption of the SLIL or LT interosseous ligament (Table 4).


Early ligamentous injuries may produce no abnormalities on plain radiographs. If the mechanism and physical exam suggest ligamentous injury, further studies are indicated.


D. Scapholunate ligament injuries


1. Epidemiology—Scapholunate ligament injuries are the most common form of traumatic carpal instability.


2. Pathomechanics—Disruption in the scapholunate relationship can lead to the following:


a. Unopposed extension forces on the lunate imparted by the triquetrum, leading to DISI deformity.


b. Abnormal scaphoid motion and dorsal subluxation of the scaphoid from the radial fossa during wrist flexion, leading to eventual wrist arthritis.


c. Migration of the capitate proximally between the scaphoid and capitate, leading to stage III SLAC arthritis (Figure 5).


3. Evaluation


a. Physical examination


i. Positive scaphoid shift test or Watson maneuver—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 increase in pain dorsally over scapholunate articulation. With complete tears, an audible clunk may be heard as the scaphoid is actively subluxated with dorsal pressure and spontaneously reduces into the radial fossa when the thumb is removed.


ii. The scaphoid shift test may be falsely positive in up to one third of individuals because of ligamentous laxity without injury, so both sides should always be checked.



Table 5. Geissler Classification of Carpal Instability]

b. Radiographs—PA and lateral views should be obtained.


i. Scapholunate angle: 46° is normal; >60° is considered abnormally elevated


ii. Diastasis between the scaphoid and lunate: >2 mm is abnormal.


iii. "Signet ring" sign: As the scaphoid flexes, the distal pole will appear as a ring on PA radiographs.


iv. Radiolunate angle: >15° dorsal indicates a DISI deformity.


v. Disruption of Gilula lines—With advanced carpal instability, the capitate migrates into the proximal carpal row, causing a disruption of the Gilula lines and a change in the carpal height ratio with the wrist held in neutral flexion/extension and neutral deviation.


vi. The clenched-fist view may show early SLIL changes (dynamic instability) with widening of the scapholunate interval or increase in the scapholunate angle as the capitate is driven down into the scapholunate interspace.


vii. Even complete division of the SLIL will not always produce an abnormality on plain radiographs because of the substantial number of secondary stabilizers of the scaphoid in addition to the SLIL.


c. Arthrography—May show communication between the midcarpal and radiocarpal joint with a dye leak seen at the SLIL indicating a tear.


d. Arthroscopy


i. Arthroscopy is now the gold standard for diagnosis of instability patterns. It allows for direct inspection of SLIL ligament in addition to evaluation of supporting extrinsic ligaments.


ii. Arthroscopic instability is graded by the Geissler classification (Table 5).


iii. Midcarpal arthroscopy is the key to assessing the stability of the scapholunate joint. From the midcarpal perspective, the normal scapholunate joint is smooth, without a step-off or diastasis.


e. Stages of scapholunate instability (

Table 6)


4. Treatment—Treatment of scapholunate injuries depends on whether the injury is acute, chronic, or chronic with arthritis (SLAC).


a. Acute injuries—Treatment includes open repair and cast immobilization.


b. Chronic injuries (dynamic or static)


i. Indications for open repair—Satisfactory ligament remains for repair; the scaphoid and lunate remain easily reducible; no degenerative changes within the carpus.


ii. Soft-tissue procedures


(a) Dorsal capsulodesis or tenodesis prevents dynamic or static scaphoid flexion.


(b) The Brunelli procedure uses a strip of the flexor carpi radialis brought palmarly through a bone tunnel in the distal scaphoid. The tendon is then brought dorsally and proximally and attached to the distal radius in an attempt to limit scaphoid flexion and stabilize the SLIL and STIL ligaments. A modification of the Brunelli procedure involves attaching the flexor carpi radialis to the lunate.


(c) Ligament reconstruction—Attempts have been made to reconstruct the SLIL with bone-ligament-bone constructs from the carpus, foot, and extensor retinaculum.


(d) Arthrodesis—Scaphotrapezial or scaphocapitate arthrodesis can be used to stabilize the scaphoid.


c. Chronic injuries with arthritis (SLAC changes)—See

Table 7.


[Table 6. Stages of Scapholunate Instability]

[Table 7. Treatment of SLAC Changes]

E. Lunotriquetral ligament injuries


1. Fixed carpal collapse (VISI) seen on radiographs represents static instability and is classified as LT ligament dissociation.


2. Anatomy of the LT ligament


a. Like the scapholunate ligament, the LT interosseous ligaments are C-shaped ligaments, spanning the dorsal, proximal, and palmar edges of the joint surfaces.


b. The palmar region of the LT is the thickest and strongest region.


c. The dorsal LT ligament region is most important in rotational constraint.


3. Pathomechanics


a. With loss of the integrity of the lunotriquetral ligament, the triquetrum tends to extend and the scaphoid and lunate attempt to flex.


b. A complete LT ligament dissociation is not sufficient to cause a static carpal collapse into a VISI stance.


4. Physical examination


a. Ulnar deviation with pronation and axial compression will elicit dynamic instability with a painful snap if a nondissociative midcarpal joint or LT ligament injury is present.


b. Useful tests include the LT ballottement, shear, and compression tests.


5. Radiographic evaluation


a. With LT ligament tears, radiographs are often normal.


b. LT dissociation


i. LT dissociation results in a disruption of the smooth arcs formed by the proximal and distal joint surfaces of the proximal carpal row (carpal arcs of Gilula I and II) and the proximal joint surfaces of the distal carpal row (carpal arc of Gilula III).


ii. LT dissociation also results in proximal translation of the triquetrum and/or LT overlap. Unlike scapholunate injuries, no LT gap occurs. The longitudinal axis of the triquetrum, defined as a line passing through the distal triquetral angle and bisecting the proximal articular surface, forms a 14° angle (range, +31° to -3°) with the lunate longitudinal axis, defined as a line passing perpendicularly to a line drawn from the distal dorsal and volar edges of the lunate. LT dissociation results in a negative angle (mean value, -16°).


iii. If a VISI deformity is present with LT dissociation, the scapholunate and capitolunate angles will be altered. The scapholunate angle may be diminished from its normal 47° to 40° or less but is often normal. The lunate and capitate, which are normally co-linear, will collapse in a zigzag fashion, resulting in an angle greater than 10°.


6. Arthroscopy


a. Arthroscopy is performed through the ulnocarpal and midcarpal portals.


b. Arthroscopy is diagnostic for LT injuries.


7. Treatment


a. Surgical treatment for LT injuries—Treatment options include LT ligament repair, LT ligament reconstruction, and LT arthrodesis. A comparison of results and outcomes following arthrodesis, ligament repair, and reconstruction has demonstrated superior results with LT ligament repair or reconstruction.


b. Treatment for attritional LT instability secondary to ulnar positive variance


i. Attritional LT instability secondary to ulnar positive variance refers to LT instability secondary to a long ulna that chronically impacts the triquetrum, resulting in a LT tear with instability. This is often associated with a degenerative (nonrepairable) tear of the triangular fibrocartilage complex.


ii. Ulnar shortening is an attractive alternative in these cases.


F. Perilunate dislocations


1. Epidemiology and mechanism of injury


a. Perilunate dislocations are rare injury patterns.


b. They are usually associated with significant trauma (eg, a fall from a height).


2. Pathoanatomy


a. The lunate often remains bound to the carpus by stout radiolunate ligaments, but the carpus dislocates around it. The capitate may move dorsally to cause dorsal perilunate dislocation (common) or palmarly to cause palmar perilunate dislocation (rare).


b. Lunate dislocation occurs when the lunate dislocates from radial fossa palmarly (palmar lunate dislocation, common) or dorsally (dorsal lunate dislocation, rare).


c. Fractures may pass through any bone found within the "greater arc" of the wrist and include the distal radius, scaphoid, trapezium, capitate, hamate, and triquetrum.


d. "Lesser arc" injuries pass only through ligamentous structures, with no corresponding fractures.


3. Evaluation


a. Diagnosis can be delayed because some radiographic findings may be subtle; 25% of these injuries are missed during initial presentation.


b. The physical examination may reveal significant swelling, ecchymosis, and decreased range of motion.


c. The chance of acute carpal tunnel syndrome can be as high as 25%.


d. Radiographs


i. PA views will show disruption of the carpal arcs of Gilula and overlapping of carpal bones (

Figure 6, A).


ii. Lateral views will show dislocation of the capitate or lunate (Figure 6, B).


e. Scintigraphy, CT, and MRI are usually not required to make the diagnosis.


4. Treatment


a. Acute presentation


i. Closed reduction may be preformed initially for pain relief, but surgery is the definitive treatment.


ii. Lunate dislocations usually require an extended carpal tunnel approach initially for lunate reduction if the lunate cannot be reduced by closed means.


b. Delayed presentation


i. Outcomes are worse than for injuries repaired acutely.


[Figure 6. PA (A) and lateral (B) views of a transscaphoid perilunate dislocation. Note the disruption of the carpal arcs of Gilula on the PA view.]

ii. Treatment options include ORIF, proximal row carpectomy, and total wrist fusion.


iii. Studies have shown that in patients treated 6 weeks or longer after injury, ORIF provided the most reliable improvement in function and pain.

X. Fractures of the Distal Radius

A. Overview


1. Fractures of the distal radius are among the most common fractures seen in the emergency department.


2. Patients of advanced age who have osteoporosis have an increased fracture risk with low-energy falls.


3. Fracture patterns vary depending on the mechanism of injury.


4. Principles of treatment—The goal of surgery is to restore the anatomy of the radius and its relationship with the carpus and the distal ulna.


B. Management of distal radius fractures


1. Options include closed reduction and cast immobilization, closed reduction and percutaneous pinning with or without external fixation, and ORIF.


2. Surgical treatment indications


a. Loss of reduction following attempt at closed treatment and/or excessive shortening ≥5 mm; dorsal articular tilt ≥15° (ie, apex volar angulation); loss of radial inclination >10°


b. 2 mm or more of articular displacement


c. Volar oblique fracture (Smith fracture)


d. Intra-articular volar shear fracture (Barton fracture)


e. Die-punch fracture


f. Significant dorsal comminution involving more than one third of the anteroposterior dimension of the radius


g. Open fractures


h. Multiple trauma (relative indication)


3. Closed treatment


a. Long-arm sugar-tong splint or cast in the initial period (up to 2 weeks) with the wrist in neutral position to avoid median nerve compression


b. Graduation to short arm cast after swelling diminishes


c. Total length of immobilization: approximately 6 weeks


4. Surgical treatment procedures


a. Closed reduction and percutaneous pinning with or without external fixation


i. A combination of 0.62- and 0.45-in K-wires is used to maintain reduction.


ii. The wires are inserted from the radial styloid to the intact radial metaphysis or diaphysis, with care taken to avoid injury to the superficial branch of the radial nerve. Limited incisions and protective devices minimize risk.


iii. Subchondral pins help to maintain the articular surface reduction.


iv. Kapandji pins (through the dorsal aspect of the fracture and directed proximally and volarly) are used to buttress and maintain the reduction (volar tilt).


b. External fixator


i. External fixation provides ligamentotaxis.


ii. Beware of overdistraction, which can lead to complex regional pain syndrome, stiffness, or limited finger ROM. Full passive finger ROM following fixator placement suggests that the amount of distraction is appropriate.


iii. Full incisions over the radius and index metacarpal at the time of fixator pin placement minimize the risk of iatrogenic nerve injury.


iv. Adjustable fixators allow for modifications of the wrist position after securing the device.


v. The fixator and pins typically remain in place no longer than 4 to 6 weeks.


vi. Bone graft can be used to structurally support bone defects.


c. Open reduction and internal fixation


i. ORIF allows for earlier rehabilitation and recovery.


ii. Locking plates provide a stronger construct than nonlocked plates or external fixation and are able to maintain the tendency of the fracture to fall dorsally.


iii. Approach is through a volar incision between the flexor carpi radialis and radial artery.


iv. Potential pitfalls include intra-articular distal screw/peg placement; injury to the radial artery, median nerve, or lateral antebrachial cutaneous nerve; and carpal tunnel syndrome.


v. Dorsal plating has both advantages and disadvantages. Advantages include the fact that the plate is on the biomechanically favorable side of the fracture and fewer neurovascular structures are at risk. Disadvantages include the possibility of tendon adhesions and rupture, which have been reported with previous plate designs, and the potential need to remove the plate following fracture healing.


C. Smith fracture—This volarly displaced fracture of the distal radius ("reverse Colles") is an inherently unstable fracture pattern.


1. Classification


a. Type 1: Extra-articular


b. Type II: Intra-articular (similar to volar Barton fracture pattern)


c. Type III: Juxtaphyseal fracture pattern


2. Surgical treatment—ORIF with a volar buttress plate.


D. Fractures of the radial styloid ("chauffeur" fractures)


1. These fractures may be associated with scapholunate ligament injuries because the intra-articular fracture line extends into the joint at that level. Therefore, in the setting of isolated radial styloid fractures, intercarpal ligament injuries must be suspected.


2. Treatment


a. Nonsurgical—If the fracture is completely nondisplaced, it may be treated nonsurgically


b. Surgical—Intra-articular displacement (or diastasis) greater than 1 to 2 mm is an indication for surgery. Compression screw fixation with partially threaded 3.5 or 4.0 cancellous screws can effectively compress the fragments and maintain the reduction. Alternative fixation options include K-wires and plate and screw fixation.


E. Distal radioulnar joint


1. The distal radioulnar joint must be assessed following stabilization of the radius.


2. Preoperative comparison with the unaffected side is helpful.


F. Malunions


1. Malunions following distal radius fracture are associated with pain and disability.


2. Indications for surgery


a. Loss of radial height ≥5 mm


b. Loss of >10° of radial inclination


c. Dorsal tilt ≥15°


3. Surgical procedures


a. Surgery must correct all three parameters: radial height, radial inclination, and volar tilt.


b. The osteotomy should be made in the sagittal plane, parallel to the joint surface.


c. Autogenous (iliac crest) bone graft is preferred.


d. Fixation options include dorsal plating and locked volar plating.

Top Testing Facts

1. In index and long finger MCP fractures, 15° to 20° of angulation is acceptable; in fractures of the ring and little fingers, 30° to 40° of angulation is acceptable.


2. The main deforming force in a Bennett fracture is provided by the abductor pollicis longus. In a "baby Bennett" fracture, it is the extensor carpi ulnaris.


3. In complex MCP dislocations, the metacarpal head is caught between the volar plate, flexor tendon, lumbrical, and A1 pulley.


4. Bennett fractures are best viewed on the Robert (hyperpronated) view.


5. Dorsal PIP joint dislocations may lead to pseudoboutonniere deformity. Volar PIP joint dislocations may lead to boutonniere deformity.


6. Nondisplaced scaphoid waist fractures, as verified by CT, can be treated with cast immobilization in a long arm-thumb spica cast, which has been shown to produce the smallest amount of internal scaphoid motion. Indications for surgery include any displacement, a radiolunate angle >15°, associated perilunate ligamentous injuries, and proximal pole fractures.


7. The SLAC pattern of arthritis progresses from the radioscaphoid joint to the scaphocapitate joint to the capitolunate joint.


8. Surgical indications for distal radius fractures include loss of reduction following attempt at closed treatment and/or excessive shortening (≥5 mm), dorsal angulation ≥15°, loss of radial inclination >10°, or ≥2 mm articular displacement.


9. In the setting of isolated radial styloid fractures, intercarpal ligament injuries must be suspected.


Cooney WP III, Linscheid RL, Dobyns JH: Carpal instability: Treatment of ligament injuries of the wrist. Instr Course Lect 1992;41:33-44.

Mack GR, Bosse MJ, Gelberman RH, Yu E: The natural history of scaphoid non-union. J Bone Joint Surg Am 1984;66: 504-509.

Mayfield JK, Johnson RP, Kilcoyne RK: Carpal dislocations: Pathomechanics and progressive perilunar instability. J Hand Surg [Am] 1980;5:226-241.

Sheetz KK, Bishop AT, Berger RA: The arterial blood supply of the distal radius and ulna and its potential use in vascularized pedicled bone grafts. J Hand Surg [Am] 1995;20: 902-914.