Kenneth R. Means, Jr. and Thomas J. Graham
DEFINITION
These injuries include fractures of the lunate, triquetrum, pisiform, hamate body or hook, capitate, trapezoid, and trapezial body or ridge.
Any fracture involving the carpal bones should raise suspicion of associated carpal instability.
ANATOMY
Certain anatomic features of the carpal bones make them more susceptible to injury. These include the unique osteologic regions of some of the carpal bones, such as the hook of the hamate, the ridge or tubercle of the trapezium, and the neck of the capitate.
The slender shape and projection of the hamate hook make it an obvious injury target for direct trauma to the palmar-ulnar surface of the wrist (FIG 1A). The hook can be identified before incision by placing the interphalangeal joint of the surgeon's thumb on the pisiform and flexing the thumb toward the first web space. The surgeon's thumb tip will land directly on top of the hook.
The trapezial ridge may be considered a radial-sided analogue to the hamate hook in that it is a relatively prominent volar projection, further accentuated by the deep groove for the flexor carpi radialis tendon that runs along its ulnar side (FIG 1B).
The strong, inelastic transverse carpal ligament attaches to the hamate hook ulnarly and the trapezial tubercle radially.
These facts make the ridge of the trapezium more susceptible to fracture after direct trauma to the thenar region of the hand.
The constricted neck portion of the capitate lies between the dense head proximally and the body distally. The body, which accounts for the distal half of the capitate, is rigidly constrained by its associations with the index, middle, and ring finger metacarpal bases, the trapezoid, and the hamate. As a result the capitate neck is a biomechanically vulnerable area.
Transverse plane fractures through the capitate neck are reported as being the most common.
Fractures across the neck place the head at risk for avascular necrosis because the blood supply to the capitate flows retrograde toward the head proximally.
FIG 1 • A. CT scan showing hamate hook. B. CT scan showing trapezial ridge.
PATHOGENESIS
Traumatic fractures of the carpal bones may occur via direct or indirect mechanisms.
Direct mechanisms include crush injuries, which should alert the physician to the possible development of compartment syndrome of the hand. Compressive trauma to the hand in the anteroposterior plane will flatten the palmarly directed concave longitudinal and horizontal arches of the carpus and should raise suspicion for potential carpal body fractures and axial disruptions.
The presence of a seemingly unusual carpal bone fracture may be a herald of a globally destructive injury to the hand and other associated injuries, such as carpometacarpal (CMC) fracture-dislocations, longitudinal fractures of the metacarpals, severe thumb damage, and significant soft tissue injuries. This constellation of pathologies has been referred to as the “exploded hand” (FIG 2).
More focused direct trauma to individual carpal bones may also cause a fracture. Examples of this include direct blows to the dorsum of the hand, causing capitate fractures, or direct injury from a racquet or club, causing a hamate hook fracture.
FIG 2 • “Exploded hand” is a constellation of injuries that can include carpometacarpal fracture-dislocations, longitudinal fractures of the metacarpals, severe thumb damage, and significant soft tissue damage. (Reprinted from Graham TJ. The exploded hand syndrome: logical evaluation and comprehensive treatment of the severely crushed hand. J Hand Surg Am 2006;31A:1012–1023; copyright 2006, with permission from Elsevier.)
Indirect trauma includes the progressive perilunate instability patterns that are well described and may lead to fractures of the lunate, capitate, triquetrum, or other carpal bones.
Scaphocapitate syndrome involves a dorsiflexion and radial deviation mechanism by which the scaphoid bone fractures and is followed by a fracture of the capitate through the neck in the coronal plane. The capitate head may rotate up to 180 degrees from its anatomic position.
A progressive perilunate instability pattern can produce a similar coronal fracture through the capitate neck but normally without such a severe degree of capitate head rotation.
More minor indirect trauma mechanisms can cause isolated carpal bone fractures.
The commonly seen avulsion fractures from the dorsum of the triquetrum may occur when a fall onto the palmar-flexed wrist causes the dorsal radiotriquetral (also known as dorsal radiocarpal) ligament to avulse a portion of the dorsal cortex.
An impaction type of fracture of the triquetrum may be seen more often in patients with an elongated ulnar styloid.
NATURAL HISTORY
The natural history of carpal bone fractures depends both on the specific bone in question as well as associated impairment of other structures.
All of the carpal bones have at least three articular surfaces, except the pisiform, which articulates only with the triquetrum. Anatomic reduction of articular facets is a primary surgical goal in an effort to decrease the incidence and severity of posttraumatic arthritis.
Avascular necrosis can have a profoundly negative impact on final outcome after carpal bone fracture.
Concerns of vascular disruption arise when lunate and capitate fractures occur, although generally fractures of the lunate are not associated with avascularity.
The potential for nonunion is most often seen with hamate hook fractures, capitate neck fractures, and trapezial ridge fractures, especially Palmer type II fractures that involve the tip and not the base of the ridge.
Barring nonunion, the related instabilities and involvement of other hand components are the most troublesome and will most significantly affect patient outcome.
PATIENT HISTORY AND PHYSICAL FINDINGS
Ascertaining the mechanism of injury is the most important component of the patient history.
Neurovascular symptoms should be explored, especially when a severe crush or high-energy mechanism is involved, or in cases of hamate hook or pisiform fractures, with special attention to the ulnar neurovascular structures within the canal of Guyon.
A complete evaluation of the median, radial, ulnar, and digital nerves is warranted. Assessment of capillary refill, color, temperature, and Doppler signal determines the vascular status.
The examiner should observe the patient's hand and wrist for swelling, deformity, and skin and soft tissue injuries, including possible open fractures or fracture-dislocations.
Swelling and soft tissue damage give an indication as to the severity of the injury. The presence of deformity alerts the examiner to possible carpal dislocations that require emergent reduction. Open fractures and fracture-dislocations will guide surgical management.
The examiner should ask the patient where the pain is most significant. The examination should start away from and progress toward this point. The hand, forearm, and elbow should also be palpated to assess for possible associated injuries.
The most obvious area of pain and tenderness is usually the most structurally significant. However, it may mask other more subtle injuries that should be detected by a more thorough global examination.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Routine AP, lateral, and oblique views of the wrist and hand are obtained (FIG 3A).
Radiographs of the elbow and forearm are ordered if indicated.
Fluoroscopic images, including dynamic stress and distraction views, help to rule out carpal instability.
Special views, often best performed with fluoroscopy, help to profile difficult-to-see structures.
The hook of the hamate is evaluated with the carpal tunnel view and supinated and oblique lateral view with the wrist in radial deviation and the thumb abducted, as if the patient was holding a cup (referred to as the papillon view) (FIG 3B).
The trapezial ridge is visualized on the carpal tunnel view (FIG 3C).
The pisotriquetral joint is best seen on a 45-degree supinated lateral view of the wrist.
CT scans effectively assess osseous detail and will often detect more subtle associated carpal fractures that may be missed on routine radiographs.
CT is considered the imaging modality of choice for confirming a hamate hook fracture if plain films are nondiagnostic.
NONOPERATIVE MANAGEMENT
Isolated carpal bone fractures without associated carpal instability, significant displacement, or intra-articular stepoff may be managed nonoperatively.
This usually includes use of a cast or brace for several weeks (usually 4 to 6 weeks) until symptoms have improved, tenderness is resolving, and radiographs are stable.
Short-arm thumb spica casts or splints have been recommended for isolated trapezium and capitate fractures. The digits should be left free.
A specific fracture of note is the hamate hook.
These fractures can be treated with cast immobilization if nondisplaced and acute (less than 1 month).
There is a relatively high rate of symptomatic nonunion, and surgical intervention may eventually be necessary.
Similar to the treatment of the hamate hook, trapezial ridge fractures may be initially immobilized and later excised if symptomatic nonunion develops.
SURGICAL MANAGEMENT
Indications
Indications for surgical management of these fractures include those that significantly involve an articular surface or are structurally destabilizing to the remainder of the carpus, such as a displaced or unstable capitate body fracture.
Other operative indications include those that are true for most fractures, such as open injuries and those requiring nerve, vessel, tendon, ligament, or soft tissue repair.
FIG 3 • A. AP radiograph of wrist showing trapezial body fracture. B. Supination, oblique, radial deviation radiograph showing normal hamate hook. C. Carpal tunnel view showing normal hamate hook (large arrow) and trapezial ridge (small arrow).
If stable and near-anatomic reduction of carpal fractures is not possible, primary limited arthrodesis or carpectomy may be indicated.
Because of the unique nature of each carpal bone, more specific indications will be considered for each fracture.
Late reconstructive options include partial or total wrist arthrodesis or proximal row carpectomy for symptomatic arthritic changes.
Trapezial excision with thumb metacarpal suspensionplasty may be used for posttraumatic arthritis after trapezial body fractures.
Total or hemi-wrist arthroplasty for select cases may become a more popular option as techniques improve.
Lunate Fractures
In general, fractures that are of sufficient size and displacement should be reduced and internally fixed.
Fractures that involve the palmar surface of the lunate where stout volar extrinsic wrist ligaments (long and short radiolunate) and vascular conduits (radioscapholunate ligament of Testut) attach should be stabilized.
If the capitate is subluxated volarly relative to the lunate and radius, such as when there is a lunate palmar lip fracture, this must be corrected with reduction and fixation of the lunate palmar fragment.
These fractures are routinely approached palmarly as described in Techniques.
Alternatively, a standard 3–4 interval dorsal exposure (described under capitate fractures) can be used if the fracture pattern dictates a dorsal approach and fixation.
Triquetral Fractures
In general, displaced fractures of the triquetral body that are of sufficient size are best treated by open reduction and internal fixation (ORIF).
This can be accomplished through use of pins or screws into the triquetrum alone or in combination with pinning to the lunate or to the hamate as dictated by the fracture.
The triquetrum may be removed in its entirety if it is not amenable to repair.
An apparently isolated fracture of the triquetrum may in fact be part of a reverse perilunate instability pattern (in which the portal of energy entry is at the ulnar wrist) and may be associated with other fractures and ligament disruptions.
Pisiform Fractures
The pisiform, similar to another sesamoid bone, the patella, most often fractures in a transverse pattern via an indirect avulsion mechanism through the flexor carpi ulnaris (FCU) or in a pattern of comminution from a direct blow.
Virtually all pisiform fractures are treated nonoperatively initially and then excised late if immobilization of the fracture fails to relieve symptoms after 2 or 3 months.
Fractures that are of sufficient size and displacement can be reduced and internally fixed, although this is rarely indicated.
The approach described in Techniques can be used for fixation or excision of the pisiform.
The pisiform is the last carpal bone to ossify, usually by age 12, and may have a nonpathologic fragmented appearance before complete ossification.
Hook of Hamate Fractures
Like pisiform fractures, most acute hamate fractures are treated nonoperatively initially. If the fracture remains persistently symptomatic or nonunited, excision is indicated, even for base fractures (FIG 4A).
ORIF is associated with relatively high complication rates and provides little or no advantage over simple fragment excision.
If ORIF is desired, the hamulus is exposed as described in Techniques and standard internal screw fixation principles are used.
Hamate Body Fractures
Fractures of the hamate body are often associated with fourth or fifth CMC dislocations (FIG 4B,C). ORIF is recommended to reduce the articular surfaces and stabilize the CMC joints.
These injuries most often result from a dorsal shear mechanism with fracture of the hamate body in the frontal plane. The metacarpals displace dorsally and proximally with the dorsal hamate fracture fragment.
FIG 4 • Hamate fractures. A. Supination, oblique, radial deviation radiograph showing hamate hook fracture. B,C. AP and lateral radiographs of a hamate body dorsal shear fracture associated with the small finger and ring finger carpometacarpal articulation as well as a fracture of the base of the ring finger metacarpal.
Capitate Fractures
Capitate fractures are by and large associated with significant trauma to the wrist.
In addition to fractures associated with progressive perilunate instability patterns and the scaphocapitate syndrome, capitate fractures may also occur due to axial loading along the middle finger ray or via direct trauma.
If caused by axially directed forces, the fracture line is often in the frontal plane, similar to the hamate dorsal shear fractures described earlier. The capitate may be essentially divided in half in this frontal plane.
In these cases, ORIF is performed through a dorsal approach.
Truly isolated capitate fractures with minimal displacement heal by immobilization, but this often takes time.
Trapezoid Fractures
The trapezoid is believed to be the least frequently fractured carpal bone.
As with the other bones of the distal carpal row, assessment of the associated index CMC joint is necessary to rule out a fracture-dislocation.
Frontal plane dorsal shear fractures of the trapezoid can destabilize the index CMC.
These fractures and fracture-dislocations can often be treated by closed reduction and pinning.
If an open approach is required to reduce the articular surface and CMC joint, a standard 3–4 dorsal approach may be used. Fixation can be accomplished with pins or screws.
A limited exposure (as described below) is an alternative.
Trapezium Fractures
Fractures of the body of the trapezium nearly always involve one of its four articular facets and frequently lead to subluxation of the thumb CMC joint (FIG 5).
If internal fixation is not possible, trapezial excision and palmar oblique ligament reconstruction, or an alternative procedure used for routine thumb CMC osteoarthritis, is performed.
Preoperative Planning
Examination under anesthesia, possibly with concomitant fluoroscopic imaging, helps confirm whether carpal instability coexists.
The surgeon should ensure that all needed fixation implants and systems are available before bringing the patient to the operating room.
A hand table, a well-padded upper arm tourniquet, and a mobile mini-fluoroscopy unit are used.
Anesthesia and analgesia may be obtained through regional or general methods.
Approach
Carpal fractures may be approached dorsally, palmarly, radially, or ulnarly depending on the reduction needs, implants used, and fracture location and characteristics.
Some surgeons use wrist or small joint arthroscopy as an aid to fracture reduction and management.
FIG 5 • Trapezial body fractures.
TECHNIQUES
ORIF OF LUNATE FRACTURES
Incision and Dissection
An extended carpal tunnel approach is used for palmar exposure.
The incision begins in the palm, just ulnar to the thenar crease and in line with the radial border of the ring finger. If the surgeon is comfortable with the deep anatomy, especially the possible anatomic variations involving the thenar motor branch, the incision in the palm may also be along the thenar crease itself.
It is extended proximally until the distal volar wrist crease is reached.
A curved or zigzag continuation of the incision is made at the crease so as to avoid crossing perpendicular to the wrist crease, which might cause excessive scarring and a flexion contracture.
The incision may be continued into the distal forearm, staying ulnar to the palmaris longus so as to avoid damage to the palmar cutaneous branch of the median nerve (TECH FIG 1A).
It is deepened distally until the palmar fascia is encountered (TECH FIG 1B). This fascia is incised in line with the skin incision.
The transverse carpal ligament is opened longitudinally, just radial to the hamate hook.
The incision is continued proximally, releasing the distal volar forearm fascia, again staying ulnar to the palmaris longus.
The contents of the carpal canal are now visualized (TECH FIG 1C).
The digital flexors and median nerve are gently and bluntly retracted radially, revealing the floor of the canal that overlies the volar carpus (TECH FIG 1D).
The volar capsule of the wrist joint is incised longitudinally, providing exposure of the volar carpus and radiocarpal joint.
Reduction and Fixation
The palmar lip fracture of the lunate is identified, cleaned, and anatomically reduced.
The fracture may be fixed with small interfragment screws or buried Kirschner wires (TECH FIG 2).
Screws are favored if at all possible to minimize chances of hardware migration into the carpal tunnel.
TECH FIG 1 • Fixation of lunate palmar lip fractures. A. Carpal tunnel approach. The incision can be continued into the distal forearm, staying ulnar to the palmaris longus to avoid damage to the palmar cutaneous branch of the median nerve. B. Palmar fascia and antebrachial fascia exposed. C. Transverse carpal ligament released from hamate hook. D. Volar wrist capsule exposed.
TECH FIG 2 • Palmar lunate lip exposed and instrumented.
Fluoroscopic images are necessary to confirm that the volar carpal subluxation has been corrected with fixation of the lunate fracture.
The volar wrist capsule is repaired with permanent suture and the median nerve and digital flexors are allowed to return to their normal resting position.
The transverse carpal ligament may be repaired in a lengthened fashion or left divided (our preference).
Subcutaneous tissue and skin closure is performed according to the surgeon's routine.
ORIF OF TRIQUETRAL FRACTURES
Access to the triquetrum is usually achieved through the standard dorsal approach to the wrist that is described for capitate fractures.
If there is truly isolated triquetral pathology, a more limited dorsal approach between the fifth and sixth extensor compartments is used.
This incision is centered distal to that which would be used for distal radioulnar joint (DRUJ) exposure.
The fifth compartment (extensor digiti minimi [EDM]) is retracted radially while the sixth compartment (extensor carpi ulnaris [ECU]) is retracted ulnarly.
The carpal capsule is incised longitudinally or obliquely depending on the fracture and the integrity of the dorsal radiotriquetral ligament.
The triquetral fracture may now be cleaned, reduced, and fixed with mini-screws or Kirschner wires as the fracture pattern prescribes.
Supplemental pinning to the lunate or hamate is performed as needed.
The capsule is closed with nonabsorbable suture, followed by routine subcutaneous tissue and skin closure.
EXCISION OR ORIF OF PISIFORM FRACTURES
A curvilinear incision is made with special care not to cross the distal volar wrist crease perpendicularly. The incision is made centered on or just radial to the pisiform.
The ulnar neurovascular bundle is identified proximally and traced distally just past the pisiform body.
The pisohamate ligament is divided.
The flexor carpi ulnaris (FCU) tendon insertion, if intact, is divided longitudinally and subperiosteally elevated from the radial and ulnar margins of the pisiform.
At this point the pisiform can be excised or internally fixed with mini-fragment screws or Kirschner wires.
The risk for hardware migration, penetration into the pisotriquetral joint, and other complications in the region of the ulnar neurovascular bundle must be weighed against the good results expected with simple excision.
The split FCU is closed with a nonabsorbable suture and the subcutaneous tissue and skin are sutured in routine fashion.
HOOK OF HAMATE EXCISION
The hook can be identified before incision by placing the interphalangeal joint of the surgeon's thumb on the pisiform and flexing the thumb toward the first web space. The surgeon's thumb tip will land directly on top of the hook.
The hamate hook can be approached through a volar incision (preferred) or directly ulnar, proceeding palmar to the small finger metacarpal and dorsal to the abductor digiti minimi.
A longitudinal or curvilinear skin incision is made, centered over the hook (TECH FIG 3A).
The ulnar nerve and artery are identified proximally first and then traced distally, ulnar and superficial to the hamate hook (TECH FIG 3B–D).
Once the level of the hook is reached distally, the ulnar neurovascular bundle is gently retracted ulnarly.
Soft tissue attachments to the tip of the hook are incised longitudinally, including the transverse carpal ligament radially and the pisohamate ligament ulnarly and proximally.
The deep motor branch of the ulnar nerve should be identified as it passes distally around the base of the hamate hook in an ulnar-to-radial direction and must be protected during excision (TECH FIG 3E).
The digital flexors within the carpal canal are identified. The ring and small finger flexors, especially the profundus tendons, are inspected to ensure integrity and should be débrided or repaired as needed (TECH FIG 3F).
The tendons are then gently retracted radially.
TECH FIG 3 • Excision of hamate hook fractures. A. The cardinal line of Kaplan, drawn from the apex of the first web space to the ulnar border of the hand, intersects a second line drawn along the ulnar margin of the ring digit at the hamate hook (circle). A 3-cm incision is centered over the hamate hook, gently curving with the radial border of the hypothenar eminence. B. The ulnar nerve and artery can be found proximally first and then traced distally, ulnar and superficial to the hamate hook. C. The ulnar artery is encountered first, volar and radial to the ulnar nerve. D. With the artery retracted ulnarly, the common digital nerve to the fourth web space and the small digit ulnar sensory nerve are visualized. The deep motor branch and the hypothenar motor branch have already been given off. E. The hamate hook is subperiosteally exposed and its margins are palpated with an elevator. The deep motor branch curves radially, closely associated with the distal surface of the hook. F. Care is also taken to protect the flexor tendons during exposure and resection, seen here on the radial margin of the hook.
The hook is cleared of all soft tissue attachments down to the level of the fracture site.
A no. 69 Beaver blade helps make this exposure precise.
Using a rongeur or similar tool, the fractured hook is removed piecemeal, again with care to protect the deep ulnar motor branch and other structures.
Once the fragment is removed, the remaining base is inspected and smoothed with a rongeur, curette, or similar tool until there are no sharp bony prominences.
The surrounding periosteum is closed if possible.
Subcutaneous tissue and skin closure is performed in a routine manner.
HAMATE BODY FRACTURES
A dorsal longitudinal or curvilinear incision is made centered over the ring or small finger CMC joints (TECH FIG 4A).
The ring and small finger extensor tendons are retracted radially or ulnarly together or individually as needed.
There can be significant variation in the anatomic appearance and interconnections of the extensor digitorum communis tendons to the ring and small fingers as well as the EDM (TECH FIG 4B). These variations usually dictate which direction to retract the tendons and whether to retract them together or individually to give the best access to the CMC joints.
The CMC joint capsule and dorsal CMC ligaments are incised longitudinally. The CMC joint is cleared of any hematoma and bone fragments (TECH FIG 4C).
The fracture site is cleared of hematoma and reduced while directly visualizing the distal articular surface.
A dental pick is useful to reduce small fragments.
The fracture is temporarily stabilized with Kirschner wires and fluoroscopic images are taken to confirm reduction (TECH FIG 4D,E).
If there is a large dorsal fragment, two or more dorsalto-volar lag screws (usually 2.0-mm screws or smaller) are placed perpendicular to the fracture line into the hamate body (TECH FIG 4F,G).
If there are several small fragments, individual screws may be used for each piece, or a dorsal plate may be more effective (TECH FIG 4H).
Fluoroscopic images are necessary to confirm that the screws do not protrude outside of the hamate hook, potentially damaging ulnar neurovascular structures or flexor tendons.
The dorsal capsuloligamentous sleeve is closed if possible, thus providing a smooth gliding surface between the extensor tendons and the CMC joint and hardware.
The CMC joints may be pinned temporarily if still unstable.
In the acute setting, if the dorsal hamate fracture is of sufficient size and securely stabilized and the joint capsule is closed, this is usually not necessary.
Soft tissues and skin are closed in a routine manner.
TECH FIG 4 • Fixation of hamate dorsal shear fractures. A. Dorsal curvilinear incision centered on ring finger–small finger carpometacarpal joint. B. Extensor tendons exposed. C. Ring finger–small finger carpometacarpal joint exposed. D. Dorsal hamate reduced and instrumented. E. Temporary Kirschner wire. F,G. Screw fixation. H. Plate fixation.
CAPITATE FRACTURES
Often a standard approach to the dorsal carpus is required and is carried out through the routine 3–4 extensor compartment interval.
A dorsal midline longitudinal or curvilinear skin incision is made, in line with the middle finger ray and centered on the capitate.
Full-thickness skin flaps are elevated radially and ulnarly.
The extensor pollicis longus (EPL) is identified, released from its third extensor compartment, and transposed radially.
The plane between the extensor tendons and the wrist capsule is developed by elevating the second and fourth compartments radially and ulnarly, respectively.
The joint capsule and dorsal intercarpal ligament are usually divided longitudinally for access to the capitate body.
Alternatively, the capsule can be opened longitudinally distal to the dorsal intercarpal ligament (TECH FIG 5).
The capsule can be incised transversely distal to the ligament and in line with its fibers, provided that exposure of the capitate is adequate for reduction and fixation of the fracture.
The fracture site is explored, cleaned as necessary, and stabilized with mini-screws, plates, or pins as indicated.
The capsule and dorsal intercarpal ligament, if divided, are repaired.
The EPL tendon is left transposed, superficial to the extensor retinaculum.
The retinaculum is closed over the second and fourth compartments, followed by routine closure of subcutaneous tissue and skin.
TECH FIG 5 • Dorsal intercarpal ligament anatomy.
TRAPEZOID FRACTURES
The trapezoid is approached through a limited dorsal longitudinal or curvilinear incision centered over the index CMC.
Care must be exercised to identify and protect dorsal radial sensory nerve branches.
The EPL tendon is identified, released, and transposed radially if needed.
In the case of limited exposure of the trapezoid, simple retraction of the EPL distal to the extensor retinaculum is effective.
A longitudinal interval is developed between the extensor carpi radialis longus (ECRL) and brevis (ECRB) tendons with radial and ulnar retraction, respectively.
It is important to stay ulnar to the ECRL to avoid inadvertent damage to the dorsal branch of the radial artery.
The capsule is divided longitudinally, exposing the trapezoid and the index CMC joint.
Fracture fixation is carried out with mini-screws or pins, the capsule is closed, and routine subcutaneous tissue and skin closure is performed.
TRAPEZIUM FRACTURES
Fractures of sufficient size and significant displacement are internally fixed (TECH FIG 6).
Excision rather than internal fixation may be warranted based on preoperative and intraoperative considerations.
Unless the fracture planes dictate a specific approach for fixation, the surgeon has the option of using whichever approach he or she is most comfortable with for routine surgical treatment of thumb CMC arthritis (see Chap. HA-102).
The Wagner approach (described below) is one such approach frequently used for surgical reconstruction of thumb CMC arthritis and is an effective exposure for internal fixation of body fractures.
Isolated trapezial ridge fractures and nonunions are best approached using the flexor carpi radialis (FCR) approach centered on the scaphotrapezial joint, with retraction of the FCR ulnarly or radially out of its trapezial groove to gain access to the ridge. The Wagner approach is also effective.
TECH FIG 6 • Open reduction and internal fixation of a trapezial body fracture.
For the Wagner approach, an incision is made along the radial border of the thumb metacarpal at the glabrous skin border.
At the distal volar wrist crease, the incision is continued ulnarly to the level of the FCR tendon.
Superficial radial sensory nerve and lateral antebrachial cutaneous nerve branches may be encountered and should be carefully preserved.
The thenar musculature is elevated in a radial-to-ulnar direction off the thumb metacarpal base.
Once the FCR tendon sheath is reached, it is incised longitudinally and the tendon is retracted ulnarly if necessary.
The capsule overlying the trapeziometacarpal and scaphotrapezial joints is opened and the joints are visualized.
The entire length of the trapezium may be exposed if needed, but it is critical to avoid subperiosteal dissection where not necessary for accurate fracture reduction.
Extensive exposure may result in delayed union or nonunion.
At this point, internal fixation is performed if technically feasible, usually using lag screw fixation.
The capsule is carefully reapproximated and the subcutaneous tissues and skin are closed.
POSTOPERATIVE CARE
Patients are placed in a well-padded volar plaster wrist splint postoperatively.
The digits, including the metacarpophalangeal (MCP) joints, are left free unless there is some contraindication, like a dorsal hamate fracture with CMC dislocation, which may require inclusion of MCP joints.
This allows early digital range of motion and elevation.
Following ORIF of a trapezial fracture, a short-arm thumb spica splint is applied.
Two weeks postoperatively the patient is placed in a custom fabricated splint (assuming there is no associated carpal instability).
If pins were used and are left outside of the skin, pin care is initiated at this time. Pins are usually removed 4 to 8 weeks postoperatively.
In the case of a CMC joint fracture in which relatively large fracture fragments are anatomically stabilized with rigid internal fixation, near-immediate postoperative range of motion is initiated.
For most other fractures, a total of about 6 weeks of wrist immobilization is followed by progressive range of motion.
OUTCOMES
Most isolated carpal bone body fractures unite, and it is generally thought that these patients do quite well with regard to symptomatic and functional recovery.
The potentially symptomatic exceptions involving the hamate hook and trapezial ridge are easily treated by excision. Posttraumatic symptoms from other fractures, such as of the pisiform, trapezium, or triquetrum, may usually be addressed with isolated carpal bone excision with or without reconstruction, depending on the bone in question and other soft tissue and ligamentous considerations. For those carpal bones that cannot typically be simply excised, such as the hamate body and capitate, symptomatic posttraumatic changes may require partial or total wrist arthrodesis or other reconstructive options.
Associated injuries are often the most problematic, and patients must understand the guarded prognosis for severe destabilizing carpal injuries.
COMPLICATIONS
Those complications common to all surgical procedures may occur, including but not limited to bleeding, infection, damage to structures, failure of surgery, potential need for more surgery, and untoward effects of anesthesia.
Patients must also understand the relative severity of their injuries and risk for pain, stiffness, and loss of function.
Capitate neck fractures are sometimes associated with nonunion or delayed union (up to 50% or more of isolated fractures) and may be analogous to scaphoid proximal pole fractures.
Treatment of such nonunions is similar for both entities.
Although rare, avascular necrosis of the capitate head may follow a capitate neck fracture that disrupts the vascular supply.
The capitate head may be excised with or without interpositional arthroplasty if attaining union is not likely because of avascularity or other issues.
Intra-articular fractures of the carpal bones are often complicated by posttraumatic arthritis. When symptomatic, treatment with traditional arthritis remedies, such as activity modification, anti-inflammatory medications, immobilization, or steroid injection, can be tried. If these fail to relieve the patient's symptoms to his or her satisfaction, the patient may elect to proceed with partial or total wrist arthrodesis, partial carpectomy, whether of the proximal row or otherwise, or selective arthroplasties as indicated.
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