7. Hand and Wrist MCQs

The radiograph shows the proximal phalanx nearly parallel with the metacarpal, where the simple dorsal dislocation of the phalanx is nearly perpendicular to the joint. A simple dislocation can be converted into a complex dislocation with attempts at closed reduction. The palmar plate, which is entrapped within the MP joint, should be incised longitudinally through its midline, allowing the metacarpal head to be reduced. For reduction of a simple dislocation, the wrist should be flexed to allow relaxation of the flexor tendons, and distal traction as well as volar-directed pressure to the base of the proximal phalanx can be successful in reducing a simple dislocation. Surgical reduction can be approached either dorsally or volarly. The volar approach jeopardizes the digital nerve. With a dorsal approach, the extensor hood and dorsal capsule should be incised longitudinally.

The piano key sign is a demonstration of instability at the DRUJ, typically seen after healing from a distal radius fracture with an associated ulnar styloid fracture (as in this case) or other wrist injury. The hand is pushed down against a table top, and the distal radius translates dorsally (with the distal ulna apparently moving volarly). In fact, the distal radius is the mobile segment, while the distal ulna is fixed in space. Treatment involves repair or reconstruction of the foveal insertion of the triangular fibrocartilage complex (TFCC) and distal radioulnar ligaments. This type of instability is also common in malunions of the distal radius or distal one-third of the radial shaft (Galeazzi-type fractures). In malunions, DRUJ instability can be treated with a corrective osteotomy of the distal radius to restore the anatomic relationship between the distal ulna and the distal radius at the DRUJ. Radiocarpal and midcarpal instability do not involve the DRUJ. Disruption of the interosseous membrane (in isolation, with intact distal radioulnar ligaments and an intact TFCC) does not lead to translational instability of the DRUJ. Although hypermobility syndrome may lead to ligamentous laxity, it does not lead to unilateral DRUJ instability.

The injury represents a somewhat uncommon problem after surgical treatment of distal radius fractures; however, vigilance is required to detect the acute presentation of a carpal tunnel syndrome. In this case, urgent release of the tunnel is recommended. Bivaling the cast alone is indicated when the pain is less severe, and only when the numbness is very minimal and more generalized. Compartment syndrome of the hand is almost unheard of in the setting of a distal radius fracture; rather it is more commonly associated with a crush injury to the hand. There is no role for emergent nerve conduction velocity studies or brachial plexus exploration.

DISCUSSION: The patient has an unstable oblique fracture of the proximal phalanx that is easily reducible but unstable; therefore, the treatment of choice is closed reduction and percutaneous pin fixation, followed by casting. Closed reduction and percutaneous pin fixation offers a better functional result than open reduction and plate fixation. Repeat closed reduction and buddy taping is inadequate because of the inherently unstable fracture pattern. Buddy taping will allow the dislocation to recur. The other options represent more aggressive surgical techniques than are necessary to treat this fracture. REFERENCES: Stern PJ: Fractures of the metacarpals and phalanges, in Green DP, Hotchkiss RN, Pederson WC (eds): Green’s Operative Hand Surgery, ed 4. Philadelphia, PA, 1999, pp 711-771. Green DP, Anderson JR: Closed reduction and percutaneous pin fixation of fractured phalanges. J Bone Joint Surg Am 1973;55:1651-1653.

EXPLANATION: This patient demonstrates scapholunate dissociation with an associated dorsal intercalated segment instability deformity. Chronic scapholunate ligament tears lead to scapholunate advanced collapse (SLAC) wrist. Watson and Ballet describe SLAC wrist as having a predictable progression of arthritic changes, starting at the radial styloid, progressing to the radioscaphoid joint, and advancing to the lunocapitate joint. Some authors have described the radiolunate joint as being affected in very late-stage SLAC wrist.

Injuries to the ulnar collateral ligament of the MCP joint of the thumb commonly occur in recreational skiers. Historically, this injury has been referred to as “gamekeeper’s thumb.” The ligament consists of the proper collateral ligament and the more volar accessory collateral ligament. In extension, the accessory ligament is taut, and in flexion, the proper ligament is taut. For a complete tear of the ligament complex to occur, there must be laxity in full extension. Incomplete tears respond well to thumb spica splinting or casting for 2 to 3 weeks and gradual resumption of range of motion. Prolonged immobilization of incomplete injuries leads to higher rates of MCP joint stiffness.

DISCUSSION: The PCBMN originates from the median nerve proper between 3 and 21 cm proximal to the wrist with moderate variation. It virtually always originates from the radial side of the nerve and travels distally with the median nerve, radial to the palmaris longus, and ulnar to the flexor carpi radialis. REFERENCES: Hobbs RA, Magnussen PA, Tonkin MA: Palmar cutaneous branch of the median nerve. J Hand Surg Am 1990;15:38-43. Netter F: The Ciba Collection of Medical Illustrations: The Musculoskeletal System: Part 1, Anatomy, Physiology and Metabolic Disorders. West Caldwell, NJ, Ciba-Geigy, 1991, vol 8, p 52.

DISCUSSION: The patient has a chronic flexor tendon laceration. There are options to restore motion and strength; therefore, fusion is not necessary. Full range of motion is present so the soft tissues are suitable for a tendon transfer. A transfer of the flexor digitorum superficialis of the ring finger to the insertion of the flexor pollicis longus on the distal phalanx provides good results with a one-stage operation. REFERENCES: Schneider LH, Wiltshire D: Restoration of flexor pollicis longus function by flexor digitorum superficialis transfer. J Hand Surg Am 1983;8:98-101. Posner MA: Flexor superficialis tendon transfers to the thumb: An alternative to the free tendon graft for treatment of chronic injuries within the digital sheath. J Hand Surg Am 1983;8:876-881.

Medoff described the radiographic teardrop of the distal radius. This radiographic landmark matches the critical volar ulnar corner of the distal radius. A malreduction of the volar ulnar corner of the distal radius in an intra-articular distal radius fracture leads to volar subluxation of the lunate and the rapid development of posttraumatic arthritis at the distal radioulnar and radiolunate joints. Knowledge of the specific shape and appearance of this radiographic landmark helps the surgeon when he or she is critically analyzing postreduction imaging. The volar portion of the ulnar head may be mistaken for this teardrop sign and should be separately identified as distinct from the distal radius. The radial styloid and Lister tubercle are not part of the volar aspect of the lunate facet.

Resection of the distal pole of the scaphoid eliminates the arthritic contact at the scaphotrapeziotrapezoid joint; however, it functionally shortens the scaphoid. Theoretically, the lunate is at equilibrium between the extension moment of the capitate and the triquetrum and the flexion moment of the scaphoid. Shortening the scaphoid allows the extension moment of the triquetrum to predominate, pulling the lunate into extension and creating a DISI deformity. Concomitant capsulodesis or interposition is recommended by some authors to prevent this complication.

This patient has late-stage Kienböck disease. According to the Lichtman classification for Kienböck disease, this would represent stage IIIB, with lunate collapse/fragmentation, loss of carpal height secondary to proximal capitate migration, and a flexed scaphoid. The lateral radiograph reveals a radioscaphoid angle exceeding 60 degrees. According to Condit and associates, when the presurgical radioscaphoid angle exceeds 60 degrees, results are poor when an attempt to maintain the lunate is made. As a result, the procedure with the most predictable outcome is a proximal row carpectomy.

The PA view of the wrist shows a pisiform fracture. Pisiform fractures constitute 1% to 3% of all carpal bone fractures. This fracture can be further evaluated with a carpal tunnel view or a supination oblique view of the wrist. Initial management should consist of immobilization with a short arm cast. If nonsurgical measures fail, bony excision is warranted.

The patient’s symptoms and examination findings are consistent with ulnar neuritis/cubital tunnel syndrome, most probably exacerbated by javelin throwing. The first step includes rest and extension splinting. Surgical intervention should only be considered after failure of nonsurgical management.

DISCUSSION: The first extensor compartment of the wrist typically contains a single extensor pollicis brevis tendon and the abductor pollicis longus tendon that nearly always has multiple tendon slips. The extensor pollicis brevis tendon is frequently found to be separated from the slips of the abductor pollicis longus tendon by an intracompartmental septum. During surgery, this septum must be divided to complete the release of the compartment. REFERENCES: Jackson WT, Viegas SF, Coon TM, Stimpson KD, Frogameni AD, Simpson JM: Anatomical variations in the first extensor compartment of the wrist: A clinical and anatomical study. J Bone Joint Surg Am 1986;68:923-926. Minamikawa Y, Peimer CA, Cox WL, Sherwin FS: DeQuervain’s syndrome: Surgical and anatomical studies of the fibro-osseous canal. Orthopedics 1991;14:545-549.

DISCUSSION: Mallet fingers without DIP joint subluxation can be treated with extension splinting. Surgical fixation may be necessary in bony mallet injuries when the joint is subluxated. Size of the bony fragment, while often correlating with stability, is not always an indication for fixation. Buddy taping allows motion; therefore, the fragment will not heal in the appropriate position. Intermittent splinting with range-of-motion exercises also will not allow the fragment to heal in the appropriate position. REFERENCES: Crawford GP: The molded polyethylene splint for mallet finger deformities. J Hand Surg Am 1984;9:231-237. Wehbe MA, Schneider LH: Mallet fractures. J Bone Joint Surg Am 1984;66:658-669.

DISCUSSION: This Galeazzi fracture is an injury that requires surgical treatment in an adult. The algorithm includes anatomic reduction of the radial shaft and closed reduction of the DRUJ with assessment of stability. If the DRUJ remains unstable, supination of the wrist may reduce the DRUJ. If not, either open or closed reduction with pinning is undertaken. The closer the radius fracture is to the DRUJ, the more likely it is to be unstable. REFERENCE: Rettig ME, Raskin KB: Galeazzi fracture-dislocation: A new treatment-oriented classification. J Hand Surg Am 2001;26:228-235.

DISCUSSION: Vascular anastamoses are exceedingly difficult with amputations distal to the nail fold as the digital vessels bifurcate or trifurcate at this level, and little functional benefit is gained compared to other means of soft-tissue coverage. Single digit amputations, other than the thumb, are a relative contraindication for replantation. Replantations at the level of the proximal phalanx lead to poor motion of the proximal interphalangeal joint. In a healthy active adult, an amputation through the wrist is an appropriate situation to proceed with a replantation. A transverse forearm amputation is a good indication with a warm ischemia time of less than 6 hours.

DISCUSSION: The tendon most prone to rupture in a patient with rheumatoid arthritis of the wrist is the extensor digiti quinti. It can be a silent injury since the extensor digitorum communis can provide extension to the fifth finger. The extensor digiti quinti is at high risk since it is overlying the ulnar head where it is prone to attritional rupture (Vaughan-Jackson syndrome).

Retrovascular cords are common in Dupuytren’s disease and commonly require surgical treatment. Nerve injury in Dupuytren’s surgery is an infrequent complication that occurs partly because the digital nerves can be displaced from their normal anatomic relationships by retrovascular cords. The nerves are displaced superficially, toward the center of the digit (palmarly and ulnarly). This displacement is typically seen at the level of the metacarpophalangeal joint.

The MRI scan shows a large mass (lipoma) in the thenar muscles of the palm. The recurrent motor branch of the median nerve innervates the thenar muscles. The anterior interosseous nerve (AIN) in the proximal forearm innervates the flexor pollicis longus, pronator quadratus, and flexor digitorum pollicis to the index and frequently the middle finger. The terminal branch of the AIN innervates only the wrist capsule. The palmar cutaneous branch of the ulnar nerve is a sensory structure to the hypothenar area. There is no commonly described recurrent branch of the ulnar nerve.