7. Hand and Wrist MCQs

The superior ulnar collateral, inferior ulnar collateral, and posterior ulnar recurrent arteries provide consistent vascular supply to the ulnar nerve. This supply is segmental in nature. The inferior ulnar collateral artery provides the only direct vascularization to the nerve and is located in the region just proximal to the cubital tunnel. The segmental nature of the blood supply to the ulnar nerve underscores the importance of its preservation during transposition.

DISCUSSION: The collateral ligaments of the MCP joint of the thumb can be isolated by flexing the joint to 30 degrees. Full extension is best to assess the accessory collaterals and the palmar plate. The ulnar collateral ligament nearly always separates from the base of first phalanx of the thumb; it frequently becomes lodged between adductor pollicis aponeurosis and its normal position (Stener lesion). The creation of a Stener lesion requires significant radial deviation of the phalanx along with combined tears of the proper and accessory collateral ligaments in order for the ligament to be displaced above the adductor aponeurosis. REFERENCES: Koval KJ (ed): Orthopaedic Knowledge Update 7. Rosemont, IL, American Academy of Orthopaedic Surgery, 2002, pp 339-358. Stener B: Displacement of the ruptured ulnar collateral ligament of the MP joint of the thumb: A clinical and anatomical study. J Bone Joint Surg Br 1962;44:869-879.

Discussion: In the midforearm, the ulnar nerve travels deep to the flexor carpi ulnaris muscle and ulnar to the ulnar artery as it lies on the flexor digitorum profundus muscle. In this region, the ulnar nerve and artery lie side-by-side, whereas more proximal in the forearm, the ulnar artery originates from the brachial artery in the antecubital fossa, and the ulnar nerve lies within the cubital tunnel.

Explanation: If a single flexor digitorum profundus (FDP) tendon is debrided more than 1 cm prior to repair, the tendon is advanced too far distally, essentially shortening the musculotendon unit. The finger will likely develop a flexion posture. Because of the common muscle belly and interconnections of the profundi, the long and small fingers adjacent to the injured finger will be affected because of loss of some of their normal proximal excursion. The result is an inability of the adjacent fingers to completely flex. This condition, known as quadrigia, is named after the Roman chariot driver who held control of the reins of 4 horses, forcing them to move as 1. Quadrigia occurs when the FDP tendon is advanced too far distally, when a tendon graft is too short, or when the profundus is sutured over the end of an amputated digit.

The patient has an avulsion of the flexor digitorum profundus. Treatment should include surgical exploration and tendon reinsertion. This is not an avulsion of the flexor digitorum superficialis because the patient’s deficiency is the inability to flex the distal interphalangeal joint, not the proximal interphalangeal joint. Surgical release of the anterior interosseous nerve is not indicated because the flexor digitorum profundus of the ring finger is innervated by the ulnar nerve.

The arrow is pointing to the ulnar nerve within Guyon’s canal. Guyon’s canal is approximately 4 cm long, beginning at the proximal extent of the transverse carpal ligament and ending at the aponeurotic arch of the hypothenar muscles. Within Guyon’s canal, the ulnar nerve bifurcates into the superficial and deep branches. The ulnar artery is immediately adjacent and radial to the ulnar nerve.

Hypothenar atrophy is a nonspecific sign that can be seen in ulnar neuropathy, C8 radiculopathy, or even cervical myelopathy; however, the atrophy usually is not unilateral and includes other muscle groups. The Spurling test is an excellent method of eliciting cervical radicular pain but involves hyperextension and ipsilateral rotation of the cervical spine, resulting in nerve root compression by reducing the cross-sectional area of the ipsilateral neuroforamen. Tinel’s sign at the levator scapulae, if present, is indicative of an upper cervical (C3 or C4) radiculopathy. A subluxable ulnar nerve at the cubital tunnel, while often asymptomatic, points toward cubital tunnel syndrome as an etiology for this patient’s pain. The shoulder abduction relief (SAR) sign (relief of upper extremity pain with shoulder abduction) is virtually pathognomic of cervical radiculopathy because this maneuver results in relaxation of a compressed and/or inflamed cervical nerve root. The SAR sign is the converse analog of the straight leg raising sign in the lumbar examination for lumbar radiculopathy, as it relieves tension in the nerve root, thereby relieving symptoms.

The history and examination findings suggest an acute fracture of the hook of the hamate. The radiographic study considered most helpful in identifying this type of fracture is the carpal tunnel view.

The clinical photographs indicate that the tenodesis effect of digit flexion with passive wrist extension and digit extension with passive wrist flexion is intact, indicating no discontinuity of the extensor or flexor tendons. The most likely injury is a laceration of the posterior interosseous nerve.

The CT scan shows prominent dorsal hardware a few millimeters ulnar to Lister’s tubercle. The contents of the fourth dorsal compartment run just ulnar to Lister’s tubercle. The EDC tendon is likely irritated in this patient.

Only the flexor sheaths of the thumb and small finger are continuous from the digit through the carpal canal and into the distal forearm. If one of the sheaths ruptures from synovitis, it may contaminate the other sheath through Parona’s space in the distal forearm.

According to the referenced article by Jupiter and Fernandez, the most common scenario of extensor pollicis longus rupture after a distal radius fracture is when the fracture is non or minimally displaced. The hypothesis is that the rupture happens at an area of relative hypovascularity and healing callus can aggravate this area, leading to a degenerative tear.

DISCUSSION: The wound described indicates loss of soft tissue directly to the level of the tendon, precluding use of skin grafts if excursion of the tendon is desired. A cross-finger flap is ideal for small wounds on the volar aspect of digits. A thenar flap is suitable for tip injuries. A lateral arm flap will not reach the fingers. A Moberg flap is limited to distal injuries of the thumb.

DISCUSSION: The treatment of choice for proximal pole scaphoid fractures is open reduction and internal fixation with a differential pitch screw via a dorsal approach. Healing rates of 100% have been reported for these acute fractures. Casting results in slow healing, with recommendations including 16 weeks or more in a cast. Vascularized bone grafts are not indicated for acute fractures. REFERENCES: Rettig ME, Raskin KB: Retrograde compression screw fixation of acute proximal pole scaphoid fractures. J Hand Surg 1999;24:1206-1210. Raskin KB, Parisi D, Baker J, et al: Dorsal open repair of proximal pole scaphoid fractures. Hand Clin 2001;17:601-610.

The patient has acute rupture of the extensor tendons to the fifth and fourth fingers. Her X-rays show generalized severe arthritis, consistent with rheumatoid arthritis, in the distal radius and ulna, the carpals, and MCPs. There also appears to be a sharp osteophyte on the dorsal surface of the distal ulna (Fig 39c). Rheumatoid arthritis affects both joints and tendons because both are lined with synovium. The distal ulna typically becomes roughened with a sharp edge which acts“like a buzzsaw” on the overlying tendons. This is called a Vaughan-Jackson lesion when extensor tendons are ruptured at the distal radial-ulnar joint. Of the dorsal/extensor compartments, typically the digiti minimi is involved first and further ruptures progress radially as the hand ulnarly deviates and the other tendons sublux and are brought within range of the “buzzsaw.” The cited articles state that after a dorsal exposure the hypertrophic tenosynovium is removed from each tendon sytematically, and the wrist joint then evaluated. Any bony spicules which may further damage tendons are removed, and the distal ulna is excised. Tendon transfers, grafts, or repairs are then performed. Surgical results tend to be better with single or double tendon ruptures than with multiple tendon ruptures.

The clinical photograph shows a classic boutonniere deformity. It is likely that the patient sustained a volar dislocation of the proximal interphalangeal joint, with a concomitant rupture of the central slip insertion of the extensor tendon.

The MRI scan reveals a laceration through the abductor hallucis musculature and lateral plantar nerve, producing numbness along its distribution. There is no evidence of a foreign body on the MRI scan. Baxter’s nerve, or nerve to the abductor digiti quinti muscle, is the first branch off the lateral plantar nerve and impingement of this nerve typically produces a Tinel’s sign along the nerve branch deep to the abductor hallucis muscle. Interdigital neuroma would be suggested by the presence of a Mulder’s click. A digital nerve laceration would exhibit isolated numbness more distally.

The correct progression of the annular and cruciform pulley in the digits is A1, A2, C1, A3, C2, A4, C3. The two cruciform pulleys are collapsible elements adjacent to the more rigid annular pulleys of the flexor tendon sheath. This arrangement enables unrestricted flexion of the proximal interphalangeal joint.

DISCUSSION: The arteriogram shows generalized disease of all vascular structures. Even though the image was obtained following an infusion of nitroglycerin, little flow is present to the fingers. Based on the history of soft-tissue calcifications and telangiectasia, the most likely diagnosis is CREST (calcinosis, Raynaud’s phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasias). The arteriogram reveals Raynaud’s phenomenon or the “R” component of CREST. Buerger’s disease, or thromboangiitis obliterans, is strongly associated with a history of smoking. Hypothenar hammer syndrome involves repetitive trauma to the ulnar artery at the wrist, resulting in well-defined filling defects in the superficial palmar arch of the hand.

The video shows the lack of tenodesis caused by the incompetence of the FDP tendon to the ring finger, which can be attributable to a laceration, tendon rupture, or avulsion. Note how the ring finger stays extended (compared to the other digits) when the extensor tendons are tightened during wrist extension. The other fingers are pulled into flexion by the FDP tendons when the extensor tendons are relaxed during wrist extension. With the wrist flexed, the extensor mechanism to all fingers appears to be functioning normally. Findings indicating a trigger finger would be locking in flexion of the proximal interphalangeal joint. FDS incompetence can only be detected by blocking FDP function of the other fingers and actively flexing the examined finger.