Following reestablishment of arterial and venous flow, which of the following is the most appropriate management of the nerve injuries?

(A) Delayed reconstruction following healing and stabilization of the humerus fracture
(B) Use of absorbable polyglycolic acid conduits to bridge the gap between nerve endings
(C) Sural nerve cable grafting to bridge the gap between nerve endings
(D) Transfer of the ipsilateral intercostal nerves to the distal ends of the radial and median nerves
(E) Humeral shortening with primary repair of the proximal and distal nerve ends

The correct response is Option E.

Following reestablishment of arterial and venous flow, the most appropriate next step is humeral shortening with primary repair of the proximal and distal nerve ends. Nerve repair should ideally be performed as a primary end-to-end repair without tension; in patients with bone comminution, the bone can be shortened within limits to alleviate tension. Shoulder abduction will increase median nerve length by 2.5 cm and ulnar nerve length by 2 cm; elbow flexion will increase the length of both the median and ulnar nerves by an additional 4 cm.

Delayed reconstruction will ultimately be more difficult because the injured nerves will have become retracted and scarred, and mobilization will be limited.

Absorbable polyglycolic acid conduits have been used successfully in bridging digital nerve gaps of 4 mm or less. However, success has not been reported with the use of this material for repair of major peripheral nerves.

Non-interfascicular nerve cable grafts do not optimize fascicle-to-fascicle opposition and thus provide poor results; interfascicular nerve grafts are now used instead. Results seen with nerve grafting are typically less satisfactory than primary repair, especially in older patients. Interfascicular sural nerve grafts can be used in patients in whom humeral shortening is not an option.

Nerve transfer is inappropriate in this patient because the proximal, median, and radial nerves can be repaired instead. Likewise, a neurotization procedure, which involves embedding of the distal end of a nerve in continuity with the spinal cord directly into a recipient muscle, is also not indicated because the distal nerve ends are available for use.

References
1. Brushart TM. Nerve repair and grafting. In: Green DP, Hotchkiss RN, Pederson WC, eds. Operative Hand Surgery. 4th ed. New York, NY: Churchill Livingstone, Inc; 1999;2:1381-1403.
2. Trumble TE, McCallister WV. Repair of peripheral nerve defects in the upper extremity. Hand Clin. 2000;16:37-52.
3. Weber RA, Breidenbach WC, Brown RE, et al. A randomized prospective study of polyglycolic acid conduits for digital nerve reconstruction in humans. Plast Reconstr Surg. 2000;106:1036-1045.

A 15-year-old boy has a 1-cm defect of the ulnar nerve after sustaining a laceration of the nerve at the distal wrist crease, just proximal to Guyon's canal. During dissection of the ulnar nerve at the wrist in preparation for nerve repair, the motor fascicular group can be identified at which of the following sites?

(A) Interwoven with the sensory group
(B) Radial and dorsal to the sensory group
(C) Radial and palmar to the sensory group
(D) Ulnar and dorsal to the sensory group
(E) Ulnar and palmar to the sensory group

The correct response is Option D.

During dissection of the ulnar nerve at the wrist in preparation for nerve repair, the motor fascicular group can be identified ulnar and dorsal to the sensory group at the wrist. The motor fascicles in the arm are consistently found between the sensory fascicles to the dorsal sensory nerve branch and the ulnar sensory fascicles to the ring and small fingers. Beyond the dorsal cutaneous nerve branch, the fascicles lie ulnar and slightly dorsal to the sensory fascicular group and then pass dorsal and radial to the cutaneous fascicular group in Guyon's canal.

References
1. Mackinnon SE, Dellon AL. Ulnar nerve entrapment at the wrist. In: Mackinnon SE, Dellon AL, eds. Surgery of the Peripheral Nerve. New York, NY: Thieme Medical Publishers, Inc; 1988:197-216.
2. Mackinnon SE. Nerve injuries: primary repair and reconstruction. In: Cohen M, ed. Mastery of Plastic and Reconstructive Surgery. Boston, Mass: Little, Brown & Co; 1994;3:1598-1624.
3. Sunderland S. Nerve and Nerve Injuries. Baltimore, Md: Williams & Wilkins; 1968:758-762.

PHOTO

A 65-year-old man with tetraplegia to the level of C5-6 has the forearm supination deformity shown in the photograph above. On examination, the supination deformity can be passively corrected. In order to relieve the deformity and improve arm function, which of the following is the most appropriate management?

(A) Release of the biceps tendon
(B) Redirecting the brachioradialis tendon into the flexor carpi ulnaris tendon
(C) Redirecting the biceps tendon through the interosseous membrane
(D) Transfer of the triceps tendon to the biceps tendon
(E) Transfer of the biceps tendon to the brachialis tendon

The correct response is Option C.

In order to permanently correct this patient's supination deformity and improve arm function, the biceps tendon should be redirected through the interosseous membrane. The supination deformity shown in the photograph is common to patients who have C5-6 tetraplegia, but the resting hand position results in loss of function and a displeasing aesthetic appearance. Functional improvement can be achieved by performing a tendon transfer to place the hand in a pronated position (eg, a palm-down position on a table top). This will improve the current aesthetic appearance and allow further tendon transfers to potentially establish key pinch. Because the biceps tendon is the strongest supinator in the forearm, it can be redirected through the interosseous membrane, then reattached to itself to establish forearm pronation. Redirecting the tendon insertion will convert a supinator tendon into a pronator tendon.

Release of the biceps tendon will impair elbow flexion and further weaken upper extremity strength. The brachioradialis tendon, which is the strongest elbow flexor, inserts into the ulna and does not influence supination and pronation in the forearm. Transferring the triceps to the biceps or the biceps to the brachioradialis will not correct the supination deformity.

References
1. McDowell CL, House JH. Tetraplegia. In: Green DP, Hotchkiss RN, Pederson WC, eds. Operative Hand Surgery. 4th ed. New York, NY: Churchill Livingstone, Inc; 1999;2:1594.
2. Zancolli E. Surgery for the quadriplegic hand with active, strong wrist extension preserved: a study of 97 cases. Clin Orthop. 1975;112:101-113.

An otherwise healthy 64-year-old man is unable to extend the left wrist and fingers 24 hours after undergoing release of Dupuytren's contractures of the ring and small fingers. Anesthesia for the procedure was provided using a brachial plexus block with 1% lidocaine and inflation of the pneumatic tourniquet to 300 mmHg for 70 minutes. On current examination, active flexion of the wrist and fingers is possible. Capillary refill is less than 3 sec in all digits.

These findings are most consistent with which of the following?

(A) Compartment syndrome
(B) Extensor mass ischemia
(C) Persistent brachial plexus block
(D) Post-tourniquet syndrome
(E) Radial nerve palsy

The correct response is Option E.

This patient has findings consistent with radial nerve palsy. Complications associated with pneumatic tourniquets have been reported in one of every 5000 to 8000 patients following tourniquet use. Post-tourniquet nerve palsies are more frequently associated with the use of rubber bandages. The most common complication following tourniquet use is nerve injury; the radial nerve is affected most frequently. Such nerve palsies result from pressure beneath the cuff rather than prolonged ischemia; most cases reportedly result from use of faulty pressure gauges. Permanent nerve deficits are rare; most patients have resolution of symptoms within six months. Tourniquet times of two hours at a pressure of 250 mmHg are commonly used in adults.

Although compartment syndrome has been reported as a complication of pneumatic tourniquet use, it typically occurs secondary to prolonged ischemia.

Muscle weakness resulting from intraoperative ischemia is unlikely in this patient because the pneumatic tourniquet was inflated for only 70 minutes.

In a patient who receives a brachial plexus block with 1% lidocaine, numbness should resolve within six hours.

Findings of post-tourniquet syndrome include edema, stiffness, pallor, weakness without paralysis, and subjective numbness without anesthesia. This condition results from prolonged ischemia, not direct tourniquet pressure, and may even be a mild form of compartment syndrome or ischemic reperfusion.

References
1. Gersoff WK, Ruwe P, Jokl P, et al. The effect of tourniquet pressure on muscle function. Am J Sports Med. 1989;17:123-127.
2. Guerra JJ, Bednar JM. Equipment malfunction in common hand surgical procedures: complications associated with the pneumatic tourniquet and with the application of casts and splints. Hand Clin. 1994;10:45-52.
3. O'Neil D, Sheppard JE. Transient compartment syndrome of the forearm resulting from venous congestion from a tourniquet. J Hand Surg. 1989;14A:894-896.

A 37-year-old man has severe pain, swelling, and discoloration of the right hand one month after sustaining a crush injury to the dorsal aspect of the hand. A 4-cm laceration was repaired at the time of injury; there were no fractures or tendon injuries. On examination, the hand is swollen and stiff.

These findings are most consistent with which of the following conditions?

(A) Osteomyelitis
(B) Posttraumatic arthritis
(C) Reflex sympathetic dystrophy
(D) Secretan's disorder
(E) Suppurative tenosynovitis

The correct response is Option C.

This patient's findings are most consistent with reflex sympathetic dystrophy (RSD) or complex regional pain syndrome (CRPS), which manifests as a progressive or complex pain syndrome. Severe pain, swelling, stiffness, and
discoloration of the affected part are characteristic. These changes are thought to result from vasomotor instability of the sympathetic nervous system. Hyperhidrosis, osteoporosis, and trophic changes may also occur. The stages of reflex sympathetic dystrophy are acute, subacute, and chronic.

Osteomyelitis is a bone infection that develops secondary to an adjacent wound, joint, or tenosynovial infection. Osteomyelitis can also arise from blood-borne pathogens.

Patients with posttraumatic arthritis have joint pain, stiffness, and swelling that develop following intra-articular injury; however, the pain is typically less severe than in patients with RSD.

Secretan's disorder or peritendinous fibrosis is often associated with minor work-related trauma. It is characterized by edema of the dorsal aspect of the hand and factitious lymphedema of the hand. This condition is typically not associated with the severe pain of RSD.

Suppurative tenosynovitis is characterized by fusiform swelling, tenderness along the flexor tendon sheath, and increased pain with passive extension or semiflexed positioning of the finger.

References
1. Doyle JR. Extensor tendons Ð acute injuries. In: Green DP, Hotchkiss RN, Pederson WC, eds. Operative Hand Surgery. 4th ed. New York, NY: Churchill Livingstone, Inc; 1999;2:1950-1987.
2. Neviaser RJ. Acute infections. In: Green DP, Hotchkiss RN, Pederson WC, eds. Operative Hand Surgery. 4th ed. New York, NY: Churchill Livingstone, Inc; 1999;2:1033-1047.
3. Soucacos PN, Disnitsas LA, Beris AE, et al. Reflex sympathetic dystrophy of the upper extremity. Hand Clin. 1997;13:339-354.
4. Wolfe SW. Tenosynovitis. In: Green DP, Hotchkiss RN, Pederson WC, eds. Operative Hand Surgery. 4th ed. New York, NY: Churchill Livingstone, Inc; 1999;2:2022-2044.

A 35-year-old assembly-line worker has pain in the right upper extremity. On examination, there is pain and tenderness over the mobile wad; long finger extension and resisted supination tests are positive. These findings are most consistent with which of the following syndromes?

(A) Carpal tunnel syndrome
(B) Cubital tunnel syndrome
(C) Intersection syndrome
(D) Radial tunnel syndrome
(E) Wartenberg's syndrome

The correct response is Option D.

This patient has symptoms consistent with radial tunnel syndrome, which is characterized by pain and tenderness over the mobile wad (radial tunnel) that occurs with extension, supination against resistance, or passive flexion and pronation of the wrist. Pain is localized just below the elbow in the extensor mass and along the course of the radial nerve. Radial tunnel syndrome has no sensory or motor loss. The compressing structures are the vascular leash, the arcade of Frohse, and the extensor carpi radialis brevis tendon.

Patients with carpal tunnel syndrome have pain at night, numbness, and tingling in the thumb, index, and long fingers and the radial side of the ring finger. Thenar weakness can develop. Associated findings include a positive Tinel's sign over the carpal tunnel and positive findings on both the Phalen's and reverse Phalen's tests.

Cubital tunnel syndrome, or compression of the ulnar nerve at the elbow, is characterized by numbness and tingling in the ring and small fingers, pain over the medial aspect of the elbow, and sensory deficits along the ulnar side of the palm and in the ring and small fingers. Weakness develops in both the ulnar extrinsic and intrinsic motors. In patients with entrapment of the ulnar nerve at the wrist, numbness and tingling in the ring and small fingers are also presenting signs. These patients can also develop ulnar intrinsic weakness.

Intersection syndrome is a pain syndrome localized to the distal forearm at the intersection of the first extensor compartment (which contains the abductor pollicis longus and extensor pollicis brevis muscle bellies) and the second extensor compartment (which contains the extensor carpi radialis longus and brevis tendons). Patients with intersection syndrome have pain, swelling, and crepitus in the distal forearm proximal to the Lister tubercle. Symptoms are caused by tightness of the retinaculum over the first and second dorsal compartments associated with tenosynovitis of the tendons. Corticosteroid injections or tenosynovectomy are recommended for treatment.

In Wartenberg's syndrome (ie, cheiralgia paresthetica), the radial nerve is compressed beneath the edge of the brachioradialis muscle at the level of the wrist. Affected patients have persistent pain on the dorsoradial surface of the hand and distal aspect of the forearm. Examination is most likely to show sensitivity to percussion over this area; Tinel's sign is most likely to be positive over the course of the superficial radial sensory nerve along the dorsal edge of the brachioradialis muscle. The patient should first be instructed to avoid wearing tight jewelry or bracelets in the area. Operative exploration may be indicated in patients with persistent symptoms; however, decompression procedures are only associated with moderate success rates.

References
1. Barnum M, Mastey RD, Weiss AP, et al. Radial tunnel syndrome. Hand Clin. 1996;12:679-689.
2. Campion D. Electrodiagnostic testing in hand surgery. J Hand Surg. 1996;21A:947-956.
3. Jebson PJ, Engber WD. Radial tunnel syndrome: long-term results of surgical decompression. J Hand Surg. 1997;22A:889-896.
4. Kleinert JM, Mehta S. Radial nerve entrapment. Orthop Clin North Am. 1996;27:305-315.

Which of the following sensations is detected by the Pacinian corpuscles located within the skin and subcutaneous tissue?

(A) Burning pain
(B) Moving two-point discrimination
(C) Sharp pain
(D) Static two-point discrimination
(E) Vibration

The correct response is Option E.

The Pacinian corpuscles detect vibration to a sensitivity of 250 Hz. These rapidly adapting receptors are found in the subcutaneous tissue and can be identified easily on sight. They relay their signals through small myelinated A-beta fibers. However, each receptor covers a large area of skin and does not localize vibration sensation well.

Burning pain is detected by the free endings of C fibers, while sharp pain is detected by the free endings of A-delta fibers. Specific receptors are not involved.

Meissner's corpuscles are located at the sides of the intermediate dermal ridge. These rapidly adapting receptors, which have a small area of skin sensitivity, fire at the beginning of a stimulus and occasionally at the end but never in between, and, therefore, are able to detect moving two-point discrimination.

Merkel cells detect static two-point discrimination. These receptors can be found around the sweat ducts on the underside of the intermediate dermal ridge. These slowly adapting receptors continue to fire for the duration of the stimulus. The sensory skin area connected to one Merkel cell is also well circumscribed, measuring from 2 to 4 mm. Meissner's corpuscles and Merkel cells also relay signals via A-beta fibers.

References
1. Brushart TM. Peripheral nerve biology. In: Hand Surgery Update. Englewood, Co: American Society for Surgery of the Hand; 1994;1:20-21.
2. Gilman S, Newman SW, eds. Ascending and descending pathways. In: Manter and Gatz's Essentials of Clinical Neuroanatomy and Neurophysiology. Philadelphia, Pa: FA Davis Co; 1996.

Which of the following is the most likely site of entrapment of the posterior interosseous nerve in the forearm?

(A) Arcade of Frohse
(B) Arcade of Struthers
(C) Band of Osborne
(D) Lacertus fibrosis
(E) Ligament of Struthers

The correct response is Option A.

Nerves of the upper extremity are prone to entrapment in areas of tight passage or at sharp inflection points. The site or level of compression defines the sensory and motor findings. The median nerve can become entrapped proximally in the arm by the ligament of Struthers, which is a dense band that can form between the supracondylar humeral process and the medial epicondyle. More distally, the median nerve can become entrapped beneath the lacertus fibrosis, which is a dense fascial sheet that extends proximally to the biceps tendon from the antebrachial fascia.

The ulnar nerve exits the arm in the medial intermuscular septum. Fascial folds in this area are known as the arcade of Struthers and can pinch the nerve, especially following anterior transposition. As the ulnar nerve passes through the cubital tunnel, a constricting band can form. This band, known as the band of Osborne, must be released during neuroplasty.

The radial nerve exits the arm after passing posterior to the humerus. It divides into the superficial and deep branches; the deep branch of the radial nerve, also known as the posterior interosseous nerve, can become entrapped, typically due to a fascial band over the supinator called the arcade of Frohse. The radial nerve here can also be compromised by vascular leashes, the edge of the extensor carpi radialis brevis, the edge of the proximal supinator, and the edge of the distal supinator. Proximal compression leads to weakness of extension of the wrist, finger, and thumb, often with radial deviation of the wrist because the extensor carpi radialis longus tendon is innervated proximally.

References
1. Dawson D, Hallett M, Millender L, eds. Entrapment Neuropathies. Boston, Mass: Little, Brown & Co; 1990:97-100, 136-144, 201-208.
2. Mackinnon SE, Dellon AL, eds. Surgery of the Peripheral Nerve. New York, NY: Thieme Medical Publishers Inc; 1988:171, 226, 292.

A 45-year-old woman has pain and numbness in the right hand and forearm. There are no motor disturbances. Semmes-Weinstein monofilament testing shows decreased sensation in the index and long fingers, thumb, and palm. Phalen's and Tinel's signs are negative over the carpal tunnel.

These findings are most consistent with which of the following?

(A) Anterior interosseous syndrome
(B) C5 cervical radiculopathy
(C) Carpal tunnel syndrome
(D) Cubital tunnel syndrome
(E) Pronator syndrome

The correct response is Option E.

Although the sensory and motor deficits of carpal tunnel syndrome and pronator syndrome are similar, the sensory deficit within the palmar cutaneous region best differentiates pronator syndrome from carpal tunnel syndrome. This patient has findings consistent with pronator syndrome, or compression of the median nerve within the proximal
forearm. Sites of potential entrapment of the median nerve include the ligament of Struthers in the distal arm, the lacertus fibrosis at the level of the elbow, the pronator teres muscle, and the arch of the flexor digitorum superficialis muscle. Although symptoms are similar to carpal tunnel syndrome, sensory findings typically occur more proximally. Symptoms can be reproduced with active elbow flexion with the elbow in pronation, resisted elbow flexion, or resisted pronation with flexion of the wrist. Phalen's sign is negative in most patients with pronator syndrome.

Anterior interosseous syndrome results from compression of the anterior interosseous branch of the median nerve in the forearm. Affected patients have poorly defined pain in the forearm and weakness of the profundus tendon of the index finger and the flexor pollicis longus tendon but no sensory deficit. Cervical radiculopathy at C5 is characterized by radicular-type pain in the lateral aspect of the upper arm and forearm. Cubital tunnel syndrome is caused by entrapment of the ulnar nerve in the region of the elbow. Affected patients have sensory deficits in the small finger and ulnar aspect of the ring finger.

References
1. Olehnik WK, Manske PR, Szerzinski J. Median nerve compression in the proximal forearm. J Hand Surg. 1994;19A:121-126.
2. Szabo RM. Entrapment and compression neuropathies. In: Green DP, Hotchkiss RN, Pederson WC, eds. Operative Hand Surgery. 4th ed. New York, NY: Churchill Livingstone, Inc; 1999;2:1404.

In a patient with late Volkmann's contracture, which of the following is the most common finding?

(A) Fibrosis of the extensor muscles
(B) Fibrosis of the flexor muscles
(C) Intrinsic plus deformity
(D) Ischemic necrosis of the digits
(E) Radial nerve palsy

The correct response is Option B.

Volkmann's contracture may develop as a result of compartment syndrome occurring secondary to arterial injury or direct muscle trauma. Children who sustain supracondylar fractures are most frequently affected because the brachial artery is compromised. Affected patients have myonecrosis that leads to muscle fibrosis. The fibrosed muscle results in markedly decreased muscle strength and excursion. Ischemic or compressive neuropathy may be seen in surrounding peripheral nerves.

The severity of Volkmann's contracture correlates with the physiologic depth or location of the affected muscle and nerve. Patients with mild Volkmann's contracture have involvement of the muscle bellies of the flexor digitorum profundus (FDP) with mild impairment.

Moderate Volkmann's contracture occurs in most patients and is characterized by involvement of the FDP and flexor pollicis longus muscles; fibrosis of the flexor digitorum superficialis, flexor carpi ulnaris, and flexor carpi radialis muscles may also be seen. Affected patients have contractures of the extrinsic flexor muscles, resulting in claw hand. Neuropathy of the median nerve is most common. The ulnar nerve is less likely to be affected, and the radial nerve is rarely involved.

In patients with severe Volkmann's contracture, fibrosis of the forearm flexor muscles is most common and tends
to be uniform. Involvement of the forearm extensor muscles varies.

Thus, the typical Volkmann's contracture deformity is characterized by flexion of the wrist, flexion and adduction of the thumb, extension of the metacarpophalangeal (MP) joints, and flexion of the proximal interphalangeal (PIP) and distal interphalangeal joints.

Intrinsic plus deformities, which can result from contracture of the intrinsic muscles, are characterized by flexion of the MP joints and extension of the PIP joints.

Although untreated severe compartment syndrome can lead to ischemic necrosis of the digits, this finding is not typical of late Volkmann's contracture.

References
1. Botte MJ, Keenan MA, Gelberman RH. Volkmann's ischemic contracture of the upper extremity. Hand Clin. 1998;14:483-497.
2. Tsuge K. Management of established Volkmann's contracture. In: Green DP, Hotchkiss RN, Pederson WC, eds. Operative Hand Surgery. 4th ed. New York, NY: Churchill Livingstone, Inc; 1999;1:592-603.