7. Hand and Wrist MCQs

DISCUSSION: All other factors being equal, a patient’s age is the most important factor in determining outcome after peripheral nerve injury. Repair of a nerve laceration within the first 2 weeks is generally considered appropriate. Fascicular repair may be of benefit in larger proximal nerves to reapproximate appropriate nerve bundles; distally perineural or epineural repair is sufficient. Use of a fibrin tissue sealant for nerve repair does not result in improved outcomes over suture repair. Nerve conduits have shown promise in digital nerves but do not have proven benefit in larger caliber nerves.

DISCUSSION: The arrows in the figure show the deep branch of the ulnar nerve (more radial) and the superficial branch of 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 ends at the aponeurotic arch of the hypothenar muscles. Many structures comprise the boundaries of Guyon’s canal. The floor, for example, consists of the transverse carpal ligament, the pisohamate and pisometacarpal ligaments, and the opponens digiti minimi. 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. The median nerve is visualized within the carpal tunnel, and the palmar cutaneous branch is more radial to Guyon’s canal and volar to the carpal tunnel. The radial and ulnar digital nerves to the little finger are branches off of the superficial branch of the ulnar nerve distal to its emergence from Guyon’s canal. The ulnar artery is the round structure located radial to the branches of the ulnar nerve within Guyon’s canal. Adjacent to the ulnar artery are two small veins. The dorsal cutaneous branch of the ulnar nerve branches from the ulnar nerve in the distal forearm, well proximal to Guyon’s canal. The common digital artery to the fourth web branches from the superficial palmar arch distal to Guyon’s canal. The hook of the hamate is clearly seen in the figure, orienting the observer to the ulnar side of the wrist. REFERENCES: Gross MS, Gelberman RH: The anatomy of the distal ulnar tunnel. Clin Orthop Relat Res 1985;196:238-247. Denman EE: The anatomy of the space of Guyon. The Hand 1978;10:69-76.

DISCUSSION: The extensor digiti minimi is most typically a tendon with two slips. The abductor pollicis longus has multiple slips that insert in order of frequency on the base of the first metacarpal, trapezium, and thenar muscles. The extensor pollicis longus, extensor carpi radialis brevis, and extensor indicis proprius consistently have only one slip. REFERENCES: von Schroeder HP, Botte MJ: Anatomy of the extensor tendons of the fingers: Variations and multiplicity. J Hand Surg Am 1995;20:27-34. Bouchlis G, Bhatia A, Asfazadourian H, et al: Distal insertions of abductor pollicis longus muscle and arthritis of the first carpometacarpal joint in 104 dissections. Ann Chir Main Memb Super 1997;16:326-338.

DISCUSSION: This patient had mild median paresthesias preoperatively that have significantly worsened postoperatively. Immediate carpal tunnel release is the most appropriate next step in treatment. Patients with acute carpal tunnel syndrome (ACTS) who undergo carpal tunnel release early have significantly better outcomes than those with delayed treatment.

DISCUSSION: Flexor digitorum profundus ruptures are classified into three types. In type I, the tendon retracts into the palm. In type II, the tendon retracts to the level of the proximal phalanx, the vinculum remains intact, and the blood supply is preserved to the tendon. A small fleck of bony fragment observed at the A2 pulley is pathognomonic for a type II rupture. Successful primary repair of the type II rupture has been reported as late as 2 months after the injury.

Transfer of fascicles from (1) ulnar nerve to the nerve to the biceps and (2) median nerve to the motor nerve of the brachialis would be appropriate in the treatment of an acute (<3-6 months) upper brachial plexus palsy. Upper trunk injury (C5, C6) often results from the avulsion of both the C5 and C6 nerve roots. Injuries of this nature usually result from a downward force on the shoulder with lateral bending of the cervical spine in the opposite direction. This results in what is commonly called an Erb-Duchenne palsy. Patients often present with a flail shoulder and loss of elbow flexion. Liverneaux et al. looked at short term results of this double nerve transfer technique in 15 patients with acute C5 - C6 nerve root avulsion injuries. Grade 4 elbow flexion was restored in each of the 10 patients. They concluded that this double nerve transfer technique will likely reduce the need for secondary procedures to augment elbow flexion.

DISCUSSION: Dodds and associates looked at short (compared to long) scaphoid screws placed down the central axis in cadavers. A long screw placed along the central axis was significantly more stable when tested in all planes of motion about the wrist. McCallister and associates examined central placement and eccentric placement in a cadaver model. Central positioning produced 43% more stiffness and 113% more load (P < .01). RECOMMENDED READINGS: Bedi A, Jebson PJ, Hayden RJ, Jacobson JA, Martus JE. Internal fixation of acute, nondisplaced scaphoid waist fractures via a limited dorsal approach: an assessment of radiographic and functional outcomes. J Hand Surg Am. 2007 Mar;32(3):326-33. Dodds SD, Panjabi MM, Slade JF 3rd. Screw fixation of scaphoid fractures: a biomechanical assessment of screw length and screw augmentation. J Hand Surg Am. 2006 Mar;31(3):405-13. McCallister WV, Knight J, Kaliappan R, Trumble TE. Central placement of the screw in simulated fractures of the scaphoid waist: a biomechanical study. J Bone Joint Surg Am. 2003 Jan;85-A(1):72-7.

The Arcade of Frohse is a fibrous band at the proximal edge of the superficial head of the supinator muscle and is the most common site of compression for the posterior interosseous nerve (PIN). PIN compression presents with motor weakness of the wrist and finger extensors (often sparing the ECRL, leading to radial deviation on wrist extension) without sensory deficits.

The LABC nerve is the most commonly injured nerve during a single-incision anterior distal biceps repair due to lateral retraction. The PIN is classically at risk during a two-incision approach if the forearm is not fully supinated during the deep dissection.

DISCUSSION: Plantar fibromas have an extremely high recurrence rate (approximately 60%) with local excision only. Resection of the entire plantar fascia is effective at eradicating the lesion. There is no role for chemotherapy or amputation with plantar fibromatosis. Radiation therapy may be helpful in combination with resection of the plantar fascia.

DISCUSSION: Apert syndrome is characterized by craniosynostosis (towered cranium), midface hypoplasia, and complex syndactyly of the hands and feet.

DISCUSSION: In this patient, examination reveals an inability to extend the fingers with the wrist extended, but full extension is possible with wrist flexion. These findings demonstrate isolated tenodesis of the flexor digitorum to the ring and little fingers. These findings are not consistent with compartment syndrome or nerve injury. Scarring or entrapment of tendons in forearm fractures can occur. REFERENCES: Watson PA, Blair W: Entrapment of the index flexor digitorum profundus tendon after fracture of both forearm bones in a child. Iowa Orthop J 1999;19:127-128. Shaw BA, Murphy KM: Flexor tendon entrapment in ulnar shaft fractures. Clin Orthop 1996;330:181-184. Kolkman KA, van Niekerk JL, Rieu PN, et al: A complicated forearm greenstick fracture: Case report. J Trauma 1992;32:116-117. Hendel D, Aner A: Entrapment of the flexor digitorum profundus of the ring finger at the site of an ulnar fracture: A case report. Ital J Orthop Traumatol 1992;18:417-419.

Due to radial inclination, a true lateral view of the wrist will not show whether screws from a volar plate are intra-articular; a 23° elevated lateral view is needed to adequately assess this.The amount of elevation will depend on the degree to which the surgeon restores radial inclination; for example, if the surgeon only restores 15° of radial inclination, then the surgeon would only have to elevate the wrist 15° from a true lateral in order to have the radiographic beam point down the joint line. Failure to diagnose intra-articular screws intraoperatively can lead to degenerative changes.Tweet et al. performed a survey of orthopedic surgeons regarding their preferred method of visualizing screw placement during wrist fixation. The majority of surgeons reported that they obtain multiple views, including AP/PA wrist views, a 23° lateral inclination view, and a true lateral view. They also performed a cadaveric study looking at different x-ray views and screw penetration. They reported that live rotational fluoroscopy provided the highest sensitivity (93%) and specificity (96%) for the detection of intra-articular screw penetration.Patel et al. evaluated the ability of surgeons at different levels to critically assess distal radius fixation and screw placement. They found that supplementation with a 23° lateral view increased accuracy and confidence in all position, specialty, and experience groups. Confidence scores were significantly higher following the evaluation of three views versus two views. Residents exhibited the greatest improvements in accuracy and confidence. For first-phase (standard view) assessments, accuracy scores were significantly better for attendings with less than 10 years of post-fellowship experience than those with more.Illustration A is a non-elevated lateral of the wrist, while illustration B is a 23° elevated lateral radiograph. Illustration C is an example of a skyline view, which assesses for screws penetrating the dorsal cortex.Incorrect Answers:check for long distal screws.OrthoCash 2020

There are many causes of inability to extend the MCP joints in a patient with rheumatoid arthritis. The most common cause is rupture of the extensor tendons. An intact tenodesis test suggests that the extensor tendons are intact, thus surgical exploration is not indicated and would not confirm the diagnosis. The patient has normal alignment of the fingers without ulnar deviation, suggesting that there are no MCP dislocations to account for the inability to extend the MCP joints; therefore, radiographs would not confirm the diagnosis. The most likely cause of inability to extend the fingers in this patient is posterior interosseous nerve (PIN) palsy. Electrodiagnostic studies would confirm the presence of PIN palsy. An MRI of the elbow may show synovitis at the radiocapitellar joint, which can cause the PIN palsy. This finding however, is nonspecific and many patients without PIN palsy would also demonstrate synovitis at the radiocapitellar joint. Therefore, although an MRI would be helpful in localizing a potential cause of PIN compression, it would not in itself confirm the diagnosis.

DISCUSSION: This is a classic situation for a distal phalanx tuft fracture with associated nail bed injury and subungual hematoma. In general, when the subungual hematoma is greater than 50% of the surface area under the nail plate, treatment should consist of nail plate removal, nail bed repair, oral antibiotics, and a fingertip splint. Oral antibiotics and fingertip splinting alone do not address the nail bed laceration, which will most likely lead to nail plate deformity if not repaired. Kirschner pin stabilization is not indicated because these fractures are nondisplaced and usually are inherently stable after nail bed repair. The use of IV antibiotics alone does not address the nail bed laceration surgically. Casting, followed by hydrotherapy and topical antibiotics, is not indicated because it does not address the nail bed laceration. Further, a nondisplaced distal phalangeal tuft fracture does not require cast immobilization. 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. Zook EG, Guy RJ, Russell RC: A study of nail bed injuries: Causes, treatment, and prognosis. J Hand Surg Am 1984;9:247-252.

Explanation: Approximately 70% laceration of the flexor digitorum profundus tendon with active locking is best treated with epitendinous sutures. Performing this procedure under local anesthetic allows for better assessment of whether the triggering has been resolved. Cyclic loading has been shown to increase with high-grade partial lacerations. Use of core sutures adds little strength to a partial laceration. Debridement alone is reserved for injuries involving less than 60% of the tendon diameter. Release of the A2 would compromise pulley function.

Discussion: Ganglion cysts are the most common mass or mass-like lesions seen in the hand and wrist. They arise in a variety of locations, including synovial joints or tendon sheaths. The most common location is the dorsal/radial wrist arising from the dorsal scapholunate interosseous ligament.

DISCUSSION: A volar lunate fragment of a distal radial fracture is considered a critical component to overall joint stability and function. Obtaining a reduction is difficult through a standard volar approach to the radius between the flexor carpi radialis and radial artery. Visualization and reduction of the ulnar volar facet is not possible from this approach. An extended carpal tunnel incision provides access to the entire articular surface, except for the distal radial styloid component.

DISCUSSION: Closed ruptures of the central slip of the extensor tendon may occur with volar proximal interphalangeal joint dislocation, forced flexion of the proximal interphalangeal joint, or blunt trauma to the dorsum of the proximal interphalangeal joint. The other structures are not typically injured in proximal interphalangeal joint dislocations. Treatment typically requires static splinting of the proximal interphalangeal joint. In the more common dorsal proximal interphalangeal joint dislocation, the volar plate is injured, and early range of motion may be started after reduction.

Pasteurella multocida is the most common and rapidly presenting pathogen following a cat bite (often presenting within 24 hours). The prophylactic and empiric treatment of choice is Amoxicillin-clavulanate (Augmentin). Eikenella is associated with human bites, and Capnocytophaga with dog bites.