18: Tendon Transfers for Carpal Tunnel Syndrome

Procedure 18 Tendon Transfers for Carpal Tunnel Syndrome



Sandeep J. Sebastin, Kevin C. Chung


image See Video 14: Tendon Transfer for Anterior Interosseous Nerve Palsy (FDS to FPL)



Indications




image Severe carpal tunnel syndrome (CTS) with thenar atrophy and inability to abduct or oppose the thumb


image Failed nerve recovery after repair/reconstruction of the median nerve


image Hansen disease (leprosy)


image Neurologic disorders (for example, Charcot-Marie-Tooth disease, syringomyelia)


image Congenital differences



Examination/Imaging



Clinical Examination




image Sensation: It is important to document the level of sensation in the thumb and fingers preoperatively. Patients may also have diminished sensation in the ulnar nerve distribution. The potential functional benefit of a tendon transfer will be diminished in a patient with sensory loss, and these patients must be counseled about the likely poorer outcome after surgery.


image Joints: To get a good result from the tendon transfer, patients must have good passive range of motion at the thumb metacarpophalangeal (MCP) joint and the thumb carpometacarpal (CMC) joint. It is not uncommon for patients to have basal joint arthritis with a supination and adduction deformity of the thumb and first web-space contracture. This should be addressed before a tendon transfer is considered.


image Motor: Many motors have been described for opponensplasty. Our first preference is the palmaris longus (PL) followed by the extensor indicis proprius (EIP), if the PL is absent. We rarely use the flexor digitorum superficialis (FDS) of the ring finger because of the greater morbidity (weakening the power grip, risk for proximal interphalangeal [PIP] joint flexion contracture, swan-neck deformity) and because the soft tissue pulley attenuates over time. Although the tension fraction of PL (1.2%) and EIP (1%) is theoretically less than the combined tension fraction of abductor pollicis brevis (APB) (1.1%) and opponens pollicis (OP) (1.9%), the transfer only needs enough strength to position the thumb in abduction.


image The transfer of the PL (Camitz transfer) is typically performed for an elderly patient with CTS and severe thenar atrophy. The Camitz transfer is considered a “freebie” procedure because the incision used for CTS can be extended to the wrist in a zigzag fashion to obtain the PL augmented by the palmar fascia to attach into the ABP insertion at the radial MCP joint. As with any freebie procedure, however, the direction of tendon pull is not in line with the APB muscle but rather is more parallel to the forearm, which does diminish the biomechanical construct of this tendon transfer procedure. For an elderly patient with modest functional requirements, this transfer does serve the purpose of restoring some abduction and will permit the patient to recover acceptable thumb function.


image We use the test described by Mishra to determine the presence of the PL. The traditional test described by Schaeffer requires the patient to abduct and oppose the thumb to the small finger and flex the wrist. A patient with thenar atrophy will find it difficult to do so. The Mishra test is performed by holding the patient’s wrist and fingers in hyperextension, while asking the patient to flex the wrist. This stretches the palmar aponeurosis and makes the PL taut when the patient attempts wrist flexion (Fig. 18-1).


image

FIGURE 18-1



Imaging




image X-ray of the hand to look for basal joint arthritis


image Nerve conduction studies



Surgical Anatomy




image Thumb opposition is a complex movement produced by a combination of flexion, palmar abduction, and pronation and requires participation of both the MCP and CMC joints. The prime muscle of thumb opposition is believed to be the APB with contributions from the OP and flexor pollicis brevis (FPB).


image The muscles affected after low median nerve palsy are the APB, OP, superficial head (radial head) of the FPB, and the radial two lumbricals (first and second). The first three muscles are innervated by the recurrent motor branch of the median nerve, whereas the latter two are innervated by the first and second common palmar digital nerve branch of the median nerve.


image Reasonable thumb abduction and opposition may be retained after isolated median nerve injury or severe carpal tunnel syndrome as a result of preserved ulnar nerve function (retained innervation of the deep head of the FPB and variability in thenar muscle innervation by connection between the ulnar and median nerves). Figure 18-2 shows the preoperative appearance of the hand with severe CST on the right. Note the thenar atrophy and inability to palmarly abduct the right thumb.


image The midpalmar portion of the palmar aponeurosis has three layers: superficial longitudinal fibers, deeper transverse fibers, and deepest vertical fibers. Only the superficial longitudinal fascia is obtained in continuity with the PL to maximize the length of this tendon to reach the APB insertion.


image

FIGURE 18-2



Positioning




image The procedure is performed under tourniquet control. It is usually performed under sedation and local anesthesia because this procedure is rather expedient and there is no need to take unnecessary anesthetic risk in elderly patients. The patient is positioned supine with the affected extremity on a hand table.



Exposures


Related posts:

28: Pronator Teres Rerouting 34: Reconstruction of the Central Slip with the Transverse Retinacular Ligament for Boutonnière Deformity 85: Wrist Denervation 38: Reconstruction for Congenital Thumb Hypoplasia 65: Arthroscopic Treatment for Septic Arthritis 89: Total Wrist Fusion

Stay updated, free articles. Join our Telegram channel
Tags:
Mar 5, 2016 | Posted by in Hand surgery | Comments Off on 18: Tendon Transfers for Carpal Tunnel Syndrome

Full access? Get Clinical Tree
Get Clinical Tree app for offline access