Mannerfelt Syndrome Treatment & Management

Medical management of the inflamed tenosynovium may reduce destructive pannus and spur formation and thereby also decrease the risk of tendon rupture.

A linear incision is made over the fourth ray in the proximal palm and extended across the wrist in a zigzag manner. Care must be taken to avoid the motor branch and the palmar cutaneous branches of the median nerve. The bony spur is excised either from the scaphoid or the trapezium. Adjacent soft tissues are mobilized to cover the exposed bone. The defect can be covered with a silicone membrane, a transverse carpal ligament flap, or a tendon graft. Tendon repair can be performed with a short (bridge) tendon graft, a standard full-length tendon graft, or a tendon transfer.

A short tendon graft is recommended when both tendon ends are at the wrist level. This short graft can be obtained from the palmaris longus, flexor carpi radialis, or abductor pollicis longus.^{[23, 24]} When the distal tendon end is beyond the wrist and cannot be retrieved in the wound, a full-length tendon graft or tendon transfer is recommended.

For a full-length tendon graft, a volar zigzag incision is used on the thumb and extended proximally into the palm. The ruptured distal tendon part is resected. Care is taken not to injure any of the pulleys. Through another incision at the distal forearm, the musculotendinous junction of the flexor pollicis longus is identified. The palmaris longus or plantaris tendon is harvested. With a pediatric feeding tube or a tendon passer, the tendon graft is brought through the sheath and pulleys. The distal end of the graft is attached to the terminal phalanx with a pull-out suture or suture anchor. Setting the tendon tension requires positioning of the wrist in a neutral position, with the thumb opposed to the index finger, and the thumb interphalangeal joint at 30° flexion. Then the proximal end of the graft is woven into the flexor pollicis longus tendon.

After wound closure, the wrist is kept at 15-20° flexion, and the thumb is at 30° palmar abduction. A dorsal splint is applied allowing passive flexion of both thumb joints. After 6 weeks, the pull-out suture is removed.

A clear indication for a tendon transfer is a nonfunctioning flexor pollicis longus muscle. Compared with a tendon graft, a tendon transfer has only 1 juncture site, it provides a more viable tendon, it requires no extra procedure for tendon graft harvest, and it provides a motor in cases of direct flexor pollicis longus muscle damage or nerve injury. Possible disadvantages are proximal interphalangeal joint hyperextension and loss of flexor power in the donor finger.^[25]

The flexor digitorum sublimis tendon of the long finger is used for a tendon transfer because it is longer than the rest of the flexor tendons, and the ring and small fingers are not impaired. The flexor digitorum sublimis tendon is distally detached from the middle phalanx of the donor finger, passed under the median nerve, and brought through the tendon sheath and pulleys of the thumb using a pediatric feeding tube or a tendon passer. The flexor pollicis longus stump is resected, and the underlying volar proximal surface of the distal phalanx is trimmed.

With a pull-out suture, the flexor digitorum sublimis tendon is secured at the volar aspect of the distal phalanx of the thumb. A bone anchor can be used instead of the pull-out suture. It, too, is placed in the volar proximal edge of the distal phalanx. The ring or small finger sublimis tendon transfer can be used as an alternative procedure. A flexor tendon tenosynovectomy is also performed to prevent further ruptures. Wrist and thumb are immobilized in flexion for 3 weeks. Then passive and gentle active motion is allowed. If a pull-out wire is used, it is removed after 6 weeks.

If the interphalangeal joint of the thumb is arthritic or unstable, fusion may be a better procedure for a functional thumb. Arthrodesis of the interphalangeal joint of the thumb can provide a strong pinch and improve function. Some authors recommend fusion at 0-5° flexion, while others prefer 15-20° flexion. Many fusion techniques with high success rates are available.

Prior to exploration, written informed consent should be obtained. The patient should be informed of the possibility of needing one of the reconstruction options mentioned above. The patient should also be informed that the procedure does not cure the underlying problem (eg, rheumatoid arthritis). Therefore, recurrence of tenosynovitis and additional ruptures are possible.

See Treatment, Surgical therapy, above.

Complications are minimal, although rupture of the tendon reconstruction or nonunion of an interphalangeal fusion can occur. Tenolysis may also be required.^[26]

Schneider and Wiltshire treated 14 patients who underwent ring-finger flexor digitorum sublimis transfer for the treatment of irreparable lesions of the flexor pollicis longus. Results measured by return of interphalangeal joint motion were good in 12 patients, 1 patient had a fair result, and failure occurred in 1 patient.^[27] Ertl et al reported an average thumb interphalangeal motion of 23° with a range of 0-45°.