Extensor Pollicis Brevis Spiral Tenodesis for Combined Metacarpophalangeal Instability and Trapeziometacarpal Arthritis.

Abstract

In more advanced stages of trapeziometacarpal arthritis, the thumb metacarpal may develop an adduction contracture, leading to secondary hyperextension instability of the metacarpophalangeal joint. Following trapeziometacarpal arthroplasty, uncorrected substantial metacarpophalangeal hyperextension may contribute to ongoing Z-collapse deformity, weakness of pinch and grip, and patient perception of diminished function. We prospectively analyzed a consecutive case series of 55 trapeziometacarpal arthroplasty patients (mean age, 60 years; 7 males) who received simultaneous extensor pollicis brevis spiral tenodesis for thumb metacarpophalangeal hyperextension of at least 50°. Preoperative/postoperative (mean, 24 weeks) objective measurements and Disabilities of the Arm, Shoulder and Hand (DASH) scores were compared using paired t tests with P < .05. Mean preoperative/postoperative measurements were as follows: metacarpophalangeal hyperextension, 62.0°/-1.7°; metacarpophalangeal flexion, 52.1°/50.1°; interphalangeal arc of motion, 66.4°/65.5°; key pinch, 3.6/5.4 kg; grip strength, 14.1/20.1 kg; DASH score, 56.6/8.4. Differences were statistically significant for metacarpophalangeal hyperextension, key pinch, grip strength, and DASH score. Differences were not significant for metacarpophalangeal flexion or interphalangeal arc of motion. No patient demonstrated paresthesias or hypersensitivity of the digital nerves. All patients achieved stability at the metacarpophalangeal joint. One Kirschner wire was removed earlier than planned after migration and penetration through the skin. Performed in conjunction with trapeziometacarpal arthroplasty, spiral tenodesis effectively stabilizes the metacarpophalangeal joint without compromising metacarpophalangeal flexion, interphalangeal motion, or the digital nerves. Postoperatively, patients demonstrate significant improvements in key pinch, grip strength, and DASH scores.