Supporting the collateral ligament complex in radial polydactyly type Wassel IV.

Despite anatomical metacarpophalangeal joint (MCPJ) reconstruction in radial polydactyly (RP) Wassel IV, the prevention of long-term deformity and instability is still an issue. We report on clinical results following our modified surgical procedure with additional support of the hypoplastic radial collateral ligament complex (RCLC) after musculoligamentous MCPJ reconstruction. Fourteen patients (male: 10, female: 4) with radial resection of isolated RP Wassel IV (1987-2006), average age at surgery 1.7 years (0.6-8.6) were included. Distribution to group A and B depended on the procedure for MCPJ reconstruction. In group A (N = 7), RCLC reinsertion + reinforcement using autologous tendon grafts was performed (follow-up: 4.6 years (1.4-6.9)). Group B (RCLC reinsertion without support) consisted of N = 7 patients; follow-up: 9.6 years (8.2-20.2). The healthy contralateral hand (control A/control B) served as a control. Results were evaluated using our modified Tada-score considering: range of motion (ROM), interphalangeal joint (IPJ) and MCPJ stability on stress examination, palmar abduction and grip strength. Better score results (maximum 10) were seen in A: 7.3 (6-9) compared to B: 6.6 (4-10). Subscore 'stability' A: 1.1 (0-2); B: 0.9 (0-2) and 'alignment' A: 0.86 (0-2); B: 0.57 (0-2) showed greatest influence on the score result. Ulnar angulation at MCPJ level compared to healthy thumbs (control A + B) was greater (p < 0.05), with 11.4° (10-20) in group A and 14.3° (-5 to 30) in group B compared to 0° in control A and 5.7° (0-17) in control B. MCPJ ulnar deviation in A + B: 25° (0-35) compared to healthy thumbs control A + B was higher (p < 0.05). Ulnar deviation was higher in B 45° (30-60) compared to 34° (20-50) in A. In B, instability was evident in four, in A, only in one patient. In B, one patient required two re-operations due to MCPJ instability. Equivalent results were recorded regarding pinch grip and palmar abduction. Anatomical MCPJ reconstruction in combination with autologous support of the hypoplastic RCLC to enhance long-term stability is recommended.