Duplication of the thumb. A retrospective review of two hundred and thirty-seven cases.

Bifid thumb type IV in children: Transferring an epiphyseal segment of the proximal phalanx with insertion of the abductor pollicis brevis tendon

“…The zigzag deformities are reported to be more severe and complex [18,25]. In our study, 15 thumbs were angulated radially at the IPJ and ulnarward at the MPJ.…”

“…Based on the experience in this study, the most suitable time for the initial surgery is about 6 months after birth to 1 year old for type IV. In a survey of the literature, most surgeons who have operated on bifid thumb type IV in children suggested the same timing of the initial surgery [16,18,28]. In our own study, 122 of 164 patients (74.4%) were operated on when they were under 12 months of age.…”

“…But eccentric insertions of the flexor pollicis longus and/or extensor pollicis longus are common in patients in whom the IPJs are angulated preoperatively [12,28]. Some authors propose that the flexor and extensor tendon insertions should be carefully examined, and tendon realignment should be performed if necessary [6,14,35] to provide the balancing of unbalanced tendons [18,25]. The imbalance of tendons in these thumbs may have caused the angulation deformity.…”

“…To avoid the residual angular deformities in the remaining thumb, numerous refinements in the technique exist, such as adequate collateral ligaments reconstruction, flexor and extensor tendons centralization, alignment of the joint surfaces perpendicular to the long axis by osteotomies, and balancing muscle power by tendon transfer [6,8,9,12,18,35,36].…”

“…In the treatment of thumb polydactyly, the simple ablation of one digit has not produced satisfactory results, and doing so frequently results in retained deviation or ligamentous instability of the remaining thumb [9,12,13,17,18]. Moreover, the reconstructed thumb often later develops complications of physeal growth disturbance and joint stiffness.…”