Pentadactyly is treated like thumb hypoplasia, with first web space creation.1
Complications
In polydactyly, a reoperation rate of up to 25% has been reported, with most reoperations performed because of residual or subsequent deformity.5,30,31,38 Risk factors for reoperation are type IV thumb duplication, preoperative “zigzag” deformity, and radially deviated thumb elements at presentation.5 The delta phalanx may not show on radiographs until the patient is 18 months old, but functional deformity will worsen as long as it is present. Zigzag deformity may be due to the delta phalanx or to musculotendinous imbalance, such as a radially inserted flexor pollicis longus (FPL) or lack of stable MCP abduction. Miura31 found that careful reconstruction of the joint capsule and thenar muscles from the ablated digit to the remnant digit is the key to a successful initial surgery. Lee and colleagues39 defined zigzag deformity as more than 20° MCP and IP angulation; for cases present before surgery, they recommended FPL relocation by the pullout technique in addition to osteotomies to prevent further interphalangeal deviation (Figures 17, 18).
Abnormal physeal growth, joint instability, and stiffness can all occur. Stiffness is particularly difficult to treat but seldom presents a functional problem. Joint enlargement, which is not uncommon, results from either broad articular surfaces or retained cartilage from the perichondral ring after resection that later ossifies.5,38 Nubbin-type duplications may not fall off after suture ligation, necessitating further excision, and a cosmetic bump is seen after 40% of suture ligations.3 Patillo and Rayan28 and Rayan and Frey29 warned against suture ligation unless the nubbin has a small stalk because of the possibility of infection and gangrene. The excised nubbin tissue is histologically nervous, and there have been reports of painful neuromas in the remaining scar of a ligated nubbin that respond well to excision.26,27,40 It is thought that these painful lesions form because the ligature prevents the digital nerves to the vestigial digit from retracting.27 Nail deformity and IP joint stiffness are seen with the Bilhaut-Cloquet procedure, though often finger function remains satisfactory.
Conclusion
Polydactyly is a common congenital hand abnormality. Its true incidence is unknown because of inconsistent documentation. Surgeons must strive for a functional, cosmetic hand, given a diverse set of possible anomalies. Hypoplasia is the rule; tissue should be ablated and augmented as necessary. Musculotendinous insertions may need to be centralized. Patients’ family members should always be counseled that more surgery may be needed in the future, as further deformity can occur with growth. Surgically corrected thumb duplications will be stiffer, shorter, and thinner than their normal counterparts. Nail ridges are common. However, it should be noted that 88% of these patients are satisfied with their results.41 Some amount of contracture and abnormal function should be expected with index-, long-, and ring-finger duplications. The only remnant of type B postaxial duplications may be a slight discoloration or bump, though stiffness and deformity can happen with a type A deformity. A “duplicated” digit that requires surgical correction will never be completely normal, but acceptable function is routinely achievable.