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Thumb duplication at the metacarpophalangeal joint. Management and a new classification
1Department of Orthopaedics and Traumatology, Chinese University of Hong Kong, Prince of Wales Hospital, Shatin.
Insights
This study presents a surgical protocol for Wassel Type IV thumb duplication, the most common form of polydactyly. Early surgical intervention within one year yields satisfactory cosmetic and functional outcomes for complex thumb deformities.
Area of Science:
- Hand Surgery
- Pediatric Orthopedics
- Congenital Hand Anomalies
Background:
- Wassel Type IV thumb duplication, occurring at the metacarpophalangeal joint, is the most frequent type of polydactyly, comprising 50% of cases.
- This type is further classified into subtypes A, B, C, and D, with Type D exhibiting the most complex bone and soft tissue anomalies, leading to a higher likelihood of residual deformities.
Purpose of the Study:
- To present a standardized surgical protocol for managing Wassel Type IV thumb duplication.
- To evaluate the cosmetic and functional outcomes of this surgical protocol in pediatric patients.
Main Methods:
- A surgical protocol involving early operation (within 1 year of age), single-stage osteotomy, collateral ligament repair, and abductor pollicis brevis tendon reattachment was implemented.
- Twenty-one cases of Wassel Type IV thumb duplication were reviewed retrospectively with an average follow-up of 5.25 years.
Main Results:
- The surgical protocol resulted in satisfactory cosmetic and functional outcomes, with a mean score of 17.9 out of 20.
- Fifteen patients demonstrated a good range of motion, and 17 patients were satisfied with the surgical results. Metacarpophalangeal joint stability was achieved in all but one patient.
- Scar hypertrophy was noted in 2 patients, representing a minor complication.
Conclusions:
- The presented surgical protocol is effective for treating Wassel Type IV thumb duplication, achieving good functional and cosmetic results.
- Early surgical intervention, combined with meticulous repair of soft tissues and bone, is crucial for optimizing outcomes in complex thumb polydactyly.
- The protocol demonstrates a high patient satisfaction rate and a low incidence of significant complications.
Abstract:
Duplication at the metacarpophalangeal joint level (Wassel Type IV) is the most common type thumb duplication (polydactyly), accounting for 50%. It can be subdivided into 4 types: (A) hypoplastic (12%), (B) ulnar deviated (64%), (C) divergent (15%), and (D) convergent (complex) (9%). Type D has the most complex bone and soft tissue anomalies and is most likely to have residual deformities. A surgical protocol emphasizing early operation within 1 year of age, 1 stage osteotomy, meticulous collateral ligament repair, and abductor pollicis brevis tendon reattachment is presented. Twenty-one cases with an average followup of 5.25 years were reviewed. The cosmetic and functional results were satisfactory. Of a score system of 20 points, the mean score was 17.9. All except 1 patient had a stable metacarpophalangeal joint. Fifteen patients had a good range of movement, and 17 patients are satisfied with the outcome of surgery. Scar hypertrophy occurred in 2 patients.