Wassel classification

Wassel Classification refers to a system used to categorize and describe the various types of radial polydactyly, a congenital condition characterized by the duplication of the thumb. The classification was introduced by Harold A. Wassel in 1969 following his study on the surgical outcomes of patients with this condition. The Wassel Classification is instrumental in guiding the surgical approach and predicting the functional and cosmetic outcomes for individuals affected by radial polydactyly.

Overview

Radial polydactyly, or preaxial polydactyly, is a condition where an individual has an extra thumb, which can vary significantly in size, structure, and functionality. The Wassel Classification divides these variations into seven types, based on the level of duplication of the thumb's bone structure. This classification is crucial for medical professionals to determine the most appropriate surgical intervention to improve hand function and appearance.

Wassel Classification Types

The Wassel Classification categorizes radial polydactyly into the following types:

• Type I: Duplication of the distal phalanx
• Type II: Duplication of the entire phalanx
• Type III: Duplication of the distal interphalangeal joint
• Type IV: Duplication of the proximal phalanx
• Type V: Duplication of the metacarpophalangeal joint
• Type VI: Duplication of the metacarpal
• Type VII: Triphalangism, where the thumb has an extra phalanx

Each type represents a different level of complexity and presents unique challenges for surgical correction. The most common types are IV and VII, which involve duplication at the level of the proximal phalanx and the presence of an extra phalanx, respectively.

Surgical Considerations

The primary goal of surgery for radial polydactyly is to remove the extra digit and reconstruct a functional and aesthetically pleasing thumb. The choice of surgical technique depends on the Wassel type, with considerations including the need to preserve or reconstruct joints, tendons, and nerves. Surgical outcomes are generally favorable, but complications such as joint stiffness, deformity recurrence, and growth disturbances can occur.

Conclusion

The Wassel Classification remains a fundamental tool in the diagnosis and treatment planning for radial polydactyly. By providing a clear framework for categorizing the condition, it aids surgeons in selecting the most appropriate surgical technique, ultimately improving the quality of life for individuals with this congenital anomaly.