New Classification System for Radially Deviated Thumb Polydactyly.

Area of Science:

• Hand surgery
• Congenital hand differences
• Orthopedic classification systems

Background:

• Radially deviated thumb polydactyly (RDTP) is a congenital condition that can lead to secondary deformities.
• A comprehensive characterization and classification system for RDTP has been lacking.
• Effective surgical management requires a clear understanding of RDTP subtypes.

Purpose of the Study:

• To develop and validate a novel classification system for RDTP based on preoperative radiographic findings.
• To establish a reliable system that can guide surgical decision-making in RDTP.
• To categorize RDTP into distinct types to better understand its presentation.

Main Methods:

• Retrospective review of 29 patients with RDTP from January 2015 to December 2021.
• Classification of RDTP into four types (D-shaped, bell-shaped, radial-concave phalanges, asymmetric Wassel III-like) based on preoperative radiographs.
• Assessment of the reliability of the proposed classification system using interobserver and intraobserver kappa values.

Main Results:

• Twenty-nine thumbs with RDTP were classified into four types: Type I (n=9), Type II (n=10), Type III (n=8), and Type IV (n=2).
• The classification system demonstrated high reliability, with interobserver kappa of 0.928 and intraobserver kappa of 0.963.
• Radiographic measurements and intraoperative findings were reviewed to support the classification.

Conclusions:

• The proposed four-type classification system for RDTP is reliable and reproducible.
• This new classification system provides valuable guidance for surgical approaches in treating RDTP.
• Further validation may enhance its utility in managing patients with this condition.