Radiographic indicators of a shared epiphysis in radial polydactyly.

Area of Science:

• Orthopedic Surgery
• Pediatric Radiology
• Hand Surgery

Background:

• Classifying radial polydactyly by Wassel type is challenging in infants due to unvisualized thumb epiphyses on radiographs.
• Distinguishing between separate and shared epiphyses is crucial for operative planning and prognosis.

Purpose of the Study:

• To identify radiographic features differentiating separate from shared thumb epiphyses in radial polydactyly.
• To assist in surgical planning and prognosis determination for radial polydactyly.

Main Methods:

• Retrospective review of 34 radial polydactyly patients' surgical records and radiographs.
• Measurement of thumb bone dimensions and angles by four blinded observers, calculating inter-observer reliability.
• Creation of indices from measurements to distinguish between shared and separate epiphyses.

Main Results:

• Radiographic measurements demonstrated high inter-observer reliability.
• Statistically significant differences were found in the width shaft index, interspace distance, angle × interspace distance, and angle × interspace index between separate and shared epiphyses.
• Specific indices showed predictive value for epiphysis status.

Conclusions:

• Distinct radiographic differences exist between separate and shared thumb epiphyses in radial polydactyly.
• Shared epiphyses are associated with smaller, closer, and less divergent radial thumbs.
• Identified threshold values for key indices can predict epiphysis status preoperatively, aiding surgical decisions.