# Extensor Pollicis Brevis Tendon Transfer for Thumb Reconstruction in Radial Nerve Palsy: A Comparative Cadaveric Study

## TL;DR

A new tendon transfer method for thumb reconstruction in radial nerve palsy is proposed and shown to be more effective than an existing method.

## Contribution

A novel tendon transfer technique using palmaris longus to extensor pollicis brevis is introduced and compared biomechanically to the Tsuge method.

## Key findings

- The proposed method achieved superior thumb radial abduction at 15 N and 20 N traction forces.
- Thumb extension and abduction can be reconstructed without a pulley using the new method.
- Interphalangeal joint extension concerns can be mitigated by suturing the EPB and EPL.

## Abstract

In this study, we proposed a new tendon transfer method for thumb function reconstruction to treat radial nerve injuries. We specifically focused on enhancing thumb radial abduction by transferring the palmaris longus (PL) to the extensor pollicis brevis (EPB) while preserving the first compartment.

Eight freshly frozen cadaver specimens were used to compare our proposed technique (transferring the PL to the EPB while preserving the first compartment) with the Tsuge method (transferring the extensor pollicis longus (EPL) and fixing the abductor pollicis longus to the flexor carpi radialis). Thumb radial deviation, palmar abduction, and interphalangeal joint extension angles were measured at various traction forces.

This method demonstrated superior efficiency in thumb radial abduction (especially at traction forces of 15 N and 20 N) compared to the Tsuge method.

Using the proposed method, the thumb extension and abduction functions can be reconstructed without requiring a pulley. However, concerns were raised about potential inadequate interphalangeal joint extension, although this can be mitigated by suturing the EPB and EPL. Our findings indicate that this method is suitable for our biomechanics study, suggesting its potential applications for cases in which radial nerve injuries necessitate tendon transfer.

The proposed method of transferring the PL to the EPB achieves more effective radial deviation of the thumb than the Tsuge method, highlighting its clinical applicability.