Tendon Transfer for Correction of the Radial Deviation Deformity of the Wrist and Centralization in Posterior Interosseous Nerve Palsy.

There are very few descriptions of tendon transfers designed specifically to address the reconstruction of posterior interosseous nerve palsy (PINP). Unlike a radial nerve palsy (RNP), a patient with a PINP is able to extend their wrist but in radial deviation, because of the preserved innervation of the extensor carpi radialis longus (ECRL). Tendon transfers to restore finger and thumb extension in PINP have been extrapolated from tendon transfers to restore these functions in RNP, specifically using flexor carpi radialis, not flexor carpi ulnaris, so as not to further exacerbate the distinctive radial deviation deformity of the wrist. However, the standard pronator teres to extensor carpi radialis brevis transfer for a RNP fails to address or correct the radial deviation deformity in PINP. We present a simple tendon transfer specifically to address this radial deviation deformity in a PINP, by performing a side-to-side tenorrhaphy of the ECRL tendon to the extensor carpi radialis brevis tendon, followed by transection of the ECRL insertion onto the base of the index finger metacarpal distal to the tenorrhaphy. This technique converts a functioning ECRL from a radially deforming force, transferring its vector of pull onto the base of the middle finger metacarpal and so producing centralization of wrist extension in axial alignment with the forearm.