THE SURGICAL ANATOMY OF THE ULNAR-SIDED EXTENSOR TENDONS OF THE HAND – A CADAVERIC STUDY OF 49 HANDS

Introduction and Aims: To explore the variability of tendon slips, insertions and juncturae tendinae (JT) of extensor digitorum communis (EDC) and extensor digiti quinti proprius (EDQP). Method: The extensor tendons to digits three, four and five (middle, ring and little fingers respectively) were dissected in 49 adult preserved cadaver hands. Results: The most common patterns of tendon slip origin/insertion were: the insertion of two slips from EDQP into digit five (84%); the presence of both slips from EDQP lying in a non-septate tunnel separate to that from the EDC (100%); the presence of a single slip from EDC of the ring finger inserting radial to EDQP into digit five (94%); the constant presence of an oblique juncturae tendinum between EDC middle finger and EDC ring finger (100%); and the universal absence of a juncturae tendinum to either slips of EDQP. The most common relevant variations included: a juncturae tendinum between EDC ring and EDC little finger (39%); and an extra slip from EDQP inserting into ring finger (10%). Whereas variations are not uncommon (Von Schroeder & Botte, 2001), it is the more constant features (presence or absence) which are of surgical relevance and which our study emphasises. Conclusion: We conclude that the ulnar EDQP slip can be safely and easily harvested as a free tendon graft without any consequential loss of extension of little finger and with minimal surgical trauma. It also follows that rupture of the radial side of the extensor hood of the middle finger predisposes to ulnar subluxation of the middle finger EDC, and we describe two such clinical cases.