The Effect of Distal Phalanx Bony Dimensions in Suture Anchor Fixations of Tendon Avulsion

Background: The terminal phalanx of the fingers carries the attachment of the Flexor Digitorum Profundus (FDP) on the volar surface and the extensor on the dorsal surface. Avulsion of these tendons has traditionally been repaired with pull-through sutures. Recently, bone anchor sutures have been found to be of comparable biomechanical strength but with the added advantage of technical ease and fewer complications. However, the dimensions of the bone, at the site of insertion of the anchors, have never been studied. Methods: Following some cases of penetration of the dorsal cortex by the anchors, we measured the antero-posterior dimensions of the terminal phalanx in 251 digits from plain radiographs and compared these with the dimensions of the commonly used bone anchors. We also compared male and female digits. Results: The anchors were oversized in 76% of index, 78% of ring and 100% of little fingers in the female population and in 49%, 44% and 97% of index, ring and little fingers respectively in the male population. Conclusions: This analysis of bone dimensions can be a useful guide to surgeons in choosing the appropriate implant for flexor tendon avulsions.