240 Flexor Digitorum Profundus Tendon Segment Length Estimation via Measurement of Adjacent Landmarks in the Secondary Repair of Jersey Finger

Abstract

Abstract Aim Jersey finger describes injury involving the rupture of a Flexor Digitorum Profundus (FDP) tendon. The rupture occurs at its point of insertion, at the base of the distal phalanx. Cause of injury is forced hyperextension of FDP. Correct tendon tensioning correlates with tendon length during repair and is vital to optimise restoration of function. No evidence-based approach to tendon tensioning exists hitherto. We used cadaveric dissection to measure anatomical landmarks associated with the FDP tendon and assess whether these can be used to estimate the length of the adjacent tendon segments. Method Eight cadaveric hands were dissected (four fresh-frozen and four formalin-fixed). Lumbrical muscles, A1 pulley and distal FDP insertion for digits II-IV were identified. Lengths between the most distal point of the lumbrical origin; proximal and distal ends of the A1 pulley and FDP insertion were recorded. Results Measurements involving the A1 pulley showed a great degree of variation and no clear trend across the digits studied. Conversely, lumbrical origin to FDP insertion lengths were consistent relative to the adjacent digit measurements across all cadavers for digits II, II and IV. This was confirmed by a linear regression analysis (R2 >0.97). Conclusions This study demonstrates how distal lumbrical origin to FDP tendon insertion measurements in digit III can be used to estimate the length of the tendon graft required in digit II or IV, during repair. This injury manifests most commonly in digit IV. Therefore, our finding furthers surgical knowledge and is likely to improve patient outcomes.