Volar Locking Plate Implant Prominence and Flexor Tendon Rupture

BACKGROUND: Flexor tendon injury is a recognized complication of volar plate fixation of distal radial fractures. A suspected contributing factor is implant prominence at the watershed line, where the flexor tendons lie closest to the plate. METHODS: Two parallel series of patients who underwent volar locked plating of distal radial fractures from 2005 to 2008 and with at least six months of follow-up were retrospectively reviewed. Group 1 included seventy-three distal radial fractures that were treated by three orthopaedic hand surgeons with use of a single plate design at one institution, and Group 2 included ninety-five distal radial fractures that were treated by four orthopaedic hand surgeons with use of a different plate design at another institution. On the postoperative lateral radiographs, a line was drawn tangential to the most volar extent of the volar rim, parallel to the volar cortical bone of the radial shaft. Plates that did not extend volar to this line were recorded as Grade 0. Plates volar to the line, but proximal to the volar rim, were recorded as Grade 1. Plates directly on or distal to the volar rim were recorded as Grade 2. RESULTS: In Group 1, the average duration of follow-up was thirteen months (range, six to forty-nine months). Three cases of flexor tendon rupture were identified among seventy-three plated radii (prevalence, 4%). Grade-2 plate prominence was found in two of the three cases with rupture and in forty-six cases (63%) overall. In Group 2, the average duration of follow-up was fifteen months (range, six to fifty-six months). There were no cases of flexor tendon rupture and no plates with Grade-2 prominence among ninety-five plated radii. CONCLUSIONS: Flexor tendon rupture after volar plating of the distal part of the radius is an infrequent but serious complication. The plate used in Group 1 is prominent at the watershed line of the distal part of the radius, which may increase the risk of tendon injury. We found no ruptures in Group 2, perhaps as a result of the lower profile of the plate. Further studies are needed before recommending one plate over another. Regardless of plate selection, surgeons should avoid implant prominence in this area.