Tibial Tubercle-Medial Malleolar Distance in Determining Tibial Nail Length

OBJECTIVE:To assess the accuracy of a previously undescribed method of determining tibial nail length based on anatomic landmarks. DESIGN:Cadaveric study. METHODS:Four methods of tibial nail length determination were compared. Nail lengths for each of fourteen cadaveric lower extremities were determined using full-length scanograms, spotograms, acrylic template overlays, and the distance between the tibial tubercle and the medial malleolus (TMD). Each tibia was then nailed. The accuracy of each method was then evaluated. RESULTS:The full-length scanogram method resulted in incorrect nail lengths in eleven of fourteen (79 percent) cases. Six of fourteen (43 percent) incorrect nail lengths resulted from the use of spotograms. All measurements made with the Template technique yielded nails that were too short (100 percent). The TMD method rendered four of fourteen (29 percent) nails of incorrect size. CONCLUSION:The tibial tubercle-medial distance (TMD) proved an easy, inexpensive, and accurate method of preoperative nail assessment.