Biomechanical properties of the central third patellar tendon graft: effect of rotation

The results of this study suggest that the central third of the patellar tendon may be stronger than previously reported. The mean ultimate load of a 15-mm bone-patellar tendon-bone composite was 4389 N (+/- 709 N); of the 10-mm wide composites, 2977 N (+/- 516 N); and of the 7-mm composites, 2238 N (+/- 316 N). Twisting the graft 90 degrees increased the strength (P < 0.05). Further twisting to 180 degrees had no significant effect compared with twisting to 90 degrees. This study supports the practice of using smaller (10 mm) bone-patellar tendon-bone grafts to avoid the potential complications of patellar fracture and graft impingement in the notch, and suggests the value of rotating the graft prior to tibial fixation.