Distalising tibial tubercle osteotomy decreases patellar tendon force — A treatment rationale for recalcitrant patellar tendinopathy

Abstract

BackgroundPatellar tendinopathy is an overuse condition affecting athletes, often with a high morbidity if left untreated. High-level evidence fails to support the use of surgery. A tibial tubercle osteotomy (TTO) has been suggested as a surgical option to improve patient outcomes. Our aim was to explore whether a distalising TTO will alter the patellar tendon to quadriceps tendon force ratio and the sagittal patellar tilt. MethodsSix cadaver limbs were placed in a custom jig with a mechanical testing machine applying cyclical loads of 200–500 N to the quadriceps tendon. The knee was fixed at 0, 15, 30, 45, 60, 75 and 90° of flexion and a buckle transducer recorded the resultant patellar tendon force. Testing was performed with the native tibial tubercle position and with the tubercle distalised by 11 mm. Testing was also performed with the tubercle anteriorised by 10 mm at both of these tubercle positions, a total of four different testing positions. ResultsThere was a significant decrease in the patellar tendon to quadriceps tendon force ratio from 30–60° of knee flexion. There was a significant increase in the sagittal patellar tilt at 30° of knee flexion with distalisation. ConclusionThis biomechanical study shows that the patellar tendon to quadriceps tendon force ratio can be altered with a distalising tibial tubercle osteotomy. A tibial tubercle osteotomy may be a biomechanical treatment option for recalcitrant patellar tendinopathy by decreasing the load through the patellar tendon, allowing the athlete to maintain higher training volumes and loads.