Tensions in the quadriceps tendon and infrapatellar ligament were measured as a function of flexion angle in eight cadaver knees using a load cell of a materials tester to determine the quadriceps force and a spring balance to quantify the patellar tendon force. The ratio between the tensions in the quadriceps tendon and the patellar tendon ( FQ FP) ranged from 1.55 at 70° of flexion to 0.86 at 10° of flexion. The patello-femoral joint reaction (PFJR) force for extension against resistance was maximal at 60°. No change in the quadriceps force required to extend the knee occurred with changes of the Q-angle of ±5°. This study demonstrates that FQ does not equal FP as several authors have reported (Bandi, 1972; Barry, 1979; Ficat and Hungerford, 1977; Hungerford and Barry, 1979; Reilly and Martens, 1972; Smidt, 1973). Furthermore, the difference in FQ and FP influences both the magnitude and direction of PFJR. Studies that assess the influence of surgical procedures which alter the patello-femoral joint or the extensor mechanism must take these differences into account.
ASJC Scopus subject areas
- Orthopedics and Sports Medicine
- Biomedical Engineering