title: Experimental determination of forces transmitted through the patello-femoral joint.
abstract: 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 degrees of flexion to 0.86 at 10 degrees of flexion. The patello-femoral joint reaction (PFJR) force for extension against resistance was maximal at 60 degrees. No change in the quadriceps force required to extend the knee occurred with changes of the Q-angle of +/- 5 degrees. 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.
authors.affiliation: Johns Hopkins University School of Medicine, Department of Orthopaedic Surgery, Good Samaritan Hospital, Baltimore, MD 21239.
authors.forename: H U
authors.initials: HU
authors.lastname: Buff
authors.forename: L C
authors.initials: LC
authors.lastname: Jones
authors.forename: D S
authors.initials: DS
authors.lastname: Hungerford
mesh_terms: D001696:Biomechanical Phenomena; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D009068:Movement; D010329:Patella / Q000502:physiology