Hamstrings and iliotibial band forces affect knee kinematics and contact pattern

Many clinical studies have emphasized the role of the hamstrings and the il iotibial band on knee mechanics, although few biomechanical studies have in vestigated it. This study therefore examined two hypotheses: (a) with loadi ng of the hamstrings, the tibia translates posteriorly and rotates external ly and the tibial contact pattern shifts anteriorly; furthermore, the chang es in tibial kinematics alter patellar kinematics and contact: and (b) load ing the iliotibial band alters the kinematics and contact pattern of the ti biofemoral joint similarly to loading the hamstrings, and loading the iliot ibial band laterally translates the patella and its contact location. Five cadaveric knee specimens were tested with a specially designed knee-joint t esting machine in an open-chain configuration. At various flexion angles, t he knees were tested always with a quadriceps force but with and without a hamstrings force and with and without an iliotibial band force. The results support the first hypothesis. Hence, the hamstrings may be important anter ior and rotational stabilizers of the tibia, a role similar to that of the anterior cruciate ligament. The results also support the second hypothesis, although the iliotibial band force had a smaller effect on the tibia than did the hamstrings force. Both forces also changed patellar kinematics and contact, demonstrating that these structures should also be considered duri ng the clinical management of patellar disorders.