The functional relationship of the posterior oblique ligament to the medial collateral ligament of the human knee.

Strain in the human knee medial collateral ligament (MCL) was measured in cadavers with a Hall effect strain transducer during normal passive knee flexion, as well as knee flexion accompanied by applied external tibial rotation and valgus torques. In an attempt to determine the contribution of the posterior oblique ligament (POL) to the strain behavior of the MCL, the POL was systematically separated from the MCL and changes in strain in the MCL were observed. These changes in strain were mild and variable, except in the one knee which was later found to be lacking an anterior cruciate ligament. In that particular knee, strain in the MCL increased up to 9.97% under the influence of a valgus torque once the POL fibers had been separated from the MCL. Anatomical dissection and transillumination techniques of the MCL/POL complex demonstrated definite ligament fibers connecting the MCL to the POL. The results demonstrate an intimate anatomical relationship between the POL and MCL. However, the POL and MCL appear to work independently from each other according to our test method.