The popliteofibular ligament

Abstract

We designed an experimental study to prove the existence of the popliteofibular ligament (PFL) and to define its role in providing static stability of the knee. We also examined the contribution of the lateral collateral ligament (LCL). We found this ligament to be present in all eight human cadaver knees examined. These specimens were mounted on a specially designed rig and subjected to posterior, varus and external rotational forces. We used the technique of selective sectioning of ligaments and measured the displacement with a constant force applied, before and after its division. We recorded the displacement in primary posterior translation, coupled external rotation, primary varus angulation and primary external rotation. Statistical analysis using the standard error of the mean by plotting 95% confidence intervals, was used to evaluate the results. The PFL had a significant role in preventing excessive posterior translation and varus angulation, and in restricting excessive primary and coupled external rotation. Isolated section of the belly of popliteus did not cause significant posterolateral instability of the knee. The LCL was also seen to act as a primary restraint against varus angulation and secondary restraint against external rotation and posterior displacement. Our findings showed that in knees with isolated disruption of the PFL stability was restored when it was reconstructed. However in knees in which the LCL was also disrupted, isolated reconstruction of the PFL did not restore stability.

Importance of the different posterolateral knee static stabilizers: biomechanical study

“…Pasque et al6 and LaPrade et al8 in turn reported that the popliteus tendon and the popliteofibular ligament were not important in the stabilization of varus at any degree of flexion, contradicting our results and those obtained by Gollehon et al1 and Shahane et al5 We note that in the study of Pasque et al6 these structures were evaluated in knees that had the LCL intact, whereas in our study, the LCL had been previously sectioned. Knowing that the LCL is the main knee stabilizer for varus1,2,5,8 and with it intact, the isolated section of the popliteus tendon (in its joint portion with the popliteofibular ligament) did not lead to any increase in angular deformity.…”

“…Several papers1,2,5,8 have reported similar results, concluding that the LCL was important in the stabilization in varus at all degrees of flexion.…”

“…When we section the popliteofibular complex, we are evaluating in a more objective manner the popliteofibular ligament, which loses its function in this situation. The study by Shahane et al5 shows data that contributes toward this reasoning. In his study, the popliteus tendon section did not alter stabilization in varus, whereas the popliteofibular ligament section remained important.…”

“…Gollehon et al1 observed that the popliteus tendon section associated with that of the arcuate ligament generated varus increases at 90 degrees of flexion. Shahane et al5 tested the “popliteus complex” in varus, dividing it into two components: the popliteofibular ligament and the popliteus tendon. They concluded that the popliteus tendon section was not important in restriction for varus, but the popliteofibular ligament section was important at 60 and 90 degrees of flexion.…”

“…Gollehon et al1 and Shahane et al5 argue that the popliteus tendon presents a static and dynamic stabilization function, and Shahane et al5 declare that static stabilization is produced by the popliteofibular ligament. When we section the popliteofibular complex, we are evaluating in a more objective manner the popliteofibular ligament, which loses its function in this situation.…”