Ligament restraints to terminal knee extension are poorly understood. This study hypothesized (1) as with other motions of the knee, genu recurvatum is limited primarily by a named, identifiable structure, and (2) as the largest static structure of the posterior knee, the oblique popliteal ligament is uniquely suited to act as a checkrein to knee hyperextension.
The greatest increase in knee hyperextension was observed after sectioning the oblique popliteal ligament. This was independent of cutting order, consistent across groups, and statistically significant. In all groups, the increase in knee hyperextension after sectioning the oblique popliteal ligament approached or exceeded the increases seen after sectioning the anterior and posterior cruciate ligaments combined. Overall, less knee hyperextension was seen in knees with increased posterior tibial slope.