Lower peak torque knee extension strength a possible risk factor for patellofemoral pain syndrome

Lankhorst NE. J Orthop Sports Phys Ther. 2011. doi:10.2519/jospt.2012.3803.

A systematic review of multiple prospective studies involving patients with patellofemoral pain syndrome revealed lower knee extension torque strength as a potential risk factor for the syndrome.

Researchers analyzed 3,845 articles for relevancy, identifying seven studies eligible for their investigation which examined 135 different variables that might contribute to patellofemoral pain syndrome (PFPS). They ultimately found 13 potential PFPS risk factors for the condition among the studies, which all had 20 or more patients and focused on at least one risk factor.

Based on pooled data, the researchers found significantly lower knee extension peak torques in the groups with PFPS compared to controls. In the study, they measured mean differences in torque at two standards relative to body weight, two measurements relative to body mass index (BMI) and two non-standardized levels in a concentric mode, reporting 60°/s torque = -0.24 Nm and 240°/s = -0.11 Nm for body weight; 60°/s = - 0.84 Nm and 240°/s = -0.32 Nm for BMI; and 60°/s = -17.54 Nm and 240°/s = -7.72 Nm for non-standardized in a concentric mode.

“Because several other risk factors for PFPS were described only in single studies, these additional risk factors, as well as those with conflicting evidence, need to be confirmed in future studies,” the authors wrote.