Biomechanical differences between military patients with patellar tendinopathy and asymptomatic controls during single-leg squatting and gait – a statistical parametric mapping study

Background: Prior identification of biomechanical differences between patients with patellar tendinopathy and healthy controls has utilised time-discrete analysis which is susceptible to type I error when multiple comparisons are uncorrected. We employ statistical parametric mapping to minimise the risk of such error, enabling more appropriate clinical decision-making.

Methods: Lower-limb biomechanics of 21 patients with patellar tendinopathy and 22 controls were captured during walking and three types of squats. A statistical parametric mapping two-sample t-test was used to identify kinematic and kinetic differences between groups for each joint. Paired t-tests were used to compare pain before and after tasks, in patients with patellar tendinopathy.

Findings: During walking, cases demonstrated reduced knee joint power during initial contact and hip joint power during terminal stance. In squatting, cases demonstrated increased knee abduction angles at various time points of the small knee bend and single-leg squat. Cases demonstrated reduced knee internal rotation moment during the deepest portion of the single-leg squat and single-leg decline squat.

Interpretation: Gait appears unaffected by patellar tendinopathy, likely due to low task difficulty. Elevated knee abductions angles during squatting were confirmed as a key difference in patients with patellar tendinopathy. Reduced knee internal rotation moments in patients were attributed to a potential reduction in hip external rotator strength and possible pain avoidance strategy; however further evidence is required to substantiate these claims. Findings provide a clear rationale for rehabilitation programs to focus on knee stabilisation and strengthening of the muscles surrounding the hip.