Effects of Anterior Knee Displacement During Squatting on Patellofemoral Joint Stress.

CONTEXT: Squatting is a common rehabilitation training exercise for patellofemoral pain syndrome (PFPS). Patellofemoral joint stress (PFJS) during squatting with more anterior knee displacement has not been systematically investigated.

OBJECTIVE

To compare PFJS during squatting using 2 techniques: squat while keeping the knees behind the toes (SBT) and squat while allowing the knees to go past the toes (SPT).

SETTING

University research laboratory.

PARTICIPANTS

Twenty-five healthy females (age: 22.69 (0.74) y; height: 169.39 (6.44) cm; mass: 61.55 (9.74) kg) participated.

MAIN OUTCOME MEASURES: Three-dimensional kinematic and kinetic data were collected at 180 and 1800 Hz, respectively. A musculoskeletal model was used to calculate muscle forces through static optimization. These muscle forces were used in a patellofemoral joint model to estimate PFJS.

RESULTS

The magnitudes of PFJS, reaction force, and quadriceps force were higher (P < .001) during SPT compared with the SBT technique. Knee flexion, hip flexion, and ankle dorsiflexion angles were reduced when using the SBT technique.

CONCLUSIONS

Findings provide some general support for minimizing forward knee translation during squats for patients that may have patellofemoral pain syndrome.