Hip adduction during running and knee-related symptoms - Sex differences and longitudinal associations in runners with a history of knee surgery: Two-year data from the TRAIL cohort.

BACKGROUND: Increased peak hip adduction during running has been observed in runners with knee pain and is thought to increase knee joint loading and symptom development. This study aimed to explore: (i) sex differences in peak hip adduction during running and knee-related symptoms in runners with a history of knee surgery; and (ii) associations between baseline hip adduction and knee-related symptoms at baseline and two-year follow-up. METHODS: Runners with a history of knee surgery, who ran ≥3 times and ≥10 km per week, were recruited. Overground running biomechanics at baseline were recorded via three-dimensional motion capture and embedded force plates at both 3-3.5 m/s and 5-6 m/s. Surgical limb peak hip adduction during stance was extracted. Knee-related symptoms were assessed using the Knee injury and Osteoarthritis Outcome Score 4 and the patellofemoral subscale at baseline and two-year follow-up. Linear regressions explored sex differences in peak hip adduction while generalised linear models explored sex differences in knee-related symptoms and associations between hip adduction and symptoms cross-sectionally and longitudinally. FINDINGS: 108 runners with a history of knee surgery completed baseline testing (53 females; 55 males). Females demonstrated greater peak hip adduction (3.42° for 3-3.5 m/s and 1.09° for 5-6 m/s) and worse knee-related symptoms (-5.61 to -8.18) than males. No significant associations were found between hip adduction and symptoms (baseline or two-year follow up). INTERPRETATION: Female runners with a history of knee surgery demonstrated greater hip adduction and worse knee-related symptoms than males. Peak hip adduction was not significantly associated with knee-related symptoms at baseline or two years.