Hip Strength Is Greater in Athletes Who Subsequently Develop Patellofemoral Pain

Abstract

Background Hip and knee strength abnormalities have been implicated in patellofemoral pain (PFP) in multiple studies. However, the relationship is unclear, as many of these studies have been retrospective. Purpose To compare prospective hip and knee isokinetic strength in young female athletes who subsequently went on to develop PFP relative to their uninjured, healthy peers. Study Design Descriptive epidemiology study. Methods Adolescent female athletes (N = 329) were tested for isokinetic strength of the knee (flexion and extension) and hip (abduction) and screened for the prevalence of PFP before their basketball seasons. After exclusion based on current PFP symptoms, 255 participants were prospectively enrolled in the study. A 1-way analysis of variance was used to determine between-group differences in incident PFP and the referent (no incident PFP) participants. Results The cumulative incidence rate for the development of PFP was 0.97 per 1000 athlete-exposures. Female athletes who developed PFP demonstrated increased normalized hip abduction strength (normalized torque, 0.013 ± 0.003) relative to the referent control group (normalized torque, 0.011 ± 0.003) (P <.05). Unlike hip strength, normalized knee extension and knee flexion strength were not different between the 2 groups (P > .05). Conclusion The findings in this study indicate that young female athletes with greater hip abduction strength may be at an increased risk for the development of PFP. Previous studies that have looked at biomechanics indicated that those with PFP have greater hip adduction dynamic mechanics. Clinical Relevance Combining the study data with previous literature, we theorize that greater hip abduction strength may be a resultant symptom of increased eccentric loading of the hip abductors associated with increased dynamic valgus biomechanics, demonstrated to underlie increased PFP incidence. Further research is needed to verify the proposed mechanistic link to the incidence of PFP.

Risk factors for patellofemoral pain: a systematic review and meta-analysis

“…Quadriceps weakness was not identified as a risk factor for future PFP in an adolescent group 27. While this further validates the importance of investigating risk factors within homogenous groups, it is also important to consider the implications of these findings in relation to risk modification interventions within differing populations.…”

“…When the data were pooled for the adolescent cohort, there is moderate evidence from one HQ27 and one MQ study26 that increased hip abduction strength is a risk factor for future PFP ( I 2 =0%, SMD 0.71, CI 0.39, 1.04) (see figure 12B) when measured isometrically with a HHD. Data pooling was not possible for the military or recreational runner subgroups.…”

“…However, increased baseline isometric hip abduction strength predicts future PFP in adolescents 26 27. Herbst et al 27 make the suggestion that increased hip abduction strength could be the result of greater eccentric hip abductor demands due to higher peak hip adduction during dynamic tasks. When pooling data from both military and adolescent cohorts, dynamic knee valgus angle was also not a risk factor for future PFP.…”

“…The mean age of the Herbst et al 27 cohort is 12.7 years and may therefore have increased lower limb muscle strength as a consequence of high physical activity levels. It may be that lower limb muscle strength correlates with duration of symptoms in adolescents, with strength deficits presenting later in life when symptoms persist and if activity levels subsequently reduce 39.…”

Patellofemoral Kinematics and Tibial Tuberosity–Trochlear Groove Distances in Female Adolescents With Patellofemoral Pain

“…Two other studies, 2, 10 also focused on adolescent cohorts with patellar instability, reported higher rates of dislocation in adolescent patients with increased distance between the tibial tuberosity and trochlear groove (TT-TG). Finally, studies 19, 26, 27 have identified increased hip and knee abduction moments as risk factors for the development of PFP in adolescents. While the implied consequence of these abnormalities is altered patellofemoral tracking patterns and increased patellofemoral contact pressures, confirmation of these fundamental findings in adolescent females with PFP is currently lacking.…”