Leg dominance as a risk factor for femoroacetabular impingement syndrome.

One etiological factor of femoroacetabular impingement syndrome (FAIS) is high impact athletics involving deep hip flexion, axial loading and jumping during skeletal development. Previous work has established that there is physiologic asymmetry of the lower limbs regarding function, with the dominant limb being primarily responsible for propulsion and kicking while the non-dominant limb is responsible for stability and planting. The authors hypothesize that the dominant limb will be more likely to undergo hip arthroscopy for symptomatic FAIS. Four hundred and sixty-nine patients at a single surgical center who underwent primary or revision hip arthroscopy for cam-type FAIS were identified. Patients were asked to identify their dominant lower extremity, defined as the lower extremity preferred for kicking. Sixty patients who indicated bilateral leg dominance were excluded. It was assumed that with no association between limb dominance and the need for surgery, the dominant side would have surgery 50% of the time. Enrichment for surgery in the dominant limb was tested for using a one-sample test of proportions, determining whether the rate differed from 50%. The enrichment for surgery on the dominant side was 57% (95% confidence interval 52-62%) which was significantly different from the rate expected by chance (50%),  = 0.003. No other significant differences were noted between groups. Limb dominance appears to be an etiological factor in the development of cam-type FAIS. Patients are more likely to undergo arthroscopic treatment of FAIS on their dominant lower extremity, although the non-dominant lower extremity frequently develops FAIS as well.