A prospective study of 390 infantry recruits revealed that the medial
tibial intercondylar distance and that the isometric strength of the
quadriceps, tested at 85 degrees of flexion of the knee, had a
statistically significant correlation with the incidence of patellofemoral
pain caused by overactivity. Increased medial tibial intercondylar distance
and increased strength of the quadriceps were therefore deemed to be risk
factors for this syndrome.