Intra- and Inter-session Reliability of Static and Dynamic Postural Control in Participants with and without Patellofemoral Pain Syndrome.

PURPOSE To determine the intra- and inter-session reliability of balance performance in people with patellofemoral pain syndrome (PFPS) and matched controls. METHODS In this methodological study, single-leg-stance performance of 15 participants with unilateral PFPS and 15 healthy matched controls was assessed using the Biodex Balance System (BBS) under 4 task difficulty levels (static and dynamic, with and without visual feedback). Intra-class correlation coefficients (ICCs), standard errors of measurement, and coefficients of variation were calculated for the overall stability index, anterior-posterior stability index, and medial-lateral stability index. RESULTS Static and dynamic postural performance during single-leg stance showed moderate to very high reliability in the PFPS group (ICCs=0.53-0.96) and in healthy control participants (ICCs=0.51-0.91). Both measures were more reliable with eyes closed than with eyes open. CONCLUSION BBS stability indices appear to have acceptable reliability in people with PFPS, particularly in more challenging conditions, and may be incorporated into the evaluation and rehabilitation of this patient group.