Exercise for treating patellofemoral pain syndrome

Background Patellofemoral pain syndrome (PFPS) is a common knee problem, which particularly affects adolescents and young adults. PFPS, which is characterised by retropatellar (behind the kneecap) or peripatellar (around the kneecap) pain, is often referred to as anterior knee pain. The pain mostly occurs when load is put on the knee extensor mechanism when climbing stairs, squatting, running, cycling or sitting with flexed knees. Exercise therapy is often prescribed for this condition. Objectives To assess the effects (benefits and harms) of exercise therapy aimed at reducing knee pain and improving knee function for people with patellofemoral pain syndrome. Search methods We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register (May 2014), the Cochrane Central Register of Controlled Trials (2014, Issue 4), MEDLINE (1946 to May 2014), EMBASE (1980 to 2014 Week 20), PEDro (to June 2014), CINAHL (1982 to May 2014) and AMED (1985 to May 2014), trial registers (to June 2014) and conference s. Selection criteria Randomised and quasi‐randomised trials evaluating the effect of exercise therapy on pain, function and recovery in adolescents and adults with patellofemoral pain syndrome. We included comparisons of exercise therapy versus control (e.g. no treatment) or versus another non‐surgical therapy; or of different exercises or exercise programmes. Data collection and analysis Two review authors independently selected trials based on pre‐defined inclusion criteria, extracted data and assessed risk of bias. Where appropriate, we pooled data using either fixed‐effect or random‐effects methods. We selected the following seven outcomes for summarising the available evidence: pain during activity (short‐term: ≤ 3 months); usual pain (short‐term); pain during activity (long‐term: > 3 months); usual pain (long‐term); functional ability (short‐term); functional ability (long‐term); and recovery (long‐term). Main results In total, 31 heterogeneous trials including 1690 participants with patellofemoral pain are included in this review. There was considerable between‐study variation in patient characteristics (e.g. activity level) and diagnostic criteria for study inclusion (e.g. minimum duration of symptoms) and exercise therapy. Eight trials, six of which were quasi‐randomised, were at high risk of selection bias. We assessed most trials as being at high risk of performance bias and detection bias, which resulted from lack of blinding. The inclu