{Reference Type}: Journal Article {Title}: Clinical classification of patellofemoral pain syndrome: guidelines for non-operative treatment. {Author}: Witvrouw E;Werner S;Mikkelsen C;Van Tiggelen D;Vanden Berghe L;Cerulli G; {Journal}: Knee Surg Sports Traumatol Arthrosc {Volume}: 13 {Issue}: 2 {Year}: Mar 2005 {Factor}: 4.114 {DOI}: 10.1007/s00167-004-0577-6 {Abstract}: The patellofemoral pain syndrome (PFPS) remains a challenging musculoskeletal entity encountered by clinicians. Reviewing the literature, conflicting data seem to exist regarding the effect of non-operative treatment in PFPS patients. A possible explanation may be lack of a clear classification system of patients with PFPS. It is our opinion that the term PFPS still is a 'wastebasket', which probably comprises several different entities. Therefore, it seems important to subdivide this broad group of patients into different categories with a specific rehabilitation approach. In this study, we introduce a classification system, which reflects a consensus reached by the European Rehabilitation Panel. This classification system should help the clinicians to identify the cause(s) of patellofemoral pain, and consequently help to select the most appropriate non-operative treatment. The authors are aware that no rehabilitation protocol will work for all PFPS patients, since the underlying mosaic of pathophysiology and tissue-healing responses are unique. Therefore, the aim of this study with a classification system was to guide the clinician through clinical examination in order to develop a non-operative treatment protocol, specific for each individual with PFPS.