Search Strategy and Eligibility Criteria

This review followed the PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta-analyses). The search string was developed by 1 author (J.W.), a clinical informationist at the National Institutes of Health Library with 14 years of experience, using input from all authors. The search of the literature was conducted in July 2018 and then updated in September 2019 with the following databases: Embase, PubMed, Scopus, and Web of Science. The search strategy included 3 keyword strings and their associated range of terms (Appendix Table A1, available in the online version of this article). We included all studies irrespective of publication year, but limited inclusion to full-text English-language publications. The updated search was limited to publications published after 2017 that were not included in the original search.

This preliminary database was screened per the predetermined eligibility criteria. A study was included into the final review only if (1) it evaluated patellofemoral alignment and/or tracking in individuals with idiopathic PFP or pain secondary to subluxation, dislocation of the patella, or recurrent patellofemoral instability and (2) the results were reported at or near full extension (≤10° of knee flexion). A study was eliminated if (1) its participants had previous leg trauma, pathology, or surgery or displayed signs of osteoarthritis; (2) it did not quantitatively report the main findings or evaluate controls; and (3) its primary aim was to assess the therapy or treatment efficacy. Two reviewers (C.G. and C.N.F.) independently screened titles and abstracts to identify the initial study database. Finally, full-text manuscripts were screened according to the inclusion and exclusion criteria for final inclusion. A third reviewer (J.M.) was consulted when a consensus could not be reached.