Purpose The purpose of this study was to determine the utilization and responsiveness of common patient-reported outcomes (PROs) in patients undergoing surgery for patellar instability. Methods Using PRISMA guidelines, a systematic review of studies reporting outcomes following surgical intervention for patellar instability was conducted using Pubmed, Cochrane, OVID Medline, and Google Scholar. Subgroup analysis of articles reporting at least two PROs with baseline and follow-up data were used to evaluate responsiveness of instruments using relative eiciency and efect size. Results From the search, 2,848 unique articles were found, of which 178 were included in inal analysis (7,122 patients, mean age 22.6, 63.6% female). The most commonly used PRO was the Kujala score (79.2%), followed by the Lysholm (34.8%), and Tegner (30.9%). Seventy-nine articles were eligible for subgroup analysis. The Kujala had a higher relative eiciency than ten of the 14 instruments to which it was compared but had lower relative eiciency compared to the IKDC and Lysholm scores. The Banf Patella Instability Instrument (BPII) and the Norwich score, condition-speciic tools, were unable to be fully assessed due to rarity of use and lack of comparisons.
ConclusionThe hypothesis that the Kujala score is the most commonly used PRO for patellar instability, although other instruments ofer greater eiciency was supported by our results. The IKDC and Lysholm scores had similar efect sizes but higher relative eiciencies than the Kujala, thus suggesting better responsiveness. This analysis adds useful information for surgeons on the efectiveness of the most common PRO's for evaluating patellofemoral instability outcomes. Level of evidence Level III.