Review: Patient-reported outcome scores following patellar i
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.

Using PRISMA guidelines, a systematic review of studies reporting outcomes following surgical intervention for patellar instability was conducted. Subgroup analysis of articles reporting at least two PROs with baseline and follow-up data were used to evaluate responsiveness of instruments using relative efficiency and effect size.

--From the search, 2,848 unique articles were found, of which 178 were included in final 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%).

--79 articles were eligible for subgroup analysis. The Kujala had a higher relative efficiency than 10 of the 14 instruments to which it was compared but had lower relative efficiency compared to the IKDC and Lysholm scores.

--The Banff Patella Instability Instrument (BPII) and the Norwich score, condition-specific tools, were unable to be fully assessed due to rarity of use and lack of comparisons.

In conclusion, the hypothesis is that the Kujala score is PRO for patellar instability, however these results have validated alternative instruments with higher efficiency. The scores of IKDC and Lysholm had a similar effect but were somewhat more efficient than the Kujala, indicating superior reactivity. This report gives surgeons useful information on the efficacy of the most used PROs in assessing outcomes of PPF.