The Forgotten Joint Score Shows High Correlation With Established Anterior Cruciate Ligament Reconstruction Patient-Reported Outcome Measures While Capturing Joint Awareness and Functional Recovery: A Systematic Review.

PURPOSE: To systematically review and analyze the existing literature on the use of the Forgotten Joint Score-12 (FJS-12) in patients undergoing anterior cruciate ligament reconstruction (ACLR), with the aim of evaluating its effectiveness as a complementary tool to traditional patient-reported outcome measures (PROMs) in assessing postoperative outcomes. METHODS: PubMed, Embase, and MEDLINE were searched on February 7, 2026. Studies were included if they used the FJS-12 to assess patients after ACLR. The quality of included studies was appraised, and data were extracted on demographics, surgical details, and outcome measures including FJS-12 and its correlations with other PROMs. Descriptive statistics were used to summarize the findings. RESULTS: Thirteen studies encompassing 1295 patients and 1316 knees were included. The mean age was 31.3 years, and the mean follow-up time was 44.3 months (range of means, 12.0-139.0 months). FJS-12 scores ranged widely from 37.0 to 92.6. The score showed strong, significant positive correlations with International Knee Documentation Committee subjective knee form score, Lysholm, and Knee Osteoarthritis and Outcome Score (r > 0.80 in 3 of 4 studies reporting correlations), particularly in isolated ACLR cases. FJS-12 showed a significant low-to-moderate correlation with Tegner activity levels (r = 0.318-0.606, P ≤ .003) in 2 of 3 studies. Subgroup analyses suggested higher FJS-12 scores in patients with restoration of hyperextension >5° and symmetrical range of motion to the contralateral limb. Factors such as radiographic osteoarthritis and partial meniscectomy were associated with lower FJS-12 scores. Across studies evaluating sex-based differences, no consistent or clinically meaningful differences in FJS-12 scores were observed between men and women. CONCLUSIONS: The FJS-12 is a patient-centered PROM that complements traditional metrics by capturing the subjective experience of joint awareness after ACLR. It shows moderate-to-strong correlations with established ACLR PROMs, supporting construct validity, and clinically meaningful thresholds have been reported, supporting clinical interpretability; however, the magnitude of responsiveness over time cannot be fully characterized because of limited reporting of longitudinal effect sizes. LEVEL OF EVIDENCE: Level IV, systematic review of Level II to IV studies.