Background: Long-term patient-reported outcome measures (PROMs), rates of return to sport, and revision risk after anterior cruciate ligament (ACL) reconstruction (ACLR) are not well understood. Purpose: To provide long-term follow-up of PROMs, return-to-sport rates, and revision rates after ACLR and to identify predictors for poor outcome. Study Design: Case-control study; Level of evidence, 3. Methods: A total of 2042 patients were included in an institutional ACL registry (2009-2013) and longitudinally followed. PROMs were completed preoperatively and at all follow-up time points. Questions regarding return to sport and knee stability were completed at final follow-up. Predictors for poor outcome on the International Knee Documentation Committee (IKDC) score were estimated in a regression model incorporating risk factors such as patient characteristics, graft choice, and concomitant injuries. Revision rates and risk of subsequent non-ACL surgeries were calculated. Results: Autografts were used in 76% of the patients (patellar tendon, 62%; hamstring grafts, 38%). Allografts were used in 24% of patients. The questionnaires were returned by 1045 (51.2%) patients at a mean of 7.2 years (range, 5.0-9.8 years) after surgery. Improvements in IKDC score of >30 points were sustained for all patient categories. The strongest predictor for lesser improvement in IKDC score was a cartilage lesion >2 cm2 identified during surgery. Male sex and college education completion were associated with improved IKDC scores. Meniscal lesions did not predict change) in the IKDC score. A total of 69% of patients had returned to sport after 8.1 years (range, 6.7-9.8 years). The main reason for not returning to sport was fear of reinjury. The revision rate was 7.2% after 9 years (range, 8-11 years), 13% of patients needed subsequent ipsilateral non-ACL surgery, and 6% underwent contralateral ACLR. The absence of a meniscal tear, younger age, and male sex were predictors for revision. Graft choice did not predict PROM results or revision risk. Conclusion: Improvements in IKDC scores were sustained 7 years after ACLR. The strongest predictor for poor outcome was a cartilage lesion >2 cm2. Patients can expect a 70% return-to-sport rate and an 87% chance of their knee feeling stable during daily and athletic activities after 8 years. Young male patients have better PROM scores but a higher risk of revision. There is a 26% chance of subsequent knee surgery within 9 years, including a revision rate of 7%, subsequent non-ACL surgery to the operated knee in 13%, and a 6% chance of contralateral ACLR.

Background: Loss to follow-up in registry studies might affect generalizability and interpretation of results. Purpose: To evaluate the effect of nonresponder bias in our anterior cruciate ligament (ACL) registry. Study Design: Case-control study; Level of evidence, 3. Methods: A total of 2042 patients with ACL reconstruction in the Hospital for Special Surgery ACL Registry between 2009 and 2013 were included in the study. Patients who completed the patient-reported outcome measures at 2 or 5 years were considered responders (n = 808). Baseline data and patient characteristics were compared between responders and nonresponders (n = 1234). Both responders and nonresponders were contacted and invited to complete the International Knee Documentation Committee (IKDC) and Marx scores electronically and respond to questions regarding return to sports and subsequent surgeries. Nonresponders who completed the questionnaires after reminders were considered late responders. The remaining nonresponders were considered never-responders. The late responders (n = 367) completed the questionnaires after a mean follow-up of 7.8 years (range, 6.7-9.6 years), while follow-up for the responders was 6.8 years (range, 5.0-9.7 years). Responders and late responders were then compared in terms of differences in IKDC and Marx scores from baseline to final follow-up. Results: Nonresponders were younger (28.5 vs 31.5 years; P < .001) and more often male (60% vs 53%; P = .003) compared with responders. Responders had a higher level of education and were more likely to be White (79% vs 74%; P = .04). There were no substantial differences in patient characteristics or baseline IKDC and Marx scores between the late responders and never-responders. There were no statistically significant differences in patient-reported outcomes, return to sports, or subsequent surgeries between responders and late responders at a mean follow-up time of 8.8 years (range, 6.7-9.7 years). Repeat email reminders and telephone calls increased response rate by 18% (from 40% to 58%). Conclusion: There was no difference in clinical outcome as evaluated using IKDC and Marx scores between responders and late responders.

Background: Recall bias is a systematic error caused by inaccuracy in reporting past health status and can be a substantial methodological flaw in the retrospective collection of data. Little is known about recall bias following anterior cruciate ligament reconstruction (ACLR). The purpose of this study was to evaluate patients’ recall bias regarding preinjury knee function at 2 years after ACLR. Methods: Patients undergoing ACLR were enrolled in an institutional ACL registry. Preoperatively and at 2 years postoperatively, patients quantified their preinjury knee function on a scale of 0 to 10 (10 = best). Recall bias was quantified as the difference in the reported preinjury function between the 2 time points. The clinical result of ACLR was evaluated according to the International Knee Documentation Committee (IKDC) Subjective Knee Evaluation score. Patients meeting the minimal clinically important difference (MCID) in the IKDC score were considered to have had a good outcome, while patients who did not reach the MCID were considered to have had failure of treatment. Recall bias was compared between the 2 groups. Results: Of 2,109 patients enrolled in the registry, 1,219 were included in the study. Patients with a good outcome remembered their preinjury knee function on a 0-to-10 scale to be better than what they reported at baseline, by a mean difference of 0.40 points (95% confidence interval [CI], 0.22 to 0.58 points). The recall bias was stronger for patients with a poor outcome, who remembered their knee function to be worse than reported at baseline, by a mean difference of −0.81 (95% CI, −1.4 to −0.26). The mean difference in recall between the 2 groups was −1.21 (95% CI, −1.74 to −0.67) (p < 0.0001). Conclusions: The recall bias of preinjury knee function following ACLR was small and not clinically meaningful for the majority of patients. However, patients with a poor outcome had a clinically relevant and significant recall bias. Clinical Relevance: Our findings suggest that patients with a poor outcome have a substantial recall bias. This has clinical relevance when considering treatment effects of revision surgery, whereby the clinical benefit of the treatment might be affected by recall bias.