Objectives:Retear of an ACL after an ACL reconstruction (ACLR) is devastating for all involved. Understanding risk factors and predictors of subsequent ACL tear after an ACLR is vital for patient education of subsequent risk of injury and if a predictor is modifiable, to make adjustments to minimize the risk of repeat ACL tear. The objectives of this study were 1) to identify the risk factors and predictors for ispilateral and contralateral ACL tears after primary ACLR and 2) to compare retear risk between the 2002/03 and 2007/08 cohorts. This is the largest and most comprehensive prospective analysis of this kind in the literature.Methods:Data from the 2002-2008 MOON database was used to identify risk factors for ACL retear. Subjects who had a primary ACLR with no history of contralateral knee surgery and had 2 year follow-up data were included. Subjects who had multiligament surgery were excluded. Graft type (auto-BTB, auto-hamstring, allograft), age, Marx score at time of index surgery, sport played post ACLR, sex, smoking status, lateral meniscus tear at the time of ACLR, medial meniscus tear at the time of ACLR, BMI, and MOON site were evaluated to determine their contribution to both ipsilateral retear and contralateral ACL tear. The analysis was repeated using the 2002/3 and 2007/8 cohort and included age, graft, sex, and Marx. An ANOVA with post-hoc analysis was performed to detect significant differences in age and Marx score by graft type over time.Results:A total of 2801 subjects met all inclusion/exclusion criteria. There were 165/2801 (5.89%) ipsilateral and 177/2801 (6.32%) contralateral ACL tears identified in the cohort at the two year follow-up. The odds of ipsilateral retear are 1.68 times greater for hamstring autograft (p=0.04) and 4.67 times greater for an allograft (p<0.001) compared to auto-BTB. The odds of ipsilateral retear decrease by 8% for every yearly increase in age (p < 0.001) and increases by 6% for every increased point on the Marx score (p = 0.017). The odds of contralateral ACL tear increase by 7% for every increased point on the Marx score (p = 0.004) and decreases by 5% for every one point increase in BMI (p = 0.03). In 2002/3, there were 61/815 (7.5%) retears compared to 37/1056 (3.5%) in 2007/8. The odds of retear by for the 2002/03 and 2007/08 cohorts are summarized in table 1. The mean age (figure 1) of subjects receiving BTB and hamstring remained constant over time whereas the mean age of subjects receiving allograft rose by seven years (p < 0.001). Hamstring use was a predictor of retear compared to BTB in the 02/03 group (7.9% vs. 4.2%), but not in the 07/08 group (4.1% vs. 3.4%).Conclusion:Age, activity, and graft type were predictors of increased risk of ipsilateral graft failure after ACLR. Higher activity and lower BMI were found to be risk factors in contralateral ACL tears. Allograft use in young active patients was shown to be a risk factor for graft retear in the 02/03 group, subsequent to this, graft choice changed to using allografts in older and less active ...

Purpose The purpose of this study is to evaluate the effect of graft size on patient-reported outcomes and revision risk following ACL reconstruction. Methods A retrospective chart review of prospectively collected cohort data, 263 of 320 consecutive patients (82.2%) undergoing primary ACL reconstruction with hamstring autograft were evaluated. Graft size, femoral tunnel drilling technique, patient age, sex, and BMI at the time of ACL reconstruction, pre-operative and 2-year post-operative KOOS and IKDC scores, and whether each patient underwent revision ACL reconstruction during the 2 year follow-up period were recorded. Revision was used as a marker for graft failure. The relationship between graft size and patient-reported outcomes was determined by multiple linear regression. The relationship between graft size and risk of revision was determined by dichotomizing graft size at 8mm and stratifying by age. Results After controlling for age, sex, operative side, surgeon, BMI, graft choice, and femoral tunnel drilling technique, a 1 mm increased in graft size was noted to correlate with 3.3-point increase in the KOOS-pain subscale (p = 0.003), a 2.0-point increased in the KOOS activities of daily living subscale (p = 0.034), a 5.2-point increase in the KOOS-sport/recreation function subscale (p = 0.004), and a 3.4-point increase in the subjective IKDC score (p = 0.026). Revision was required in 0 of 64 patients (0.0%) with grafts greater than 8mm in diameter and 14 of 199 patients (7.0%) with 8 mm or smaller grafts (p = 0.037). Among patients age 18 and under, revision was required in 0 of 14 patients (0.0%) with grafts greater than 8mm in diameter and 13 of 71 patients (18.3 %) with 8 mm or smaller grafts. Conclusions Smaller hamstring autograft size is a predictor of poorer KOOS Sport and Recreation function 2 years following primary ACL reconstruction. Larger sample size is required to confirm the relationship between graft size and risk of revision ACL reconstruction. Level of Evidence Level 3

Background The predictors of ACL reconstruction outcome at six years as measured by validated patient based outcomes instruments are unknown. Hypothesis We hypothesize that certain variables evaluated at the time of ACL reconstruction will predict return to sports function (as measured by the IKDC and KOOS Sports and Recreation subscale), knee-related quality of life (as measured by the KOOS Knee Related Quality of Life subscale), and activity level (as measured by the Marx scale). Potential predictor variables include demographics, surgical technique and graft choice for ACL reconstruction, and intra-articular injuries and treatment. Study Design Prospective cohort, Level 1 Methods All unilateral ACL reconstructions from 2002 currently enrolled in the Multicenter Orthopaedic Outcomes Network (MOON) cohort were evaluated. Patients preoperatively completed a series of validated outcome instruments, including the IKDC, KOOS, and Marx activity level. Physicians documented intra-articular pathology, treatment, and surgical techniques utilized at the time of surgery. At 2 and 6 years postoperatively, patients completed the same validated outcome instruments. Results Follow-up was obtained on 395/448 (88%) at 2 years and 378/448 (84%) at 6 years. The cohort was 57% male with median age of 23 at the time of enrollment. The ability to perform sports function was maintained at six years (IKDC T2 = 75, T6 = 77; KOOSsports/rec T2 = 85, T6 = 90). The Marx activity level continued to decline from baseline (T0 = 12, T2 = 9, T6 = 7). Revision ACL reconstruction and use of allograft predicted worse outcomes on the IKDC and both KOOS subscales. Lateral meniscus treatment, smoking status, and BMI at T0 were each predictors on two of three scales. The predictors of lower activity level were revision ACL reconstruction and female sex. Conclusions Six years after ACL reconstruction, patients are able to perform sports-related functions and maintain a high knee-related quality of life similar to their two year level, although their physical activity level (Marx) drops over time. Choosing autograft rather than allograft, not smoking, and having normal BMI are advised to improve long-term outcomes.

Background:Tearing an anterior cruciate ligament (ACL) graft is a devastating occurrence after ACL reconstruction (ACLR). Identifying and understanding the independent predictors of ACLR graft failure is important for surgical planning, patient counseling, and efforts to decrease the risk of graft failure.Hypothesis:Patient and surgical variables will predict graft failure after ACLR.Study Design:Prospective cohort study.Methods:A multicenter group initiated a cohort study in 2002 to identify predictors of ACLR outcomes, including graft failure. First, to control for confounders, a single surgeon’s data (n = 281 ACLRs) were used to develop a multivariable regression model for ACLR graft failure. Evaluated variables were graft type (autograft vs allograft), sex, age, body mass index, activity at index injury, presence of a meniscus tear, and primary versus revision reconstruction. Second, the model was validated with the rest of the multicenter study’s data (n = 645 ACLRs) to evaluate the generalizability of the model.Results:Patient age and ACL graft type were significant predictors of graft failure for all study surgeons. Patients in the age group of 10 to 19 years had the highest percentage of graft failures. The odds of graft rupture with an allograft reconstruction are 4 times higher than those of autograft reconstructions. For each 10-year decrease in age, the odds of graft rupture increase 2.3 times.Conclusion:There is an increased risk of ACL graft rupture in patients who have undergone allograft reconstruction. Younger patients also have an increased risk of ACL graft failure.Clinical Relevance:Given these risks for ACL graft rupture, allograft ACLRs should be performed with caution in the younger patient population.

Higher activity level after reconstruction and allograft use for reconstruction are risk factors for ACL graft failure. Stratum-specific odds ratios show a multiplicative interaction between higher activity level after ACL reconstruction and allograft use, greatly increasing the odds for ACL graft failure.