Avoiding Graft Failure: Lessons Learned from the Stability Trial.

The Stability Study was a multicenter, pragmatic, parallel groups, randomized clinical trial comparing hamstring tendon autograft anterior cruciate ligament reconstruction with or without the addition of lateral extra-articular tenodesis in young patients at high risk of graft failure. Having recruited 618 patients with a 5% loss to follow up, we were able to demonstrate a clinically and statistically significant reduction in clinical failure and graft rupture at 2 years postoperative. No differences in patient-reported outcomes (PROs) were demonstrated between groups; however, patients who experienced an adverse event had significantly worse PROs than those who did not.

Quantitative MRI Analysis of Patellofemoral Joint Cartilage Health 2 Years After Anterior Cruciate Ligament Reconstruction and Lateral Extra-Articular Tenodesis.

BACKGROUND: The addition of an iliotibial band-based lateral extra-articular tenodesis (LET) to anterior cruciate ligament (ACL) reconstruction (ACLR) has been shown to reduce failure rates. However, there are concerns as to the potential overconstraint of tibiofemoral kinematics that may increase the risk of cartilage degradation. To date, no clinical study has investigated the effect of LET on patellofemoral joint articular cartilage health. HYPOTHESIS: It was hypothesized that at 2 years postoperatively, (1) the addition of LET at the time of ACLR would have no effect on cartilage health on magnetic resonance imaging (MRI), and (2) higher cartilage relaxation values would be associated with worse patient-reported and functional outcomes. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A subset of patients from the STABILITY 1 randomized controlled trial were included. All patients underwent primary ACLR with a hamstring autograft. Patients were randomized to either LET augmentation or not. Cartilage status in the patellofemoral joint between the ACLR group and ACLR+LET group was compared using 2-year postoperative quantitative MRI and the ACL osteoarthritis scores of both the surgical and the contralateral nonsurgical knees. Objective functional outcomes and patient-reported outcome measures (PROMs) were attained. RESULTS: A total of 92 patients (43 patients in the ACLR group; mean age, 18.9 ± 3.2 years; 60.5% female; and 49 patients in the ACLR+LET group; mean age, 18.7 ± 3.2 years, 63.3% female) were included. No significant differences were seen in the mean values (ms) for adjusted T1ρ/T2 relaxation times in the medial patella (47.8/42.2 vs 47.3/43.2), central patella (45.5/42.5 vs 44.1/42.7), lateral patella (48.2/43.5 vs 47.3/43.0), medial trochlea (54.7/50.9 vs 56.4/50.9), central trochlea (53.3/51.1 vs 53.1/52.0), and lateral trochlea (54.9/52.1 vs 53.9/52.6) between the ACLR and ACLR+LET groups. No difference in overall ACL osteoarthritis scores was observed (P = .99). An increase in medial patellar T2 relaxation times was associated with a decreasing International Knee Documentation Committee score (P = .046), Knee injury and Osteoarthritis Outcome Score (KOOS) Symptoms subscale score (P = .01), and total KOOS (P = .01). CONCLUSION: There was no statistical difference in patellofemoral cartilage health between knees 2 years after primary ACLR with hamstring tendon autograft with or without LET. Statistically significant correlations were found between quantitative MRI relaxation times, functional outcome scores, and PROMs; however, the correlations were weak and the clinical significance is unknown. REGISTRATION: NCT02018354 (ClinicalTrials.gov identifier).

Precision Anterior Cruciate Ligament Reconstruction.

Precision anterior cruciate ligament reconstruction (ACLR) refers to the individualized approach to prerehabilitation, surgery (including anatomy, bony morphology, and repair/reconstruction of concomitant injuries), postrehabilitation, and functional recovery. This individualized approach is poised to revolutionize orthopedic sports medicine, aiming to improve patient outcomes. The purpose of this article is to provide a summary of precision ACLR, from the time of diagnosis to the time of return to play, with additional insight into the future of ACLR.

Quantitative Magnetic Resonance Imaging of Lateral Compartment Articular Cartilage After Lateral Extra-articular Tenodesis.

BACKGROUND: Concerns have arisen that anterior cruciate ligament reconstruction (ACLR) with lateral extra-articular tenodesis (LET) may accelerate the development of posttraumatic osteoarthritis in the lateral compartment of the knee. PURPOSE/HYPOTHESIS: The purpose of this study was to evaluate whether the augmentation of ACLR with LET affects the quality of lateral compartment articular cartilage on magnetic resonance imaging (MRI) at 2 years postoperatively. We hypothesized that there would be no difference in T1rho and T2 relaxation times when comparing ACLR alone with ACLR + LET. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: A consecutive subgroup of patients at the Fowler Kennedy Sport Medicine Clinic participating in the STABILITY 1 Study underwent bilateral 3-T MRI at 2 years after surgery. The primary outcome was T1rho and T2 relaxation times. Articular cartilage in the lateral compartment was manually segmented into 3 regions of the tibia (lateral tibia [LT]-1 to LT-3) and 5 regions of the femur (lateral femoral condyle [LFC]-1 to LFC-5). Analysis of covariance was used to compare relaxation times between groups, adjusted for lateral meniscal tears and treatment, cartilage and bone marrow lesions, contralateral relaxation times, and time since surgery. Semiquantitative MRI scores according to the Anterior Cruciate Ligament OsteoArthritis Score were compared between groups. Correlations were used to determine the association between secondary outcomes (including results of the International Knee Documentation Committee score, Knee injury and Osteoarthritis Outcome Score, Lower Extremity Functional Scale, 4-Item Pain Intensity Measure, hop tests, and isokinetic quadriceps and hamstring strength tests) and cartilage relaxation. RESULTS: A total of 95 participants (44 ACLR alone, 51 ACLR + LET) with a mean age of 18.8 years (61.1% female [58/95]) underwent 2-year MRI (range, 20-36 months). T1rho relaxation times were significantly elevated for the ACLR + LET group in LT-1 (37.3 ± 0.7 ms vs 34.1 ± 0.8 ms, respectively; P = .005) and LFC-2 (43.9 ± 0.9 ms vs 40.2 ± 1.0 ms, respectively; P = .008) compared with the ACLR alone group. T2 relaxation times were significantly elevated for the ACLR + LET group in LFC-1 (51.2 ± 0.7 ms vs 49.1 ± 0.7 ms, respectively; P = .03) and LFC-4 (45.9 ± 0.5 ms vs 44.2 ± 0.6 ms, respectively; P = .04) compared with the ACLR alone group. All effect sizes were small to medium. There was no difference in Anterior Cruciate Ligament OsteoArthritis Scores between groups (P = .99). Weak negative associations (rs = -0.27 to -0.22; P < .05) were found between relaxation times and quadriceps and hamstring strength in the anterolateral knee, while all other correlations were nonsignificant (P > .05). CONCLUSION: Increased relaxation times demonstrating small to medium effect sizes suggested early biochemical changes in articular cartilage of the anterolateral compartment in the ACLR + LET group compared with the ACLR alone group. Further evidence and long-term follow-up are needed to better understand the association between these results and the potential risk of the development of osteoarthritis in our patient cohort.

Editorial Commentary: Locking Plate Removal Is Safe and May Improve Function 1 Year After Medial Opening Wedge High Tibial Osteotomy.

The development of angular stable locking late fixation in realignment osteotomy has resulted in the ability to be more aggressive with weight bearing and rehabilitation after high tibial osteotomy. One of the downsides of some of these plate fixators is the degree of soft-tissue irritation and discomfort that can be experienced by many patients, resulting in the need for hardware removal. Studies have shown greater than 50% of patients requiring hardware removal with no resulting loss of correction, although there may be cultural reasons for the higher number, not solely attributable to the symptom profile. It is encouraging to see that after 1 year postoperatively, hardware removal after high tibial osteotomy not only is safe but also results in a clinically important improvement in pain and function, with progressive bone healing out to 2 years.

Anterior Cruciate Ligament Reconstruction Plus Lateral Extra-articular Tenodesis Has a Similar Return-to-Sport Rate to Anterior Cruciate Ligament Reconstruction Alone but a Lower Failure Rate.

PURPOSE: To determine whether the addition of lateral extra-articular tenodesis (LET) to anterior cruciate ligament reconstruction (ACLR) would improve return-to-sport (RTS) rates in young, active patients who play high-risk sports. METHODS: This multicenter randomized controlled trial compared standard hamstring tendon ACLR with combined ACLR and LET using a strip of the iliotibial band (modified Lemaire technique). Patients aged 25 years or younger with an anterior cruciate ligament-deficient knee were included. Patients also had to meet 2 of the following criteria: (1) pivot-shift grade 2 or greater, (2) participation in a high-risk or pivoting sport, and (3) generalized ligamentous laxity. Time to return and level of RTS were determined via administration of a questionnaire at 24 months postoperatively. RESULTS: We randomized 618 patients in this study, 553 of whom played high-risk sports preoperatively. The proportion of patients who did not RTS was similar between the ACLR (11%) and ACLR-LET (14%) groups; however, the graft rupture rate was significantly different (11.2% in ACLR group vs 4.1% in ACLR-LET group, P = .004). The most cited reason for no RTS was lack of confidence and/or fear of reinjury. A stable knee was associated with nearly 2 times greater odds of returning to a high-level high-risk sport postoperatively (odds ratio, 1.92; 95% confidence interval, 1.11-3.35; P = .02). There were no significant differences in patient-reported functional outcomes or hop test results between groups (P > .05). Patients who returned to high-risk sports had better hamstring symmetry than those who did not RTS (P = .001). CONCLUSIONS: At 24 months postoperatively, patients who underwent ACLR plus LET had a similar RTS rate to those who underwent ACLR alone. Although the subgroup analysis did not show a statistically significant increase in RTS with the addition of LET, on returning, the addition of LET kept subjects playing longer by reducing graft failure rates. LEVEL OF EVIDENCE: Level I, randomized controlled trial.

A bifactor model supports unidimensionality of the International Knee Documentation Committee Subjective Knee Form in young active patients with anterior cruciate ligament tears: a retrospective analysis of a randomized controlled trial.

BACKGROUND: The International Knee Documentation Committee Subjective Knee Form (IKDC) is the most highly recommended patient reported outcome measure for assessing patients with anterior cruciate ligament (ACL) injuries and those undergoing ACL reconstruction (ACLR) surgery. The IKDC was developed as a unidimensional instrument for a variety of knee conditions. Structural validity, which determines how an instrument is scored, has not been definitively confirmed for the IKDC in respondents with ACL injuries, and in fact an alternative two-factor/subscale structure has been proposed in this population. The purpose of this study was to determine the most appropriate structure and scoring system for the IKDC in young active patients following ACL injury. METHODS: In total, 618 young patients deemed at high risk of graft rupture were randomized into the Stability 1 trial. Of the trial participants, 606 patients (98%) completed a baseline IKDC questionnaire used for this analysis. A cross sectional retrospective secondary data analysis of the Stability 1 baseline IKDC data was completed to assess the structural validity of the IKDC using exploratory and confirmatory factor analyses. Factor analyses were used to test model fit of the intended one-factor structure, a two-factor structure, and alternative four-factor and bifactor structures (i.e., a combination of a unidimensional factor with additional specific factors) of the IKDC, in a dataset of young active ACL patients. RESULTS: The simple one-factor and two-factor structures of the IKDC displayed inadequate fit in our dataset of young ACL patients. A bifactor model provided the best fit. This model contains one general factor that is substantially associated with all items, plus four secondary, more specific content factors (symptoms, activity level, activities of daily living, and sport) with generally weaker associations to subsets of items. Although the single-factor model did not provide unambiguous support to unidimensionality of the IKDC based on fit indices, the bifactor model supports unidimensionality of the IKDC when covariance between items with similar linguistic structure, response options, or content are acknowledged. CONCLUSIONS: Overall, findings of a bifactor model with evidence of a reliable general factor well defined by all items lends support to continue interpreting and scoring this instrument as unidimensional. This should be confirmed in other samples. Clinically, based on these findings, the IKDC can be represented by a single score for young active patients with ACL tears. A more nuanced interpretation would also consider secondary factors such as sport and activity level. TRIAL REGISTRATION: The Stability 1 trial for which these data were collected was registered on ClinicalTrial.gov (NCT02018354).

External Validation of the KOOS-ACL in the MOON Group Cohort of Young Athletes Followed for 10 Postoperative Years.

BACKGROUND: The Knee injury and Osteoarthritis Outcome Score-Anterior Cruciate Ligament (KOOS-ACL) is a short form version of the KOOS, developed to target populations of young active patients with ACL tears. The KOOS-ACL consists of 2 subscales: Function (8 items) and Sport (4 items). The KOOS-ACL was developed and validated using data from the Stability 1 study from baseline to postoperative 2 years. PURPOSE: To validate the KOOS-ACL in an external sample of patients matching the outcome's target population. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 1. METHODS: The Multicenter Orthopaedic Outcomes Network group cohort of 839 patients aged 14 to 22 years who tore their ACLs while playing sports was used to assess internal consistency reliability, structural validity, convergent validity, responsiveness to change, and floor/ceiling effects of the KOOS-ACL at 4 time points: baseline and postoperative 2, 6, and 10 years. Detection of treatment effects between graft type (hamstring tendon vs bone-patellar tendon-bone) were also compared between the full-length KOOS and KOOS-ACL. RESULTS: The KOOS-ACL demonstrated acceptable internal consistency reliability (α = .82-.89), structural validity (Tucker-Lewis index and comparative fit index = 0.98-0.99; standardized root mean square residual and root mean square error of approximation = 0.04-0.07), convergent validity (Spearman correlation with International Knee Documentation Committee subjective knee form = 0.66-0.85; Western Ontario and McMaster Universities Osteoarthritis Index function = 0.84-0.95), and responsiveness to change across time (large effect sizes from baseline to postoperative 2 years; d = 0.94 [Function] and d = 1.54 [Sport]). Stable scores and significant ceiling effects were seen from 2 to 10 years. No significant differences in KOOS or KOOS-ACL scores were detected between patients with different graft types. CONCLUSION: The KOOS-ACL shows improved structural validity when compared with the full-length KOOS and adequate psychometric properties in a large external sample of high school and college athletes. This strengthens the argument to use the KOOS-ACL to assess young active patients with ACL tears in clinical research and practice.

Development and Preliminary Validation of the KOOS-ACL: A Short Form Version of the KOOS for Young Active Patients With ACL Tears.

BACKGROUND: The Knee injury and Osteoarthritis Outcomes Score (KOOS) is a widely used region-specific outcome measure for assessing patients of all ages with a variety of knee conditions. Use of the KOOS for young active patients with anterior cruciate ligament (ACL) tear has been called into question regarding its relevance and interpretability for this specific population. Furthermore, the KOOS does not have adequate structural validity for use in high-functioning patients with ACL deficiency. PURPOSE: To develop a condition-specific short form version of the KOOS that is appropriate for the young active population with ACL deficiency: the KOOS-ACL. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 2. METHODS: A baseline data set of 618 young patients (≤25 years old) with ACL tears was divided into development and validation samples. Exploratory factor analyses were conducted in the development sample to identify the underlying factor structure and to reduce the number of items based on statistical and conceptual indicators. Confirmatory factor analyses were conducted to check fit indices of the proposed KOOS-ACL model in both samples. Psychometric properties of the KOOS-ACL were assessed using the same data set, expanded to include patient data from 5 time points (baseline and postoperative 3, 6, 12, and 24 months). Internal consistency reliability, structural validity, convergent validity, responsiveness to change, floor/ceiling effects, and detection of treatment effects between surgical interventions (ACL reconstruction alone vs ACL reconstruction + lateral extra-articular tenodesis) were assessed. RESULTS: A 2-factor structure was deemed most appropriate for the KOOS-ACL. Of 42 items, 30 were removed from the full-length KOOS. The final KOOS-ACL model showed acceptable internal consistency reliability (α = .79-.90), structural validity (comparative fit index and Tucker-Lewis index = 0.98-0.99; root mean square error of approximation and standardized root mean square residual = 0.04-0.07), convergent validity (Spearman correlation with International Knee Documentation Committee subjective knee form = 0.61-0.83), and responsiveness across time (significant small to large effects; P < .05). CONCLUSION: The new KOOS-ACL questionnaire contains 12 items and 2 subscales-Function (8 items) and Sport (4 items)-relevant to young active patients with an ACL tear. Use of this short form would reduce patient burden by more than two-thirds; it provides improved structural validity as compared with the full-length KOOS for our population of interest; and it demonstrates adequate psychometric properties in our sample of young active patients undergoing ACL reconstruction.

Closing-Wedge Posterior Tibial Slope-Reducing Osteotomy in Complex Revision ACL Reconstruction.

Background: A posterior tibial slope (PTS) >12° has been shown to correlate with failure of anterior cruciate ligament (ACL) reconstruction (ACLR). PTS-reducing osteotomy has been described to correct the PTS in patients with a deficient ACL, mostly after failure of primary ACLR. Purpose: To report radiologic indices, clinical outcomes, and postoperative complications after PTS-reducing osteotomy performed concurrently with revision ACLR (R-ACLR). Study Design: Case series; Level of evidence, 4. Methods: A review of medical records at 3 institutions was performed of patients who had undergone PTS-reducing osteotomy concurrently with R-ACLR between August 2010 and October 2020. Radiologic parameters recorded included the PTS, patellar height according to the Caton-Deschamps Index (CDI), and anterior tibial translation (ATT). Patient-reported outcomes (International Knee Documentation Committee [IKDC] and Knee injury and Osteoarthritis Outcome Score [KOOS]), reoperations, and complications were evaluated. Results: Included were 23 patients with a mean follow-up of 26.7 months (range, 6-84 months; median, 22.5 months). Statistically significant differences from preoperative to postoperative values were found in PTS (median [range], 14.0° [12°-18°] vs 4.0° [0°-15°], respectively; P < .001), CDI (median, 1.00 vs 1.10, respectively; P = .04) and ATT (median, 8.5 vs 3.6 mm, respectively; P = .001). At the final follow-up, the IKDC score was 52.4 ± 19.2 and the KOOS subscale scores were 81.5 ± 9.5 (Pain), 74 ± 21.6 (Symptoms), 88.5 ± 8 (Activities of Daily Living); 52.5 ± 21.6 (Sport and Recreation), and 48.8 ± 15.8 (Quality of Life). A traumatic ACL graft failure occurred in 2 patients (8.7%). Reoperations were necessary for 6 patients (26.1%) because of symptomatic hardware, and atraumatic recurrent knee instability was diagnosed in 1 patient (4.3%). Conclusion: Tibial slope-reducing osteotomy resulted in a significant decrease of ATT and can be considered in patients with a preoperative PTS ≥12° and ≥1 ACLR failure. In highly complex patients with multiple prior surgeries, the authors found a reasonably low graft failure rate (8.7%) when utilizing PTS-reducing osteotomy. Surgeons must be aware of potential complications in patients with multiple previous failed ACLRs.

Performance of 5-Strand Hamstring Autograft Anterior Cruciate Ligament Reconstruction in the STABILITY Study: A Subgroup Analysis.

BACKGROUND: Anterior cruciate ligament (ACL) reconstructions (ACLRs) with graft diameters <8mm have been shown to have higher revision rates. The 5-strand (5S) hamstring autograft configuration is a proposed option to increase graft diameter. PURPOSE: To investigate the differences in clinical outcomes between 4-strand (4S) and 5S hamstring autografts for ACLR in patients who underwent ACLR alone or concomitantly with a lateral extra-articular tenodesis (LET) procedure. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Data from the STABILITY study were analyzed to compare a subgroup of patients undergoing ACLR alone or with a concomitant LET procedure (ACLR + LET) with a minimum graft diameter of 8mm that had either a 4S or 5S hamstring autograft configuration. The primary outcome was clinical failure, a composite of rotatory laxity and/or graft failure. The secondary outcome measures consisted of 2 patient-reported outcome scores (PROs)-namely, the ACL Quality of Life Questionnaire (ACL-QoL) and the International Knee Documentation Committee (IKDC) score at 24 months postoperatively. RESULTS: Of the 618 patients randomized in the STABILITY study, 399 (228 male; 57%) fit the inclusion criteria for this study. Of these, 191 and 208 patients underwent 4S and 5S configurations of hamstring ACLR, respectively, with a minimum graft diameter of 8mm. Both groups had similar characteristics other than differences in anthropometric factors-namely, sex, height, and weight, and Beighton scores. The primary outcomes revealed no difference between the 2 groups in rotatory stability (odds ratio [OR], 1.19; 95% CI, 0.77-1.84; P = .42) or graft failure (OR, 1.13; 95% CI, 0.51-2.50; P = .76). There was no significant difference between the groups in Lachman (P = .46) and pivot-shift (P = .53) test results at 24 months postoperatively. The secondary outcomes revealed no differences in the ACL-QoL (P = .67) and IKDC (P = .83) scores between the 2 subgroups. CONCLUSION: At the 24-month follow-up, there were no significant differences in clinical failure rates and PROs in an analysis of patients with 4S and 5S hamstring autografts of ≥8mm diameter for ACLR or ACLR + LET. The 5S hamstring graft configuration is a viable option to produce larger-diameter ACL grafts.

Meniscal repair at the time of primary ACLR does not negatively influence short term knee stability, graft rupture rates, or patient-reported outcome measures: the STABILITY experience.

PURPOSE: To assess how meniscal repair and excision impact short term patient-reported outcome measures (PROMs), knee stability, and early graft rupture rates following primary hamstring anterior cruciate ligament reconstruction (ACLR) with or without lateral extra-articular tenodesis (LET) in a group of young active patients where meniscal repair is commonly advocated. METHODS: Six hundred and eighteen patients under 25 years of age at high-risk of graft failure following ACLR were recruited to the Stability 1 study. Multivariable regression models were developed to identify statistically and clinically significant surgical and demographic predictors of Knee Injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee Subjective Knee Form (IKDC), ACL Quality of Life Questionnaire (ACL-QOL) and Marx Activity Rating Scale (MARS) scores. Chi-Square tests of independence were used to explore the association between meniscal status (torn, not torn), meniscal treatment (excision or repair), graft rupture, and rotatory knee laxity. RESULTS: Medial meniscus repair was associated with worse outcomes on the KOOS (ß = -1.32, 95% CI: -1.57 to -1.10, p = 0.003), IKDC (ß = -1.66, 95% CI: -1.53 to -1.02, p = 0.031) and ACL-QOL (ß = -1.25, 95% CI: -1.61 to 1.02, p = n.s.). However, these associations indicated small, clinically insignificant changes based on reported measures of clinical relevance. Other important predictors of post-operative PROMs included age, sex, and baseline scores. Medial meniscus excision and lateral meniscus treatment (repair or excision) did not have an important influence on PROMs. There was no significant association between meniscal treatment and graft rupture or rotatory knee laxity. CONCLUSION: While repairing the medial meniscus may result in a small reduction in PROM scores at two-year follow-up, these differences are not likely to be important to patients or clinicians. Any surgical morbidity associated with meniscal repair appears negligible in terms of PROMs. Meniscal repair does not affect rotatory laxity or graft failure rates in the short term. Therefore, meniscal repair should likely be maintained as the standard of care for concomitant meniscal tears with ACLR. LEVEL OF EVIDENCE: III.

The Knee Injury and Osteoarthritis Outcome Score Does Not Have Adequate Structural Validity for Use With Young, Active Patients With ACL Tears.

BACKGROUND: The Knee Injury and Osteoarthritis Outcome Score (KOOS) is well known and commonly used to assess young, active patients with ACL injuries. However, this application of the outcome measure has been called into question. There is currently no evidence supporting the structural validity of the KOOS for this patient population. Structural validity refers to whether a questionnaire meant to provide scores on different subscales behaves as intended in the populations of interest. Structural validity should be assessed for all questionnaire measures with multiple items or subscales. QUESTIONS/PURPOSES: Does the KOOS demonstrate adequate structural validity in young, active patients with ACL tears, when evaluated using (1) exploratory and (2) confirmatory factor analyses? METHODS: Between January 2014 and March 2017, 1033 patients were screened for eligibility in the Stability 1 randomized controlled trial from nine centers in Canada and Europe. Patients were eligible if they had an ACL deficient knee, were between 14 and 25 years old, and were thought to be at higher risk of reinjury based on the presence of two or more of the following factors: participation in pivoting sports, presence of a Grade 2 pivot shift or greater, generalized ligamentous laxity (Beighton score of 4 or greater), or genu recurvatum greater than 10°. Based on this criteria, 367 patients were ineligible and another 48 declined to participate. In total, 618 patients were randomized into the trial. Of the trial participants, 98% (605 of 618) of patients had complete baseline KOOS questionnaire data available for this analysis. Based on study inclusion criteria, the baseline KOOS data from the Stability 1 trial represents an appropriate sample to investigate the structural validity of the KOOS, specifically for the young, active ACL deficient population.A cross sectional retrospective secondary data analysis of the Stability 1 baseline KOOS data was completed to assess the structural validity of the KOOS using exploratory and confirmatory factor analyses. Exploratory factor analysis investigates how all questionnaire items group together based on their conceptual similarity in a specific sample. Confirmatory factor analysis is similar but used often in a second stage to test and confirm a proposed structure of the subscales. These methods were used to assess the established five-factor structure of the KOOS (symptoms [seven items], pain [nine items], activities of daily living [17 items], sport and recreation [five items], and quality of life [four items]) in young active patients with ACL tears. Incremental posthoc modifications, such as correlating questionnaire items or moving items to different subscales, were made to the model structure until adequate fit was achieved. Model fit was assessed using chi-square, root mean square error of approximation (RMSEA) and an associated 90% confidence interval, comparative fit index (CFI), Tucker-Lewis index (TLI), as well as standardized root mean square residual (SRMR). Adequate fit was defined as a CFI and TLI > 0.9, and RMSEA and SRMR < 0.08. RESULTS: Structural validity of the KOOS was not confirmed when evaluated using (1) exploratory or (2) confirmatory factor analyses. The exploratory factor analysis, where the 42 KOOS items were allowed to group naturally, did not reflect adequate fit for a five-factor model (TLI = 0.828). Similarly, the confirmatory factor analysis used to investigate the KOOS structure as it was originally developed, revealed inadequate fit in our sample (RMSEA = 0.088 [90% CI 0.086 to 0.091]). Our analysis suggested a modified four-factor structure may be more appropriate in young, active ACL deficient patients; however, the final version presented here is not appropriate for clinical use because of the number and nature of post-hoc modifications required to reach adequate fit indices. CONCLUSION: The established five-factor structure of the KOOS did not hold true in our sample of young, active patients undergoing ACL reconstruction, indicating poor structural validity. CLINICAL RELEVANCE: We question the utility and interpretability of KOOS subscale scores for young, active patients with ACL tears with the current form of the KOOS. A modified version of the KOOS, adjusted for this patient population, is needed to better reflect and interpret the outcomes and recovery trajectory in this high-functioning group. A separate analysis with a defined a priori development plan would be needed to create a valid alternative.

Predictors of Graft Failure in Young Active Patients Undergoing Hamstring Autograft Anterior Cruciate Ligament Reconstruction With or Without a Lateral Extra-articular Tenodesis: The Stability Experience.

BACKGROUND: Anterior cruciate ligament (ACL) reconstruction (ACLR) has higher failure rates in young active patients returning to sports as compared with older, less active individuals. Augmentation of ACLR with an anterolateral procedure has been shown to reduce failure rates; however, indications for this procedure have yet to be clearly defined. PURPOSE/HYPOTHESIS: The purpose of this study was to identify predictors of ACL graft failure in high-risk patients and determine key indications for when hamstring ACLR should be augmented by a lateral extra-articular tenodesis (LET). We hypothesized that different preoperative characteristics and surgical variables may be associated with graft failure characterized by asymmetric pivot shift and graft rupture. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: Data were obtained from the Stability 1 Study, a multicenter randomized controlled trial of young active patients undergoing autologous hamstring ACLR with or without a LET. We performed 2 multivariable logistic regression analyses, with asymmetric pivot shift and graft rupture as the dependent variables. The following were included as predictors: LET, age, sex, graft diameter, tear chronicity, preoperative high-grade knee laxity, preoperative hyperextension on the contralateral side, medial meniscal repair/excision, lateral meniscal repair/excision, posterior tibial slope angle, and return-to-sports exposure time and level. RESULTS: Of the 618 patients in the Stability 1 Study, 568 with a mean age of 18.8 years (292 female; 51.4%) were included in this analysis. Asymmetric pivot shift occurred in 152 (26.8%) and graft rupture in 43 (7.6%). The addition of a LET (odds ratio [OR], 0.56; 95% CI, 0.37-0.83) and increased graft diameter (OR, 0.62; 95% CI, 0.44-0.87) were significantly associated with lower odds of asymmetric pivot shift. The addition of a LET (OR, 0.40; 95% CI, 0.18-0.91) and older age (OR, 0.83; 95% CI, 0.72-0.96) significantly reduced the odds of graft rupture, while greater tibial slope (OR, 1.15; 95% CI, 1.01-1.32), preoperative high-grade knee laxity (OR, 3.27; 95% CI, 1.45-7.41), and greater exposure time to sport (ie, earlier return to sport) (OR, 1.18; 95% CI, 1.08-1.29) were significantly associated with greater odds of rupture. CONCLUSION: The addition of a LET and larger graft diameter were significantly associated with reduced odds of asymmetric pivot shift. Adding a LET was protective of graft rupture, while younger age, greater posterior tibial slope, high-grade knee laxity, and earlier return to sport were associated with increased odds of graft rupture. Orthopaedic surgeons should consider supplementing hamstring autograft ACLR with a LET in young active patients with morphological characteristics that make them at high risk of reinjury.

Predicting Patient Loss to Follow-up in the STABILITY 1 Study: A Multicenter, International, Randomized Controlled Trial of Young, Active Patients Undergoing ACL Reconstruction.

BACKGROUND: Patients lost to follow-up (LTF) impact even the most meticulously planned randomized controlled trials. Identifying patients at high risk for becoming LTF and employing strategies to retain these patients may reduce attrition bias. METHODS: A cohort of 618 young, active patients undergoing anterior cruciate ligament reconstruction in the STABILITY 1 study was analyzed. Patients completed clinical testing and 9 questionnaires at 3, 6, 12, and 24 months. Multivariable logistic regression was performed for 5 different definitions of LTF. Patient characteristics and study site were included as predictors. RESULTS: The LTF rate was 8.3%. Current or previous smokers (odds ratio [OR] = 2.77; 95% confidence interval [CI]: 1.20 to 5.96), those employed part-time (OR = 2.31; 95% CI: 1.04 to 5.14), and those with body mass index (BMI) of ≥25 kg/m2 had significantly greater odds of becoming LTF compared with nonsmokers, students, and those with BMI of <25 kg/m2, respectively. Those employed part-time were >8 times more likely (95% CI: 2.66 to 26.28) to become LTF compared with students within the first year. Postoperative BMI of ≥25 kg/m2 was significantly associated with 2 times greater odds of missing the in-person clinical examination at any visit or becoming LTF after the first postoperative year. The clinical site was the single largest predictor of missing data at any visit. CONCLUSIONS: Current or previous smoking, part-time employment, and BMI of ≥25 kg/m2 were significant predictors of becoming LTF, and part-time employment was significantly associated with early LTF. BMI of ≥25 kg/m2 was also associated with late LTF and clinical LTF. The clinical site was significantly associated with missing data at any visit. While we cannot accurately predict who will become LTF, investigators should be aware of these factors to identify high-risk patients and focus retention strategies accordingly. CLINICAL RELEVANCE: Understanding factors related to becoming LTF in young, active patients undergoing anterior cruciate ligament reconstruction can help investigators target retention strategies to reduce LTF in studies requiring clinical follow-up in similar populations.

Quadriceps tendon autograft is becoming increasingly popular in revision ACL reconstruction.

PURPOSE: To evaluate trends in revision anterior cruciate ligament reconstruction (ACL-R), with emphasis on intra-articular findings, grafts, and concurrent procedures. It was hypothesized that revision ACL-Rs over time show a trend toward increased complexity with increased use of autografts over allografts. METHODS: This was a two-center retrospective study including patients undergoing revision ACL-R between 2010 and 2020. Demographic and surgical data including intra-articular findings and concurrent procedures were collected and compared for the time periods 2010-2014 and 2015-2020. All collected variables were compared between three pre-defined age groups (< 20 years, 20-30 years, > 30 years), right and left knees, and males and females. A time series analysis was performed to assess trends in revision ACL-R. RESULTS: This study included 260 patients with a mean age of 26.2 ± 9.4 years at the time of the most recent revision ACL-R, representing the first, second, third, and fourth revision ACL-R for 214 (82%), 35 (14%), 10 (4%), and 1 (< 1%) patients, respectively. Patients age > 30 years showed a significantly longer mean time from primary ACL-R to most recent revision ACL-R (11.1 years), compared to patients age < 20 years (2.2 years, p < 0.001) and age 20-30 years (5.5 years, p < 0.05). Quadriceps tendon autograft was used significantly more often in 2015-2020 compared to 2010-2014 (49% vs. 18%, p < 0.001). A high rate of concurrently performed procedures including meniscal repairs (45%), lateral extra-articular tenodesis (LET; 31%), osteotomies (13%), and meniscal allograft transplantations (11%) was shown. Concurrent LET was associated with intact cartilage and severely abnormal preoperative knee laxity and showed a statistically significant and linear increase over time (p < 0.05). Intact cartilage (41%, p < 0.05), concurrent medial meniscal repairs (39%, p < 0.05), and LET (35%, non-significant) were most frequently observed in patients aged < 20 years. CONCLUSION: Quadriceps tendon autograft and concurrent LET are becoming increasingly popular in revision ACL-R. Intact cartilage and severely abnormal preoperative knee laxity represent indications for LET in revision ACL-R. The high rate of concurrent procedures observed demonstrates the high surgical demands of revision ACL-R. LEVEL OF EVIDENCE: Level III.

Clinical outcomes of contemporary lateral augmentation techniques in primary ACL reconstruction: a systematic review and meta-analysis.

PURPOSE: The purpose of this investigation was to systematically review the contemporary literature to determine if a lateral augmentation (LA) added to an Anterior Cruciate Ligament Reconstruction (ACLR) provides better clinical and patient reported outcomes compared to an isolated ACLR. METHODS: A systematic review and meta-analysis was performed according to the Preferred Reporting Items for Systematic reviews and Meta-analyses (PRISMA) criteria. Two authors independently conducted an electronic search using MEDLINE® and Embase® on February 6th, 2021 for level I-III randomized controlled trials (RCT) and prospective cohort studies without randomization, published after 2012 and with a minimum of two year follow-up. Publications were included when they reported on the objective knee stability examination, patient reported outcome scores, return to sports or graft rupture rate of any type of primary, isolated ACLR compared to ACLR combined with any type of LA. RESULTS: A total of 11 studies that reported on a combined total of 1892 unique patients were eligible for data extraction, including five RCTs and six prospective cohort studies. In 6 studies, an Anterolateral Ligament reconstruction (ALLR) was the LA of choice, while the 5 other publications used different types of Lateral Extra-articular Tenodesis (LET). A significant reduction in graft ruptures was found in patients treated with ACLR + LA (3%) compared to isolated ACLR (12%). Rotational laxity was significantly higher in isolated ACLR (14%) compared to ACLR + LA (6%). Addition of a LA reduced anterior translation when assessed via instrumented laxity testing. No significant difference was found in the patient reported outcome scores (IKDC and Tegner) between both patient groups, except for the Lysholm Score which was significant in favour of the ACLR + LA group. CONCLUSION: Combination of a primary ACLR with a LA can significantly reduce the risk of graft rupture and provide better rotatory stability, without jeopardizing patient reported outcomes. LEVEL OF EVIDENCE: Level III, Systematic Review of Level I, II and III studies.

Validation of a Risk Calculator to Personalize Graft Choice and Reduce Rupture Rates for Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Anterior cruciate ligament reconstructions (ACLRs) fail at an alarmingly high rate in young active individuals. The Multicenter Orthopaedic Outcomes Network (MOON) knee group has developed an autograft risk calculator that uses patient characteristics and lifestyle to predict the probability of graft rupture if the surgeon uses a hamstring tendon (HT) or a bone-patellar tendon-bone (BPTB) graft to reconstruct the ligament. If validated, this risk calculator can be used during the shared decision-making process to make optimal ACLR autograft choices and reduce rupture rates. The STABILITY 1 randomized clinical trial offers a large, rigorously collected data set of similar young active patients who received HT autograft with or without lateral extra-articular tenodesis (LET) for ACLR. PURPOSE/HYPOTHESIS: The purpose was to validate the ACLR graft rupture risk calculator in a large external data set and to investigate the utility of BPTB and LET for ACLR. We hypothesized that the risk calculator would maintain adequate discriminative ability and calibration in the external STABILITY 1 data set when compared with the initial MOON development data set. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 1. METHODS: The model predictors for the risk calculator include age, sex, body mass index, sport played at the time of injury, Marx Activity Score, preoperative knee laxity, and graft type. The STABILITY 1 trial data set was used for external validation. Discriminative ability, calibration, and diagnostic test validity of the model were assessed. Finally, predictor strength in the initial and validation samples was compared. RESULTS: The model showed acceptable discriminative ability (area under the curve = 0.73), calibration (Brier score = 0.07), and specificity (85.3%) to detect patients who will experience a graft rupture. Age, high-grade preoperative knee laxity, and graft type were significant predictors of graft rupture in young active patients. BPTB and the addition of LET to HT were protective against graft rupture versus HT autograft alone. CONCLUSION: The MOON risk calculator is a valid predictor of ACLR graft rupture and is appropriate for clinical practice. This study provides evidence supporting the idea that isolated HT autografts should be avoided for young active patients undergoing ACLR. REGISTRATION: NCT00463099 (MOON); NCT02018354 (STABILITY 1) (ClinicalTrials.gov identifiers).

Association of Ligamentous Laxity, Male Sex, Chronicity, Meniscal Injury, and Posterior Tibial Slope With a High-Grade Preoperative Pivot Shift: A Post Hoc Analysis of the STABILITY Study.

BACKGROUND: A spectrum of anterolateral rotatory laxity exists in anterior cruciate ligament (ACL)-injured knees. Understanding of the factors contributing to a high-grade pivot shift continues to be refined. PURPOSE: To investigate factors associated with a high-grade preoperative pivot shift and to evaluate the relationship between this condition and baseline patient-reported outcome measures (PROMs). STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A post hoc analysis was performed of 618 patients with ACL deficiency deemed high risk for reinjury. A binary logistic regression model was developed, with high-grade pivot shift as the dependent variable. Age, sex, Beighton score, chronicity of the ACL injury, posterior third medial or lateral meniscal injury, and tibial slope were selected as independent variables. The importance of knee hyperextension as a component of the Beighton score was assessed using receiver operator characteristic curves. Baseline PROMs were compared between patients with and without a high-grade pivot. RESULTS: Six factors were associated with a high-grade pivot shift: Beighton score (each additional point; odds ratio [OR], 1.17; 95% CI, 1.06-1.30; P = .002), male sex (OR, 2.30; 95% CI, 1.28-4.13; P = .005), presence of a posterior third medial (OR, 2.55; 95% CI, 1.11-5.84; P = .03) or lateral (OR, 1.76; 95% CI, 1.01-3.08; P = .048) meniscal injury, tibial slope >9° (OR, 2.35; 95% CI, 1.09-5.07; P = .03), and chronicity >6 months (OR, 1.70; 95% CI, 1.00-2.88; P = .049). The presence of knee hyperextension improved the diagnostic utility of the Beighton score as a predictor of a high-grade pivot shift. Tibial slope <9° was associated with only a high-grade pivot in the presence of a posterior third medial meniscal injury. Patients with a high-grade pivot shift had higher baseline 4-Item Pain Intensity Measure scores than did those without a high-grade pivot shift (mean ± SD, 11 ± 13 vs 8 ± 14; P = .04); however, there was no difference between groups in baseline International Knee Documentation Committee, ACL Quality of Life, Knee injury and Osteoarthritis Outcome Score, or Knee injury and Osteoarthritis Outcome Score subscale scores. CONCLUSION: Ligamentous laxity, male sex, posterior third medial or lateral meniscal injury, increased posterior tibial slope, and chronicity were associated with a high-grade pivot shift in this population deemed high risk for repeat ACL injury. The effect of tibial slope may be accentuated by the presence of meniscal injury, supporting the need for meniscal preservation. Baseline PROMs were similar between patients with and without a high-grade pivot shift.