Effect of High-Grade Preoperative Knee Laxity on 6-Year Anterior Cruciate Ligament Reconstruction Outcomes

Anterior Cruciate Ligament Tears among Football Players

PURPOSE OF REVIEW

Anterior Cruciate Ligament (ACL) tears are one of the most common causes of lost playing time in American football athletes. Recently, there has been a push to get athletes back to sport faster. As such, numerous studies have evaluated management and rehabilitation protocols for return to play after ACL injury in football players. The purpose of this review is to synthesize information, both classic and new, to aid orthopedic surgeons in treatment of football players with ACL injuries.

RECENT FINDINGS

Recent studies have demonstrated that not all ACL injuries are alike. Management should be a shared decision-making process between athlete and surgeon. Studies have demonstrated low failure rates when using bone-patellar tendon-bone (BTPB) autograft which is the most common graft utilized for elite football athletes. Outcomes are continually being evaluated by multicenter study groups such as the Multicenter Orthopaedic Outcome Network which has established a thorough rehabilitation protocol focusing on athlete milestones. ACL tears in the football athlete are common and challenging injuries. Treatment revolves around ACL reconstruction, most commonly with BTPB autograft. Post-operative rehabilitation is essential and should focus on objective criteria rather than time elapsed. Return to play criteria rely upon symptoms, athlete confidence, strength, and both functional and football specific testing. Return-to-play timelines are individualized for each football athlete but recent trends have highlighted a more delayed return of at least 7-9 months. Rate of returning to play varies from 63-82% and depends upon many factors including level of play and position.

Increased anterior tibial subluxation and differences between anterior tibial subluxation in the lateral and medial compartments are associated with failure of primary anterior cruciate ligament reconstruction: A systematic review and meta-analysis

PURPOSE

The purpose of this study is to investigate whether increased anterior tibial subluxation (ATS) and differences between ATS in the lateral and medial compartments (ATSL-M) are associated with primary anterior cruciate ligament (ACL) reconstruction (ACLR) failure.

METHODS

PubMed, Scopus, Embase and Web of Science were systematically searched from their inception through 21 November 2023. The focus was on comparative studies reporting ATS in patients who experienced primary ACLR failure, in contrast to patients after primary ACLR with no evidence of graft failure. A random-effects model was employed to calculate the overall standardized mean difference between the two groups.

RESULTS

A total of eight studies involving 963 patients were included in the final review. Three studies (64 cases and 171 controls) measured ATS on radiographs. The failed ACLR group exhibited a significantly increased ATS on radiographs compared to the control group (p < 0.001). Six studies (324 cases and 488 controls) measured lateral ATS on magnetic resonance imaging and five of them (285 cases and 374 controls) also measured medial ATS. The average values of lateral and medial ATS, as well as ATSL-M, were calculated and compared between the two groups. The failed ACLR group demonstrated significantly increased lateral (p < 0.001) and medial ATS (p < 0.001), the average value of lateral and medial ATS (p < 0.001) and ATSL-M (p = 0.039) compared to the control group.

CONCLUSION

Increased ATS and ATSL-M are associated with primary ACLR failure. The measurement of tibiofemoral position shows promise for its application in preoperative planning and postoperative management of ACLR.

LEVEL OF EVIDENCE

Level III.

Novel arthrometer for quantitative clinical examination of the knee in three planes: Safety, reliability, minimum detectable changes, and side-to-side differences in healthy subjects

Physical examination of the knee joint is used to diagnose the type and severity of knee ligament injury; however, these exams are qualitative and subjective. To perform common physical examinations, we developed an arthrometer which quantitatively measures the load-displacement response in anterior-posterior (AP) translation, internal-external rotation (IER) and varus-valgus (VV) rotation. Here we describe safety, reliability, minimum detectable changes (MDCs), and absolute side-to-side differences in twenty young, healthy subjects (ten male, ten female, mean age: 28 ± 6 years). The arthrometer consists of an instrumented mechanical linkage, a force-moment sensor, and software for real-time visualization and recording of the load-displacement responses. During testing, the subject sits reclined in a chair with their knee fixed at 30° of flexion. Two examiners tested both knees of each subject twice to assess reliability via intraclass correlation coefficients (ICC). All subjects completed the test protocol with minimal pain and stated that they would volunteer to be tested again. Each knee required on average five minutes to test. All intra-test reliabilities were excellent (≥0.91). Intra-examiner reliabilities ranged from good to excellent (0.62-0.89), and inter-examiner reliabilities were good to excellent (≥0.72). MDCs for repeat measures were ≤ 4.5 mm, 4.6°, and 2.3° for AP, IER, and VV, respectively. The absolute side-to-side differences for this cohort averaged 3.8 mm in AP, 5.5° in IER, and 2.2° in VV. Our arthrometer was safe, testing was time-efficient, and MDCs in our cohort of healthy subjects support utilization of this device for clinical research.

Assessment of knee instability in ACL-injured knees using weight-bearing computed tomography (WBCT): a novel protocol and preliminary results

OBJECTIVE

To propose a protocol for assessing knee instability in ACL-injured knees using weight-bearing computed tomography (WBCT).

MATERIALS AND METHODS

We enrolled five patients with unilateral chronic ACL tears referred for WBCT. Bilateral images were obtained in four positions: bilateral knee extension, bilateral knee flexion, single-leg stance with knee flexion and external rotation, and single-leg stance with knee flexion and internal rotation. The radiation dose, time for protocol acquisition, and patients' tolerance of the procedure were recorded. A blinded senior radiologist assessed image quality and measured the anterior tibial translation (ATT) and femorotibial rotation (FTR) angle in the ACL-deficient and contralateral healthy knee.

RESULTS

All five patients were male, aged 23-30 years old. The protocol resulted in a 16.2 mGy radiation dose and a 15-min acquisition time. The procedure was well-tolerated, and patient positioning was uneventful, providing good-quality images. In all positions, the mean ATT and FTR were greater in ACL-deficient knees versus the healthy knee, with more pronounced differences observed in the bilateral knee flexion position. Mean lateral ATT in the flexion position was 9.1±2.8 cm in the ACL-injured knees versus 4.0±1.8 cm in non-injured knees, and mean FTR angle in the bilateral flexion position was 13.5°±7.7 and 8.6°±4.6 in the injured and non-injured knees, respectively.

CONCLUSION

Our protocol quantitatively assesses knee instability with WBCT, measuring ATT and FTR in diverse knee positions. It employs reasonable radiation, is fast, well-tolerated, and yields high-quality images. Preliminary findings suggest ACL-deficient knees show elevated ATT and FTR, particularly in the 30° flexion position.

Secondary restraints in ACL reconstruction: State-of-the-art

At-risk patients continue to experience a high likelihood of graft rupture after anterior cruciate ligament (ACL) reconstruction (ACLR). This narrative review seeks to provide the reader with an evidence-based synopsis of state-of-the-art concepts related to secondary restraint lesions, and how addressing them surgically might result in improved outcomes of ACLR.

Ensemble Algorithm for Risk Prediction of Clinical Failure After Anterior Cruciate Ligament Reconstruction

Background

Patient-specific risk profiles of clinical failure after anterior cruciate ligament reconstruction (ACLR) are meaningful for preoperative surgical planning and postoperative rehabilitation guidance.

Purpose

To create an ensemble algorithm machine learning (ML) model and ML-based web-based tool that can predict the patient-specific risk of clinical failure after ACLR.

Study Design

Cohort study; Level of evidence, 3.

Methods

Included were 432 patients (mean age, 26.8 ± 8.4 years; 74.1% male) who underwent anatomic double-bundle ACLR with hamstring tendon autograft between January 2010 and February 2019. The primary outcome was the probability of clinical failure at a minimum 2-year follow-up. The authors included 24 independent variables for feature selection and model development. The data set was split randomly into training sets (75%) and test sets (25%). Models were built using 4 ML algorithms: extreme gradient boosting, random forest, light gradient boosting machine, and adaptive boosting. In addition, a weighted-average voting (WAV) ensemble model was constructed using the ensemble-voting technique to predict clinical failure after ACLR. Concordance (area under the receiver operating characteristic curve [AUC]), calibration, and decision curve analysis were used to evaluate predictive performances of the 5 models.

Results

Clinical failure occurred in 73 of the 432 patients (16.9%). The 8 most important predictors for clinical failure were follow-up period, high-grade preoperative knee laxity, time from injury to ACLR, participation in competitive sports, posterior tibial slope, graft diameter, age at surgery, and medial meniscus resection. The WAV ensemble algorithm achieved the best predictive performance based on concordance (AUC, 0.9139), calibration (calibration intercept, -0.1806; calibration slope, 1.2794; Brier score, 0.0888), and decision curve analysis (greatest net benefits) and was used to develop an web-based application to predict a patient's clinical failure risk of ACLR.

Conclusion

The WAV ensemble algorithm was able to accurately predict patient-specific risk of clinical failure after ACLR. Clinicians and patients can use the web-based application during preoperative consultation to understand individual prediction outcomes.

An Update on Emerging Techniques and Considerations in Revision Anterior Cruciate Ligament Reconstruction

» The rate of primary anterior cruciate ligament reconstruction (ACLR) failure in at-risk populations remains unacceptably high and necessitates thorough evaluation of native alignment and concomitant injuries.» Posterior tibial slope of >12° is a substantial risk factor of ACLR failure and should be corrected through anterior closing wedge osteotomy.» Varus malalignment of >5° exacerbates stress on the ACL graft, increases ACLR failure risks, and should be considered for correction through high tibial osteotomy at the time of revision ACLR.» Injuries to the anterolateral ligamentous complex are prevalent in ACL ruptures, and high-risk patients have shown benefit from anterolateral ligament reconstruction or lateral extra-articular tenodesis in the revision setting.» Addressing posterolateral corner, collateral ligament, and meniscal injuries, during revision ACLR, is vital to mitigate increased graft forces and optimize knee stability and functional outcomes.

Effects of higher femoral tunnels on clinical outcomes, MRI, and second-look findings in double-bundle anterior cruciate ligament reconstruction with a minimal 5-year follow-up

BACKGROUND

To perform anatomical anterior cruciate ligament reconstruction (ACLR), tunnels should be placed relatively higher in the femoral anterior cruciate ligament (ACL) footprint based on the findings of direct and indirect femoral insertion. But the clinical results of higher femoral tunnels (HFT) in double-bundle ACLR (DB-ACLR) remain unclear. The purpose was to investigate the clinical results of HFT and lower femoral tunnels (LFT) in DB-ACLR.

METHODS

From September 2014 to February 2016, 83 patients who underwent DB-ACLR and met the inclusion and exclusion criteria were divided into HFT-ACLR (group 1, n = 37) and LFT-ACLR (group 2, n = 46) according to the position of femoral tunnels. Preoperatively and at the final follow-up, clinical scores were evaluated with International Knee Documentation Committee (IKDC), Tegner activity, and Lysholm score. The stability of the knee was evaluated with KT-2000, Lachman test, and pivot-shift test. Cartilage degeneration grades of the International Cartilage Repair Society (ICRS) were evaluated on magnetic resonance imaging (MRI). Graft tension, continuity, and synovialization were evaluated by second-look arthroscopy. Return-to-sports was assessed at the final follow-up.

RESULTS

Significantly better improvement were found for KT-2000, Lachman test, and pivot-shift test postoperatively in group 1 ( P >0.05). Posterolateral bundles (PL) showed significantly better results in second-look arthroscopy regarding graft tension, continuity, and synovialization ( P <0.05), but not in anteromedial bundles in group 1. At the final follow-up, cartilage worsening was observed in groups 1 and 2, but it did not reach a stastistically significant difference ( P >0.05). No statistically significant differences were found in IKDC subjective score, Tegner activity, and Lysholm score between the two groups. Higher return-to-sports rate was found in group 1 with 86.8% (32/37) vs. 65.2% (30/46) in group 2 ( P = 0.027).

CONCLUSION

The HFT-ACLR group showed better stability results, better PL, and higher return-to-sports rate compared to the LFT-ACLR group.

Comparison of Revision ACL Reconstruction Using Iliotibial Band Augmented With Allograft Versus Bone-Patellar Tendon-Bone Autograft With Lateral Extra-articular Tenodesis

Background

Bone-patellar tendon-bone (BTB) anterior cruciate ligament reconstruction (ACLR) is one of the conventional techniques in the revision setting especially after a primary hamstring tendon graft. The use of the iliotibial band (ITB) augmented with allograft (AG) is an encouraging graft alternative for ACLR in terms of clinical and biomechanical data in the literature.

Purpose

To compare the clinical outcomes of BTB graft with lateral extra-articular tenodesis, modified Lemaire (BTB-LET), and an ITB graft augmented with hamstring AG (ITB-AG) in the setting of revision ACLR.

Study Design

Cohort study; Level of evidence, 3.

Methods

Descriptive data and clinical outcomes were prospectively collected from patients who underwent revision ACLR with either the BTB-LET or ITB-AG technique between 2012 and 2020 and who had a minimum follow-up of 2 years. The clinical outcomes were assessed by the Lysholm, Tegner, Anterior Cruciate Ligament-Return to Sport after Injury, International Knee Documentation Committee subjective knee evaluation form, and Knee injury and Osteoarthritis Outcome Score. Return to sports, complications, and revisions were also analyzed.

Results

A total of 167 patients were included, with 106 patients in the BTB-LET group and 61 patients in the ITB-AG group. There were no significant group differences in sociodemographic characteristics; however, the mean follow-up was significantly longer in the BTB-LET compared with the ITB-AG group (52.0 vs 38.8 months, respectively; P = .0001). There were no significant differences in postoperative outcome scores; however, patients in the ITB-AG group had a higher rate of return to competitive pivoting sports (32.8% vs 17.9%; P = .0288) and a higher overall rate of return to preinjury sport (63.9% vs 47.2%; P = .0365). Complications, including revisions for meniscal or chondral lesions and retears (8 [8.3%] in the BTB-LET group and 2 [4.0%] in the ITB-AG group), were not significantly different. All retears were due to sports-related accidents.

Conclusion

In this study, ITB-AG was not different from BTB-LET in terms of functional outcomes scores but allowed better return to sport rate. Performing ITB-AG reconstruction in the setting of revision ACLR appears to be safe, effective, and associated with a satisfying return-to-sports rate.

Risk Factors for Revision or Rerupture After Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis

BACKGROUND

The rerupture or need for revision after anterior cruciate ligament reconstruction (ACLR) is a serious complication. Preventive strategies that target the early identification of risk factors are important to reduce the incidence of additional surgery.

PURPOSE

To perform a systematic review and meta-analysis to investigate risk factors for revision or rerupture after ACLR.

STUDY DESIGN

Systematic review and meta-analysis; Level of evidence, 4.

METHODS

Literature searches were performed in PubMed, Embase, and Web of Science from database inception to November 2021 and updated in January 2022. Quantitative, original studies reporting potential adjusted risk factors were included. Odds ratios (ORs) were calculated for potential risk factors.

RESULTS

A total of 71 studies across 13 countries with a total sample size of 629,120 met the inclusion criteria. Fifteen factors were associated with an increase in the risk of revision or rerupture after ACLR: male sex (OR, 1.27; 95% CI, 1.14-1.41), younger age (OR, 1.07; 95% CI, 1.05-1.08), lower body mass index (BMI) (OR, 1.03; 95% CI, 1.00-1.06), family history (OR, 2.47; 95% CI, 1.50-4.08), White race (OR, 1.32; 95% CI, 1.08-1.60), higher posterolateral tibial slope (OR, 1.15; 95% CI, 1.05-1.26), preoperative high-grade anterior knee laxity (OR, 2.30; 95% CI, 1.46-3.64), higher baseline Marx activity level (OR, 1.07; 95% CI, 1.02-1.13), return to a high activity level/sport (OR, 2.03; 95% CI, 1.15-3.57), an ACLR within less than a year after injury (OR, 2.05; 95% CI, 1.81-2.32), a concomitant medial collateral ligament (MCL) injury (OR, 1.62; 95% CI, 1.31-2.00), an anteromedial portal or transportal technique (OR, 1.36; 95% CI, 1.22-1.51), hamstring tendon (HT) autografts (vs bone-patellar tendon-bone [BPTB] autografts) (OR, 1.60; 95% CI, 1.40-1.82), allografts (OR, 2.63; 95% CI, 1.65-4.19), and smaller graft diameter (OR, 1.21; 95% CI, 1.05-1.38). The other factors failed to show an association with an increased risk of revision or rerupture after ACLR.

CONCLUSION

Male sex, younger age, lower BMI, family history, White race, higher posterolateral tibial slope, preoperative high-grade anterior knee laxity, higher baseline Marx activity level, return to a high activity level/sport, an ACLR within less than a year from injury, a concomitant MCL injury, an anteromedial portal or transportal technique, HT autografts (vs BPTB autografts), allografts, and smaller graft diameter may increase the risk of revision or rerupture after ACLR. Raising awareness and implementing effective preventions/interventions for risk factors are priorities for clinical practitioners to reduce the incidence of revision or rerupture after ACLR.

Ceiling Effect of the Combined Norwegian and Danish Knee Ligament Registers Limits Anterior Cruciate Ligament Reconstruction Outcome Prediction

BACKGROUND

Clinical tools based on machine learning analysis now exist for outcome prediction after primary anterior cruciate ligament reconstruction (ACLR). Relying partly on data volume, the general principle is that more data may lead to improved model accuracy.

PURPOSE/HYPOTHESIS

The purpose was to apply machine learning to a combined data set from the Norwegian and Danish knee ligament registers (NKLR and DKRR, respectively), with the aim of producing an algorithm that can predict revision surgery with improved accuracy relative to a previously published model developed using only the NKLR. The hypothesis was that the additional patient data would result in an algorithm that is more accurate.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Machine learning analysis was performed on combined data from the NKLR and DKRR. The primary outcome was the probability of revision ACLR within 1, 2, and 5 years. Data were split randomly into training sets (75%) and test sets (25%). There were 4 machine learning models examined: Cox lasso, random survival forest, gradient boosting, and super learner. Concordance and calibration were calculated for all 4 models.

RESULTS

The data set included 62,955 patients in which 5% underwent a revision surgical procedure with a mean follow-up of 7.6 ± 4.5 years. The 3 nonparametric models (random survival forest, gradient boosting, and super learner) performed best, demonstrating moderate concordance (0.67 [95% CI, 0.64-0.70]), and were well calibrated at 1 and 2 years. Model performance was similar to that of the previously published model (NKLR-only model: concordance, 0.67-0.69; well calibrated).

CONCLUSION

Machine learning analysis of the combined NKLR and DKRR enabled prediction of the revision ACLR risk with moderate accuracy. However, the resulting algorithms were less user-friendly and did not demonstrate superior accuracy in comparison with the previously developed model based on patients from the NKLR alone, despite the analysis of nearly 63,000 patients. This ceiling effect suggests that simply adding more patients to current national knee ligament registers is unlikely to improve predictive capability and may prompt future changes to increase variable inclusion.

Effect of Tibiofemoral Rotation Angle on Graft Failure After Anterior Cruciate Ligament Reconstruction

BACKGROUND

Coronal and sagittal malalignment of the knee are well-recognized risk factors for failure after anterior cruciate ligament (ACL) reconstruction (ACLR). However, the effect of axial malalignment on graft survival after ACLR is yet to be determined.

PURPOSE

To evaluate whether increased tibiofemoral rotational malalignment, namely, tibiofemoral rotation angle (TFA) and tibial tubercle-trochlear groove (TT-TG) distance, is associated with graft failure after ACLR.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

In this retrospective matched control study of a single center's database, 151 patients who underwent revision ACLR because of graft failure (ACLR failure group, defined as symptomatic patients with anterior knee instability and an ACL graft tear appreciated on magnetic resonance imaging [MRI] and confirmed during arthroscopic surgery) were compared with a matched control group of 151 patients who underwent primary ACLR with no evidence of failure after ≥2-year follow-up (intact ACLR group). Patients were matched by sex, age, and meniscal injury during primary ACLR. Axial malalignment was assessed on preoperative MRI through the TFA and the TT-TG distance. Sagittal alignment was measured through the posterior tibial slope on MRI. The optimal TFA cutoff associated with graft failure was identified by a receiver operating characteristic curve. The Kaplan-Meier curve with log-rank analysis was performed to evaluate the influence of the TFA on ACLR longevity.

RESULTS

The mean age was 25.7 ± 10.4 years for the ACLR failure group and 25.9 ± 10.0 years for the intact ACLR group. Among all the included patients, 174 (57.6%) were male. In the ACLR failure group, the mean TFA was 5.8°± 4.5° (range, -5° to 16°), while it was 3.0°± 3.3° (range, -3° to 15°) in the intact ACLR group (P < .001). Neither the TT-TG distance nor the posterior tibial slope presented statistical differences between the groups. The receiver operating characteristic curve suggested an optimal TFA cutoff of 4.5° for graft failure (area under the curve = 0.71; P < .001; sensitivity, 68.2%; specificity, 75.5%). Considering this a threshold, patients who had a TFA ≥4.5° had 6.6 times higher odds of graft failure compared with patients with a TFA <4.5° (P < .001). Survival analysis demonstrated a 5-year survival rate of 81% in patients with a TFA <4.5°, while it was 44% in those with a TFA ≥4.5° (P < .001).

CONCLUSION

An increased TFA was associated with increased odds of ACLR failure when the TFA was ≥4.5°. Measuring the TFA in patients with ACL tears undergoing reconstruction may inform the surgeon about additional factors that may require consideration before ACLR for a successful outcome.

Association Between Anterior Tibial Subluxation of Lateral Compartment and High-Grade Knee Laxity in Patients With Anterior Cruciate Ligament Deficiency

BACKGROUND

High-grade knee laxity and excessive anterior tibial subluxation (ATS) are correlated with poor clinical outcomes in patients with anterior cruciate ligament (ACL) deficiency and share similar risk factors; however, the association between excessive ATS and high-grade knee laxity remains unclear.

PURPOSE

To identify the association between excessive ATS and high-grade knee laxity in patients with ACL deficiency and determine the possibility that ATS can predict high-grade knee laxity.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A total of 226 patients who underwent ACL reconstruction between May 2018 and March 2022 were analyzed in the present study; the high-grade group consisted of 113 patients who had a grade 3 result on the preoperative anterior drawer test, Lachman test, or pivot-shift test while under anesthesia, and the low-grade group consisted of 113 matched patients. The ATS values for medial and lateral compartments (ATSMC and ATSLC) were measured on magnetic resonance imaging while patients relaxed the quadriceps in the supine position under no anesthesia. The optimal cutoff values of ATSMC and ATSLC for high-grade knee laxity were determined using receiver operating characteristic curves. Univariate and multivariate logistic regression analyses with stratification were performed to identify the association between excessive ATS and high-grade knee laxity.

RESULTS

Compared with the low-grade group, the high-grade group had a longer time from injury to surgery; higher rates of medial meniscus posterior horn tear (MMPHT), lateral meniscus posterior horn tear (LMPHT), and anterolateral ligament (ALL) abnormality; and larger lateral tibial slope, ATSMC, and ATSLC. The optimal cutoff value was 2.6 mm (sensitivity, 52.2%; specificity, 76.1%) for ATSMC and 4.5 mm (sensitivity, 67.3%; specificity, 64.6%) for ATSLC in predicting high-grade knee laxity. After adjustment for covariates, ATSLC ≥4.5 mm (odds ratio [OR], 2.94; 95% CI, 1.56-5.55; P = .001), MMPHT (OR, 2.62; 95% CI, 1.35-5.08; P = .004), LMPHT (OR, 2.39; 95% CI, 1.20-4.78; P = .014), and ALL abnormality (OR, 2.09; 95% CI, 1.13-3.89; P = .019) were associated with high-grade knee laxity. The association between excessive ATSLC and high-grade knee laxity was validated in patients with acute ACL injury as well as those with chronic ACL injury.

CONCLUSION

Excessive ATSLC was associated with high-grade knee laxity in patients who had ACL deficiency, with a predictive cutoff value of 4.5 mm. This study may help surgeons estimate the degree of knee instability more accurately before anesthesia and may facilitate preliminary surgical decision-making, such as appropriate graft choices and consideration of extra-articular augmentation.

Predicting anterior cruciate ligament failure load with T2* relaxometry and machine learning as a prospective imaging biomarker for revision surgery

Non-invasive methods to document healing anterior cruciate ligament (ACL) structural properties could potentially identify patients at risk for revision surgery. The objective was to evaluate machine learning models to predict ACL failure load from magnetic resonance images (MRI) and to determine if those predictions were related to revision surgery incidence. It was hypothesized that the optimal model would demonstrate a lower mean absolute error (MAE) than the benchmark linear regression model, and that patients with a lower estimated failure load would have higher revision incidence 2 years post-surgery. Support vector machine, random forest, AdaBoost, XGBoost, and linear regression models were trained using MRI T2* relaxometry and ACL tensile testing data from minipigs (n = 65). The lowest MAE model was used to estimate ACL failure load for surgical patients at 9 months post-surgery (n = 46) and dichotomized into low and high score groups via Youden's J statistic to compare revision incidence. Significance was set at alpha = 0.05. The random forest model decreased the failure load MAE by 55% (Wilcoxon signed-rank test: p = 0.01) versus the benchmark. The low score group had a higher revision incidence (21% vs. 5%; Chi-square test: p = 0.09). ACL structural property estimates via MRI may provide a biomarker for clinical decision making.

Outcomes of Combined Anterior Cruciate Ligament and Anterolateral Ligament Reconstruction According to GNRB Arthrometer Measurement

Background and Objectives: To investigate the prognosis of combined anterior cruciate ligament (ACL) and anterolateral ligament (ALL) reconstruction, we used a GNRB (Genourob, Laval, France) arthrometer to measure surgical outcomes. Materials and Methods: This retrospective study reviewed patients who underwent combined ACL and ALL reconstruction and had a minimum follow-up of 2 years. Subjective outcomes, namely the International Knee Documentation Committee (IKDC) evaluation form scale scores and Lysholm scores, were evaluated preoperatively and postoperatively. We used a GNRB arthrometer to test the side-to-side laxity under pressures of 134 and 200 N, and we calculated the differential of the slope of the curves. We also recorded complications. Results: Our study examined 18 patients (mean age: 30.56 ± 8.9 years, range: 19-53) with a mean follow-up of 27.37 ± 3.4 months (range: 24-36). Both Lysholm and IKDC scores were significantly improved following the operation. The GNRB arthrometer measured mean anteroposterior laxity side-to-side as 0.76 ± 0.78 mm and 0.82 ± 0.8 mm under pressures of 134 and 200 N, respectively. The mean side-to-side differential slope under 200 N was 3.52 ± 2.17 μm/N. These values indicated that patients displayed no graft tear or low functional knee instability. All patients had a grade 3 pivot shift preoperatively; only two patients had a grade 1 pivot shift postoperatively, with the rest having a negative pivot shift. Conclusions: Our study revealed that combined ACL and ALL reconstruction has an excellent prognosis. GNRB measurement demonstrated excellent stability, and most patients had no residual pivot shift.

A novel digital arthrometer to measure anterior tibial translation

BACKGROUND

Measurement of knee laxity after anterior cruciate ligament (ACL) injury is crucial for appropriate treatment and rehabilitation decision-making. This study examined the potential of a new digital arthrometer (Ligs, Innomotion, Shanghai, China) to quantify anterior tibial translation (ATT) in patients with ACL injuries and in healthy subjects.

METHODS

A total of 60 participants included 30 subjects with single-leg ACL injuries and 30 healthy subjects included as controls. The lower leg was immobilized. The thruster is positioned posterior to the lower leg and parallel to the tibial tuberosity in the sagittal plane. The load is applied vertically to the tibia under a dynamic load of 0-150 N, with continuous displacement recorded. The intrarater and interrater reliability will be examined. ATT and side-to-side differences (SSD) between the control and ACL injury groups were compared. Receiver operating characteristic (ROC) curves were analyzed, and the area under the curve (AUC) was calculated to determine the diagnostic accuracy of the Ligs.

RESULTS

The interrater ICC was 0.909 and the intrarater ICC was 0.943. Significant differences in the SSD were observed between the control and ACL injury groups (for all P < 0.05), with the largest effect size (ES = 1.12) at 80 N. When comparing ATT at different loads between injured and healthy sides in the ACL injury group, displacement was statistically significant at different loads. At a load of 150 N, the AUC was the maximum (0.857) and the sensitivity and specificity were 0.87 and 0.73, respectively.

CONCLUSIONS

A digital arthrometer can be used as a quantitative instrument to quantify knee laxity. Quantitative measurement of ATT and SSD under controlled loading can be an objective and effective tool for clinical practice.

Pivot shift intraoperative quantitative assessment using a smartphone accelerometer in ACL deficient knees

PURPOSE

The Pivot Shift (PS) test is a complex clinical sign that assesses the internal rotation and anterior tibial translation, which occurs abnormally in ACL deficient-knees. Because of the high inter-observer variability, different devices have been designed to characterize this complex movement in quantitative variables. The objective of this pilot study is to validate the reproducibility of intraoperative quantitative assessment of the PS with a smartphone accelerometer.

METHODS

Twelve ACL-injured knees were included and compared with the contralateral uninjured side. The PS was measured by two independent observers utilizing a smartphone accelerometer and graded according to the IKDC classification. Measurements were taken preoperatively, intraoperatively and postoperatively. Intraoperative readings were taken during each stage of reconstruction or repair of meniscoligamentous lesions including meniscal lesions, ramp lesions, ACL reconstruction and lateral tenodesis. Reproducibility of the measurements were evaluated according to an intraclass correlation coefficient (ICC).

RESULTS

The intra-observer reliability was good for the first examiner and excellent for the second examiner, with the ICC 0.89 [0.67, 0.98] p < 0,001 and ICC 0.97 [0.91, 1.0] p < 0,001 respectively. The inter-observer reliability was excellent between the two observers with the ICC 0.99 [0.97, 1.0] p < 0,001. The mean tibial acceleration measured 3.45 m.s² (SD = 1.71) preoperatively on the injured knees and 1.03 m.s² (SD = 0.36) on the healthy knees, demonstrating a significant difference following univariate analysis p < 0.001. Postoperatively, no significant difference was observed between healthy and reconstructed knees The magnitudes of tibial acceleration values were correlated with the PS IKDC grade.

CONCLUSION

The smartphone accelerometer is a reproducible device to quantitatively assess the internal rotation and anterior tibial translation during ACL reconstruction surgery. The measurements are influenced by the different surgical steps. Other larger cohort studies are needed to evaluate the specific impact of each step of the ACL reconstruction and meniscal repair on this measurement. An external validation using other technologies are needed to validate the reliability of this device to assess the PS test.

LEVEL OF EVIDENCE

Level IV, case series, pilot study.

Return to Sports: A Risky Business? A Systematic Review with Meta-Analysis of Risk Factors for Graft Rupture Following ACL Reconstruction

BACKGROUND

The risk of sustaining a graft rupture after anterior cruciate ligament reconstruction (ACLR) is high. Contributing risk factors are, however, still not clearly identified.

OBJECTIVE

The aim of this systematic review was to identify and quantify risk factors for graft rupture after ACLR.

METHODS

A systematic review with meta-analysis (PROSPERO CRD42020140129) based on PRISMA guidelines was performed. MEDLINE, CINAHL and EMBASE were searched from inception to September 2021. Prospective and retrospective studies addressing risk factors for graft rupture after ACLR in males/females of all ages were considered. Meta-analyses using a random effect model (effect measure: odds ratio [OR] with 95% confidence interval [CI]) were performed. The GRADE tool was used to assess evidence quality.

RESULTS

Following full-text screening of 310 relevant papers, 117 were eventually included, incorporating up to 133,000 individuals in each meta-analysis. Higher Tegner activity level (≥ 7 vs < 7) at primary injury (OR 3.91, 95% CI 1.69-9.04), increased tibial slope (degrees) (OR 2.21, 95% CI 1.26-3.86), lower psychological readiness to return to sport (RTS) (OR 2.18, 95% CI 1.32-3.61), early surgery (< 12 vs ≥ 12 months) (OR 1.87, 95% CI 1.58-2.22), RTS (pre-injury level) (OR 1.87, 95% CI 1.21-2.91) and family history of ACL injury (OR 1.76, 95% CI 1.34-2.31) were all associated with increased odds of graft rupture. Higher age (OR 0.47, 95% CI 0.39-0.59), female sex (OR 0.88, 95% CI 0.79-0.98), fewer self-reported knee symptoms pre-reconstruction (OR 0.81, 95% CI 0.69-0.95) and concomitant cartilage injuries (OR 0.70, 95% CI 0.62-0.79) instead decreased the odds. Meta-analysis revealed no association between body mass index, smoking, joint laxity, RTS time, knee kinematics, muscle strength or hop performance and graft rupture.

CONCLUSION

Conspicuous risk factors for graft rupture were mainly sports and hereditary related. Few studies investigated function-related modifiable factors or included sports exposure data.

Lateral Extra-Articular Tenodesis Staple Risks Penetration of Anterior Cruciate Ligament Reconstruction Tunnel

Purpose

To identify the risk of anterior cruciate ligament (ACL) femoral tunnel penetration with the use of a staple for lateral extra-articular tenodesis (LET) graft fixation and to determine whether this varied between 2 different techniques for ACL femoral tunnel drilling.

Methods

Twenty paired, fresh-frozen, cadaver knees underwent ACL reconstruction with a LET. Left and right knees were randomized to ACL reconstruction with femoral tunnel creation by use of either a rigid guide pin and reamer through the accessory anteromedial portal or by the use of a flexible guide pin and reamer through the anteromedial portal. Immediately after tunnel creation, the LET was performed and fixated with a small Richard's staple. Fluoroscopy was used to obtain a lateral view of the knee to determine staple position, and visualization of the ACL femoral tunnel was performed with the arthroscope to investigate penetration of the staple into the femoral tunnel. The Fisher exact test was conducted to determine whether there was any difference in tunnel penetration between tunnel creation techniques.

Results

The staple was noted to penetrate the ACL femoral tunnel in 8 of 20 (40%) extremities. When stratified by tunnel creation technique, the Richards staple violated 5 of 10 (50%) of the tunnels made via the rigid reaming technique compared with 3 of 10 (30%) of those created with a flexible guide pin and reamer (P = .65).

Conclusions

A high incidence of femoral tunnel violation is seen with lateral extra-articular tenodesis staple fixation.

Level of Evidence

Level IV, controlled laboratory study.

Clinical Relevance

The risk of penetrating the ACL femoral tunnel with a staple for LET graft fixation is not well understood. Yet, the integrity of the femoral tunnel is important for the success of ACL reconstruction. Surgeons can use the information in this study to consider adjustments to operative technique, sequence, or fixation devices used when performing ACL reconstruction with concomitant LET to avoid the potential for disruption of ACL graft fixation.

Predicting the Objective and Subjective Clinical Outcomes of Anterior Cruciate Ligament Reconstruction: A Machine Learning Analysis of 432 Patients

BACKGROUND

Sports levels, baseline patient-reported outcome measures (PROMs), and surgical procedures are correlated with the outcomes of anterior cruciate ligament reconstruction (ACLR). Machine learning may be superior to conventional statistical methods in making repeatable and accurate predictions.

PURPOSE

To identify the best-performing machine learning models for predicting the objective and subjective clinical outcomes of ACLR and to determine the most important predictors.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

A total of 432 patients who underwent anatomic double-bundle ACLR with hamstring tendon autograft between January 2010 and February 2019 were included in the machine learning analysis. A total of 15 predictive variables and 6 outcome variables were selected to validate the logistic regression, Gaussian naïve Bayes machine, random forest, Extreme Gradient Boosting (XGBoost), isotonically calibrated XGBoost, and sigmoid calibrated XGBoost models. For each clinical outcome, the best-performing model was determined using the area under the receiver operating characteristic curve (AUC), whereas the importance and direction of each predictive variable were demonstrated in a Shapley Additive Explanations summary plot.

RESULTS

The AUC and accuracy of the best-performing model, respectively, were 0.944 (excellent) and 98.6% for graft failure; 0.920 (excellent) and 91.4% for residual laxity; 0.930 (excellent) and 91.0% for failure to achieve the minimal clinically important difference (MCID) of the Lysholm score; 0.942 (excellent) and 95.1% for failure to achieve the MCID of the International Knee Documentation Committee (IKDC) score; 0.773 (fair) and 70.5% for return to preinjury sports; and 0.777 (fair) and 69.2% for return to pivoting sports. Medial meniscal resection, participation in competitive sports, and steep posterior tibial slope were top predictors of graft failure, whereas high-grade preoperative knee laxity, long follow-up period, and participation in competitive sports were top predictors of residual laxity. High preoperative Lysholm and IKDC scores were highly predictive of not achieving the MCIDs of PROMs. Young age, male sex, high preoperative IKDC score, and large graft diameter were important predictors of return to preinjury or pivoting sports.

CONCLUSION

Machine learning analysis can provide reliable predictions for the objective and subjective clinical outcomes (graft failure, residual laxity, PROMs, and return to sports) of ACLR. Patient-specific evaluation and decision making are recommended before and after surgery.

Meniscal resection increases the risk of residual knee laxity even in patients undergoing anatomic double-bundle anterior cruciate ligament reconstruction with eight strands of hamstring autografts

PURPOSE

To compare the midterm clinical outcomes of different meniscal surgeries in patients undergoing anatomic double-bundle anterior cruciate ligament reconstruction (DB-ACLR) with eight strands of hamstring (HT8) autografts and explore the potential predictive risk factors for residual knee laxity.

METHODS

From 2010 to 2017, a total of 410 patients who underwent anatomic trans-tibial DB-ACLR with HT8 autografts (169 patients without meniscal surgery, 105 patients with meniscal repair, and 136 patients with meniscal resection) were included in this study. The equivalent graft diameter was introduced to make the total graft size of DB-ACLR comparable with that of single-bundle ACLR and calculated as the square root of the quadratic sum of the diameter for each bundle. Residual laxity was defined as excessive anterior tibial translation or residual pivot shift at any follow-up visit, while graft rupture was confirmed by second-look arthroscopy or magnetic resonance imaging.

RESULTS

The mean follow-up period was 8.3 ± 2.2 years. The mean equivalent graft diameter was 9.9 ± 0.7 mm. Graft rupture was confirmed in 16 (3.9%) patients, while residual laxity was detected in 72 (17.6%) patients (34 [25.0%] in the meniscal resection group vs. 22 [13.0%] in the no meniscal surgery group, p = 0.021). In the multivariate logistic regression analysis, high-grade preoperative knee laxity (odds ratio OR 2.04, p = 0.020), equivalent graft diameter < 9 mm (OR 3.31 compared with 9-10 mm, p = 0.012; OR 3.28 compared with ≥ 10 mm, p = 0.019), and meniscal resection (OR 1.94 compared with no meniscal surgery, p = 0.045) were associated with residual laxity.

CONCLUSION

During a midterm follow-up, meniscal resection increased the risk of residual knee laxity even in patients undergoing anatomic DB-ACLR with HT8 autografts. Increasing the hamstring graft diameter and preserving the menisci are important strategies for ACLR to restore knee stability.

LEVEL OF EVIDENCE

Level III.

The coronal lateral collateral ligament sign in the anterior cruciate ligament-injured knees was observed regardless of the knee laxity based on the quantitative measurements

PURPOSE

The coronal lateral collateral ligament (LCL) sign has been reported to be associated with deviated position of the tibia on MRI due to anterior cruciate ligament (ACL) injuries. However, the relationships between LCL sign and clinical knee laxity evaluations are still unclear. The purpose of the study was to investigate the relationship between the coronal LCL sign and knee laxity measurements.

METHODS

A retrospective review of unilateral ACL injured patients who underwent ACL reconstruction was performed. The coronal LCL sign was determined using magnetic resonance imaging (MRI). Clinical grading of the pivot-shift test, KT-1000 measurements, and quantitative measurements of the Lachman test and the pivot-shift test using an electromagnetic system, were compared between patients with positive and negative coronal LCL sign. A subgroup analysis of different age groups was then performed, dividing patients to adolescent (age ≤ 18 years) and adult (age > 18 years) groups.

RESULTS

A total of 85 patients were enrolled, of which 45 patients had coronal LCL signs. The coronal LCL sign was not associated with the pivot-shift test clinical grading (n.s), KT-1000 measurement (n.s), the tibial translation during the Lachman test (n.s), or with tibia acceleration (n.s) and translation (n.s) during the pivot-shift test. The subgroup analysis also showed that the aforementioned parameters were not associated with the coronal LCL sign in either adolescent or adult subgroups.

CONCLUSION

The occurrence of coronal LCL sign in MRI did not imply greater clinical knee laxity evaluations in patients with ACL tears. The knee laxity should routinely be evaluated regardless the coronal LCL sign.

LEVEL OF EVIDENCE

Level III.

The presence of high-grade pivot shift test preoperatively is associated with inferior functional outcomes

BACKGROUND

The effect of high-grade preoperative pivot shift test on outcomes of anterior cruciate ligament (ACL) reconstruction surgery is not very well established. The present study was conducted to study the factors associated with high-grade pivot shift test and effect of high-grade preoperative pivot shift test on functional outcomes after ACL reconstruction surgery.

METHODS

Three hundred and sixty-two patients who underwent primary ACL reconstruction surgery were enrolled in the study. The pivot shift test was performed preoperatively under anesthesia in all patients. Side of the meniscal tear, if present at the time of ACL reconstruction, was documented. Patients were divided into two groups depending upon the grade of pivot shift test: group H, high-grade pivot shift (n = 84/362; 23%); and group L, low-grade pivot shift (n = 278/362; 77%). Patients were further divided into two groups depending upon the duration of injury: acute (<6 months) and chronic (>6 months). The functional assessment was done using Lysholm score and Tegner activity scale.

RESULTS

The presence of lateral meniscus tear (27/84 vs. 53/278) or both menisci tear (29/84 vs. 60/278) was associated with high-grade pivot shift (p < 0.05). Chronic ACL tears were also observed to be associated with high-grade pivot shift (p = 0.03). The mean Lysholm score in group H and group L patients was 93.8 ± 5.1 and 95.2 ± 5.3, respectively (p = 0.04). The mean post-op Tegner activity scale in group H was 6.8 and in group L was 7.3 (p = 0.0001). Also, 181/253 (71.5%) patients returned to same or higher level of sports activity in group L as compared to 33/72 (46%) patients in group H. The incidence of graft failure in groups H and L was 6.5% (5/77) and 1.6% (4/257; p = 0.03), respectively.

CONCLUSIONS

The high-grade pivot shift is associated with chronic ACL tear (>6 months) and concomitant lateral meniscus tear. The presence of high-grade pivot shift preoperatively is associated with inferior clinical outcomes and lower rate of return to sports.

LEVEL OF EVIDENCE

Level IV, case-control study.

Controversies in ACL revision surgery: Italian expert group consensus and state of the art

BACKGROUND

Revision ACL reconstruction is a complex topic with many controversies and not-easy-to-make decisions. The authors' aim is to provide some feasible advice that can be applied in daily clinical practice with the goal of facilitating the decision-making process and improving the outcomes of patients subjected to revision ACL reconstruction.

METHODS

A national survey with seven questions about the most controversial topics in revision ACL reconstruction was emailed to members of two societies: SIOT and SIAGASCOT. The participants' answers were collected, the most recent literature was analyzed, and a consensus was created by the authors, according to their long-term surgical experience.

CONCLUSIONS

The decision-making process in revision ACL reconstruction starts with a standardized imaging protocol (weight-bearing radiographs, CT scan, and MRI). One-stage surgery is indicated in almost all cases (exceptions are severe tunnel enlargement and infection), while the choice of graft depends on the previously used graft and the dimensions of the tunnels, with better clinical outcomes obtained for autografts. Additional procedures such as lateral extra-articular tenodesis in high-grade pivot-shift knees, biplanar HTO in the case of severe coronal malalignment, and meniscal suture improve the clinical outcome and should be considered case by case.

LEVEL OF EVIDENCE

V (Expert opinion).

Grade III pivot shift as an early sign of knee decompensation in chronic ACL-injured knees with bimeniscal tears

PURPOSE

To analyse possible associations between the preoperative pivot shift (PS) test and both patient and injury characteristics in anterior cruciate ligament (ACL)-injured knees, considering previously neglected meniscal injuries such as ramp and root tears. The hypothesis was that a preoperative grade III PS was associated with the amount of intra-articular soft-tissue damage and chronicity of the injury.

METHODS

The cohort involved 376 patients who underwent primary ACL reconstruction (239 males/137 females; median age 26). Patients were examined under anesthesia before surgery, using the PS test. During arthroscopy, intra-articular soft-tissue damage of the injured knee was classified as: (1) partial ACL tear; (2) complete isolated ACL tear; (3) complete ACL tear with one meniscus tear; and (4) complete ACL and bimeniscal tears. Chi-square and Mann-Whitney U tests were used to evaluate whether sex, age, body mass index, sport at injury, mechanism of injury, time from injury and intra-articular damage (structural damage of ACL and menisci) were associated with a grade III PS. Intra-articular damage was further analyzed for two sub-cohorts: acute (time from injury ≤ 6 months) and chronic injuries (> 6 months).

RESULTS

A grade III PS test was observed in 26% of patients. A significant association with PS grading was shown for age, time from injury and intra-articular soft-tissue damage (p < 0.05). Further analyses showed that grade III PS was associated with intra-articular damage in chronic injuries only (p < 0.01). In complete ACL and bimeniscal tears, grade III PS was more frequent in chronic (53%) than in acute knee injuries (26%; p < 0.01). Patients with chronic complete ACL and bimeniscal tears had a grade III PS 3.3 [1.3-8.2] times more often than patients in the acute sub-cohort.

CONCLUSION

In ACL-injured patients, a preoperative grade III PS was mainly associated with a higher amount of intra-articular soft-tissue damage and chronicity of the injury. Patients with complete chronic ACL injuries and bimeniscal tears were more likely to have a preoperative grade III PS than their acute counterparts. This suggests that grade III PS may be an early sign of knee decompensation of dynamic rotational knee laxity in chronic ACL-injured knees with bimeniscal lesions.

LEVEL OF EVIDENCE

Level III.

Trends in Anterolateral Ligament Reconstruction and Lateral Extra-articular Tenodesis With ACL Reconstruction in Children and Adolescents

Background:

Anterolateral ligament reconstruction (ALLR) and lateral extra-articular tenodesis (LET) show promise in lowering the risk of rerupture after anterior cruciate ligament reconstruction (ACLR), but there are little data on surgeon practices and preferences in children and adolescents.

Purpose:

To quantify surgeon practices regarding ALLR and LET in the pediatric population.

Study Design:

Cross-sectional study.

Methods:

An electronic survey was administered to 87 surgeons in the Pediatric Research in Sports Medicine society. The questionnaire asked several questions about surgeon and practice characteristics as well as indications, preferences, and techniques for ALLR or LET in the context of primary and revision pediatric ACLR. Chi-square and Fisher exact tests were used to evaluate factors that affect surgical preferences.

Results:

A total of 63 surgeons completed the survey, of whom 62% performed ≥50 pediatric ACLRs annually; 56% sometimes performed anterolateral augmentation with primary ACLR, and 79% with revision ACLR. The most common indications for ALLR or LET in the primary setting were high-grade pivot shift, knee hyperextension, generalized laxity, and type of sports participation. Surgeons whose practice was >75% sports medicine were more likely to perform ALLR or LET with both primary and revision ACLR (P = .005 and P < .001, respectively). Those who had completed a sports medicine fellowship were more likely to perform these procedures than those with only pediatric orthopaedic training, in both primary (68% vs 36%; P = .01) and revision scenarios (92% vs 60%; P = .002). Of the 28 respondents who did not perform ALLR or LET with primary ACLR, 75% cited insufficient evidence as the reason. However, 96% of surgeons who did perform these procedures expressed interest in studying them prospectively, and 87% were willing to randomize patients.

Conclusion:

Findings indicated that 56% of pediatric sports surgeons sometimes perform anterolateral augmentation with primary ACLR and 79% with revision ACLR. Surgeons with sports medicine fellowship training or a mostly sports practice were more likely to perform these procedures. Insufficient evidence was the most common reason given by surgeons who did not perform anterolateral augmentation. However, there was substantial willingness to prospectively study and even randomize pediatric patients to assess the impact of ALLR or LET in this population.

Does anterolateral ligament internal bracing improve the outcomes of anterior cruciate ligament reconstruction in patients with generalized joint hypermobility?

BACKGROUND

Generalized joint hypermobility (GJH) is a risk factor for anterior cruciate ligament (ACL) injury and ACL graft failure and is considered an indication for anterolateral ligament (ALL) reconstruction. The aim of this retrospective study was to compare functional outcomes, rupture rates, and residual instability in patients with GJH undergoing isolated ACL reconstruction or combined ACL reconstruction and ALL augmentation with internal bracing (ALL-IB).

METHODS

Sixty-eight patients with GJH and unilateral ACL injury were randomly assigned to undergo either isolated ACL reconstruction (Group 1) or combined ACL reconstruction and ALL-IB (Group 2). The patients were evaluated pre- and postoperatively; their medical histories; physical examination results; anterior knee translation, as measured using the KT-1000 arthrometer; and scores of validated knee assessments were recorded.

RESULTS

Groups 1 and 2 consisted of 37 and 31 patients, respectively. The mean follow-up was 30.1±4.1 and 28.1±2.9 months, respectively. In the final evaluation, the patients in Group 2 showed better rotational stability, as evaluated by the pivot-shift test (p=0.013); better anteroposterior stability, as evaluated by KT-1000 arthrometry (p=0.001); similar function (p=0.14 for the Lysholm, p=0.11 for the Cincinnati, and p=0.19 for the International Knee Documentation Committee subjective score); and failure rate (p=0.41).

CONCLUSION

The functional outcomes were similar between the groups. The stability outcomes after combined ACL and ALL-IB were better than those after isolated ACL reconstruction in patients with GJH. However, the technique and its results need to be validated in larger patient series and prospective randomized controlled trials.

Reliability of a Novel Automatic Knee Arthrometer for Measuring Knee Laxity After Anterior Cruciate Ligament Ruptures

Background:

The accuracy of existing devices for measuring knee laxity is adversely affected by examiner reliability.

Purpose:

To compare the accuracy of a novel automatic knee arthrometer (AKA) to that of the KT-2000 arthrometer for measuring knee laxity after anterior cruciate ligament (ACL) ruptures.

Study Design:

Cohort study; Level of evidence, 2.

Methods:

We measured anterior displacement and the anterior displacement difference (ADD) at 134 N of anterior force in 221 healthy volunteers and 200 patients with ACL ruptures. All trials were performed by the same 2 examiners. We first analyzed the effects of examiner, side assessed, and device type using the intraclass correlation coefficient (ICC), t test, and F test. We then used the receiver operating characteristic curve to compare the diagnostic value of the measurements between devices.

Results:

In repeated measurements for a single healthy volunteer, there were no differences in the variance of the measurements between sides according to the AKA (standard deviation of right vs left knee for examiner A: 0.43 vs 0.58 mm, respectively [P = .39]; for examiner B: 0.49 vs 0.77 mm, respectively [P = .81]), while the KT-2000 measurements showed differences (standard deviation of right vs left knee for examiner A: 1.47 vs 0.80 mm, respectively [P = .02]; for examiner B: 1.78 vs 0.91 mm, respectively [P = .01]). The ADD assessed by the AKA was not significantly different between examiners A and B (0.50 vs 0.75 mm, respectively; P = .27; ICC = 0.83), but the KT-2000 showed a difference (1.07 vs 2.01 mm, respectively; P = .01; ICC = 0.55). The ADD of 20 healthy volunteers assessed by the AKA was less than that by the KT-2000 (0.98 vs 1.41 mm, respectively; P = .04). When comparing the diagnostic value of the 2 devices in the sample of 200 patients with ACL ruptures and 200 healthy controls, the area under the receiver operating characteristic curve for the AKA was larger than that for the KT-2000 (0.93 vs 0.87, respectively; P ≤ .01), and the threshold values were 1.75 and 2.73 mm, respectively.

Conclusion:

The AKA can be used to determine the degree of knee laxity in ACL injuries and to provide indications for treatment.

Increased lateral and medial femoral posterior radius ratios are risk factors for anterior cruciate ligament injury

Background

Many studies have shown that distal femoral sagittal morphological characteristics have a clear relationship with knee joint kinematics. The aim of this study was to determine the relationship between distal femoral sagittal morphological characteristics and noncontact anterior cruciate ligament (ACL) injury.

Methods

A retrospective case-control study of 148 patients was conducted. Two age- and sex-matched cohorts (each n = 74) were analysed: a noncontact ACL injury group and a control group. Several characteristics were compared between the two groups, including the lateral femoral posterior radius (LFPR), medial femoral posterior radius (MFPR), lateral height of the distal femur (LH), medial height of the distal femur (MH), lateral femoral anteroposterior diameter (LFAP), medial femoral anteroposterior diameter (MFAP), lateral femoral posterior radius ratio (LFPRR), and medial femoral posterior radius ratio (MFPRR). Receiver operating characteristic (ROC) analysis was used to evaluate the significance of the LFPRR and MFPRR in predicting ACL injury.

Results

Compared with patients in the control group, patients in the ACL injury group had an increased LFPR, MFPR, MFAP, LFPRR, and MFPRR. ROC analysis revealed that an increased LFPRR above 31.7% was associated with noncontact ACL injury, with a sensitivity of 78.4% and a specificity of 58.1%; additionally. an increased MFPRR above 33.4% was associated with noncontact ACL injury, with a sensitivity of 58.1% and a specificity of 70.3%.

Conclusion

This study showed that increased LFPRR and increased MFPRR are risk factors for developing noncontact ACL injury. These data could thus help identify individuals susceptible to ACL injuries.

MOON's Strategy for Obtaining Over Eighty Percent Follow-up at 10 Years Following ACL Reconstruction

ABSTRACT

The Multicenter Orthopaedic Outcomes Network (MOON) study of anterior cruciate ligament (ACL) reconstruction has achieved >80% follow-up for study subjects who were enrolled from 2002 to 2005; patient-reported outcome measures (PROMs) were reported at 2, 6, and 10 years through a carefully designed protocol that included surgeon involvement to encourage subjects to complete and return questionnaires. The process included emails and telephone calls from the central coordinating center, from research coordinators at each local institution, and lastly, from the subjects' surgeons for those who were less inclined to complete the follow-up. In order to quantify the effect of site and surgeon involvement, the enrollment year of 2005 was monitored for the 10-year follow-up (n = 516 subjects). In contact efforts made by the coordinating center, 73.8% (381) of study subjects were reached by the central site coordinator, contact information was verified, and questionnaires were subsequently sent, completed, and returned. An additional 54 subjects (10.5% of the overall study population) returned the questionnaire after local study site involvement, indicating the importance of individual surgeon and local site involvement to improve follow-up rates in multicenter studies in orthopaedic surgery. Follow-up rates were higher when a specific individual (the surgeon or the research coordinator) was given the task of final follow-up.

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.

The Modified Ellison Technique: A Distally Fixed Iliotibial Band Transfer for Lateral Extra-articular Augmentation of the Knee

Lateral extra-articular augmentation (LEA) of anterior cruciate ligament reconstructions significantly reduces graft failure rates. Currently, proximally fixed LEA procedures are popular techniques. However, there are concerns about these techniques regarding anterior cruciate ligament tunnel collision, kinematic overconstraint, and increasing lateral-compartment contact forces. These issues are potentially avoided by the modified Ellison procedure, which is a distally fixed LEA technique. This article describes the surgical details of this easily reproducible technique.

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.

An older age, a longer duration between injury and surgery, and positive pivot shift test results increase the prevalence of articular cartilage injury during ACL reconstruction in all three compartments of the knee in patients with ACL injuries

PURPOSE

To investigate factors that influence the prevalence of articular cartilage injury in patients with anterior cruciate ligament (ACL) injury.

METHODS

This multicentre study included patients with ACL injury. Logistic regression analysis was conducted to identify factors that influence the prevalence of cartilage injury during ACL reconstruction.

RESULTS

A total of 811 patients were enrolled. The factors that significantly influenced the prevalence of cartilage injury were age (odds ratio [OR], 1.04; P = 0.000), a positive pivot shift test result (OR, 1.43; P = 0.021), medial meniscal injury (OR, 2.55; P = 0.000), and delayed surgery (≥ 12 months) (OR, 2.52; P = 0.028) in the medial compartment of the knee; age (OR, 1.05; P = 0.000), subjective grades of apprehension during the pivot shift test (OR, 1.46; P = 0.010), lateral meniscal injury (OR, 1.98; P = 0.003), femoro-tibial angle (FTA) (OR, 0.92; P = 0.006), and delayed surgery (≥ 12 months) (OR, 2.63; P = 0.001) in the lateral compartment; and age (OR, 1.06; P = 0.000), body mass index (OR, 1.07; P = 0.028), a positive pivot shift test result (OR, 1.60; P = 0.018), FTA (OR, 0.90; P = 0.006), and delayed surgery (≥ 12 months) (OR, 3.17; P = 0.008) in the patellofemoral compartment.

CONCLUSION

An older age, a longer duration between injury and surgery, and a positive pivot shift test result were positively associated with the prevalence of cartilage injury in three compartments in patients with ACL injuries. Early ACL reconstruction is recommended to prevent cartilage injury.

LEVEL OF EVIDENCE

Level III.

Lateral Extra-articular Tenodesis Alters Lateral Compartment Contact Mechanics under Simulated Pivoting Maneuvers: An In Vitro Study

BACKGROUND

There is concern that utilization of lateral extra-articular tenodesis (LET) in conjunction with anterior cruciate ligament (ACL) reconstruction (ACLR) may disturb lateral compartment contact mechanics and contribute to joint degeneration.

HYPOTHESIS

ACLR augmented with LET will alter lateral compartment contact mechanics in response to simulated pivoting maneuvers.

STUDY DESIGN

Controlled laboratory study.

METHODS

Loads simulating a pivot shift were applied to 7 cadaveric knees (4 male; mean age, 39 ± 12 years; range, 28-54 years) using a robotic manipulator. Each knee was tested with the ACL intact, sectioned, reconstructed (via patellar tendon autograft), and, finally, after augmenting ACLR with LET (using a modified Lemaire technique) in the presence of a sectioned anterolateral ligament and Kaplan fibers. Lateral compartment contact mechanics were measured using a contact stress transducer. Outcome measures were anteroposterior location of the center of contact stress (CCS), contact force from anterior to posterior, and peak and mean contact stress.

RESULTS

On average, augmenting ACLR with LET shifted the lateral compartment CCS anteriorly compared with the intact knee and compared with ACLR in isolation by a maximum of 5.4 ± 2.3 mm (P < .001) and 6.0 ± 2.6 mm (P < .001), respectively. ACLR augmented with LET also increased contact force anteriorly on the lateral tibial plateau compared with the intact knee and compared with isolated ACLR by a maximum of 12 ± 6 N (P = .001) and 17 ± 10 N (P = .002), respectively. Compared with ACLR in isolation, ACLR augmented with LET increased peak and mean lateral compartment contact stress by 0.7 ± 0.5 MPa (P = .005) and by 0.17 ± 0.12 (P = .006), respectively, at 15° of flexion.

CONCLUSION

Under simulated pivoting loads, adding LET to ACLR anteriorized the CCS on the lateral tibial plateau, thereby increasing contact force anteriorly. Compared with ACLR in isolation, ACLR augmented with LET increased peak and mean lateral compartment contact stress at 15° of flexion.

CLINICAL RELEVANCE

The clinical and biological effect of increased anterior loading of the lateral compartment after LET merits further investigation. The ability of LET to anteriorize contact stress on the lateral compartment may be useful in knees with passive anterior subluxation of the lateral tibia.

Adolescents show a lower healing rate of anterolateral ligament injury and a higher rotational laxity than adults after anterior cruciate ligament reconstruction

BACKGROUND

This study aimed to compare anterolateral ligament (ALL) injuries in anterior cruciate ligament (ACL) ruptures, as well as ALL healing and clinical outcomes following ACL reconstruction between adolescents and adults.

METHODS

This retrospective study involved 98 patients who underwent ACL reconstruction. They were divided into two groups according to age: group A (adolescents, 16-20 years of age; n = 49) and group B (adults, 21-45 years of age; n = 49). Subjective scores including ACL-Return to Sport after Injury (ACL-RSI) scale and objective tests were assessed. Follow up magnetic resonance imaging (MRI) and second-look arthroscopy was conducted at 1-year and 2-year follow up, respectively.

RESULTS

Good healing rate of ALL was higher in adults than in adolescents (P = 0.048). Graft tension and synovial coverage showed no significant differences between two groups. Group A showed a higher rate of high-grade pivot shift and a lower ACL-RSI at last follow up than group B (P = 0.126 and P = 0.016). Poor healing of ALL was significantly associated with lower ACL-RSI and failure to return to sports (P < 0.001 and P = 0.001). Re-rupture of the ACL graft was found in four (8.2%) and one (2.0%) of group A and B, respectively.

CONCLUSIONS

Adolescents showed a lower healing rate of ALL, a lower ACL-RSI, a higher rate of high-grade pivot shift than adults. Moreover, poor healing of ALL was significantly associated with a lower ACL-RSI and failure to return to sports. We suggest that adolescents need to pay more attention to the presence of ALL injury.

Incidence and Risk Factors for Residual High-Grade Pivot Shift After ACL Reconstruction With or Without a Lateral Extra-articular Tenodesis

Background

Residual rotatory knee laxity at midterm follow-up after isolated anterior cruciate ligament reconstruction (ACLR) versus ACLR with lateral extra-articular tenodesis (LET) remains an issue.

Purpose/Hypothesis

To evaluate the outcomes of ACLR with or without additional LET at a minimum 2-year follow-up in patients with preoperative high-grade pivot shift (PS). Our hypothesis was that the addition of LET would decrease the risk of secondary meniscal injury and the presence of residual high-grade PS at follow-up.

Study Design

Cohort study; Level of evidence, 3.

Methods

A retrospective analysis performed at 3 sports medicine centers identified 266 study patients; all had a high-grade PS (grade 2 or 3) preoperatively and underwent isolated ACLR with or without LET. Four different ACLR techniques were used: single-strand quadrupled semitendinosus (ST4) ACLR without LET (ST4 group; n = 55), ST4 with anatomic LET (ST4+LET group; n = 77), bone-patellar tendon and modified Lemaire LET (BTB+LET group; n = 43), and quadriceps tendon and modified Lemaire LET (QT+LET group; n = 91). At follow-up, we evaluated for the presence of high-grade (grade ≥2) PS. Preoperative meniscal tears and their treatment were recorded.

Results

Overall, 185 (69.5%) patients had at least 1 meniscal tear at index surgery. The mean follow-up period was 44.3 months; 47 (17.7%) patients had a new meniscal tear and 64 (24%) patients had a high-grade PS at follow-up. Compared with meniscal repair, significant predictors for high-grade PS at follow-up were meniscectomy (odds ratio [OR] = 2.65 [95% CI, 1.19-5.63]; P = .02) and nonrepair of preoperative meniscal tear (OR = 3.26 [95% CI, 1.27-9.43]; P = .007). The appearance of a new symptomatic meniscal tear was the strongest significant predictor of high-grade PS at follow-up (OR = 4.31 [95% CI, 2.31-8.06]; P < .001). No significant correlation was observed between the addition of LET and the presence of high-grade PS at follow-up.

Conclusion

In the current study, 1 in 4 patients with high-grade PS before ACLR with or without LET was at risk of residual rotatory knee laxity at mean 44-month follow-up, regardless of the technique used. Repairing a pre-existing meniscal lesion was more effective than performing LET to decrease the presence of a high-grade PS at follow-up.

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.

Do Narcotic Use, Physical Therapy Location, or Payer Type Predict Patient-Reported Outcomes After Anterior Cruciate Ligament Reconstruction?

BACKGROUND

Opioid use and public insurance have been correlated with worse outcomes in a number of orthopaedic surgeries. These factors have not been investigated with anterior cruciate ligament reconstruction (ACLR).

PURPOSE/HYPOTHESIS

To evaluate if narcotic use, physical therapy location, and insurance type are predictors of patient-reported outcomes after ACLR. It was hypothesized that at 1 year postsurgically, increased postoperative narcotic use would be associated with worse outcomes, physical therapy obtained within the authors' integrated health care system would lead to better outcomes, and public insurance would lead to worse outcomes and athletic activity.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

All patients undergoing unilateral, primary ACLR between January 2015 and February 2016 at a large health system were enrolled in a standard-of-care prospective cohort. Knee injury and Osteoarthritis Score (KOOS) and the Hospital for Special Surgery Pediatric-Functional Activity Brief Scale (HSS Pedi-FABS) were collected before surgery and at 1 year postoperatively. Concomitant knee pathology was assessed arthroscopically and electronically captured. Patient records were analyzed to determine physical therapy location, insurance status, and narcotic use. Multivariable regression analyses were used to identify significant predictors of the KOOS and HSS Pedi-FABS score.

RESULTS

A total of 258 patients were included in the analysis (mean age, 25.8; 51.2% women). In multivariable regression analysis, narcotic use, physical therapy location, and insurance type were not independent predictors of any KOOS subscales. Public insurance was associated with a lower HSS Pedi-FABS score (-4.551, P = .047) in multivariable analysis. Narcotic use or physical therapy location was not associated with the HSS Pedi-FABS score.

CONCLUSION

Increased narcotic use surrounding surgery, physical therapy location within the authors' health care system, and public versus private insurance were not associated with disease-specific KOOS subscale scores. Patients with public insurance had worse HSS Pedi-FABS activity scores compared with patients with private insurance, but neither narcotic use nor physical therapy location was associated with activity scores. Physical therapy location did not influence outcomes, suggesting that patients be given a choice in the location they received physical therapy (as long as a standardized protocol is followed) to maximize compliance.

Risk Factors for Contra-Lateral Secondary Anterior Cruciate Ligament Injury: A Systematic Review with Meta-Analysis

Background

The risk of sustaining a contra-lateral anterior cruciate ligament (C-ACL) injury after primary unilateral ACL injury is high. C-ACL injury often contributes to a further decline in function and quality of life, including failure to return to sport. There is, however, very limited knowledge about which risk factors that contribute to C-ACL injury.

Objective

To systematically review instrinsic risk factors for sustaining a C-ACL injury.

Methods

A systematic review with meta-analysis was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Four databases (MEDLINE, CINAHL, EMBASE, Sport Discus) were searched from inception to January 2020. Inclusion criteria were prospective or retrospective studies investigating any intrinsic risk factor for future C-ACL injury. Meta-analysis was performed and expressed as odds ratios (OR) if two or more articles assessed the same risk factor.

Results

44 moderate-to-high quality studies were eventually included in this review, whereof 35 studies were eligible for meta-analysis, including up to 59 000 individuals. We identified seven factors independently increasing the odds of sustaining a C-ACL injury (in order of highest to lowest OR): (1) returning to a high activity level (OR 3.26, 95% CI 2.10–5.06); (2) Body Mass Index < 25 (OR 2.73, 95% CI 1.73–4.36); (3) age ≤ 18 years (OR 2.42, 95% CI 1.51–3.88); (4) family history of ACL injury (OR 2.07, 95% CI 1.54–2.80); (5) primary ACL reconstruction performed ≤ 3 months post injury (OR 1.65, 95% CI: 1.32–2.06); (6) female sex (OR 1.35, 95% CI 1.14–1.61); and (7) concomitant meniscal injury (OR 1.21, 95% CI 1.03–1.42). The following two factors were associated with decreased odds of a subsequent C-ACL injury: 1) decreased intercondylar notch width/width of the distal femur ratio (OR 0.43, 95% CI 0.25–0.69) and 2) concomitant cartilage injury (OR 0.83, 95% CI 0.69–1.00). There were no associations between the odds of sustaining a C-ACL injury and smoking status, pre-injury activity level, playing soccer compared to other sports or timing of return to sport. No studies of neuromuscular function in relation to risk of C-ACL injury were eligible for meta-analysis according to our criteria.

Conclusion

This review provides evidence that demographic factors such as female sex, young age (≤ 18 years) and family history of ACL injury, as well as early reconstruction and returning to a high activity level increase the risk of C-ACL injury. Given the lack of studies related to neuromuscular factors that may be modifiable by training, future studies are warranted that investigate the possible role of factors such as dynamic knee stability and alignment, muscle activation and/or strength and proprioception as well as sport-specific training prior to return-to-sport for C-ACL injuries.

PROSPERO: CRD42020140129.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40279-020-01424-3.

Anterior Cruciate and Anterolateral Ligament Reconstruction Using Hamstring and Peroneus Longus Tendons: Surgical Technique Description

The main objective of this study is to describe a surgical technique that combines intra- and extra-articular techniques using the semitendinosus, gracilis, and peroneus longus to perform reconstruction of the anterior cruciate ligament and anterolateral ligament. This technique offers a more stable, fast, low-cost, and widely accessible procedure and consists of drilling 3 tunnels-1 femoral and 2 tibial tunnels-in which the grafts are fixed with interference screws. The fact that the peroneus longus graft is long and thick allows for robust reconstruction of the aforementioned ligaments.

Beighton Score, Tibial Slope, Tibial Subluxation, Quadriceps Circumference Difference, and Family History Are Risk Factors for Anterior Cruciate Ligament Graft Failure: A Retrospective Comparison of Primary and Revision Anterior Cruciate Ligament Reconstructions

PURPOSE

To assess patient history, physical examination findings, magnetic resonance imaging (MRI) and 3-dimensional computed tomographic (3D CT) measurements of those with anterior cruciate ligament (ACL) graft failure compared with primary ACL tear patients to better discern risk factors for ACL graft failure.

METHODS

We performed a retrospective review comparing patients who underwent revision ACL reconstruction (ACLR) with a primary ACLR group with minimum 1-year follow-up. Preoperative history, examination, and imaging data were collected and compared. Measurements were made on MRI, plain radiographs, and 3D CT. Inclusion criteria were patients who underwent primary ACLR by a single surgeon at a single center with minimum 1-year follow-up or ACL graft failure with revision ACLR performed by the same surgeon.

RESULTS

A total of 109 primary ACLR patients, mean age 33.7 years (range 15 to 71), enrolled between July 2016 and July 2018 and 90 revision ACLR patients, mean age 32.9 years (range 16 to 65), were included. The revision ACLR group had increased Beighton score (4 versus 0; P < .001) and greater side-to-side differences in quadricep circumference (2 versus 0 cm; P < .001) compared with the primary ACLR group. A family history of ACL tear was significantly more likely in the revision group (47.8% versus 16.5%; P < .001). The revision group exhibited significantly increased lateral posterior tibial slope (7.9° versus 6.2°), anterolateral tibial subluxation (7.1 versus 4.9 mm), and anteromedial tibia subluxation (2.7 versus 0.5 mm; all P < .005). In the revision group, femoral tunnel malposition occurred in 66.7% in the deep-shallow position and 33.3% in the high-low position. The rate of tibial tunnel malposition was 9.7% from medial to lateral and 54.2% from anterior to posterior. Fifty-six patients (77.8%) had tunnel malposition in ≥2 positions. Allograft tissue was used for the index ACLR in 28% in the revision group compared with 14.7% in the primary group.

CONCLUSION

Beighton score, quadriceps circumference side-to-side difference, family history of ACL tear, lateral posterior tibial slope, anterolateral tibial subluxation, and anteromedial tibia subluxation were all significantly different between primary and revision ACLR groups. In addition, there was a high rate of tunnel malposition in the revision ACLR group.

Slope-Correction Osteotomy with Lateral Extra-articular Tenodesis and Revision Anterior Cruciate Ligament Reconstruction Is Highly Effective in Treating High-Grade Anterior Knee Laxity

BACKGROUND

Both an elevated posterior tibial slope (PTS) and high-grade anterior knee laxity are often present in patients who undergo revision anterior cruciate ligament (ACL) surgery, and these conditions are independent risk factors for ACL graft failure. Clinical data on slope-correction osteotomy combined with lateral extra-articular tenodesis (LET) do not yet exist.

PURPOSE

To evaluate the outcomes of patients undergoing revision ACL reconstruction (ACLR) and slope-correction osteotomy combined with LET.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Between 2016 and 2018, we performed a 2-stage procedure: slope-correction osteotomy was performed first, and then revision ACLR in combination with LET was performed in 22 patients with ACLR failure and high-grade anterior knee laxity. Twenty patients (6 women and 14 men; mean age, 27.8 ± 8.6 years; range, 18-49 years) were evaluated, with a mean follow-up of 30.5 ± 9.3 months (range, 24-56 months), in this retrospective case series. Postoperative failure was defined as a side-to-side difference of ≥5 mm in the Rolimeter test and a pivot-shift grade of 2 or 3.

RESULTS

The PTS decreased from 15.3° to 8.9°, the side-to-side difference decreased from 7.2 to 1.1 mm, and the pivot shift was no longer evident in any of the patients. No patients exhibited revision ACLR failure and all patients showed good to excellent postoperative functional scores (mean ± SD: visual analog scale, 0.5 ± 0.6; Tegner, 6.1 ± 0.9; Lysholm, 90.9 ± 6.4; Knee injury and Osteoarthritis Outcome Score [KOOS] Symptoms, 95.2 ± 8.4; KOOS Pain, 94.7 ± 5.2; KOOS Activities of Daily Living, 98.5 ± 3.2; KOOS Function in Sport and Recreation, 86.8 ± 12.4; and KOOS Quality of Life, 65.4 ± 14.9).

CONCLUSION

Slope-correction osteotomy in combination with LET is a safe and reliable procedure in patients with high-grade anterior knee laxity and a PTS of ≥12°. Normal knee joint stability was restored and good to excellent functional scores were achieved after a follow-up of at least 2 years.

Slope-Reducing Tibial Osteotomy Combined With Primary Anterior Cruciate Ligament Reconstruction Produces Improved Knee Stability in Patients With Steep Posterior Tibial Slope, Excessive Anterior Tibial Subluxation in Extension, and Chronic Meniscal Posterior Horn Tears

BACKGROUND

Steep posterior tibial slope (PTS; >13°), excessive anterior tibial subluxation (ATS) in extension (>10 mm), and meniscus posterior horn tears (MPHTs) have been identified to be associated with primary anterior cruciate ligament (ACL) reconstruction (ACLR) failure. Recent studies have reported that steep PTS is directly correlated with excessive ATS in extension and concomitant MPHTs, especially for those patients with chronic (>6 months) ACL deficiency. There is increasing biomechanical evidence that slope-reducing tibial osteotomy decreases ATS in extension and protects the ACL graft.

HYPOTHESIS

Slope-reducing tibial osteotomy combined with primary ACLR is effective for producing improved knee stability in patients with steep PTS (>13°), excessive ATS in extension (>10 mm), and concomitant chronic MPHTs (>6 months).

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Between June 2016 and January 2018, 18 patients with ACL injuries who had steep PTS (>13°), excessive ATS in extension (>10 mm), and concomitant chronic MPHTs (>6 months) underwent slope-reducing tibial osteotomy combined with primary ACLR. The PTS and anterior subluxation of the lateral and medial compartment (ASLC and ASMC) in extension before and after the index procedures were regarded as primary clinical outcomes. Moreover, Lysholm score, Tegner activity score, International Knee Documentation Committee (IKDC) objective grade, pivot-shift test, and KT-1000 side-to-side difference were evaluated preoperatively and at the minimum 2-year follow-up visit.

RESULTS

The mean PTS was 18.5° (range, 17°-20°) preoperatively and 8.1° (range, 7°-9°) postoperatively (P < .01). The mean ASLC and ASMC in extension were 12.1 mm and 11.9 mm preoperatively, which reduced to 1.0 mm and 1.5 mm at the last follow-up visit (P < .05). In addition, all of the following showed significant improvements (pre- vs postoperatively): mean Lysholm score (46.5 vs 89.5; P < .05), mean Tegner activity score (5.7 vs 7.3; P < .05), IKDC objective grading results (18 grade D vs 14 grade A and 4 grade B; P < .05), pivot-shift tests (15 grade 2+ and 3 grade 3+ vs 18 grade 0; P < .01), and KT-1000 side-to-side difference (13.0 mm vs 1.6 mm; P < .01). Moreover, no graft reruptures were found at the final follow-up visit.

CONCLUSION

In this study, slope-reducing tibial osteotomy combined with primary ACLR effectively improved knee stability in patients with steep PTS (>13°), excessive ATS in extension (>10 mm), and concomitant chronic MPHTs (>6 months).

Lateral Extra-articular Tenodesis Reduces Anterior Cruciate Ligament Graft Force and Anterior Tibial Translation in Response to Applied Pivoting and Anterior Drawer Loads

BACKGROUND

The biomechanical effect of lateral extra-articular tenodesis (LET) performed in conjunction with anterior cruciate ligament (ACL) reconstruction (ACLR) on load sharing between the ACL graft and the LET and on knee kinematics is not clear.

PURPOSE/HYPOTHESIS

The purpose was to quantify the effect of LET on (1) forces carried by both the ACL graft and the LET and (2) tibiofemoral kinematics in response to simulated pivot shift and anterior laxity tests. We hypothesized that LET would decrease forces carried by the ACL graft and anterior tibial translation (ATT) in response to simulated pivoting maneuvers and during simulated tests of anterior laxity.

STUDY DESIGN

Controlled laboratory study.

METHODS

Seven cadaveric knees (mean age, 39 ± 12 years [range, 28-54 years]; 4 male) were mounted to a robotic manipulator. The robot simulated clinical pivoting maneuvers and tests of anterior laxity: namely, the Lachman and anterior drawer tests. Each knee was assessed in the following states: ACL intact, ACL sectioned, ACL reconstructed (using a bone-patellar tendon-bone autograft), and after performing LET (the modified Lemaire technique after sectioning of the anterolateral ligament and Kaplan fibers). Resultant forces carried by the ACL graft and LET at the peak applied loads were determined via superposition. ATT was determined in response to the applied loads.

RESULTS

With the applied pivoting loads, performing LET decreased ACL graft force up to 80% (44 ± 12 N; P < .001) and decreased ATT of the lateral compartment compared with that of the intact knee up to 7.6 ± 2.9 mm (P < .001). The LET carried up to 91% of the force generated in the ACL graft during isolated ACLR (without LET). For simulated tests of anterior laxity, performing LET decreased ACL graft force by 70% (40 ± 20 N; P = .001) for the anterior drawer test with no significant difference detected for the Lachman test. No differences in ATT were deteced between ACLR with LET and the intact knee on both the Lachman and the anterior drawer tests (P = .409). LET reduced ATT compared with isolated ACLR on the simulated anterior drawer test by 2.4 ± 1.8 mm (P = .032) but not on the simulated Lachman test.

CONCLUSION

In a cadaveric model, LET in combination with ACLR transferred loads from the ACL graft to the LET and reduced ATT with applied pivoting loads and during the simulated anterior drawer test. The effect of LET on ACL graft force and ATT was less pronounced on the simulated Lachman test.

CLINICAL RELEVANCE

LET in addition to ACLR may be a suitable option to offload the ACL graft and to reduce ATT in the lateral compartment to magnitudes less than that of the intact knee with clinical pivoting maneuvers. In contrast, LET did not offload the ACL graft or add to the anterior restraint provided by the ACL graft during the Lachman test.

Lateral extra-articular tenodesis in patients with revision anterior cruciate ligament (ACL) reconstruction and high-grade anterior knee instability

BACKGROUND

Additional lateral extra-articular procedures can reduce the risk of failure of primary anterior cruciate ligament reconstruction (ACLR). There is limited evidence on the effect of lateral extra-articular procedures in revision ACL surgery. The purpose of this study was to evaluate the clinical outcome of patients with lateral extra-articular tenodesis (LET) in combination with revision ACLR for combined ACL graft failure and high-grade anterior knee instability.

METHODS

Between 2016 and 2018, 75 patients with graft failure after primary ACLR and high-grade anterior knee instability who received revision ACLR were included in the retrospective study. High-grade anterior knee instability was defined as high-grade pivot-shift or side-to-side difference of more than six millimeters in Rolimeter®-testing. An additional modified Lemaire tenodesis was performed in 59 patients during revision ACLR. Seventy-three patients were clinically examined with a minimum of two years after revision surgery.

RESULTS

Failure of the revision ACLR occurred in 8.2% (n = 6) of the cases. LET lead to significant decreased failure rates (five percent vs. 21%, p = .045) and decreased incidence of a positive pivot-shift in patients with revision ACLR and high-grade anterior knee instability in comparison to patients without LET. Also, postoperative functional scores were significantly increased in the group of additional LET.

CONCLUSIONS

Additional LET in patients with revision ACLR and high-grade anterior instability significantly reduces the risk of failure of revision ACLR, the incidence of pivot-shift and increases postoperative functional outcome.

Meniscus or Cartilage Injury at the Time of Anterior Cruciate Ligament Tear Is Associated With Worse Prognosis for Patient-Reported Outcome 2 to 10 Years After Anterior Cruciate Ligament Injury: A Systematic Review

OBJECTIVES

(1) To assess prognostic factors for patient-reported outcome measures (PROMs) and physical activity 2 to 10 years after anterior cruciate ligament reconstruction (ACLR) or anterior cruciate ligament (ACL) injury, and (2) to assess differences in prognostic factors between patients treated with ACLR and with rehabilitation alone.

DESIGN

Prognosis systematic review.

LITERATURE SEARCH

Systematic searches were performed in PubMed, Web of Science, and SPORTDiscus.

STUDY SELECTION CRITERIA

We selected prospective cohort studies and randomized clinical trials that included adults or adolescents undergoing either ACLR or rehabilitation alone after ACL rupture. Studies had to assess the statistical association between potential prognostic factors (factors related to patient characteristics, injury, or knee symptoms/function measured at baseline or within 1 year) and outcomes (PROMs and physical activity).

DATA SYNTHESIS

Our search yielded 997 references. Twenty studies met the inclusion criteria. Seven studies with low or moderate risk of bias remained for data synthesis.

RESULTS

Moderate-certainty evidence indicated that concomitant meniscus and cartilage injuries were prognostic factors for worse PROMs 2 to 10 years after ACLR. Very low-certainty evidence suggested that body mass index, smoking, and baseline PROMs were prognostic factors for worse outcome. Very low-certainty evidence suggested that female sex and a worse baseline Marx Activity Rating Scale score were prognostic factors for a worse Marx Activity Rating Scale score 2 to 10 years after ACLR. There was a lack of studies on prognostic factors after rehabilitation alone.

CONCLUSION

Concomitant meniscus and cartilage injuries were prognostic factors for worse long-term PROMs after ACLR. The certainty was very low for other prognostic factors. J Orthop Sports Phys Ther 2020;50(9):490-502. Epub 1 Aug 2020. doi:10.2519/jospt.2020.9451.

Greater knee joint laxity remains in teenagers after anatomical double-bundle anterior cruciate ligament reconstruction compared to young adults

PURPOSE

There is paucity in studies regarding double-bundle anterior cruciate ligament reconstruction (DB-ACLR) in teenagers. The purpose of this study is to investigate clinical outcome after DB-ACLR and analyze whether any differences exist between teenagers and young adults.

METHODS

A retrospective study was performed between 2009 and 2017. Teenagers were defined as patients between 15 and 19 years and young adults between 20 and 25 years old. Isolated anterior cruciate ligament (ACL) injuries with DB-ACLR with minimum two-year follow up were included. Pre and post-operative Lysholm score, Tegner activity scale, KT-2000 arthrometer, manual pivot-shift grade, were assessed with post-operative one-leg hop test, isokinetic knee extensor strength test at 60°/sec, International Knee Documentation Committee Score (IKDC score), and re-injury rate.

RESULTS

One-hundred and thirty-one patients, 75 patients in the teenage group (Group A) and 56 patients in the young adult group (Group B), were enrolled. Lysholm score was significantly lower in Group A (89.6 ± 21.1) compared to Group B (95.9 ± 4.6) (p = 0.04). Side to side difference in KT-2000 arthrometer (2.3 ± 2.2 mm vs 1.0 ± 2.3 mm, Group A vs Group B, respectively, p < 0.01) and ratio of post-operative positive pivot shift was significantly greater in Group A (30.7%) compared to Group B (7.1%) (p < 0.01). No significant difference was seen in re-injury rate (n.s.).

CONCLUSION

Teenage patients have a greater tendency for residual knee joint laxity after DB-ACLR. Although teenagers and patients in the early twenties are close in age, characteristic in knee joint laxity may be different and, therefore, may require attention upon surgery and post-operative follow-up.

LEVEL OF EVIDENCE

III.

Risk Factors for Grade 3 Pivot Shift in Knees With Acute Anterior Cruciate Ligament Injuries: A Comprehensive Evaluation of the Importance of Osseous and Soft Tissue Parameters From the SANTI Study Group

BACKGROUND

Preoperative grade 3 pivot shift has been reported to be associated with higher rates of anterior cruciate ligament (ACL) failure, persistent instability, and inferior patient-reported outcomes. The etiology of a high-grade pivot shift is multifactorial, and numerous factors have been suggested to be responsible. More attention has recently been focused on injury to the anterolateral structures (ALS) as a risk factor for a grade 3 pivot shift.

PURPOSE

To determine risk factors for grade 3 pivot shift, including soft tissue and osseous parameters.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A prospective evaluation was undertaken of 200 consecutive patients undergoing acute ACL reconstruction (within 10 days of injury). An open exploration of the lateral side of the injured knee was performed at the time of the index procedure. Details regarding patient and injury characteristics were recorded, as were details of soft tissue injuries, including meniscal tears, ALS lesions, medial collateral ligament tears, and chondral injuries. Osseous parameters (tibial slope and condylar ratios) were determined per established magnetic resonance imaging protocols. A multivariate logistic regression with penalized maximum likelihood was used to identify risk factors associated with International Knee Documentation Committee (IKDC) grade 3 pivot shift.

RESULTS

The mean ± SD age of the population was 28.3 ± 9.8 years; 67.5% of patients were male. Among patients, 35 (17.5%) had a high-grade pivot shift (IKDC grade 3), and 165 (82.5%) had a low-grade pivot shift (IKDC grades 1 and 2). Univariate and multivariate logistic regression analysis demonstrated that injury to the ALS was the only significant risk factor for grade 3 pivot shift (odds ratio, 13.49; 95% CI, 1.80-1725.53).

CONCLUSION

This comprehensive evaluation of soft tissue and osseous factors has identified that injury to the ALS is the most important risk factor for grade 3 pivot shift in acute ACL-injured knees.