Anatomic Anterior Cruciate Ligament Reconstruction Research Articles

What's New in Sports Medicine.

What's New in Sports Medicine.

Lateral meniscal status, chronicity of anterior cruciate ligament (ACL) deficiency, and initial graft tension were associated with abnormal knee laxity after anatomical ACL reconstruction

PurposeGraft failure or recurrence of instability without obvious trauma remains one of the problems following anterior cruciate ligament (ACL) reconstruction. This retrospective study aimed to identify risk factors for abnormal knee laxity after anatomical ACL reconstruction. MethodsA total of 291 patients who underwent primary anatomical ACL reconstruction were included in this study. Sex, age, body mass index (BMI), time to surgery, medial meniscal status, lateral meniscal status, graft materials, initial graft tension protocol, preoperative and postoperative pivot shift test and side-to-side differences in anterior tibial translation using the arthrometer were reviewed. Abnormal knee laxity was defined as constituting one or both of the following criteria: (i) a side-to-side difference of ≥3 mm by arthrometer; and (ii) a positive pivot shift test, being “glide,” “clunk”, or “gross”. ResultsAbnormal knee laxity occurred in 30 patients (10.3%) at a median follow-up of 25 months. Results of univariate analysis indicated that a higher likelihood of abnormal knee laxity was associated with female sex, greater BMI, longer time to surgery, higher initial graft tension protocol, and lateral meniscus resection. Multivariate logistic regression analysis showed that abnormal knee laxity was significantly associated with time to surgery [1-month increase; odds ratio (OR), 1.01], higher initial graft tension protocol (vs. lower tension; OR, 3.5), and lateral meniscus resection (vs. intact and repaired lateral meniscus; OR, 12.8). ConclusionHigher initial graft tension protocol, chronicity of ACL deficiency, and lateral meniscus resection were risk factors for abnormal knee laxity after anatomical ACL reconstruction. Level of evidenceLevel III retrospective prognostic study.

Preoperative Loss of Knee Extension Affects Knee Extension Deficit in Patients After Anterior Cruciate Ligament Reconstruction.

Loss of knee extension (LOE) after anterior cruciate ligament reconstruction (ACLR) is associated with limited knee joint function and increased risk for knee osteoarthritis. Preoperative LOE will affect postoperative LOE for up to 12 months after ACLR. Cohort study; Level of evidence, 2. Included were patients who underwent anatomic ACLR between June 2014 and December 2018. In all patients, the postoperative rehabilitation protocol was the same. A heel height difference (HHD) ≥2 cm between the affected and the contralateral leg was used as a measure of LOE. Based on preoperative HHD, patients were divided into LOE and no-LOE groups. The HHD was reevaluated at 1, 3, 4, 6, 9, and 12 months postoperatively. Proportional hazards analysis was used, with the dependent variable being whether a postoperative HHD <2 cm was achieved; the independent variables being the presence or absence of preoperative LOE; and the adjusted variables being age, sex, time to surgery, and presence of meniscal sutures. A total of 389 patients (208 female, 181 male; median age, 21.0 years) were included in the study. There were 55 patients in the LOE group and 334 patients in the no-LOE group. The incidence of LOE at 12 months after ACLR was 13.8% in the no-LOE group and 38.2% in the LOE group (P < .001), with an absolute risk difference of 24.4%. The hazard ratio for achieving postoperative HHD <2 cm was 2.79 for the LOE group versus the no-LOE group (P < .001). Patients with preoperative LOE were nearly 3 times more likely than those without LOE to have LOE at 12 months after ACLR.

ANTEROMEDIAL OR CENTRAL ANATOMIC ACL RECONSTRUCTION? A CADAVERIC HIP-TO-TOE STUDY.

To compare anatomic anterior cruciate ligament (ACL) reconstruction between two tunnel positions in knees with isolated ligament tears. Anatomic ACL reconstruction was performed, from hip-to-toe, on 15 fresh cadaveric specimens. No associated lesions were created to enhance knee instability. The protocol was conducted in three states: (1) complete isolated ACL deficiency; (2) anatomic femoral and tibial anteromedial ACL reconstruction (AM REC); and (3) anatomic femoral and tibial central ACL reconstruction (Central REC). The reconstruction protocols were randomly assigned. The continuous mechanized pivot-shift test was recorded dynamically with a tracking system. The Central REC group showed a smaller degree of internal rotation (0.6° ± 0.3° vs. 1.8° ± 0.3°, respectively, P < 0.05) and no difference in anterior translation (4.7 mm ± 0.4 mm vs. 4.5 mm ± 0.4 mm, respectively, P > 0.05) in the pivot-shift test, compared with the AM REC group. The central anatomic ACL reconstruction resulted in greater restriction of internal rotation than the anteromedial anatomic ACL reconstruction. Experimental Study on Cadaver.

Similar postoperative outcomes and landing test results after single-bundle anatomic anterior cruciate ligament reconstruction with or without remnant preservation

article: Similar postoperative outcomes and landing test results after single-bundle anatomic anterior cruciate ligament reconstruction with or without remnant preservation - Medicina dello Sport 2022 December;75(4):591-606 - Minerva Medica - Journals

Increased ACL direct insertion coverage provided more positive biomechanical effects on graft and bone tunnel during knee flexion: a simulation study

PurposeFlattened femoral tunnels were recently applied in anatomical single-bundle anterior cruciate ligament (ACL) reconstruction. Little is known about the biomechanical effect of such changes during knee flexion. The aim of the present simulation study was to assess the effect of altered ACL direct insertion coverage on the biomechanics of the graft and bone tunnel.MethodsFive finite element (FE) models, including a round femoral tunnel and four progressively flattened rounded rectangular femoral tunnels, were established to represent the ACL reconstructions. In vivo knee kinematics data obtained from the validated dual fluoroscopic imaging techniques controlled the FE models to simulate lunge motions. The maximal principal stress of the graft and the volume of equivalent strain within 1000–3000 microstrain (V1000-3000) of the cancellous bone were subsequently calculated at 0°, 30°, 60° and 90° of knee flexion.ResultsA lower stress state on the graft and a more beneficial strain state on the cancellous bone were observed when the femoral tunnel better covered the ACL direct insertion. The average maximal principal stress of each model were 3.93 ± 0.60 MPa, 3.82 ± 0.54 MPa, 3.43 ± 0.44 MPa, 3.45 ± 0.44 MPa and 3.05 ± 0.43 MPa, respectively. The average V1000-3000 of the cancellous bone of each model were 179.06 ± 89.62 mm3, 221.40 ± 129.83 mm3, 247.57 ± 157.78 mm3, 282.74 ± 178.51 mm3 and 295.71 ± 162.59 mm3, respectively. Both the stress and strain values exhibited two peaks during the flexion simulation. The highest value occurred at 30° of flexion, and the second highest value occurred at 90° of flexion.ConclusionsIncreased ACL direct insertion coverage provided more positive biomechanical effects after anatomical single-bundle ACL reconstruction during knee flexion.

Revision Anterior Cruciate Ligament Reconstruction (ACLR): Causes and How to Minimize Primary ACLR Failure.

Anterior cruciate ligament (ACL) tears are a common orthopaedic injury, particularly in athletic populations. Primary ACL reconstructions (ACLR) have fairly successful outcomes; however, there is a subset of patients who experience failure or re-injury and require a technically challenging revision ACLR procedure. Knowledge of the clinically relevant ACL anatomy and biomechanics, including closely associated meniscal, ligament, and osseous structures, is fundamental for an anatomic revision ACLR. Comprehensive evaluation and diagnosis are also critical to identify the causes of primary ACLR failure and determine appropriate treatment(s). Although outcomes have improved over time, revision ACLR patients still experience sub-optimal outcomes compared to primary ACLR patients. This review will highlight the current concepts of anatomy, biomechanics, clinical evaluation, treatment, outcomes, and post-operative rehabilitation to optimize outcomes for revision ACLR procedures.

A clinical study to determine the early functional outcome of ACL injuries managed by arthroscopic reconstruction using four strand hamstring graft with interferrence screw

Anterior cruciate ligament is the most commonly injured ligament. Arthroscopic reconstruction of anterior cruciate ligament with aperture fixation of graft using the interference screw on the tibial side allows for early Firm fixation and healing with tight bone-tendon interface.Even after better surgical techniques and fixation devices many athletes retire early due to residual knee instability. Hence in this study, I am making an effort to assess the early clinical outcome of anterior Cruciate Ligament injuries managed with arthroscopic reconstruction using hamstring graft with Interference screw. Due to rise of RTAs need for study of function outcome of ACL injuries treated by arthroscopic reconstruction in non sports individuals. This prospective comparative observational study related data were captured between october 2020 to april 2022 in a Karnataka institute of medical sciences. About 35 patients with arthroscopic anatomic ACL reconstruction using hamstring tendon graft with interference screw were evaluated and followed up for functional outcome. Patients were evaluated for functional outcome and stability of knee using International knee documentation committee subjective score and Lysholm score over a period of 18 months. This prospective comparative observational study related data were captured between october 2020 to april 2022 in a Karnataka institute of medical sciences. About 35 patients with arthroscopic anatomic ACL reconstruction using hamstring tendon graft with interference screw were evaluated and followed up for functional outcome. Patients were evaluated for functional outcome and stability of knee using International knee documentation committee subjective score and Lysholm score over a period of 6 months.The larger percentage of cases was operated less than 6 months from the date of injury. On evaluation of the patients during the follow up by IKDC and LGS, 100% of the patients had excellent to good results, and were able to return to pre injury level of activity.The technique of arthroscopic ACL reconstruction offers an excellent knee function, knee stability and restoration of preoperative functional status with minimal complications.

Isokinetic Muscle Strength and Knee Function in Anatomical Anterior Cruciate Ligament Reconstruction With Hamstring Autografts: A Prospective Randomized Comparative Study Between Suspensory and Expandable Femoral Fixation in Male Patients.

Background Clinical performance, anterior knee stability, and isokinetic strength after anterior cruciate ligament (ACL) reconstruction with hamstring autografts are mainly influenced by graft selection, femoral tunnel preparation, and type of femoral fixation.Expandable femoral fixation devices are expected to provide a stronger initial fixation with circular graft compression, a blind-ended tunnel in the femur with less enlargement, and a theoretical double-band ACL equivalent through graft rotation. This study aimed to evaluate isokinetic strength and functional capacity after ACL reconstruction with hamstring tendons using two different anatomical femoral fixation techniques (expandable vs fixed-looped button). Methodology A total of 48 male patients with ACL deficient knees were randomized to two different femoral fixation groups, namely, the expandable (AperFix) and the standard cortical (Button) group. The primary outcome measures were isokinetic hamstrings and quadriceps strength capabilities and the hamstrings/quadriceps ratio at 60 degrees/second (°/s) and 180°/s using a Cybex before and at three, six, nine, 12, and 24 months after surgery. Secondary measurements were anteroposterior knee stability at two years (using KT-1000 arthrometer) and the functional outcome using the International Knee Documentation Committee (IKDC 2000) form, the Tegner activity scale, and the Lysholm knee score. Data were compared using a paired t-test and analysis of variance, with a p < 0.05 level of significance. Results Most patients regained the 60°/s quadriceps strength between three and 12 months (62.5% for the Button group vs. 50% for the AperFix group), as well as the 180°/s strength (79.17% vs 70.83%); however, at the 24-month evaluation, seven (29.17%) patients in the Button group and five (20.83%) in the AperFix group had significant deficits. The 60°/s flexor strength was regained in the first six months in 19 (79.17%)patients in the Button group and in 16 (66.7%)patients in the AperFix group, whereas the percentages for the 180°/s strength were 79.17% and 75%, respectively. Beyond the 24-month evaluation, only three (12.5%) patients in the Button group and four (16.67%) in the AperFix group had significant flexor deficits. Regarding the H/Q ratio, at 60°/s, the mean recovery time was six and 7.5 months for the Button and AperFix groups, respectively, whereas 15 and 12 patients, respectively, did not recover during the two-year duration. At 180°/s, a mean recovery time of six months was needed for the button group, and nine patients did not recover two years later. For the AperFix group, nine months were needed, and 12 patients did not recover in two years. Clinical performance and anterior knee stability showed no statistically significant differences between groups. Conclusions Although there were no significant differences in clinical performance, knee stability, and isokinetic strength testing between expandable and cortical button femoral fixation groups, return to play was doubtful at two years postoperatively.

Double-bundle ACL reconstruction versus anatomic single-bundle ACL reconstruction combined with anterolateral ligament reconstruction: a comparative study of clinical outcome.

Recent studies showed increasing evidences of anterolateral ligament (ALL) reconstruction in conjunction with anterior cruciate ligament (ACL) reconstruction that proves to be more superior to the previous double-bundle (DB) ACLR technique especially in improving knee stability in biomechanic studies. However to date, there have been no studies evaluating the functional outcome of DB-ACLR vs single-bundle (SB) with ALL in ACLR. A total of 138 patients with ACL deficient knee were enrolled to the study. Double-bundle ACL reconstruction (DB-ACLR) was performed in 75 patients and single-bundle ACL reconstruction with anterolateral ligament reconstruction (SB + ALL) ACLR was performed in 63 patients. Surgical outcomes were compared with The International Knee Documentation Committee Subjective Knee Form (IKDC) and the Kujala score at the 3rd, 6th and 9th month post-operative. The IKDC score in the 3rd and 6th month was superior in the SB + ALL group compared to the DB group. However, this difference was not statistically significant. In the meantime, there were no statistically significant difference between the Kujala Score at the 3rd, 6th, and 9thmonths consecutively. There were no statistically significant differences in the functional outcomes of DB-ACLR and SB + ALL groups at the 3rd, 6th, and 9thmonths post-operative period. The functional outcome comparison showed non-superiority of SB + ALL group compared to the DB-ACLR group. The patellar pain was less found in DB-ACLR group at 6- and 9-months post-operative period.

Quality of life of patients with ACL reconstruction is interrelated with sporting activity and significantly improved when their concomitant meniscal rupture has been repaired. A long-term follow-up study

The goal of the present study is to report patient-reported outcomes after anatomic ACL reconstruction with a hamstrings autograft, to investigate how a concomitant meniscal injury and its management could affect these outcomes and to identify a possible correlation between quality of life and activity levels at a minimum of 10-years follow-up. Patients from a single center, treated with a unilateral anatomic ACL reconstruction with or without a concomitant meniscal injury, between 2003 and 2011 were investigated. Patients were asked to provide the following validated patient-reported outcome measures (PROMs): the International Knee Documentation Committee Subjective Knee Function (IKDC-SKF) score, the Knee Injury and Osteoarthritis Outcome Score (KOOS), the Lysholm knee score, the Tegner Activity Scale, the EQ-5D-5L questionnaire and a patient acceptable symptom state (PASS). Sex, age, BMI, and meniscal status were examined as patient-specific risk factors regarding long-term activity and quality of life. Mean follow-up was 13.2 years. In a total sample of 131 patients, response rate was 81% and finally, 106 patients, 90 men (85%) and 16 women (15%) were enrolled in the study. Re-tear rate was 2.8%. The majority (90.5%) of patients considered their knee state, satisfactory during follow-up. Mean IKDC score was 80 ± 16, mean KOOS score was 87 ± 15, mean Lysholm score was 90 ± 11, mean Tegner score was 5.6 ± 1.9 and mean EQ-5D-5L score was 91 ± 14. Patients who had been treated with meniscectomy had statistically significantly lower scores in all PROMs except for the Tegner score and the EQ-5D-5L score, when compared to patients treated with meniscal repair. Patient sex, age, and BMI did not affect patient-reported outcomes. There was a statistically significant, strong positive correlation between quality of life and activity levels. Patients have few or no symptoms and consider their knee state satisfactory, 13.2 years after surgery. Patients having undergone meniscal repair have improved PROMs compared to those treated with meniscectomy. Participation in sporting activities is interrelated with quality-of-life and does not seem to be affected by sex, BMI and age.

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.

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. 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. The mean follow-up period was 8.3 ± 2.2years. The mean equivalent graft diameter was 9.9 ± 0.7mm. 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 < 9mm (OR 3.31 compared with 9-10mm, p = 0.012; OR 3.28 compared with ≥ 10mm, p = 0.019), and meniscal resection (OR 1.94 compared with no meniscal surgery, p = 0.045) were associated with residual laxity. 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 III.

Combined Anterior Cruciate Ligament Reconstruction and Modified Lemaire Lateral Extra-articular Tenodesis Better Restores Knee Stability and Reduces Failure Rates Than Isolated Anterior Cruciate Ligament Reconstruction in Skeletally Immature Patients

Background: The increase in anterior cruciate ligament (ACL) injuries in pediatric patients and the high failure rate reported in the literature in this population are driving surgeons to search for specific techniques to better restore knee stability. Recent literature has reported that the combination of lateral extra-articular tenodesis (LET) and ACL reconstruction improves outcomes in high-risk patients. However, such advantages in pediatric patients have been infrequently evaluated. Purpose: To assess whether adding LET to ACL reconstruction can significantly improve knee stability, clinical outcomes, and failure rates in pediatric patients. Study Design: Cohort study; Level of evidence, 3. Methods: A multicentric study involving 3 orthopaedic teaching centers was conducted to evaluate pediatric patients aged between 12 and 16 years who had undergone primary ACL reconstruction using a physeal-sparing femoral tunnel drilling technique. A minimum 2-year follow-up evaluation was required. Based on the surgical technique performed, the patients were divided into 2 group. The patients in group 1 underwent an isolated arthroscopic ACL reconstruction, while the patients in group 2 had an arthroscopic ACL reconstruction in combination with a modified Lemaire LET procedure. Group 1 was a historical control cohort of patients, whereas group 2 was prospectively enrolled. All the patients included in the present study were clinically evaluated using the Pediatric International Knee Documentation Committee (Pedi-IKDC) subjective score and the Pediatric Functional Activity Brief Scale (Pedi-FABS) score. Anteroposterior knee stability was measured using the KT-1000 knee ligament arthrometer, and the objective pivot-shift evaluation was documented using a triaxial accelerometer (Kinematic Rapid Assessment [KiRA]). The included patients also underwent a standardized radiological protocol to evaluate leg-length discrepancies, axial deviation, and degenerative signs preoperatively and at last follow-up. Results: This study included 66 pediatric patients with an anatomic hybrid ACL reconstruction using an autologous 4-strand hamstring graft. In group 1, there were 34 patients (mean age, 13.5 ± 1.2 years), while 32 patients (mean age, 13.8 ± 1.4 years) were included in group 2. The clinical outcome scores showed no difference between the 2 groups (Pedi-IKDC, P = .072; Pedi-FABS, P = .180). Nevertheless, the patients in group 2 had better anteroposterior stability measured using a KT-1000 arthrometer (1.9 ± 1.1 mm in group 1 vs 0.8 ± 0.8 mm in group 2; P = .031), as well as better rotational stability measured using the KiRA (–0.59 ± 1.05 m/s2 in group 2 vs 0.98 ± 1.12 m/s2 in group 1; P = .012). The patients in group 1 returned to sports at the same competitive level at a rate of 82.4%, while patients included in group 2 returned at the same competitive level in 90.6% of the cases without a significant difference between the 2 groups (P = .059). No leg-length discrepancies were found between the 2 groups at last follow-up (P = .881). Two patients displayed an increased valgus deformity of 3° on the operated limb at last follow-up (1 patient in group 1 and 1 patient in group 2). Group 1 had a significatively higher cumulative failure rate (14.7% vs 6.3%; P = .021). No intra- or postoperative complications was observed between the 2 groups. Conclusion: Performing a modified Lemaire LET along with an ACL reconstruction with hamstring graft in pediatric patients reduced the cumulative failure rate and improved objective stability with no increase in intra- or postoperative complications. No significant difference was found between the 2 groups in terms of patient-reported outcomes or in the return-to-sports activity.

Multi-planar instability, laxity and reduced knee flexion during the support phase of walking are determinants of return to sports.

Background: After anterior cruciate ligament reconstruction, some patients are not recommended to return to high-level physical activity because they fail to pass return-to-sports tests. The kinematic difference between these patients and those who pass the return-to-sports tests is unclear. Methods: Eighty-two patients who received anatomic single-bundle anterior cruciate ligament (ACL) reconstruction for unilateral ACL injury underwent return-to-sport tests during a hospital visit at a minimum of 9months (9-11 months) of follow-up. Fifteen patients who passed the return-to-sports tests (RTS group) and fifteen patients who did not (NRTS group) were randomly selected to perform a treadmill walk under dual-fluoroscopic imaging system surveillance for a 6 degrees of freedom kinematic evaluation. Results: Of the 82 patients, 53 passed the return-to-sports tests 9 months after surgery, with a return-to-sports rate of 64.6%. In the stance phase, the NRTS group had a larger anterior tibial translation (1.00 ± 0.03mm vs. 0.76 ± 0.03mm, p = 0.001), a larger lateral tibial movement (1.61 ± 0.05mm vs. 0.77 ± 0.05mm, p < 0.001), a larger distal tibial displacement (-3.09 ± 0.05mm vs. -2.69 ± 0.05mm, p < 0.001), a smaller knee flexion angle (6.72 ± 0.07° vs. 8.34 ± 0.07°, p < 0.001), a larger varus angle (-0.40 ± 0.03°VS. -0.01 ± 0.03°, p < 0.001) and a larger external rotation angle (1.80 ± 0.05° vs. 1.77 ± 0.05°, p < 0.001) than the RTS group. The maximum anterior tibial translation of the NRTS group is also larger than that of the RTS group (3.64 ± 0.42mm vs. 3.03 ± 0.59mm, p = 0.003). Conclusion: Compared with patients passing RTS tests, those who fail to pass show significant anterior, lateral, and rotational instability; knee laxity; and reduced flexion angle of the knee in the support phase during walking, which may be the possible factors hindering a return to sports.

Knee Osteoarthritis Following Anterior Cruciate Ligament Reconstruction: Frequency, Contributory Elements, and Recent Interventions to Modify the Route of Degeneration.

Half of the individuals who experience an anterior cruciate ligament reconstruction (ACLR) suffer from knee osteoarthritis (OA) 12-14 years later. Elements that make a contribution to the appearance of OA following ACLR are anomalous anterior tibial displacement and anomalous tibial rotation in the course of the stance phase of walking (exhibited in 85% of operated knees). Individuals who undergo an early ACLR (5 days on average following anterior cruciate ligament [ACL] breakage) have an inferior frequency of radiographically apparent tibiofemoral OA at 32-37 years of follow-up than individuals with ACL rupture who did not experience the procedure. Nevertheless, the percentage of symptomatic OA, radiographically apparent patellofemoral OA and knee symptoms are alike in both groups. At 15 years of follow-up, 23% of knees that experienced an anatomic ACLR suffer from OA, while this percentage augments to 44% if the ACLR was non-anatomic. Knees of individuals who experience ACLR need total knee arthroplasty at an earlier age than healthy knees. Intra-articular injections of interleukin-1 receptor antagonist and corticosteroids may reduce the risk of OA after ACLR.

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.

Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction Is Not Superior to Anatomic Single-Bundle Reconstruction at 10-Year Follow-up: A Randomized Clinical Trial

Background: The anatomic double-bundle (DB) technique is purported to be a superior technique due to its mimicking of the double-stranded anatomic formation of the anterior cruciate ligament (ACL). Previous studies with 2-, 5- and 10-year follow-up are conflicted as to whether this technique is superior to the previous gold standard method of ACL reconstruction, the anatomic single-bundle (SB) reconstruction. Purpose/Hypothesis: The aim of this prospective randomized study was to compare the outcomes of the anatomic DB technique and anatomic SB technique with independent drilling at 10 years after anterior cruciate ligament (ACL) reconstruction. We hypothesized that DB ACL reconstruction would result in a better outcome in terms of the pivot-shift test. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: A total of 105 patients (33 women, 72 men; median age, 27 years [range, 18-52 years]) were randomized and underwent ACL reconstruction (DB group: n = 53; SB group: n = 52). All reconstruction procedures were performed anatomically by identifying the ACL footprint, using the anteromedial portal for femoral tunnel drilling, and utilizing interference screws for tibial and femoral fixation. One blinded observer examined the patients both preoperatively and at follow-up (median, 120 months [range, 112-134 months]). Multiple subjective and objective clinical evaluations were used to assess the outcomes. Radiographic assessments of osteoarthritis were performed using the Ahlbäck, Kellgren-Lawrence, and Fairbank classification systems early postoperatively and at the final follow-up. Results: Preoperatively, no differences were found between the study groups. Overall, 70 patients (67%; DB group: n = 39; SB group: n = 31) were available for analysis at 10-year follow-up. No significant difference could be shown between the groups in terms of the pivot-shift grade, knee laxity measurements using the KT-1000 arthrometer, manual Lachman grade, single-leg hop test result, range of motion measurements, Lysholm knee score, Tegner activity score, and Knee injury and Osteoarthritis Outcome Score (KOOS) score. Correspondingly, no differences were found between the groups regarding the presence of radiographic osteoarthritis at follow-up. Both groups improved at follow-up compared with preoperatively in terms of the pivot-shift grade, knee laxity measurements using the KT-1000 arthrometer, manual Lachman grade, Lysholm knee score, and KOOS score (P < .05 [highest P value for any comparison]). Conclusion: The anatomic DB technique was not superior to the anatomic SB technique with independent drilling at 10-year follow-up in regard to objective and subjective measurements. As such, one could argue that there is no need for the continued use of the anatomic DB technique in an unselected population.

Intra-Articular Biomechanical Changes of the Meniscus and Ligaments During Stance Phase of Gait Circle after Different Anterior Cruciate Ligament Reconstruction Surgical Procedures: A Finite Element Analysis.

The debate on the superiority of single- or double-bundle for anterior cruciate ligament reconstruction has not ceased. The comparative studies on intra-articular biomechanics after different surgical reconstructions are rare. This study is to evaluate the biomechanical stress distribution intra-knee after single- and double-bundle anterior cruciate ligament reconstruction by three-dimensional finite element analysis, and to observe the change of stress concentration under the condition of vertical gradient loads. In this study, magnetic resonance imaging data were extracted from patients and healthy controls for biomechanical analysis. Patients included in the three models were matched in age and sex. The strength and distribution of induced stresses were analyzed in two frequently used procedures, anatomical single-bundle anterior cruciate ligament reconstruction and anatomical double-bundle anterior cruciate ligament reconstruction, using femoral-graft-tibial system under different loads, to mimic a post-operation mechanical motion. The three-dimensional finite-element models for normal ligament and two surgical methods were applied. A vertical force simulating daily walking was performed on the models to assess the interfacial stresses and displacements of intra-articular tissues and ligaments. The evaluation results mainly included the stress of each part of ligament and meniscus. The stress values of different parts of three models were extracted and compared. The stress of ligament/graft at femoral side of three finite-element models was significantly higher than at tibial side, while the highest level was observed in single-bundle reconstruction finite-element model. With the increase of force, the maximum stress in the medial (7.1-7.1 MPa) and lateral (4.9-7.4 MPa) meniscus of single-bundle reconstruction finite-element model shifted from the anterior horn to the central area (p=0.0161, 0.0479, respectively). The stress was shown to be at a lower level at femoral side and posterior cruciate ligament of intra-knee in two reconstruction finite-element models than that in normal finite-element models, while presented higher level at the tibial side than normal knee (p=0.3528). The displacement of the femoral side and intra-knee areas in reconstruction finite-element models was greater than that in normal finite-element model (p=0.0855). Compared with the single-bundle technique, the graft of double-bundle anterior cruciate ligament reconstruction has better stress dissipation effect and can prevent postoperative meniscus tear more effectively.

Occurrence Rate of Cyclops Lesion After Anatomic Double-Bundle ACL Reconstruction: Comparison Between Remnant Tissue Preservation and Resection Methods.

The occurrence rate of cyclops lesion after anatomic double-bundle anterior cruciate ligament (ACL) reconstruction with remnant tissue preservation remains unclear. The study hypotheses were as follows: (1) the occurrence rate of cyclops lesion will be comparable between the remnant-preserving and remnant-resecting ACL reconstruction methods, and (2) there will be no significant differences in clinical outcomes between the remnant-preserving and remnant-resecting procedures. This retrospective comparative study involved 177 patients who underwent unilateral anatomic double-bundle ACL reconstruction using hamstring tendon autografts from 2014 to 2018 at our hospital. According to the Crain classification of ACL remnant tissue, 98 patients with remnant types I, II, or III underwent the remnant-preserving procedure (group A), and the remaining 79 patients with remnant type IV underwent the remnant-resecting procedure (group B). All patients underwent second-look arthroscopy. Patients were evaluated according to arthroscopic and clinical results at postoperative 15.2 ± 8.4 months (mean ± SD). Statistical comparisons between groups were made using the paired Student t test, chi-square test, and Fisher exact test. Cohort study; Level of evidence, 3. At second-look arthroscopy, the incidence of cyclops lesions was significantly higher in group B than in group A (29.1% vs 13.3%; P = .0139). Cyclops lesions were divided into 4 locations: femoral side (type 1), midsubstance (type 2), tibial side (type 3), and anterior (type 4) of the ACL graft. The ratio of the tibial-side cyclops lesion (type 3) was significantly higher in group B than in group A (P = .0354). There were no significant differences in the clinical evaluation scores between the procedures. Side-to-side anterior laxity was significantly less in group A than in group B (0.7 vs 1.6 mm; P = .0035). Concerning postoperative laceration and synovium coverage of the grafts, group A was significantly better than group B (P < .0001). In this cohort of patients undergoing double-bundle ACL reconstruction, resection of the ACL remnant was associated with a significantly higher rate of cyclops lesion formation when compared with preservation of the remnant.

Lateral posterior tibial slope does not affect femoral but does affect tibial tunnel widening following anatomic anterior cruciate ligament reconstruction using a Bone–Patellar Tendon–Bone graft

BackgroundTunnel widening (TW) after anterior cruciate ligament (ACL) reconstruction has been a research area of interest in ACL reconstruction. In recent years, it has been noted that posterior tibial slope (PTS) affects several types of outcomes after ACL reconstruction including TW. However, the relationships between femoral and tibial TW and between PTS and TW following anatomical ACL reconstruction using a bone–patellar tendon–bone (BTB) graft are often not understood. Therefore, the purpose of this study was to retrospectively clarify the magnitude of femoral and tibial TW and the effect of PTS on TW following anatomical ACL reconstruction using a BTB graft. MethodsA total of 111 patients who underwent isolated ACL reconstructions using BTB grafts were included in this study. Femoral and tibial tunnel aperture areas were measured using three-dimensional computed tomography (3D CT) at 1 week and 1 year postoperatively, and femoral and tibial TW (%) was calculated. Lateral and medial PTS was also measured using 3D CT. ResultsAs compared with 1 week postoperatively, the mean tibial tunnel aperture areas increased by 30.6% ± 28.5%, and the mean femoral tunnel aperture areas increased by 28.3% ± 27.9% when measured at 1 year postoperatively. Although no significant difference was observed between femoral and tibial TW, a significant positive correlation was noted between femoral and tibial TW (r = 0.240, p = 0.011). A significant correlation was observed only between lateral PTS and tibial TW (r = 0.354, p < 0.001). There was no significant correlation between medial PTS and tibial TW, lateral PTS and femoral TW, or medial PTS and femoral TW. ConclusionSignificant positive correlation was observed between femoral and tibial TW. Steeper lateral PTS correlated with greater tibial TW; on the other hand, medial PTS did not correlate with tibial TW. Although lateral PTS affected tibial TW, it did not affect femoral TW.