Kinematic Analysis of Lateral Meniscal Oblique Radial Tears in the Anterior Cruciate Ligament–Deficient Knee

Background: Lateral meniscal oblique radial tears (LMORT) occur frequently in conjunction with anterior cruciate ligament (ACL) disruption and are anatomically distinct from meniscus root tears. Hypothesis/Purpose: The purpose of this study was to characterize the effects of LMORT types 3 (LMORT3) and 4 (LMORT4) lesions on joint stability and meniscal extrusion in ACL-deficient knees. Our hypothesis was that both lesions would promote significant increases in anterior translation and meniscal extrusion, with the LMORT4 lesion having a greater effect. Study Design: Controlled laboratory study. Methods: Two matched pairs of cadaveric knees (n = 4) were used to optimize the testing sequence. Additional cadaveric knees with LMORT3 (n = 8) and LMORT4 (n = 8) lesions created after ACL transection underwent robotic kinematic testing for anterior drawer and pivot-shift simulations with associated ultrasound-measured meniscal extrusion at clinically relevant knee flexion angles. Results: Optimization testing showed no differences on the effect of LMORT4 lesions for anterior translation and lateral meniscal extrusion with ACL-intact versus ACL-deficient knees. ACL deficiency and LMORT3 and LMORT4 lesions with ACL deficiency were associated with significantly greater anterior translation compared with ACL-intact state for both anterior drawer and pivot-shift testing at all flexion angles ( P < .001). ACL deficiency with either LMORT3 or LMORT4 lesion was associated with significantly greater anterior translation than was ACL deficiency only ( P < .005) for anterior drawer testing at 90° of flexion. Meniscal extrusion was greater with LMORT3 and LMORT4 lesions compared with ACL deficiency only ( P < .05) for anterior drawer at 60° of flexion and for pivot shift at 15° of flexion. The LMORT4 lesion demonstrated increased anterior translation for anterior drawer ( P = .003) at 60° of flexion (12%) as well as for pivot shift at 15° of flexion (7%) and 30° of flexion (13%) ( P < .005) compared with ACL deficiency only. Conclusion: In this cadaveric model, the addition of an LMORT3 or LMORT4 lesion increased anterior laxity for both the anterior drawer and the pivot shift when compared with an isolated ACL tear. Lateral meniscal extrusion was also exacerbated by these LMORT lesions. Clinical Relevance: LMORT lesions, distinct from meniscus root tears, occur frequently in conjunction with ACL tears. This study characterized the biomechanical consequences of LMORT3 and LMORT4 lesions on joint stability and meniscal function, highlighting the importance of diagnosing and treating LMORT lesions at the time of ACL reconstruction.

The impact of feature extraction and selection for the classification of gait patterns between ACL deficient and intact knees based on different classification models

The anterior cruciate ligament (ACL) plays an important role in stabilizing translation and rotation of the tibia relative to the femur. Individuals with ACL deficiency usually demonstrate alterations in gait characteristics. Evidence indicates that walking speed, alterations in kinetics and kinematics on the ACL deficient limb, and inter-limb asymmetries between deficient and intact knees may contribute to poor long-term outcomes following ACL deficiency. They corrode function of the knee joint and put it at higher risk of degeneration. For the purpose of developing an automatic and highly accurate system for detection of ACL deficiency, this study investigated the classification capability of different dynamical features extracted from gait kinematic and kinetic signals when evaluating their impact on different classification models. A general feature extraction framework was proposed and various dynamical features, such as recurrence rate, determinism and entropy from the recurrence quantification analysis, fuzzy entropy, Teager-Kaiser energy feature and statistical analysis, were included. Different classification models, including support vector machine (SVM), K-nearest neighbor (KNN), naive Bayes (NB) classifier, decision tree (DT) classifier and ensemble learning based Adaboost (ELA) classifier, derived for discriminant analysis of multiple dynamical gait features were evaluated for a comparative study. The effectiveness of this strategy was verified using a dataset of knee, hip and ankle kinematic and kinetic waveforms from 43 patients with unilateral ACL deficiency. When evaluated with 2-fold, 10-fold and leave-one-out cross-validation styles, the highest classification accuracy for discriminating between groups of ACL deficient and contralateral ACL intact knees was reported to be 91.22 $$\%$$ % , 95.12$$\%$$ % and 96.34$$\%$$ % , respectively,by using the SVM classifier and the optimal feature set. For other four classifiers, KNN achieved the accuracy of 78.05$$\%$$ % , 85.37$$\%$$ % and 87.80$$\%$$ % , respectively. NB achieved the accuracy of 57.56$$\%$$ % , 60.98$$\%$$ % and 61.22$$\%$$ % , respectively. DT achieved the accuracy of 77.56$$\%$$ % , 80.49$$\%$$ % and 83.66$$\%$$ % , respectively. ELA achieved the accuracy of 73.66$$\%$$ % , 78.05$$\%$$ % and 79.27$$\%$$ % , respectively. Compared with other state-of-the-art methods, the results demonstrate superior performance and support the validity of the proposed method.

Manual Lachman Test Underestimates Tibial Translation Compared to Standardized Generated Force: A Biomechanical Study of Cadaveric Anterior Cruciate Ligament Repair Using Internal Brace (205)

Objectives: With an increasing incidence over time, anterior cruciate ligament (ACL) rupture can produce functionally limiting knee instability that requires operative treatment to address the instability as well as prevent the development of osteoarthritis. Anteroposterior instability forms the basis of the most sensitive physical exam maneuver to examine the ACL for rupture, the Lachman test. This investigation has two goals: to assess the precision and accuracy of the manual Lachman test by comparing anterior tibial translation generated to that of a standardized applied force Lachman test, and to compare the anteroposterior stability of cadaver specimens with simulated ACL ruptures which were repaired with and without internal suture tape augmentation. Methods: The tibial plateau in ten cadaveric knees was divided into medial, middle and lateral reference points, which were monitored digitally during testing using Optotrak. Intact knees were subjected to both manual Lachman tests at 30 degrees of flexion and standardized 150N force Lachman tests utilizing a hook and pulley system with force transducer. The ACL’s of all specimens were then transected, and the ACL deficient knees were subjected to both the manual and standardized Lachman tests. The specimens were then randomly divided into two groups to be repaired with or without internal suture tape augmentation, and subsequently underwent 100, 250, and 500 cycles from 90 degrees of flexion through full extension with a frequency of .1Hz, after which the same standardized Lachman test was performed on all repaired specimens. Comparison of variances were made using a two-sample F-Test for variances. Comparison of means were made using a two sample t-test assuming unequal variances and one-way ANOVA. Significance was set at p </= 0.05. Results: Comparing ACL intact to ACL deficient states, the standardized Lachman test detected a significant difference in tibial translation at the medial (14.1mm versus 20.3mm, p=.031), middle (17.5mm versus 24.6mm, p=.011), and lateral (14.8mm versus 21.5mm, p=.050) reference points while the manual Lachman test only detected a significant difference at the middle (12.6mm versus 19.8mm, p=.026) reference point. In ACL deficient knees, there was a statistically significant underestimation in tibial translation when using the manual method as compared to the standardized method (17.4mm versus 22.3mm, p=0.046). When comparing the precision of the testing methods, F-Tests for variance did not yield significant differences between variances in measured tibial translation for the manual and standardized Lachman tests in either intact or ACL deficient knees. There were no statistically significant differences in measured tibial translation between specimens with intact ACL, ACL repair, and ACL repair with internal brace at the medial (14.1mm versus 13.7mm versus 16.45mm, p=0.462), middle (17.5mm versus 16.6mm versus 18.3mm, p=0.767), lateral (14.8mm versus 15.9mm versus 15.9mm, p=0.934), or call (15.5mm versus 15.2mm versus 16.9mm, p=0.748) reference points. Conclusions: Tibial translation generated by Lachman tests performed manually may be underestimated when compared to Lachman tests performed with a standard force, lending to difficulty detecting the ACL deficient state. ACL repair both with and without internal brace augmentation allowed for a return to pre-rupture levels of anteroposterior stability.

Outcomes of Combined Unicompartmental Knee Replacement and Anterior Cruciate Ligament Reconstruction: A Systematic Review

Background The incidence of osteoarthritis of the medial compartment after ACL injury has been quoted to range from 33% to 70%. Medial osteoarthritis in ACL deficient knee is a challenge. Patients are mainly young and active. First reports highlighted a higher incidence of complications, in terms of tibial loosening and higher revision rate, when UKA were performed in ACL-deficient knees. They defined ACL deficiency is a contraindication to UKA. Objectives A systematic review and meta-analysis of literature to assess functional outcomes of combined unicompartmental knee arthroplasty with ACL reconstruction and revision rate. Data Sources The following electronic databases were searched up to 2019: PubMed, Google Scholar search engine, JBJS {Journal of bone and joint Surgery}, Cochrane database of systematic reviews, EMBASE and Science Direct. Results A total of 10 studies met the inclusion criteria encompassing 218 patients who were treated with simultaneous ACL reconstruction and unicompartmental knee arthroplasty. The mean age was 49.5 years (range from 36 to 71) with a mean follow-up of 49.3 months (range from 9 to 258). There was an improvement in mean Oxford Score from 29 to 42.5. The mean knee society score improved from 88.3 to 159. Complications reported included tibial inlay dislocation (n = 3), conversion to a total knee arthroplasty (n = 2), infection requiring two-stage revision (n = 2), stiffness requiring manipulation under anaesthesia (n = 1). Average revision rate was 1.8%. Conclusion Literature has strong evidence to support that combined UKA and ACL reconstruction show good functional outcomes and less revision rate. It is a valid treatment option for MOA more in young age group in whom MOA secondary to ACL tear and intact other knee compartments. there is no clinical trial or study suggest that UKA and ACL reconstruction is superior to UKA with tibial slope change or using fixed bearing prosthesis for MOA in ACL deficient knee with instability.

Longitudinal Changes of Patellar Alignment Before and After Anterior Cruciate Ligament Reconstruction With Hamstring Autograft

Background: Evidence has suggested that after anterior cruciate ligament (ACL) reconstruction (ACLR), individuals exhibit patellar malalignment; however, it is unknown if patellar alignment changes over time. Purpose: To examine the longitudinal changes in patellar alignment before, 6 months after, and 3 years after ACLR and to compare these variations, if present, with patellar alignment in controls. Study Design: Cohort study; Level of evidence, 2. Methods: A total of 35 patients who had ACLR using hamstring autograft (19 male; age, 29.9 ± 7.7 years; body mass index, 23.8 ± 2.5) and 20 controls (13 male; age, 30.4 ± 4.8 years; body mass index, 24.3 ± 2.7) participated. All patients underwent bilateral knee magnetic resonance imaging with the knee in extension and 30° of flexion using sagittal T2-weighted, fat-saturated fast spin-echo images to assess patellar alignment in 6 degrees of freedom: anterior-posterior, medial-lateral, and superior-inferior translations; flexion; tilt; and spin. Patients who had ACLR were assessed before (ACL-deficient state) and 6 months and 3 years after ACLR, while control participants were only assessed once. One-way repeated-measures analysis of variance was used to examine patellar alignment across time in the ACLR group. If changes were present, the independent t test was carried out to examine the differences between ACLR knees and control knees. Results: In the knee-extended condition, greater patellar lateral displacement was observed at the ACL-deficient state and 6 months after ACLR compared with 3 years after ACLR within the ACLR group ( P < .001 and P = .043, respectively) and compared with the control group ( P = .001 and P = .039, respectively). Greater patellar lateral tilt was observed at the ACL-deficient state compared with 3 years after ACLR ( P = .003) and compared with the control group ( P = .018). In the knee-flexed condition, greater anterior displacement was observed at the ACL-deficient state compared with 3 years after ACLR ( P = .001) and compared with the control group ( P = .011), and it was also observed at 6 months after ACLR compared with the control group ( P = .019). Less lateral spin was observed at the ACL-deficient state ( P = .042) and 6 months after ACLR ( P = .004) compared with 3 years after ACLR and compared with the control group ( P = .004 for both). No patellar alignment measures in the ACLR knees at 3 years were significantly different from those of the controls. Conclusion: Patellar malalignment in individuals before and after ACLR subjected to longitudinal changes, and the differences in alignment between ACLR and controls diminished over 3 years.

Patient-acceptable symptom state for reporting outcomes following unicompartmental knee arthroplasty

Aims The patient-acceptable symptom state (PASS) is a level of wellbeing, which is measured by the patient. The aim of this study was to determine if the proportion of patients who achieved an acceptable level of function (PASS) after medial unicompartmental knee arthroplasty (UKA) was different based on the status of the anterior cruciate ligament (ACL) at the time of surgery. Methods A total of 114 patients who underwent UKA for isolated medial osteoarthritis (OA) of the knee were included in the study. Their mean age was 65 years (SD 10). No patient underwent a bilateral procedure. Those who had undergone ACL reconstruction during the previous five years were excluded. The Knee injury Osteoarthritis Outcome Score Activities of Daily Living (KOOS ADL) function score was used as the primary outcome measure with a PASS of 87.5, as described for total knee arthroplasty (TKA). Patients completed all other KOOS subscales, Lysholm score, the Western Ontario and McMaster Universities Osteoarthritis Index, and the Veterans Rand 12-item health survey score. Failure was defined as conversion to TKA. Results Survivorship at ten years was 97% in both the ACL-deficient and ACL-intact groups. The mean survival was 16.1 years (95% confidence interval (CI) 15.3 to 16.8) for the ACL-deficient group and 15.6 years (95% CI 14.8 to 16.361) for the ACL-intact group (p = 0.878). At a mean of nine years (SD 3.5) in the ACL-deficient group, 32 patients (87%) reached the PASS for the KOOS ADL. In the ACL-intact group, at a mean of 8.6 years (SD 3) follow-up, 63 patients (85%) reached PASS for the KOOS ADL. There was no significant difference in the percentage of patients who reached PASS for all KOOS subscales and Lysholm between the two groups. Conclusion PASS was achieved in 85% of all UKAs for KOOS ADL, similar to reports for TKA. Fixed-bearing, medial, non-robotically-assisted UKA resulted in 97% survival at ten years in both the ACL-deficient and ACL-intact groups. There was no significant difference in all outcomes between the two groups. Understanding PASS will allow better communication between surgeons and patients to improve the surgical management of patients with single compartment OA of the knee. This study provides mid- to long-term data supporting the use of PASS to document outcomes following UKA. PASS was met in more than 85% of patients with no differences between ACL-deficient and ACL-intact knees at a mean follow-up of nine years. Cite this article: Bone Joint J 2021;103-B(8):1367–1372.

Medial and Lateral Posterior Tibial Slope Are Independent Risk Factors for Noncontact ACL Injury in Both Men and Women

Background: Higher posterior tibial slope (PTS) is a risk factor for anterior cruciate ligament (ACL) injury in men and women. The individual contribution of the lateral (LPTS) and medial (MPTS) slope has not yet been investigated. Purpose: To determine whether either the LPTS or the MPTS is an independent risk factor for ACL injury, and to determine sex-specific differences between patients with ACL-deficient and ACL-intact knees. Study Design: Cohort study; Level of evidence, 3. Methods: We reviewed knee magnetic resonance (MR) images performed on ACL-deficient and ACL-intact knees between January 2018 and June 2020 at a single institution. Inclusion criteria were isolated ACL injury and noncontact mechanism (ACL-deficient group) and nonspecific knee pain and no history of injury (ACL-intact group). Exclusion criteria for both groups were the following: previous knee surgery; meniscal, collateral ligament, posterior cruciate ligament, or multiligamentous injuries; radiological evidence of osteoarthritis; and chondral damage on the tibia. The MR images were used to establish the posterior bony slope at 25%, 50%, and 75% from the medial and/or lateral border of the tibial plateau with respect to the proximal tibial anatomic axis. One-way analysis of variance (ANOVA) was used to determine differences in PTS at the 25%, 50%, and 75% distances for the medial and lateral tibial plateau between the groups and between the sexes. Results: Overall, 325 images were included (mean age, 36.1 ± 11.1 years; 142 ACL-deficient images [82 men and 60 women]; 183 ACL-intact images [112 men and 71 women]). MPTS and LPTS were significantly higher at 25%, 50%, and 75% in the ACL-deficient group (range, –2.7° to –5.7°) compared with the ACL-intact group (range, –2.1° to 1.5°; P = .00001). Similarly, MPTS and LPTS were significantly different in men versus women ( P = .00001). ANOVA revealed that there were no significant differences in PTS between men and women for all measures (MPTS, LPTS, ACL-deficient, ACL-intact; P = .68). Conclusion: The study results demonstrated that higher MPTS and LPTS is a potential risk factor for ACL injury in both men and women. However, despite being highly statistically significant, the differences between groups and sexes were small and may not be clinically relevant.

The effect of Tibial Tuberosity Advancement on Patellar tendon force in Canine Stifle Joint under Caudal Femoral Drawer

The Tibial Tuberosity Advancement (TTA) surgical technique is used in veterinary surgery to limit cranial tibial translation during canine gait, lengthening the lever arm of the quadriceps in Anterior Cruciate Ligament-deficient (ACL-deficient) stifle joints. It is know that after TTA, the patellofemoral pressure decreases, but the Patellar Tendon (PT) behavior has not been observed experimentally yet. This study measures the PT force under caudal femoral drawer at knee flexion angles from 135° to 90° in intact and pathological knee to asses the effect of TTA on the tendon. Five fresh cadaveric adult canine stifle joint were tested in an apparatus in which muscle forces of the canine hind limb were simulated. Each knee was tested in three different conditions: intact, ACL-deficient and with TTA. PT force was measured using a electrical transducer. The greater the joint flexion angles, the greater the PT force. The knee average force of the five specimens in 90º flexion were 28.4 ± 3.2 Newtons (N) for the intact, 28.2 ± 3.4 N for the ACL-deficient and 24.9 ± 2 N for the TTA knee, which decreased compared to the healthy knee, so TTA generates a loosening of the PT force. The PT force showed a fast rate of change in the operated knee because of a shift in the pattern of knee flexion, so the biomechanics of the entire joint could be influenced by the TTA technique.