ACL-reconstructed Knees Research Articles

Persistent underloading of patellofemoral joint following hamstring autograft ACL reconstruction is associated with cartilage health

To determine the longitudinal changes of patellofemoral joint (PFJ) contact pressure following anterior cruciate ligament reconstruction (ACLR). To identify the associations between PFJ contact pressure and cartilage health. Forty-nine subjects with hamstring autograft ACLR (27 males; age 28.8 [standard deviation, 8.3] years) and 19 controls (12 males; 30.7 [4.6] years) participated. A sagittal plane musculoskeletal model was used to estimate PFJ contact pressure. A combined T1ρ/T2 magnetic resonance sequence was obtained. Assessments were performed preoperatively, at 6 months, 1, 2, and 3 years postoperatively in ACLR subjects and once for controls. Repeated Analysis of Variance (ANOVA) was used to compare peak PFJ contact pressure between ACLR and contralateral knees, and t-tests to compare with control knees. Statistical parametric mapping was used to evaluate the associations between PFJ contact pressure and cartilage relaxation concurrently and longitudinally. No changes in peak PFJ contact pressure were found within ACLR knees over 3 years (preoperative to 3 years, 0.36 [CI, -0.08, 0.81] MPa), but decreased over time in the contralateral knees (0.75 [0.32, 1.18] MPa). When compared to the controls, ACLR knees exhibited lower PFJ contact pressure at all time points (at baseline, -0.64 [-1.25, -0.03] MPa). Within ACLR knees, lower PFJ contact pressure at 6 months was associated with elevated T2 times (r=-0.47 to -0.49, p=0.021-0.025). Underloading of the PFJ following ACLR persists for up to 3 years and has concurrent and future consequences in cartilage health. The non-surgical knees exhibited normal contact pressure initially but decreased over time achieving limb symmetry.

Biomechanical Comparison of Anterior Cruciate Ligament Reconstruction Using a Single-Bundle Round or Ribbon-like Hamstring Tendon Graft

Background: Persistent instability of the knee is reported in up to 30% of patients after anterior cruciate ligament (ACL) reconstruction. Based on anatomic findings showing that ACL is a flat ribbon-like structure that twists during knee flexion, a new surgical ACL reconstruction technique using a ribbon-like graft has been developed. However the effect of this surgical technique on knee kinematics has not yet been evaluated. Purpose: To compare the anteroposterior and rotational stability of the knee after ACL reconstruction using single-bundle (SB) round and ribbon-like grafts in anterolateral-intact/deficient knees. Study Design: Controlled laboratory study. Methods: Twelve human fresh-frozen cadaveric knees were tested with a 6 degrees of freedom robotic system. Internal rotation and anterior translation of the knee were recorded from 0° to 90° of flexion. A full kinematic assessment was performed in each of the following conditions: (1) intact knee, (2) after sectioning of the ACL, (3) after ACL reconstruction using a SB hamstring tendon graft in a round configuration and a ribbon-like configuration, and (4) after sectioning of the anterolateral structures. One-way analysis of variance and post hoc Tukey tests were used for statistical analyses. Results: When compared with the intact knee, the ACL-deficient knee demonstrated a mean ± SD increase in anterior translation and internal rotation of 6.3 ± 2.5 mm (P < .01) and 5.8°± 2.3° (P < .01), respectively. After ACL reconstruction using a SB ribbon-like graft, the mean difference in anterior translation and internal rotation as compared with the intact knee was −0.1 ± 1.5 mm (P = .842) and 0.0°± 1.1° (P = .999). These differences from the intact knee were also not significant after ACL reconstruction using a round graft (−0.1 ± 1.3 mm, P = .999; −0.5°± 1.5°, P = .401). In the ACL-reconstructed knee using either a ribbon-like or round graft, sectioning of the anterolateral structures did not induce a significant increase of anterior translation and internal rotation of the knee. Conclusion: ACL reconstruction using a SB ribbon-like or round graft restored the kinematics of the intact knee at time zero. Secondary sectioning of the anterolateral structures in the ACL-reconstructed knee using both types of graft did not significantly affect the anterior translation and internal rotation of the knee. Clinical Relevance: This is the first biomechanical study on the new ACL reconstruction technique using a ribbon-like graft.

High-demand tasks show that ACL reconstruction is not the only factor in controlling range of tibial rotation: a preliminary investigation

BackgroundExcessive range of tibial rotation (rTR) may be a reason why athletes cannot return to sports after ACL reconstruction (ACLR). After ACLR, rTR is smaller in reconstructed knees compared to contralateral knees when measured during low-to-moderate-demand tasks. This may not be representative of the amount of rotational laxity during sports activities. The purpose of this study is to determine whether rTR is increased after ACL injury compared to the contralateral knee and whether it returns to normal after ACLR when assessed during high-demand hoptests, with the contralateral knee as a reference.MethodsTen ACL injured subjects were tested within three months after injury and one year after reconstruction. Kinematic motion analysis was conducted, analysing both knees. Subjects performed a level-walking task, a single-leg hop for distance and a side jump. A paired t-test was used to detect a difference between mean kinematic variables before and after ACL reconstruction, and between the ACL-affected knees and contralateral knees before and after reconstruction.ResultsRTR was greater during high-demand tasks compared to low-demand tasks. Pre-operative, rTR was smaller in the ACL-deficient knees compared to the contralateral knees during all tests. After ACLR, a greater rTR was seen in ACL-reconstructed knees compared to pre-operative, but a smaller rTR compared to the contralateral knees, even during high-demand tasks.ConclusionThe smaller rTR, compared to the contralateral knee, seen after a subacute ACL tear may be attributed to altered landing technique, neuromuscular adaptation and fear of re-injury. The continued reduction in rTR one year after ACLR may be a combination of this neuromuscular adaptation and the biomechanical impact of the reconstruction.Trial registration: The trial was registered in the Dutch Trial Register (NTR: www.trialregister.nl, registration ID NL7686).

The effects of lateral meniscus posterior root tears or repair with anterior cruciate ligament reconstruction on the pressure of the patellofemoral joint: A biomechanical evaluation.

The aim of our study was to evaluate the effect of tear and repair of the lateral meniscal posterior root (LMPR) on the patellofemoral contact pressure of the knee after anterior cruciate ligament (ACL) reconstructed. This was a descriptive study. Six fresh-frozen cadaveric knees collected by The Third Hospital of Hebei Medical University from January 2019 and January 2022 were placed on a customized testing rig. Patellofemoral contact pressures were measured at 30°, 60°, and 90° of flexion using pressure-sensitive film inserted between the patella and trochlea. The following knee states were tested: ACL reconstruction and intact lateral meniscus, ACL reconstruction, and LMPR tear, and ACL reconstruction and LMPR repair. Pressure measurements were recorded for each state. In the ACL-reconstructed knee, a tear of the LMPR increased patellofemoral contact pressure at 30° of knee flexion. The repair of the posterior root by transosseous pull-out suture reduced the patellofemoral contact pressure as the status of intact lateral meniscal posterior root at 30° of knee flexion. There was no statistical difference between ACL reconstruction with the intact meniscal root and with the meniscal root tear and with the meniscal root repair at 60° and 90° of knee flexion. The posterior root tear and repair of the lateral meniscus could have an influence on patellofemoral contact stress of the knee after ACL reconstruction at 30° of knee flexion.

Pain Early After Anterior Cruciate Ligament Reconstruction is Associated With 6-Month Loading Mechanics During Running.

Anterior cruciate ligament reconstruction (ACLR) results in persistent altered knee biomechanics, but contributing factors such as pain or patient function, leading to the altered loading, are unknown. Individuals with worse self-reported pain after ACLR would have poorer biomechanics during running, and poor loading mechanics would be present in the ACLR limb compared with contralateral and control limbs. Cohort pilot study. Level 3. A total of 20 patients after ACLR (age, 18.4 ± 2.7 years; height, 1.7 ± 0.1 m; mass, 84.2 ± 19.4 kg) completed visual analog scale and Knee Injury and Osteoarthritis Outcomes Score (KOOS) at 1 and 6 months postsurgery. At 6 months postsurgery, patients underwent biomechanical testing during running. A total of 20 control individuals also completed running biomechanical analyses. Associations between patient outcomes and biomechanics were conducted, and differences in running biomechanics between groups were analyzed. KOOS pain score 1 month after surgery was associated with peak ACLR knee abduction moment (R2 = 0.35;P = 0.01). At 6-months, KOOS sport score was related to peak abduction moment in the ACLR limb (R2 = 0.23; P = 0.05). For change scores, the improvement in pain scores related to ACLR limb peak knee abduction moment (R2 = 0.55; P = 0.001). The ACLR limb had lower knee excursion, extension moments, and ground-reaction forces compared with the uninvolved and control limb. The uninvolved limb also had higher ground-reaction forces compared with the ACLR limb and control limb. These results suggest that patient-reported outcomes 1 and 6 months after surgery are associated with running mechanics 6 months after ACLR. Further, the underloading present in the ACLR limb and overloading in the uninvolved limb indicates greater need for running rehabilitation after ACLR. Understanding pain and how it may be linked to movement dysfunction is important for improving long-term outcomes.

Range of Motion, Strength, and Function After ACL Reconstruction Using a Contralateral Patellar Tendon Graft.

Regaining preinjury levels of activity and progressing rehabilitation factors after anterior cruciate ligament (ACL) reconstruction have shown mixed results. To evaluate the timing and rate of return for knee range of motion (ROM), stability, strength, and subjective scores after ACL reconstruction with contralateral patellar tendon graft (PTG). Case series; Level of evidence, 4. Included were 2148 patients (1238 male patients, 910 female patients) who underwent primary ACL reconstruction with a contralateral PTG between 1995 and 2017 and had complete objective data through 3 months of follow-up. All patients participated in a rehabilitation program specific to goals for each knee. Patients were evaluated objectively with goniometric measurement of ROM, isokinetic quadriceps strength testing, and laxity with a KT-2000 arthrometer. Subjective data were collected at 2 and 5 years. Normal extension on the reconstructed knee was attained for 95% of patients at 1 week postoperatively; normal flexion on the reconstructed knee was reached by 77% of patients by 3 months. At 3 months postoperatively, mean limb symmetry index strength was 104%, and the strength on the ACL-reconstructed and graft-donor knees was 87% and 86% of their respective preoperative strength. Mean manual maximum side-to-side difference in laxity was 2.0 mm at 1 month. Most patients (90%) returned to level 8 sports or higher and did so at an average of 5.7 months. Mean International Knee Documentation Committee scores for the ACL-reconstructed and graft-donor knees were 89 and 91 at 2 years (n = 1015 patients) and 84 and 90 at 5 years (n = 1275 patients), respectively. Mean Cincinnati Knee Rating Scale scores for the ACL-reconstructed and graft-donor knees were 92 and 96 at 2 years (n = 1184) and 88 and 94 at 5 years (n = 1236), respectively. For patients who underwent ACL reconstruction with a contralateral PTG, postoperative ROM and strength were restored quickly by splitting the rehabilitation into different goals between the two knees. Using a contralateral PTG, this structured rehabilitation plan can lead to a relatively quick return to sport and good subjective long-term outcomes.

Detecting side-to-side differences of lower limb biomechanics during single-legged forward landing after anterior cruciate ligament reconstruction

BackgroundMotion analysis can be used to evaluate functional recovery after anterior cruciate ligament (ACL) reconstruction; however, the biomechanics parameters of the lower limb that are specifically altered in ACL-reconstructed knees compared to the contralateral side are not well understood. This retrospective study aimed to compare side-to-side differences in lower limb biomechanics during the first 100 milliseconds (ms) after initial contact in a single-leg forward landing task. MethodsUsing three-dimensional motion analysis, lower joint kinematic and kinetic variables were measured 8–10 months postoperatively in 22 patients who had undergone ACL reconstruction. We determined side-to-side differences in lower limb biomechanics over the 100-ms timeframe after landing, and receiver operating characteristic (ROC) curve analyses were performed to calculate the area under the curve (AUC) for parameters showing significant side-to-side differences. ResultsDuring the 100-ms timeframe after landing, 58 kinematic and kinetic items showed significant side-to-side differences. Side-to-side differences in lower limb biomechanics over the 40-ms timeframe after landing existed. The ROC curve analysis identified 11 items with AUC values ≥ 0.70, including hip flexion, abduction moment, and knee joint power, and their AUC values were not significantly different. ConclusionHip flexion/abduction moment and knee power after GRF max could be used as outcomes for assessing functional recovery in patients who have undergone ACL reconstruction.

Knee Kinematic Patterns and Early Cartilage Lesion Characteristics in Patients with Anterior Cruciate Ligament Reconstruction.

Specific knee kinematic alterations have been theorized to correlate with the progression of cartilage degeneration, and therefore, post-traumatic osteoarthritis in patients with anterior cruciate ligament reconstruction (ACLR). However, how specific knee kinematic alterations contribute to knee joint cartilage degenerations remains to be unclear. To solve this problem, we hypothesized that there are specific cartilage-degenerating kinematic gait patterns that could be supported by the specific areas of cartilage lesions in ACLR knees. Thirty patients with unilateral ACLR knees and 30 healthy controls were recruited for the study. The kinematic differences between the ACLR knees and the healthy control knees during the stance phase were calculated to identify the kinematic patterns. Cartilage lesion distribution characteristics were acquired for patients with ACLR knees to validate the kinematic patterns using magnetic resonance images. Two kinematic patterns were modeled, i.e., sagittal (increased flexion angle and posterior tibial translation) and coronal (increased lateral tibial translation and abduction angle) kinematic patterns. For the sagittal pattern, the cartilage lesion distributions showed that there were more cartilage lesions (CLs) in the superoposterior regions than the posterior regions in the femoral condyles (p = 0.001), and more CLs in the posterior regions than the middle regions in the tibial plateau (p < 0.001). For the coronal pattern, the cartilage lesion distributions showed that there were more CLs in the lateral compartments near the tibial spine than the medial compartments near the tibial spine (tibial sides, p = 0.005 and femoral sides, p = 0.290). To conclude, the cartilage degeneration distribution evidence largely supports that the two kinematic patterns may contribute to cartilage degeneration in ACLR knees. These findings may provide a potential strategy of delaying early cartilage degeneration in ACLR knees by using motion (kinematic) pattern modification or training. However, investigations should be conducted on the actual effects of this potential strategy.

Arthroscopic centralization reduces extrusion of the medial meniscus with posterior root defect in the ACL reconstructed knee.

The purpose of this study was to evaluate the effects of arthroscopic meniscal centralization reinforcement for a medial meniscus (MM) posterior root defect on knee kinematics and meniscal extrusion in the anterior cruciate ligament reconstructed (ACLR) knee. The hypothesis was that the medial meniscus centralization would reduce extrusion and anterior laxity in ACLR knee with a medical meniscal defect. Fourteen fresh-frozen human cadaveric knees were tested using a six-degrees-of-freedom robotic system under the following loading conditions: (a) an 89.0N anterior tibial load, (b) 5.0 Nm internal and external rotational torques, (c) a 10.0Nm valgus and varus loadings, and (d) a combined 7.0Nm valgus moment and then a 5.0Nm internal rotation torque as a static simulated pivot shift. The tested knee states included: (1) anatomic single-bundle cruciate ligament reconstruction with intact medial meniscus (MM Intact), (2) anatomic single-bundle cruciate ligament reconstruction with medial meniscus posterior root defect (MM Defect), (3) Anatomic single-bundle cruciate ligament reconstruction with medial meniscus arthroscopic centralization (MM Centralization). Medial meniscus arthroscopic centralization was performed using 1.4mm anchors with #2 suture. The MM extrusion (MME) was measured using ultrasound under unloaded and varus loading conditions at 0° and 30° of flexion. Anterior tibial translation (ATT) increased significantly with MM posterior root defect compared to MM intact at all flexion angles. With MM centralization, ATT was not significantly different from the intact meniscus at 15° and 30° of flexion. Meniscus extrusion increased significantly with the root defect compared to intact meniscus and decreased significantly with meniscal centralization compared to the root defect at both flexion angles. In ACL reconstruction, cases involving irreparable medial meniscal posterior root tears, applying arthroscopic centralization for avoiding the meniscal extrusion should be considered. Clinically, in ACL reconstruction cases with irreparable medial meniscal posterior root tears, applying arthroscopic meniscal centralization for avoiding the meniscal extrusion should be considered. Meniscal centralization decreases the extrusion of the MM and offers improvements in knee laxity.

Long-term Natural History of Unrepaired Stable Ramp Lesions: A Retrospective Analysis of 28 Patients With a Minimum Follow-up of 20 Years

Background: There is a lack of consensus about whether stable ramp lesions associated with anterior cruciate ligament (ACL) injuries need to be repaired. Purpose/Hypothesis: The purpose of this study was to evaluate how many stable ramp lesions left in situ during ACL reconstruction (ACLR) have subsequently failed after >20 years of follow-up. We hypothesized that ACL-reconstructed knees with ramp lesions left in situ without repair have a high risk of meniscal failure over the long term. Study Design: Case series; Level of evidence, 4. Methods: All patients who underwent arthroscopic ACLR by a single experienced surgeon between January 1998 and December 2000 were evaluated retrospectively. Included were all cases of longitudinal tears in the meniscocapsular junction or the red zone of the posterior horn of the medial meniscus that were left in situ and identified through the anterior portals. Successful anterior probing confirmed a meniscal tear of the posterior segment. A lesion was considered stable if it was ≤2 cm and did not extend beyond the lower pole of the femoral condyle. The following data were collected preoperatively and at the last follow-up: demographics, time to surgery, side-to-side laxity, pivot shift, Lysholm score, subjective International Knee Documentation Committee score, Knee injury and Osteoarthritis Outcome Score, Tegner activity scale, and meniscal failure rate. We defined 2 groups based on our findings: medial meniscal failure versus no medial meniscal failure. Results: A total of 716 knees underwent primary ACLR during this period. The 39 (5.4%) stable unrepaired ramp lesions identified were included in the case series. Mean ± standard deviation follow-up was 262.1 ± 10.5 months. Eleven patients (28%) were lost to follow-up. Of the remaining patients, 8 (28.6%) had a medial meniscal failure, of which 6 (21.4%) were bucket-handle tears. The average time elapsed before complications was 87.8 ± 52 months (range, 6-156 months). The medial meniscal survival rate was 93% at 5 years, 75% at 10 years, and 71% at 15 and 20 years. The failure event mainly happened between 96 and 120 months (8 and 10 years) after ACLR. No risk factors for failure were found, but some trends appeared, such as older age, higher body mass index, and preoperative rotational instability. All postoperative scores were significantly improved at the last follow-up (P < .0001); 16 patients (57%) returned to their sport of choice. Conclusion: With nearly one-third of patients developing meniscal complications, including a large share of bucket-handle tears and mostly occurring 8 years after the ACLR, it may not be wise to leave stable ramp lesions unrepaired.

Relooking at double-bundle versus single-bundle anterior cruciate ligament reconstruction: A biomechanical model to evaluate which can confer better rotatory stability

BackgroundTo treat anterior cruciate ligament (ACL) injuries, double-bundle ACL reconstruction has been proposed as a more anatomical approach relative to single-bundle reconstruction. However, controversy remains over which technique is superior in addressing knee instability, particularly rotational laxity. We hypothesize that double-bundle reconstruction better restores rotational knee laxity, while both methods are similar in restoring anterior knee laxity, to intact knee levels. MethodsA controlled laboratory study. Eight cadaveric knees were tested accordingly: (1) static anterior laxity testing under 150 N-anterior tibial loading at 20°, 60° and 90° knee flexion using a material testing machine, followed by (2) dynamic simulated pivot-shift with knee-specific loading involving iliotibial band forces, valgus and internal rotation torques, while the knee was brought from extension to 90° flexion on a 6°-of-freedom custom-designed rig. Tibiofemoral kinematics were recorded using an electromagnetic tracking system for the ACL-intact, ACL-deficient, single-bundle and double-bundle ACL-reconstructed knee conditions. FindingsDouble-bundle reconstruction reduced internal rotation under pivot-shift to levels not significantly different from ACL-intact conditions (P > .173), unlike single-bundle that remained significantly higher at 10–40° flexion (P < .05). For anterior laxity, there was no significant difference between double-bundle, single-bundle, and ACL-intact conditions under static testing (P > .175) or pivot-shift (P = .219). The maximum extent of knee envelope laxity was significantly reduced for double-bundle relative to single-bundle, particularly for the rotatory component (P = .012). InterpretationDouble-bundle was biomechanically superior to single-bundle in addressing envelope of rotation, while both techniques restored anterior knee laxity to ACL-intact levels.

Combined Anterior Cruciate Ligament and Lateral Extra-Articular Reconstruction

AbstractThe anterolateral complex (ALC) of the knee has received renewed research interest because of the potential role of this anatomic region in anterior cruciate ligament (ACL) tear biomechanics and surgical treatment outcomes. The primary structures of the ALC include the iliotibial band deep (Kaplan) fibers, the anterolateral ligament (ALL), and the capsulo-osseous layer (COL) of the iliotibial band, although there remains disagreement on the precise anatomic locations and biomechanical relevance of these structures. Sectioning studies in the ACL-deficient knee have revealed a contribution of the ALC in restraining tibial internal rotation and anterior translation. Biomechanical studies have revealed a potential role for lateral extra-articular reconstruction as an augmentation to ACL reconstruction in knees with combined ACL and ALC sectioning. Clinical studies have reported a reduced ACL reconstruction failure rate with both ALL reconstruction and lateral extra-articular tenodesis procedures.

Traditional and Additional Isokinetic Knee Strength Assessments of Athletes; Post-Operative Results of Hamstring Autograft ACL Reconstruction.

Background and Objectives: Anterior cruciate ligament (ACL) injuries are common injuries in athletes, and, accordingly, ACL reconstruction (ACLR) is one of the most common orthopedic surgical procedures performed on athletes. This study aims to compare the 6-month post-operative isokinetic knee strength evaluations of the semitendinous/gracilis (ST/G) ACLR technique performed on healthy (HK) and ACLR knees of athletes. Materials and Methods: A retrospective cohort of 29 athletes from various sports branches who underwent ST/G ACLR technique by the same surgeon were evaluated. The isokinetic knee extension (Ex) and flexion (Flx) strength of the patients on the HK and ACLR sides were evaluated with a series consisting of three different angular velocities (60, 180, and 240°/s). In addition to the traditional evaluations of peak torque (PT) and hamstring/quadriceps (H/Q) parameters, the findings were also evaluated with additional parameters such as the joint angle at peak torque (JAPT), time to peak torque (TPT), and reciprocal delay (RD). Results: There was a significant improvement in the mean Lysholm, Tegner, and IKDC scores after surgery compared with preoperative levels (p < 0.05). As for the isokinetic PT values, there were significant differences in favor of HK in the 60°/s Flx, 180°, and 240°/s Ex phases (p < 0.05). In addition, there was a significant difference in the 60° and 180°/s Flx phases in RD (p < 0.05). In H/Q ratio, TPT, and JAPT values, no significant difference was observed between HK and ACLR at all angular velocities. Conclusions: The findings showed that the ST/G 6-month post-operative isokinetic knee strength in athletes produced high results in HK, and, when evaluated in terms of returning to sports, the H/Q ratios on the ACLR side were sufficient to make the decision to return to sports. It was found that the ACLR side was slower than the HK side in the reciprocal transitions, particularly in the Flx phase. We believe that this results from the deformation of the hamstring muscle after reconstruction of the ST/G ACLR side.

Kinematic Analysis of Lateral Meniscal Oblique Radial Tears in Anterior Cruciate Ligament–Reconstructed Knees: Untreated Versus Repair Versus Partial Meniscectomy

Background: Lateral meniscal oblique radial tears (LMORTs) affect joint and meniscal stability in anterior cruciate ligament (ACL)–deficient knees. Purpose: To determine the clinically relevant kinematics associated with the most common posterior horn LMORT lesion types, types 3 (LMORT3) and 4 (LMORT4), untreated versus arthroscopic repair versus partial meniscectomy in combination with ACL reconstruction (ACLR). Study: Controlled laboratory study. Methods: Sixteen cadaveric knees underwent robotic testing for anterior drawer and pivot-shift simulations at multiple knee flexion angles in ACL-intact and ACL-deficient states, followed by sequential testing of arthroscopic ACLR, LMORT3 lesion, LMORT3 repair, and partial meniscectomy (n = 8). The same testing sequence was performed for LMORT4 lesions (n = 8). Results: ACLR restored kinematics in ACL-deficient knees to intact levels for all metrics tested. For anterior drawer, ACLR + LMORT3 tear and partial meniscectomy resulted in significantly greater anterior translation compared with ACL-intact at all angles (P < .05) and compared with ACLR at 60° and 90° (P < .014). For pivot shift, compared with ACL-intact knees, ACLR + LMORT3 tear resulted in significantly more anterior translation at 15° (P = .041); and for ACLR + partial meniscectomy, at both 0° and 15° (P < .03). ACLR + LMORT4 tear and partial meniscectomy resulted in significantly greater anterior translation for anterior drawer (P < .04) and pivot-shift testing (P < .05) compared with intact and ACLR knees at all angles tested. ACLR + LMORT3 repair and ACLR + LMORT4 repair restored kinematics to ACLR and intact levels at all angles tested. ACLR + LMORT3 tear (P < .008) and both LMORT4 tear and partial meniscectomy (P < .05) resulted in increased meniscal extrusion compared with intact and ACLR statuses at all tested angles for anterior drawer and pivot shift, while repairs restored meniscal stability to ACLR and intact levels. Conclusion: Untreated LMORT tears increased anterior translation, pivot shift, and meniscal extrusion after ACLR, while partial meniscectomy further exacerbated these detrimental effects in this cadaveric model. In contrast, arthroscopic side-to-side repair of LMORT lesions effectively restored measured knee kinematics. Clinical Relevance: LMORT lesions are common with ACL tears and adversely affect joint stability and meniscal extrusion. This study highlights the importance of repair of LMORT 3 and 4 lesions at the time of ACLR.

Paper 34: Kinematic Analysis of Lateral Meniscus Oblique Radial Tears in Anterior Cruciate Ligament Reconstructed Knees: Untreated versus Repair versus Partial Meniscectomy

Objectives:Objectives: Previous analyses have characterized the incidence of lateral meniscus oblique radial tears (LMORT) commonly seen with ACL tears, and their impact on joint and meniscus stability in the presence of ACL deficiency.Purpose:To determine the clinically relevant kinematics associated with LMORT lesions untreated versus arthroscopic repair versus partial meniscectomy in combination with anterior cruciate ligament reconstruction (ACLR).Methods:Sixteen cadaver knees underwent robotic testing for anterior drawer (AD) and pivot shift (PS) simulations at multiple knee flexion angles in intact and ACL-deficient states, followed by sequential testing of arthroscopic ACL reconstruction (ACLR), creation of a LMORT 3 lesion, LMORT 3 repair, and partial meniscectomy (PM; n=8). The same testing sequence was performed for LMORT 4 lesions (n=8). Changes (Δ) from the intact state for anterior translation, internal rotation, and valgus displacements, as well as ultrasoundographic measurements of meniscal extrusion, were measured and comparatively analyzed.Results:ACLR restored kinematics in ACL-deficient knees to intact levels for all metrics tested.For AD, ACLR + LMORT3 tear and PM resulted in significantly greater anterior translation (0.8-2.1 mm differences) compared to ACL-intact at all angles (P < 0.05) and compared to ACLR at 60o and 90o (P < 0.014). For PS, ACLR + LMORT3 tear had significantly more anterior translation (1-1.4 mm differences) at 15o than intact knees (P=0.041), and at 0o and 15o for PM (P < 0.03).ACLR + LMORT4 tear and PM resulted in significantly greater anterior translation (0.9-2.3 mm differences) for AD (P < 0.04) and PS testing (P < 0.05) compared to intact and ACLR knees at all angles tested. ACLR+LMORT 3 repair and ACLR+LMORT4 repair restored kinematics to ACLR and intact levels at all angles tested.ACLR + LMORT3 tear (P < 0.008) and both LMORT4 tear and PM (P < 0.05) resulted in increased meniscal extrusion (1.8-11 mm differences) compared to intact and ACLR statuses at all tested angles for AD and PS while repairs restored meniscus stability to ACLR and intact levels.Conclusions:Untreated LMORT 3 and 4 tears increased anterior translation, pivot shift, and meniscus extrusion even after ACLR, while partial meniscectomy further exacerbated these detrimental effects. In contrast, arthroscopic side-to-side repair of LMORT lesions effectively restored measured knee kinematics.UPLOAD-https://planion-client-files.s3.amazonaws.com/AOSSM/blobs/6bf43418-abf1-49bd-b78b-cc0c501a2da0/1/AOSSM__Images.docx UPLOAD-https://planion-client-files.s3.amazonaws.com/AOSSM/blobs/b0f0bf53-a166-4cec-bf73-176ea452b905/1/AOSSM__CHART.docx

Anterolateral Ligament Reconstruction in a Collegiate Lacrosse Athlete

A 21-year-old female lacrosse athlete with a prior left knee anterior cruciate ligament reconstruction sustained an acute, noncontact injury to the same knee during practice. Clinical examination showed adequate sagittal plane joint stability, with reduced rotational support. Radiologist’s findings following magnetic resonance imaging suggested an increased signal at the anterior cruciate ligament, presence of a subacute medial meniscus tear, and Grade II strain of the semimembranosus tendon. Surgical intervention included anterolateral ligament reconstruction and debridement. The clinical team used patient-reported outcome measures and symmetry of strength and balance to progress therapy. Although cleared for exercise, her National Collegiate Athletic Association (NCAA) eligibility expired and she never returned to sport.

Effect of Rehabilitation Training Based on Automatic Extraction Algorithm on Knee Anterior Cruciate Ligament Injury Caused by Exercise.

Objective In order to explore the effect of rehabilitation training based on automatic extraction algorithm on knee anterior cruciate ligament reconstruction under arthroscopy.Methods 81 patients with anterior cruciate ligament injury were randomly divided into observation group (42 cases) and control group (39 cases). The control group was given routine nursing, while the observation group was given rehabilitation training guidance based on automatic extraction algorithm. Lysholm score, HSS score, and range of motion of knee joint extension and flexion were used to evaluate the knee joint function before and after operation in the two groups. The quality of life of the two groups was evaluated by the concise health survey scale. The results showed that 50% of deep venous thrombosis occurred on the first day and 30% on the second day after operation. There was no significant difference in preoperative Lysholm score, HSS score, and knee flexion activity between the observation group and the control group (P > 0.01). After 1-month, 5-month, and 1-year follow-up, the effective rate of knee function recovery in the observation group was significantly better than that in the control group. Lysholm score, HSS score, and knee extension and flexion activity were significantly different from those in the control group (P < 0.01). The postoperative SF-36 quality of life score of the observation group was significantly higher than that of the control group, indicating that the quality of life of the observation group was significantly better than that of the control group. Therefore, early postoperative rehabilitation training guidance based on automatic extraction algorithm can improve local blood circulation and improve knee function and reduce pain, so as to promote the early recovery of patients.

Time-series biological responses toward decellularized bovine tendon graft and autograft for 52 consecutive weeks after rat anterior cruciate ligament reconstruction

There is an essential demand for developing biocompatible grafts for knee anterior cruciate ligament reconstruction (ACLR). This study investigated cell infiltration into decellularized bovine tendon xenografts using a rat knee ACLR model. Twelve-week-old Sprague–Dawley rats were used. At weeks 1, 2, 4, 8, 16, 26, and 52 (each period, n = 6) after ACLR, rats receiving decellularized bovine tendon (group D, n = 42) or autologous tendon (group A, n = 42) as grafts underwent peritibial bone tunnel bone mineral density (BMD), histological, and immunohistological assessments. BMD increased over time in both the groups until week 16 and then remained unchanged without exhibiting significant differences between the groups. Initially, cellularity in group D was lower than that in group A; however, by weeks 4–8, both the groups were comparable to the native anterior cruciate ligament group and cellularity remained unchanged until week 52. Initially, group A had more M1 macrophages, indicating inflammation, whereas group D had more M2 macrophages, indicating tissue regeneration. Nonetheless, the M1 and M2 macrophage counts of both the groups were comparable at most times. This study revealed the excellent recellularization and tendon–bone integration abilities of decellularized tendons using a cross-species model.

Steadiness training improves the quadriceps strength and self-reported outcomes in persistent quadriceps weakness following nine months of anterior cruciate ligament reconstruction and failed conventional physiotherapy

BackgroundPersistent quadriceps weakness may occur after anterior cruciate ligament reconstruction, limiting the strength gain. However, steadiness strengthening might change the inability to gain strength. Hence, we determined whether strength training with force steadiness and visual biofeedback can improve knee quadriceps torque, self-reported pain and knee stability in patients with persistent quadriceps weakness after knee anterior cruciate ligament reconstruction.MethodsTwenty-five patients (aged 43.7 ± 12.2 years) with persistent quadriceps weakness following knee anterior cruciate ligament reconstruction and 34-weeks of physiotherapy performed unilateral strength training for both lower limbs. Four-weeks of conventional physiotherapy at week-30 were given, confirming the inability to gain torque. Then, steadiness training (isometric knee extension with visual biofeedback) was given for 7-weeks. Knee quadriceps peak torque, strength improvement, determination of responders to the intervention, coherence of strength gain between limbs, and self-reported outcomes (pain and knee stability) were obtained. Descriptive statistics and data inference using mixed-ANOVA, McNemar test, and χ2 test were described.FindingsQuadriceps torque in the reconstructed knee improved (98.2 ± 47.2–155.2 ± 78.9 Nm; p = 0.031) for most patients (84%). Nevertheless, the torque was lower than the healthy side maintaining asymmetry (155.2 ± 78.9 vs. 209.5 ± 101.8 Nm; p = 0.026). There was high (20%) and medium coherence (80%) between limbs. Knee stability and pain improved in 72% of the patients (p < 0.001).InterpretationsSteadiness training after anterior cruciate ligament reconstruction followed 9 months of surgery and failed conventional physiotherapy, improves the persistent weakness and self-reported outcomes, but gain strength was dissimilar between limbs.

The Femoral Tunnel Drilling Angle at 45° Coronal and 45° Sagittal Provided the Lowest Peak Stress and Strain on the Bone Tunnels and Anterior Cruciate Ligament Graft.

Purpose: The aims of this study were to 1) investigate the effects of femoral drilling angle in coronal and sagittal planes on the stress and strain distribution around the femoral and tibial tunnel entrance and the stress distribution on the graft, following anterior cruciate ligament reconstruction (ACLR), 2) identify the optimal femoral drilling angle to reduce the risk of the tunnel enlargement and graft failure. Methods: A validated three-dimensional (3D) finite element model of a healthy right cadaveric knee was used to simulate an anatomic ACLR with the anteromedial (AM) portal technique. Combined loading of 103.0 N anterior tibial load, 7.5 Nm internal rotation moment, and 6.9 Nm valgus moment during normal human walking at joint flexion of 20° was applied to the ACLR knee models using different tunnel angles (30°/45°/60° and 45°/60° in the coronal and sagittal planes, respectively). The distribution of von Mises stress and strain around the tunnel entrances and the graft was calculated and compared among the different finite element ACLR models with varying femoral drilling angles. Results: With an increasing coronal obliquity drilling angle (30° to 60°), the peak stress and maximum strain on the femoral and tibial tunnel decreased from 30° to 45° and increased from 45° to 60°, respectively. With an increasing sagittal obliquity drilling angle (45° to 60°), the peak stress and the maximum strain on the bone tunnels increased. The lowest peak stress and maximum strain at the ACL tunnels were observed at 45° coronal/45° sagittal drilling angle (7.5 MPa and 7,568.3 μ-strain at the femoral tunnel entrance, and 4.0 MPa and 4,128.7 μ-strain at the tibial tunnel entrance). The lowest peak stress on the ACL graft occurred at 45° coronal/45° sagittal (27.8 MPa) drilling angle. Conclusions: The femoral tunnel drilling angle could affect both the stress and strain distribution on the femoral tunnel, tibial tunnel, and graft. A femoral tunnel drilling angle of 45° coronal/ 45° sagittal demonstrated the lowest peak stress, maximum strain on the femoral and tibial tunnel entrance, and the lowest peak stress on the ACL graft.