Chronic Anterior Cruciate Ligament Research Articles

THE RELATIONSHIP OF POSTERIOR TIBIAL SLOPE WITH CRUCIATE LIGAMENTS AND MENISCAL INJURIES BASED ON MRI– A PROSPECTIVE OBSERVATIONAL STUDY

Purpose: Various studies show that the disparities in the posterior tibial slope can make native cruciate ligaments and the menisci susceptible to tears. This study is to determine the relationship between posterior tibial slope with the anterior cruciate ligament, posterior cruciate ligament and meniscal injuries. Methods: A total of 72 subjects between 18 and 60 years having a history of traumatic knee pain were included in the study. All subjects were clinically examined, radiologically investigated, and the posterior tibial slope of the patients was calculated. Incidences of cruciate ligaments and menisci injury were identified. Results: In our study, the mean medial compartment posterior tibial slope and lateral compartment posterior tibial slope in all the Anterior Cruciate Ligament injured patients are 7.82 ± 2.56 and 10.53 ± 3.46. But in controls, it is 5.91 ± 4.49 and 6.24 ± 5.15, respectively. The differences are statistically significant ([Formula: see text]10). In cases with increased lateral Posterior Tibial Slope, more degeneration was seen in the lateral meniscus. Less Posterior Tibial Slope is associated with Posterior Cruciate Ligament tears. Conclusion: Anterior cruciate ligament is more prone to tears with a steeper posterior tibial slope. Lateral Meniscus tear is frequently associated with acute Anterior Cruciate Ligament injury and Medial Meniscus tear is predominantly associated with a chronic Anterior Cruciate Ligament injury. A decreased posterior tibial slope is more often associated with patients with a posterior cruciate ligament injury and is considered a risk factor for native Posterior Cruciate Ligament.

Effect of lyophilized exosomes derived from umbilical cord stem cells on chronic anterior cruciate ligament cell injury

BackgroundFacilitating the healing process of injured anterior cruciate ligament (ACL) tissue is crucial for patients to safely return to sports. Stem cell derived exosomes have shown positive effects on enhancing the regeneration of injured tendons/ligaments. However, clinical application of exosomes in terms of storage and pre-assembly is challenging. We hypothesized that lyophilized exosomes derived from human umbilical cord stem cells (hUSC-EX) could enhance the cell activity of chronically injured ACL cells.Materials and methodsWe harvested the 8 weeks injured ACL cells from rabbit under IACUC (No. 110232) approval. The studied exosomes were purified from the culture medium of human umbilical cord stem cells (IRB approval No. A202205014), lyophilized to store, and hydrated for use. We compared exosome treated cells with non-exosome treated cells (control group) from the same rabbits. We examined the cell viability, proliferation, migration capability and gene expression of type I and III collagen, TGFβ, VEGF, and tenogenesis in the 8 weeks injured ACL cells after hUSC-EX treatment.ResultsAfter hydration, the average size of hUSC-EX was 84.5 ± 70.6 nm, and the cells tested positive for the Alix, TSG101, CD9, CD63, and CD81 proteins but negative for the α-Tubulin protein. After 24 h of treatment, hUSC-EX significantly improved the cell viability, proliferation and migration capability of 8 weeks injured ACL cells compared to that of no exosome treatment group. In addition, the expression of collagen synthesis, TGFβ, VEGF, and tenogenesis gene were all significantly increased in the 8 weeks injured ACL cells after 24 h hUSC-EX delivery.DiscussionLyophilized exosomes are easily stored and readily usable after hydration, thereby preserving their characteristic properties. Treatment with lyophilized hUSC-EX improved the activity and gene expression of 8 weeks injured ACL cells.ConclusionLyophilized hUSC-EX preserve the characteristics of exosomes and can improve chronically injured (8 weeks) ACL cells. Lyophilized hUSC-EX could serve as effective and safe biomaterials that are ready to use at room temperature to enhance cell activity in patients with partial ACL tears and after remnant preservation ACL reconstruction.

Management of Meniscus Pathology with Concomitant Anterior Cruciate Ligament Injury.

The purpose of this review is to summarize current clinical knowledge on the prevalence and types of meniscus pathology seen with concomitant anterior cruciate ligament (ACL) injury, as well as surgical techniques, clinical outcomes, and rehabilitation following operative management of these pathologies. Meniscus pathology with concomitant ACL injury is relatively common, with reports of meniscus pathology identified in 21-64% of operative ACL injuries. These concomitant injuries have been associated with increased age and body mass index. Lateral meniscus pathology is more common in acute ACL injury, while medial meniscus pathology is more typical in chronic ACL deficiency. Meniscus tear patterns associated with concomitant ACL injury include meniscus root tears, lateral meniscus oblique radial tears of the posterior horn (14%), and ramp lesions of the medial meniscus (8-24%). These meniscal pathologies with concomitant ACL injury are associated with increased rotational laxity and meniscal extrusion. There is a paucity of comparative studies to determine the optimal meniscus repair technique, as well as rehabilitation protocol, depending on specific tear pattern, location, and ACL reconstruction technique. There has been a substantial increase in recent publications demonstrating the importance of meniscus repair at the time of ACL repair or reconstruction to restore knee biomechanics and reduce the risk of progressive osteoarthritic degeneration. Through these studies, there has been a growing understanding of the meniscus tear patterns commonly identified or nearly missed during ACL reconstruction. Surgical management of meniscal pathology with concomitant ACL injury implements the same principles as utilized in the setting of isolated meniscus repair alone: anatomic reduction, biologic preparation and augmentation, and circumferential compression. Advances in repair techniques have demonstrated promising clinical outcomes, and the ability to restore and preserve the meniscus in pathologies previously deemed irreparable. Further research to determine the optimal surgical technique for specific tear patterns, as well as rehabilitation protocols for meniscus pathology with concomitant ACL injury, is warranted.

Comparison of Side-to-Side Difference in Posterior Tibial Slope in Knees With Acute Versus Chronic Anterior Cruciate Ligament Deficiency.

The posterior tibial slope (PTS) is an important feature in knee joint biomechanics and indicates anterior-posterior knee stability. Increased PTS is a known risk factor for both primary anterior cruciate ligament (ACL) rupture and postreconstruction rerupture. To investigate the effect of long-term exposure to ACL deficiency on the PTS and the sagittal anatomy of the proximal tibia. Cross-sectional study; Level of evidence, 3. A total of 44 patients (38 men, 6 women) with a history of knee injury and ACL rupture confirmed by magnetic resonance imaging and physical examination were included in this study. Patients were divided into those with chronic ACL deficiency (group 1: injured ≥5 years prior; n = 22) and acute ACL deficiency (group 2: injured <1 year prior; n = 22). The medial and lateral tibial plateau PTS and anterior tibial translation were measured on monopodal weightbearing knee radiographs at 20° of flexion. The mechanical tibiofemoral angle (MTFA) and the medial proximal tibial angle (MPTA) were measured using an orthoroentgenogram. The side-to-side difference between the affected and unaffected knees was also calculated for all measurements. The mean duration of exposure to ACL deficiency was 7.6 years (range, 5-15 years) in group 1 and 4.4 months (range, 1-11 months) in group 2. Regarding the side-to-side differences in angular measurements, a higher medial PTS (affected vs unaffected: 12.4° vs 10.1°; P = .007), higher lateral PTS (11° vs 8.9°; P = .011), and increased varus alignment on both the MTFA (4.3° vs 2.4°; P = .036) and the MPTA (84.9° vs 86.3°; P = .033) were found in group 1, while no significant differences in angular measurements were found in group 2. Compared with group 2, patients in group 1 had a significantly higher side-to-side difference in the medial PTS (2.3° vs 0.1°; P = .0001), lateral PTS (2.1° vs 0.4°; P = .0001), and MPTA (1.4° vs 0.1°; P = .002). This study showed that the affected knees of patients with chronic ACL deficiency (≥5 years) had higher medial and lateral PTS compared with the unaffected contralateral knees. Therefore, when planning ACL reconstruction for patients with a history of long-term ACL deficiency, it is crucial to measure the preoperative PTS accurately.

Chronic ACLD Knees with Early Developmental Cartilage Lesions Exhibited Increased Posterior Tibial Translation during Level Walking.

Early articular cartilage lesion (CL) is a vital sign in the onset of posttraumatic knee osteoarthritis (PTOA) in patients with anterior cruciate ligament deficiency (ACLD). Researchers have suggested that altered kinematics could accelerate CLs and, therefore, lead to the onset of PTOA. However, little is known about whether specific knee kinematics exist that lead to early CL in chronic ACLD knees. Level walking is the most frequent and relevant in vivo activity, which greatly impacts knee health. We hypothesized that the knee kinematics during level walking in chronic ACLD knees with early tibiofemoral CL would significantly differ from those of chronic ACLD knees without early tibiofemoral CL. Thirty patients with a chronic ACLD history, including 18 subjects with CLs and 12 subjects without CLs, and 35 healthy control subjects were recruited for the study from July 2020 to August 2022. The knee kinematic data during level walking were collected using a three-dimensional motion analysis system. The kinematic differences between groups were compared using statistical parametric mapping with one dimension for One-Way ANOVA. The cartilage statuses of the ACLD knees were assessed via MRI examination. The CLs distribution of subjects was evaluated using a modified Noyes scale and analyzed by chi-square tests. ACLD knees with CLs had significantly greater posterior tibial translation (7.7-8.0mm, 12%-18% gait cycle GC, p = 0.014) compared to ACLD knees without CLs during level walking. ACLD knees with CLs had greater posterior tibial translation (4.6-5.5mm, 0%-23% GC, p < 0.001; 5.8-8.0mm, 86%-100% GC, p < 0.001) than healthy controls during level walking. In the group of ACLD knees with CLs, CL is mainly located in the back of the tibia plateau and front of load bearing area of the medial femoral condyle (p < 0.05). Chronic anterior cruciate ligament deficient knees with cartilage lesions have increased posterior tibial translation compared to anterior cruciate ligament deficient knees without cartilage lesions and healthy subjects. The posterior tibial translation may play an important role in knee cartilage degeneration in ACLD knees. The increased posterior tibial translation and cartilage lesion characteristics may improve our understanding of the role of knee kinematics in cartilage degeneration and could be a helpful potential reference for anterior cruciate ligament deficient therapy, such as physical training to improve abnormal kinematic behavior.

Diagnostic accuracy of lever sign test in acute and chronic ACL injuries

IntroductionThe anterior cruciate ligament (ACL) is a commonly affected knee ligament prone to frequent injuries. Henceforth, we aimed to determine the diagnostic accuracy of lever sign test in Acute and chronic ACL injuries. MethodAt the institution's initial outpatient visit, 150 consecutive patients (92 males and 58 females) were evaluated. Total 108 patients had injury in their right leg, whereas 42 had injury in their left leg. Based on time since injury, the patients were divided into Acute and chronic groups. Clinical examinations (lachman's test and lelli's test) of all patients were confirmed with arthroscopic findings and compared between the two groups. ResultsIn the acute ACL injury, the lever test had a kappa value 0.704. The accuracy and sensitivity of the Lachman, anterior drawer, pivot shift, and lever tests were calculated. We found that the lever test had the highest accuracy and sensitivity (85.48 %, 91.18 %) than the rest. In the chronic ACL injury, the kappa value for the results of the Lachman test evaluation was 0.723. The chronic ACL injuries accuracy and sensitivity values for the Lachman (86.36 %, 91.67 %), anterior drawer (76.14 %, 81.25 %), pivot shift (55.68 %, 58.49 %), and lever tests were determined. ConclusionThe lever sign test is more accurate and reliable in the acute ACL injuries, while the Lachman test is more accurate and reliable in the chronic ACL injuries.

Arthroscopic Evaluation of Association of Meniscus Injuries in Patients with Anterior Cruciate Ligament Injuries

Background: The knee joint's stability relies significantly on the integrity of the meniscus and the anterior cruciate ligament (ACL). Chronic ACL tears can compromise knee stability, making the meniscus a crucial stabilizer. Understanding the prevalence and patterns of meniscus injuries associated with chronic ACL tears is essential for effective management. Objective: This study aimed to assess the arthroscopic evaluation of association of meniscus injuries in patients with anterior cruciate ligament injuries. Method: A retrospective analysis was conducted on thirty-three patients diagnosed with ACL injuries at MuMCH between January 2021 and December 2023. Patients aged 18-50 with ACL injuries, with or without meniscus damage, were included. Clinical evaluations, knee MRI scans, and diagnostic knee arthroscopies were performed. The study evaluated meniscus injuries associated with chronic ACL injuries and assessed outcomes using the modified Lysholm score. Results: The study revealed a predominant occurrence of meniscus injuries (70%) among participants, with a majority falling within the 38-47 years age bracket (45.45%) and a male majority (60%). Sports and accidental injuries accounted for 40% each, while road traffic accidents contributed 20%. Lateral meniscus tears were the most prevalent (30.30%), followed by combined medial and lateral meniscus tears (33.33%). Posterior horn tears were predominant, particularly in the medial meniscus. Conclusion: The study highlights a high incidence of meniscus injuries associated with chronic ACL tears, with medial meniscus injuries prevailing over lateral tears. Posterior horn tears were predominant, emphasizing the medial meniscus's significant role in knee stability. These findings underscore the importance of early detection and appropriate management of meniscus injuries in chronic ACL-deficient knees to prevent degenerative changes and optimize patient outcomes.

Combined ACL and Anterolateral Ligament Reconstruction Using an Adjustable-Loop Fixation Device: Surgical Technique

Background: There are several techniques for the combined reconstruction of the anterior cruciate ligament (ACL) and the anterolateral ligament (ALL), but none have shown superiority. This study aims to present a surgical technique that theoretically reduces some of the risks reported in these procedures. Indications: The main indications for the ALL reconstruction include chronic ACL injuries, revision ACL reconstruction, acute ACL injuries in patients with high-grade pivot-shift (grades 2 or 3), patients involved in pivoting sports, and generalized ligament hyperlaxity or knee hyperextension. Technique Description: Hamstring tendon autografts are used for the ACL and ALL reconstruction; a common femoral ACL and ALL tunnel is made outside-in, making a short socket. A continuous looped hamstring tendon autograft attached to one button is used. The ACL is fixed with an adjustable-loop button. Through small incisions, the tibial fixation of both grafts is performed with bioabsorbable screws. Results: We present a 19-year-old professional soccer player with an acute ACL tear, with no associated meniscal or chondral lesions. Owing to his young age and high-risk sports practice, a combined ACL and ALL reconstruction was performed. The combined ACL and ALL reconstruction with a single femoral tunnel using the hamstrings tendons graft is a well-established procedure for ACL augmentation, reducing failure rates for certain risk groups, with excellent outcomes reported. The use of an adjustable-loop button on the femur is a viable option for this kind of reconstruction with postoperative stability comparable to the interference screw, classically used for this kind of reconstruction. Discussion/Conclusion: This technique has some advantages, such as the use of a short outside-in femoral socket, thus theoretically improving healing. In addition, this lowers the risk of lateral collateral ligament injury, and since the ileotibial band graft is not used, the risk of injuring the lateral inferior genicular vessels and the peroneal nerve is theoretically reduced. Besides, using an adjustable-loop cortical button in the femur can theoretically reduce potential complications such as screw migration, soft-tissue impingement, femoral-site pain, and implant removal. Finally, the reconstruction is done with small incisions, improving the aesthetic result and postoperative pain. Considering all the aforementioned factors, this technique theoretically offers some benefits. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Relationship Between Intraoperative Macroscopic Anterior Cruciate Ligament Findings, Perioperative Surgical Findings, and Postoperative Clinical Outcome After Cruciate-Retaining Total Knee Arthroplasty.

To assess how intraoperative macroscopical anterior cruciate ligament (ACL) findings affect perioperative procedures, biomarkers, and postoperative anterior-posterior (AP) laxity and range of motion (ROM) after cruciate-retaining (CR) total knee arthroplasty (TKA)and to determine how chronic ACL deficiency may affect postoperative inflammatory biomarker, AP laxity, and ROM. A total of 121 patients with varus knee osteoarthritis without a history of ACL injury who underwent ATTUNE® (DePuy Synthes, Warsaw, IN) CR TKA were analyzed. Intraoperative ACL findings were stratified into intact, damaged, and diminished, according to the tension by probing, synovial coverage, and vascularity. C-reactive protein (CRP) levels were examined at one, seven, and 14 days after surgery. Knee AP laxity measurements using Kneelax 3 (Monitored Rehab Systems, Haarlem, The Netherlands)and postoperative knee ROM were also compared. One-way ANOVA showed significant differences in CRP levels examined one day after surgery observed between the three groups (8.4 (3.8), 9.8 (4.3), and 13.2 (7.7) mg/dL, respectively; P = 0.018), with post hoc analysis showing that CRP levels one day after surgery were significantly greater in the diminished group than in the intact and damaged groups (P = 0.012 and 0.023, respectively). AP laxity in 30° of knee flexion was observed between the three groups (5.4 (2.3), 5.8 (2.5), and 7.1 (2.8) mm, respectively; P = 0.039), with post hoc analysis showing that AP laxity in 30° of knee flexion was significantly greater in the diminished group than in the intact group(P = 0.038). Knee ROM showed no significant differences. Intraoperative ACL diminishment was associated with higher CRP one day after surgery and midrange AP laxity one year after surgery.

Femoropatellar alterations in knees with chronic anterior cruciate ligament injuries: a radiographic analysis

Background: The objective of this study was to correlate the occurrence of patellofemoral malalignment in a chronic anterior cruciate ligament (ACL) deficient knee using common radiological parameters. Methods: A case-control study was conducted on 35 adult patients with previously diagnosed unilateral chronic ACL injury. The injured knee was considered as the case, while the contralateral normal knee served as the control. Radiological parameters including the Caton-Deschamps patellar height index, Merchant patellar congruence angle, and Laurin lateral patellar tilt angle were measured on X-rays obtained from both normal and ACL injured knees. A comparative analysis was performed between the two groups. Results: The Caton-Deschamps patellar height index had a mean value of 0.95±0.05 in the ACL-deficient knee. The Merchant patellar congruence angle showed mean values of 12.66±0.84 degrees in the ACL injured knee, while the Laurin lateral patellar tilt angle was 8.06±1.41 degrees in knees with ACL failure. These results indicate lower patellar height, greater lateral displacement of the patella, and increased lateral patellar tilt in knees with chronic ACL tears, thereby affecting the patellofemoral joint. Conclusions: Chronic ACL tears are associated with patellofemoral malalignment, characterized by decreased patellar height, increased lateral displacement of the patella, and greater lateral patellar tilt, thus impacting the patellofemoral joint.

The posterior cruciate ligament-posterior femoral cortex angle (PCL-PCA) and the lateral collateral ligament (LCL) sign are useful parameters to indicate the progression of knee decompensation over time after an ACL injury.

The posterior cruciate ligament-posterior cortex angle (angle between the most vertical part of the anterolateral PCL bundle and the posterior diaphyseal cortex of the femur; PCL-PCA) is the most accurate approach to describe the PCL buckling phenomenon observed in anterior cruciate ligament (ACL)-deficient knees. The aim of this study was to determine whether the PCL-PCA is associated with chronicity of the ACL rupture, the meniscal status, preoperative knee laxity or imaging signs such as the lateral collateral ligament (LCL) sign or the posterior tibial slope (PTS) in ACL-injured knees. Patients with a primary ACL reconstruction (ACLR) after physeal closure were selected retrospectively from a hospital-based ACL registry from 2015 to 2021. Exclusion criteria were: previous ipsilateral/contralateral knee surgery, previous ipsilateral ACL or meniscal tear, ipsilateral PCL and/or collateral ligament injuries or tibial plateau fracture. The ACL deficiency was defined as chronic if time from injury to MRI was > 6months. The meniscal status was assessed during ACLR, separately for the medial and lateral meniscus, and classified into no tear, minor or major unstable tear. The MRI analyses included the assessment of the PCL-PCA and the LCL sign. PTS was assessed from the lateral plain radiographs of the injured knee. The side-to-side difference in anterior tibial translation (ATT) at 200N was obtained with the GNRB. Eighty-two patients (forty-eight males/thirty-four females) were included in this study. The median PCL-PCA was 16.2° (Q1-Q3: 10.6-24.7) and differed between acute (18.4°) and chronic (10.7°) injuries (p < 0.01). The median PCL-PCA was significantly lower (- 4.6°) in patients with a positive LCL sign (p = 0.03) No significant association could be found between PCL-PCA and meniscal status, PTS or preoperative anterior knee laxity (Lachman, pivot shift and ATT in millimetres). The PCL-PCA was significantly lower in chronic ACL injuries and in patients with a positive LCL sign, indicating a higher buckling phenomenon of the PCL in these patients. These results support the fact that PCL-PCA and the LCL sign may be useful parameters to indicate the progression of knee decompensation over time after an ACL injury, and therefore may constitute a helpful tool to optimise treatment choice and timing of ACL reconstruction if necessary. III.

Arthroscopic All-Suture Anchor Technique for Unstable Ramp Lesions with Medial Meniscal Defects

A ramp lesion is a specific type of tear in the meniscocapsular junction of the posterior horn of the medial meniscus, usually associated with anterior cruciate ligament (ACL) injury. Biomechanical cadaveric studies have shown that ACL injury combined with ramp lesions significantly increases anterior tibial translation and external rotation, which ACL reconstruction alone cannot completely control. Additionally, ramp lesions are sometimes associated with medial meniscal defects, especially in cases of chronic ACL deficiency after repetitive traumatic events, in which the anatomical repair of the meniscocapsular junction is infeasible. This report describes a new arthroscopic repair technique using an all-suture anchor through a posteromedial portal for unstable ramp lesions with medial meniscal defects.

A New Algorithm to Treat Chronic Combined ACL/MCL Injuries: Let's Come Back to the “Rotatory Instability Test”

Background: Chronic combined medial collateral ligament (MCL) and anterior cruciate ligament (ACL) injuries are frequent. Medial residual laxity is a risk factor for ACL rerupture. It should be treated at the same time as the ACL reconstruction (ACLR) if necessary, but there are still questions surrounding the indications for abstention or surgery of the medial plan, especially for grade 2 MCL injuries of the Fetto and Marshall classification. Indications: The purpose is to come back to a simple test, the “Rotatory Instability Test” as described by Slocum and Larson in 1968 for systematic clinical examination of the knee to improve the sensitivity and accuracy of the deep MCL (dMCL) and superficial MCL (sMCL) examination and to propose a decision-making algorithm for the treatment of the chronic combined ACL/MCL injuries based on the assessment of anteromedial rotatory instability (AMRI). Technique Description: Examination of the ACL with Lachman test, anterior drawer in neutral rotation, and pivot shift test confirm the ACL injury. Valgus laxity is tested in extension and at 20° of flexion. Then, an anterior drawer test at 90° of flexion with external rotation is done (the anterior drawer in external rotation [ADER] test) allowing to identify isolated dMCL, dMCL + sMCL, or MCL + posterior oblique ligament (POL) injuries. Discussion: As persistent medial laxity is a risk factor for ACL graft failure and there is no reliable method of instrumented laxity assessment, careful clinical examination remains essential. Systematic examination of the medial side with valgus laxity testing at 0° and 20° flexion combined with the ADER test assessment of AMRI can guide treatment of the MCL injury component. Where there is no valgus laxity and the ADER test is negative, isolated ACLR is indicated. If there is significant medial laxity at 0°, this suggests combining sMCL and POL reconstruction with ACLR. Where the knee is stable at 0° but there is valgus laxity at 20° and a positive ADER test, the dMCL can be reconstructed using a gracilis graft or a combined sMCL and dMCL reconstruction can be added to the ACLR depending on the degree of laxity. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Chronic ACL-injured patients show increased medial and global anterior tibial subluxation measured on 1-year postoperative MR images after primary single-bundle ACL reconstruction

BackgroundThe association between chronic anterior cruciate ligament (ACL) injury and inferior postoperative outcomes following ACL reconstruction (ACLR) has been highlighted in the literature. However, the inclusion of postoperative radiological assessments in previous studies has been limited. The aim of this study is to investigate whether chronic ACL injury is associated with an inferior tibiofemoral position measured on magnetic resonance (MR) images after primary ACLR.MethodsA total of 62 patients that underwent primary ACLR were included in this study based on the time from injury to surgery, namely the acute ACL-injured group (within 6 weeks) and the chronic ACL-injured group (more than 1 year) and were matched 1:1 according to sex, age (± 2 years), and time from surgery to follow-up (± 3 months). Patient demographics, surgical records and follow-up data were retrieved and analyzed. The altered tibiofemoral position was measured quantitatively on preoperative and at least 1-year postoperative MR images and compared between the two groups, including the lateral, medial and global anterior tibial subluxation (LATS, MATS and GATS) and internal rotational tibial subluxation (IRTS).ResultsNo significant differences in preoperative LATS, MATS, GATS or IRTS were identified between the acute and chronic ACL-injured groups. The chronic ACL-injured patients showed significantly increased postoperative MATS (p = 0.001) and GATS (p = 0.012), while no significant difference was identified in postoperative LATS or IRTS. Multivariate linear regression analyses showed that chronic ACL injury resulted in an estimated increase of 2.0 mm in postoperative MATS (p = 0.012) and 1.9 mm in postoperative GATS (p = 0.040). A significant improvement in postoperative LATS was observed in the acute ACL-injured group (p = 0.044) compared to preoperative LATS, while no improvements in these MRI measurements were observed in the chronic ACL-injured group.ConclusionChronic ACL-injured patients showed increased MATS and GATS measured on 1-year postoperative MR images after primary single-bundle ACL reconstruction, while no difference was identified in rotational tibiofemoral position. The acute ACL-injured group demonstrated a significant improvement in postoperative LATS, whereas no improvements were observed in the chronic ACL-injured group.Level of evidence Level III.

Anterolateral knee complex considerations in contemporary anterior cruciate ligament reconstruction and total knee arthroplasty: a systematic review.

The anterolateral ligament (ALL) was first described in 1879 in the context of Segond fractures, which correlate with a 75-100% chance of an anterior cruciate ligament (ACL) tear or a 66-75% chance of a meniscal tear. The purpose of this paper is to provide an updated comprehensive review on the anterolateral ligament complex of the knee focusing on the: (1) anatomy of the ALL/ALC; (2) associated biomechanics/function; and (3) important surgical considerations in contemporary anterior cruciate ligament (ACL) reconstruction and total knee arthroplasty (TKA). A systematic review of studies on ALL was conducted on Pubmed/MEDLINE and Cochrane databases (May 7th, 2020 to February 1st, 2022), with 20 studies meeting inclusion/exclusion criteria. Studies meeting inclusion criteria were anatomical/biomechanical studies assessing ALL function, cadaveric and computer simulations, and comparative studies on surgical outcomes of ALLR (concomitant with ACL reconstruction). Eight studies were included and graded by MINOR and Newcastle-Ottawa scale to identify potential biases. The anatomy of the ALL is part of the anterolateral ligament complex (ALC), which includes the superficial/deep iliotibial band (including the Kaplan fiber system), iliopatellar band, ALL, and anterolateral capsule. Multiple biomechanical studies have characterized the ALC as a secondary passive stabilizer in resisting tibial internal rotation. Given the role of the ALC in resisting internal tibial rotation, lateral extra-articular procedures including ALL augmentation may be considered for chronic ACL tears, ACL revisions, and a high-grade pivot shift test. In the context of TKA, in the event of injury to the ALC, a more constrained implant or soft-tissue reconstruction may be necessary to restore appropriate knee stability.

Poster 126: Chronic ACL Injury Patients Have Lower Levels of Pro-Inflammatory Biomarkers in their Synovial Fluid and Worse ACLOAS Score at the Time of Surgery Than Those with Acute ACL Injury: A Cohort Study

Objectives: The relationship between structural abnormalities and inflammatory changes in the synovial fluid following ACL injury has not been well defined. The purpose of this study is to compare MRI findings and concentration of inflammatory biomarkers in the synovial fluid (SF) of acute and chronic anterior cruciate ligament (ACL) injury patients. Methods: Patients undergoing surgery for ACL injury from October 2011 to December 2021 were included in a database of patients who had SF samples collected at the time of surgery. From this cohort, 82 patients with acute ACL injury and 28 patients with chronic ACL injury were identified. All patients underwent a preoperative MRI examination of the knee and SF was aspirated from the operative knee prior to the surgical incision and concentrations of inflammatory biomarkers were quantified. MRI examinations were reviewed by a fellowship-trained musculoskeletal radiologist to assess radiographic features of acute and chronic knee injury using the validated ACLOAS system. Nonparametric tests were used to compare demographic factors, MRI findings, clinical symptoms, and SF inflammatory biomarkers between acute versus chronic ACL injury patients. A generalized linear model was used to assess the relationship of each SF biomarker with the ACLOAs subscores. Results: For acute ACL injury patients, mean time from injury to MRI and injury to surgery was 14 ± 35 days and 49 ± 38 days, respectively. The mean time from injury to MRI and injury to surgery was 3.2 ± 3.7 years and 3.4 ± 3.8 years, respectively, for those with chronic ACL injury. There were no significant demographic differences between groups; age (acute: 31.62 ± 8.02 years, chronic: 33.70 ± 10.60 years, p=0.130), sex (acute: 51.2% males, chronic: 57.1%, p=0.588), or body mass index (acute: 5.5 ± 4.4 kg/mm2, chronic: 25.3 ± 3.6 kg/mm2, p=0.931). Acute ACL injury patients had higher bone marrow edema severity scores (p&lt;0.001), Hoffa’s synovitis score (p=0.002), and effusion severity scores (p&lt;0.001). Chronic ACL injury patients had higher cartilage degeneration severity scores (p&lt;0.001), prevalence of meniscus tears (p=0.003), and meniscus tear severity scores (p&lt;0.001). Acute ACL injury patients had significantly higher synovial fluid levels of IL-6 (p=0.032), VEGF (p=0.002), TIMP1 (p&lt;0.001), IL1-RA (p=0.003), and MMP3 (p&lt;0.001) than chronic ACL injury patients. The generalized linear model revealed that after adjusting for age, sex, BMI, and time from injury to surgery, increased VEGF (p=0.003) and MMP3 (p=0.012) were associated with higher effusion score. MMP-3 was associated with a higher bone marrow edema score (p=0.034), and RANTES was associated with both a higher meniscus severity score (p=0.027) and increased cartilage lesions in the chronic ACL injury cohort. Conclusions: The findings from this study suggest that despite having more severe cartilage degeneration and a higher prevalence of meniscus pathology, chronic ACL injury patients had lower levels of synovial fluid inflammatory biomarkers at time of surgery compared to acute ACL injury patients. Additionally, we found that in chronic injuries, RANTES was associated with worse ACLOAS cartilage scores.

Paper 25: The Impact of Posterior Tibial Slope on Meniscal Injury in Acute ACL Ruptures: A Large, Retrospective Registry Study

Objectives: Increased posterior tibial slope has previously been associated with an elevated risk of anterior cruciate ligament (ACL) rupture. Recent studies have suggested there may be a relationship between posterior slope and meniscal tears in ACL ruptures, however, these studies have either included chronic ACL injuries, revision ACL reconstructions or an overall low number of study participants. The goal of this study is to leverage a large ACL registry to assess the impact of posterior tibial slope on meniscal tears in acute ACL ruptures. Methods: A large, single-institution knee registry was consulted to identify all patients between the age of 18 and 45 who underwent primary ACL reconstruction between Jan 2019 and July 2022 for acute, noncontact ACL rupture, defined as undergoing surgery within 90 days of injury. Patients with pre-existing meniscal pathology, chronic ACL reconstructions, revisions, multi-ligament knee injuries and nonoperatively managed ACL injuries were excluded. Preoperative MRIs were used to measure lateral and medial posterior tibial slope for all patients. Meniscal injury seen in-situ during arthroscopy was recorded based on operative reports. Demographics data, including age, sex, and body mass index, was also recorded. Independent cohorts were created based on the presence or absence of any meniscal injury. Two-tailed student’s t tests were used to compare average medial and lateral posterior tibial slopes between these groups. Separate analyses were also performed to assess the impact of posterior slope on medial and lateral meniscus tears independently. Multiple logistic regression was carried out to determine risk factors for meniscal injury in this population. Results: 1059 patients ultimately met inclusion criteria. The average age was 29.5 and there were 532 (50%) women. There were 253 (24%) patients with isolated lateral meniscus tears, 152 (14%) patients with isolated medial meniscus tears and 93 (9%) patients with both medial and lateral tears. The average lateral and medial posterior tibial slopes were 5.54 (-4.2 to 13.4) and 5.67 (0 to 15.7), respectively. Increased lateral tibial slope was associated with a statistically significant increase in rate of any meniscal tear (p=.0022). Lateral slope was also associated with a higher rate of lateral meniscal tears, specifically (p=.0009). Multiple logistic regression identified elevated BMI and male sex as independent risk factors for meniscal injury in this population. Conclusions: Increased lateral posterior tibial slope is associated with a higher rate of meniscus injury in acute ACL ruptures and should be considered when devising treatment algorithms for patients in this population. [Table: see text][Table: see text][Table: see text][Table: see text]

Poster 121: Association Between MRI Findings in ACL Injury and Subacute Synovial Fluid Inflammatory Biomarker Levels at the Time Of Surgery

Objectives: To Investigate the association between MRI findings following anterior cruciate ligament (ACL) injury and synovial fluid biomarker profile at the time of surgery Methods: Patients undergoing surgery for ACL injury from October 2011 to December 2021 were included in a database of subjects who had synovial fluid samples collected at the time of surgery. From this cohort, 82 subjects with acute ACL injury were retrospectively selected who met the following inclusion criteria: no history of prior knee trauma to suggest chronic ACL injury, history of acute non- contact knee injury, MRI examination of the knee performed within 3 weeks of knee injury, subsequent knee surgery performed between 4 and 12 weeks of knee injury, and no additional ligament tear requiring surgical treatment. All subjects underwent a preoperative MRI examination of the knee using multi-planar, multi-contrast fast spin-echo sequences. Synovial fluid was aspirated from the operative knee prior to surgical incision. Concentrations of inflammatory biomarkers including regulation on activation normal T cell expressed and secreted (RANTES), interleukin 6 (IL-6), vascular endothelial growth factor (VEGF), tissue inhibitor matrix metalloproteinase 1 (TIMP1), interleukin 1 receptor agonist (IL1-RA) and matrix metalloproteinase 3 (MMP-3) were measured. The MRI examinations of all subjects were reviewed by a fellowship trained musculoskeletal radiologist to assess the presence and severity of various MRI features of acute and chronic knee injury using the validated Anterior Cruciate Ligament Osteoarthritis Score (ACLOAS) system. Nonparametric Wilcoxon tests and Fisher’s exact test were used to compare demographic factors, MRI findings, clinical symptoms, and synovial fluid inflammatory biomarkers between clusters. K-means cluster analysis was used to identify 2 distinct clusters of subjects with acute ACL injury based on biomarkers concentrations in synovial fluid. Results: The mean age of the cohort was 31.6 ± 8 years, average body mass index (BMI) was 25.5 ± 4.4 kg/m2. There 42.7% (n=35) of the cohort was female and 85.4% (n=70) were non-smokers. Two distinct clusters were identified: cluster 1 included 45 subjects and was marked by older subjects (33.2 ± 9.1 years, p=.038) with lower levels of all inflammatory synovial fluid biomarkers. Cluster 2 included 37 subjects and was marked by younger patients (29.7 ± 6.1 years, p=.038) with a more pro-inflammatory synovial fluid biomarker profile, higher ACLOAS Hoffa’s synovitis score (p=.001), and a higher incidence of subchondral bone fractures (54%, p=.002). There were no differences between clusters in time from injury to surgery (p=), BMI (p=.141), or ACLOAS meniscus (p=.086), cartilage (p=.730), or effusion scores (p=.202) Conclusions: Given the variable outcomes seen following ACL reconstruction (ACLR) surgery, a better understanding of the pathophysiology following ACL injury is needed. This study found distinct cluster of patients who exhibited a higher inflammatory reaction at the time of surgery as well as more severe findings on preoperative MRI. These findings could be used to identified clinical parameters associated with more inflammation at the time of surgery and their effect on clinical outcomes of ACLR.

Slope and frontal axis: three-dimensional analysis and correction with patient-specific cutting guides for the proximal tibia

Three-dimensional correction of the bony alignment in the frontal and sagittal plane of the proximal tibia; surgery is performed via an open- or closing-wedge osteotomy to improve ligament stability and reduce joint degeneration. Chronic anterior cruciate ligament (ACL) or posterior cruciate ligament (PCL) instability and ligament revision surgeries; subjective knee instability in patients who are ambitious athletes and people who do physical labor; moderate joint degeneration with meniscus and cartilage damage, post-traumatic deformities. Time pressure (immediate meniscus surgery, since planning and production of patient-specific tools is time-consuming), lack of compliance (need for partial weight bearing, crutches), excessive smoking, vascular pathologies. Planning based on computed tomography (CT) data, determination of the axis of rotation with open or closing wedge, or dome osteotomy; production of corresponding patient-specific cutting blocks. Surgery is performed using the known standard approaches for a high tibial osteotomy (HTO). Exact positioning of cutting guides on the exposed bone. Sawing and adjusting the correction using an osteotomy chisel so that the reduction guide can be attached. Fixation of the achieved correction with angle-stable plate fixator. Partial weight bearing based on the extent of the correction for 6weeks, free range of motion if no additional ligamentous reconstruction was performed. Subsequent full weight bearing after X‑ray and, if necessary, CT control. No general results can be presented, since the surgical procedure, the indication, and the patient group are extremely heterogeneous. Accuracy of the cutting blocks used has been presented in other studies and is given as 0.8° ± 1.5° in relation to the frontal axis. However, the intraoperative change in the correction and adaptation to the surgical site that is presented depends on the surgeon and can greatly influence the extent of correction in terms of accuracy in complex corrections.

Translation and Validation of a Simplified Chinese Version of the Anterior Cruciate Ligament–Quality of Life Questionnaire

Background: The Anterior Cruciate Ligament–Quality of Life (ACL-QOL) questionnaire is a widely used and effective scale for quality of life in patients with chronic anterior cruciate ligament (ACL) injury. Purpose: To translate and adapt the ACL-QOL questionnaire for Chinese patients and evaluate its reliability, validity, and responsiveness in this population. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: Translation and adaptation were conducted in accordance with the guidelines of the A merican Academy of Orthopaedic Surgeons Outcome Committee. Included were 121 patients who were diagnosed with a chronic ACL injury and underwent ACL reconstruction between January 2020 and June 2021. Preoperatively, patients completed the simplified Chinese version of the ACL-QOL (ACL-QOL-C), the Knee injury and Osteoarthritis Outcome Score, and the 12-Item Short Form Health Survey. The ACL-QOL-C was also completed at 12- and 24-week follow-ups. Psychometric evaluations were then performed and included score distribution, internal consistency, test-retest reliability, construct validity, and responsiveness. Results: The Cronbach alpha ranged from .905 to .975, indicating excellent internal consistency, and the intraclass correlation coefficient ranged from 0.864 to 0.985, indicating excellent test-retest reliability. The consistency between the above results and our a priori hypotheses was more than 70% (35/42), indicating good construct validity. The standard error of measurement and effect size of the total score and each item of the ACL-QOL-C were &gt;0.8 at the final follow-up, indicating good responsiveness. Conclusion: The English version of the ACL-QOL has been successfully translated into Chinese, and it has been shown to be applicable for the assessment of the quality of life in Chinese patients with chronic ACL injury.