Fibroblasts From Common Anterior Cruciate Ligament Tendon Grafts Exhibit Different Biologic Responses to Mechanical Strain

Background: Different tendons are chosen for anterior cruciate ligament (ACL) reconstruction based on perceived advantages and disadvantages, yet there is a relative paucity of information regarding biologic responsiveness of commonly used tendon grafts to mechanical strain. Purpose: To evaluate the in vitro responses of graft fibroblasts derived from tendons used for ACL reconstruction to clinically relevant strain levels. Study Design: Controlled laboratory study. Methods: Twelve quadriceps tendons (QTs), 12 patellar tendons (PTs), and 9 hamstring tendons (HTs) were harvested from skeletally mature dogs (n = 16). Tendon fibroblasts were isolated and seeded onto BioFlex plates (1 × 105 cells/well). Cells were subjected to 3 strain conditions (stress deprivation, 0%; physiologic, 4%; high, 10%) for 5 days. Media were collected for proinflammatory and metabolic assays. RNA was extracted for gene expression analysis using real-time reverse transcription polymerase chain reaction. Results: Stress deprivation elicited significantly higher metabolic activity from HT and PT cells than from QT cells ( P < .001 and P = .001, respectively). There were no differences in metabolic activity among all 3 graft fibroblasts at physiologic and high strain. COL-1 expression was significantly higher in PT versus HT during physiologic strain ( P = .007). No significant differences with COL-3 expression were seen. TIMP-1 ( P = .01) expression was higher in PT versus HT under physiologic strain. Scleraxis expression was higher in PT versus HT ( P = .007) under physiologic strain. A strain-dependent increase in PGE2 levels occurred for all grafts. At physiologic strain conditions, HT produced significantly higher levels of PGE2 versus QT ( P < .001) and PT ( P = .005). Conclusion: Fibroblasts from common ACL graft tissues exhibited different metabolic responses to mechanical strain. On the basis of these data, we conclude that early production of extracellular matrix and proinflammatory responses from ACL grafts are dependent on mechanical loading and graft source. Clinical Relevance: Graft-specific differences in ACL reconstruction outcomes are known to exist. Our results suggest that there are differences in the biologic responsiveness of cells from the tendon grafts used in ACL reconstruction, which are dependent on strain levels and graft source. The biologic properties of the tissue used for ACL reconstruction should be considered when selecting graft source.

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Does Vancomycin Wrapping in Anterior Cruciate Ligament Reconstruction Affect Tenocyte Activity In Vitro?

Antibiotics ◽

10.3390/antibiotics10091087 ◽

2021 ◽

Vol 10 (9) ◽

pp. 1087

Author(s):

Rocco Papalia ◽

Claudia Cicione ◽

Fabrizio Russo ◽

Luca Ambrosio ◽

Giuseppina Di Giacomo ◽

...

Keyword(s):

Anterior Cruciate Ligament ◽

Acl Reconstruction ◽

Metabolic Activity ◽

Ligament Reconstruction ◽

Cruciate Ligament ◽

In Vitro Cytotoxicity ◽

In Vitro Effects ◽

Anterior Cruciate ◽

Hamstring Grafts

Knee septic arthritis is a devastating complication following anterior cruciate ligament (ACL) reconstruction. To prevent this issue, intraoperative soaking of ACL grafts with vancomycin is often performed before implantation. Although vancomycin cytotoxicity has been reported several times, little is known about its biological effect on tenocytes. The aim of this study was to evaluate the in vitro effects of vancomycin on human primary tenocytes (hTCs). hTCs were isolated from hamstring grafts of four patients undergoing ACL reconstruction. After expansion, hTCs were treated with different concentrations of vancomycin (0, 2.5, 5, 10, 25, 50 and 100 mg/mL) for 10, 15, 30 and 60 min. In vitro cytotoxicity was evaluated measuring metabolic activity, cell toxicity, and apoptosis. hTC metabolic activity was affected starting from 10 mg/mL vancomycin and decreased markedly at 100 mg/mL. Cell viability remained unaffected only at a concentration of 2.5 mg/mL vancomycin. Vancomycin cytotoxicity was detected from 10 mg/mL after 15 min and at all higher concentrations. Cells died when treated with concentrations higher than 5 mg/mL. The use of this antibiotic on tendons to prevent infections could be useful and safe for resident cells if used at a concentration of 2.5 mg/mL for up to 1 h of treatment.

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Whether Sutures Reduce the Graft Laceration Caused by Interference Screw in Anterior Cruciate Ligament Reconstruction a Biomechanical Study in Vitro

10.21203/rs.3.rs-143941/v1 ◽

2021 ◽

Author(s):

Yuanjun Teng ◽

Lijun Da ◽

Xiaohui Zhang ◽

Hong Wang ◽

Hua Han ◽

...

Keyword(s):

Anterior Cruciate Ligament ◽

Acl Reconstruction ◽

Cruciate Ligament ◽

Interference Screw ◽

Biomechanical Study ◽

Protective Effects ◽

Mineral Density ◽

Interference Screws ◽

Anterior Cruciate

Abstract Background: Interference screw is commonly used for graft fixation in anterior cruciate ligament (ACL) reconstruction However, previous studies h a d reported that the insertion of interference screws significantly caused graft laceration . The purpose of this study was to determine whether sutures reduce d the graft laceration from the insertion of interference screws in ACL reconstruction. Methods: Porcine tibias and bovine extensor tendons were used for establishing a knee model of ACL reconstruction in vitro . The ends of grafts were sutured using three different sutures, including the bioabsorbable, Ethibond and ultra high molecular weight polyethylene (UHMWPE) sutures Poly ether ether ketone (PEEK) interference screw s w ere used fortibial fixation Biomechanical tests were performed to investigate the protective effects of different sutures on grafts Results : All prepared tendons and bone specimens showed similar characteristics (length, weight, and pre tension of the tendons, tibial bone mineral density) among all groups ( P 0.05). The biomechanical test s demonstrated that PEEK interference screw s significantly caused the graft laceration P 0.05). However, all sutures (the bioabsorbable, Ethibond and UHMWPE sutures) did not reduce the graft laceration in ACL reconstruction P 0.05). Conclusions : PEEK interference screw s significantly weakened the biomechanical properties of grafts during tibial fixation in ACL reconstruction. Absorbable Ethibond and UHMWPE sutures did not provide protective effects on grafts during ACL reconstruction.

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POSTEROMEDIAL MENISCAL AND ANTERIOR CRUCIATE LIGAMENT STRAINS DURING DYNAMIC ACTIVITIES FOLLOWING ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

Journal of Musculoskeletal Research ◽

10.1142/s0218957720500104 ◽

2020 ◽

Vol 23 (02) ◽

pp. 2050010

Author(s):

Sebastian Tomescu ◽

Ryan Bakker ◽

David Wasserstein ◽

Mayank Kalra ◽

Micah Nicholls ◽

...

Keyword(s):

Anterior Cruciate Ligament ◽

Acl Reconstruction ◽

Strain Difference ◽

Cruciate Ligament ◽

Knee Simulator ◽

Lower Strain ◽

Healthy Knee ◽

Anterior Cruciate ◽

The Impact

Background: Meniscal strain patterns are not well understood during dynamic activities. Furthermore, the impact of ACL reconstruction on meniscal strain has not been thoroughly investigated. The purpose of this study was to characterize ACL and meniscal strain during dynamic activities and investigate the strain difference between ACL-intact and ACL-reconstructed ligament conditions. Methods: ACL and medial meniscal strain were measured in-vitro during gait, a double leg squat, and a single leg squat. For each activity kinematics and muscle forces were applied to seven cadaveric specimens using a dynamic knee simulator. Testing was performed in the ACL-intact and ACL-reconstructed ligament conditions. Results: Both the ACL and meniscus had distinct strain patterns that were found to have a significant interaction with knee angle during gait and double leg squat ([Formula: see text]). During gait, both tissues experienced lower strain during swing than stance (ACL: 3.0% swing, 9.1% stance; meniscus: 0.2% swing, 1.3% stance). Meniscal strain was not found to be different between ACL-intact and ACL-reconstructed conditions ([Formula: see text]). Conclusions: During dynamic activities, the strain in the meniscus was not altered between ACL ligament conditions. This indicates that meniscal mechanics after ACL reconstruction are similar to a healthy knee. These results help further the understanding of osteoarthritis risk after ACL reconstruction.

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Anterior Cruciate Ligament Reconstruction Graft Options

Orthopaedic Journal of Sports Medicine ◽

10.1177/2325967118s00048 ◽

2018 ◽

Vol 6 (6_suppl3) ◽

pp. 2325967118S0004

Author(s):

Gustavo Vinagre ◽

João Saraiva

Keyword(s):

Anterior Cruciate Ligament ◽

Acl Reconstruction ◽

Ligament Reconstruction ◽

Cruciate Ligament ◽

Return To Play ◽

Knee Stability ◽

Advantages And Disadvantages ◽

Anterior Cruciate ◽

Sports Traumatology ◽

The Ideal

Introduction: The Anterior Cruciate Ligament (ACL) tear is one of the most feared injuries since it can be crucial in the athlete’s career. The ACL reconstruction is one of the most frequent surgical procedures in Sports and the goal is to restore knee stability and avoid further injuries on the meniscus and cartilage, representing a constant topic of debate in Sports Traumatology. There are different graft options for ACL reconstruction that have been described over the years, addressed by different studies with controversy and different outcomes. The decision of the ideal graft for an ACL reconstruction is very complex, but should be consensual among all those involved in the injury process, and should be taken according to patient´s anatomy, physical demand and intrinsic graft specifications, that are key to know and understand. Objectives: Review and summarize the different graft options available for ACL reconstruction in order to make an optimal and individualized choice for each athlete to maximize the return to play and back to Sports at pre-injury levels. Methods: A literature review was performed on PubMed / Medline electronic databases with the words “ACL graft” by relevance. The articles with graft comparisons specifications were selected. Results: The results of our review were summarized with the advantages and disadvantages of the following grafts: Bone-Tendon-Bone (BTB) autograft; hamstrings autograft, quadriceps autograft and allografts. Conclusion: Taking into account the scientific knowledge available and despite the differences in each graft, the choice of the ideal graft that should be used in the ACL reconstruction should be individualized for each athlete, according to intrinsic graft specifications and extrinsic particularities of each sport and athlete.

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An Anterior Cruciate Ligament In Vitro Rupture Model Based on Clinical Imaging

The American Journal of Sports Medicine ◽

10.1177/03635465211017145 ◽

2021 ◽

pp. 036354652110171

Author(s):

Lukas Willinger ◽

Kiron K. Athwal ◽

Andy Williams ◽

Andrew A. Amis

Keyword(s):

Anterior Cruciate Ligament ◽

Acl Reconstruction ◽

Pivot Shift ◽

Cruciate Ligament ◽

Acl Injury ◽

Bone Bruise ◽

Acl Injuries ◽

Anterior Cruciate ◽

Acl Transection

Background: Biomechanical studies on anterior cruciate ligament (ACL) injuries and reconstructions are based on ACL transection instead of realistic injury trauma. Purpose: To replicate an ACL injury in vitro and compare the laxity that occurs with that after an isolated ACL transection injury before and after ACL reconstruction. Study Design: Controlled laboratory study. Methods: Nine paired knees were ACL injured or ACL transected. For ACL injury, knees were mounted in a rig that imposed tibial anterior translation at 1000 mm/min to rupture the ACL at 22.5° of flexion, 5° of internal rotation, and 710 N of joint compressive force, replicating data published on clinical bone bruise locations. In contralateral knees, the ACL was transected arthroscopically at midsubstance. Both groups had ACL reconstruction with bone–patellar tendon–bone graft. Native, ACL-deficient, and reconstructed knee laxities were measured in a kinematics rig from 0° to 100° of flexion with optical tracking: anterior tibial translation (ATT), internal rotation (IR), anterolateral (ATT + IR), and pivot shift (IR + valgus). Results: The ACL ruptured at 26 ± 5 mm of ATT and 1550 ± 620 N of force (mean ± SD) with an audible spring-back tibiofemoral impact with 5o of valgus. ACL injury and transection increased ATT ( P < .001). ACL injury caused greater ATT than ACL transection by 1.4 mm (range, 0.4-2.2 mm; P = .033). IR increased significantly in ACL-injured knees between 0° and 30° of flexion and in ACL transection knees from 0° to 20° of flexion. ATT during the ATT + IR maneuver was increased by ACL injury between 0° and 80° and after ACL transection between 0° and 60°. Residual laxity persisted after ACL reconstruction from 0° to 40° after ACL injury and from 0° to 20° in the ACL transection knees. ACL deficiency increased ATT and IR in the pivot-shift test ( P < .001). The ATT in the pivot-shift increased significantly at 0° to 20° after ACL transection and 0° to 50° after ACL injury, and this persisted across 0° to 20° and 0° to 40° after ACL reconstruction. Conclusion: This study developed an ACL injury model in vitro that replicated clinical ACL injury as evidenced by bone bruise patterns. ACL injury caused larger increases of laxity than ACL transection, likely because of damage to adjacent tissues; these differences often persisted after ACL reconstruction. Clinical Relevance: This in vitro model created more realistic ACL injuries than surgical transection, facilitating future evaluation of ACL reconstruction techniques.

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Revision Anterior Cruciate Ligament Reconstruction with Contralateral Hamstring Tendon Grafts: 6 Years Follow-Up

Joints ◽

10.1055/s-0037-1601410 ◽

2017 ◽

Vol 05 (01) ◽

pp. 017-020 ◽

Cited By ~ 5

Author(s):

Claudio Legnani ◽

Stefania Zini ◽

Enrico Borgo ◽

Alberto Ventura

Keyword(s):

Anterior Cruciate Ligament ◽

Acl Reconstruction ◽

Cruciate Ligament ◽

Hamstring Tendon ◽

Activity Level ◽

Wilcoxon Test ◽

Pivot Shift Test ◽

Tendon Grafts ◽

Anterior Cruciate

Purpose The purpose of this study was to retrospectively evaluate the clinical outcome of revision anterior cruciate ligament (ACL) reconstruction with contralateral hamstring tendon autografts, specifically with regard to patient satisfaction, return to preinjury activity level, and postoperative functional outcomes. Methods Between 2004 and 2011, 23 patients underwent revision ACL reconstruction with contralateral autogenous hamstring tendon grafts and were retrospectively reviewed at an average follow-up of 6.3 years. Subjective and functional evaluations were performed. The Tegner score, Knee Injury and Osteoarthritis Outcome Score (KOOS), and International Knee Documentation Committee (IKDC) Subjective Knee Form were used. Objective evaluation included range of motion, Lachman test, pivot-shift test, and KT-1000 instrumented laxity testing. Wilcoxon test was used to compare the preoperative and follow-up status. Differences with a p-value of <0.05 were considered statistically significant. Results No major complications were reported. The mean KOOS significantly increased from a preoperative mean of 62.8 ± 8.3 to 85.8 ± 6.9 (p < 0.001). IKDC subjective score significantly improved from 29.2 ± 10.4 to 72.8 ± 5.2 (p < 0.001). The median Tegner activity score significantly improved from a preoperative mean of 6.5 (range: 4–10) to 7.5 (range: 7–10) (p < 0.001). Most of the patients increased or returned to the same activity level, with 61% of the patients returning to cutting and pivoting sports. Conclusion The use of contralateral hamstring tendon autografts for ACL revision surgery represents a valid option following a failed primary ACL reconstruction and confirms subjective and objective clinical improvement 6 years after surgery. Level of Evidence Level IV, therapeutic case series.

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Comparison of Viscoelastic, Structural, and Material Properties of Double-Looped Anterior Cruciate Ligament Grafts Made From Bovine Digital Extensor and Human Hamstring Tendons

Journal of Biomechanical Engineering ◽

10.1115/1.1351889 ◽

2000 ◽

Vol 123 (2) ◽

pp. 162-169 ◽

Cited By ~ 98

Author(s):

Tammy L. Haut Donahue ◽

Colin Gregersen ◽

M. L. Hull ◽

Stephen M. Howell

Keyword(s):

Anterior Cruciate Ligament ◽

Creep Test ◽

Material Properties ◽

Cruciate Ligament ◽

Tendon Graft ◽

Load Relaxation Test ◽

Human Tendon ◽

Tendon Grafts ◽

Anterior Cruciate

Due to ready availability, decreased cost, and freedom from transmissible diseases in humans such as hepatitis and AIDS, it would be advantageous to use tendon grafts from farm animals as a substitute for human tendon grafts in in vitro experiments aimed at improving the outcome of anterior cruciate ligament (ACL) reconstructive surgery. Thus the objective of this study was to determine whether an anterior cruciate ligament (ACL) graft composed of two loops of bovine common digital extensor tendon has the same viscoelastic, structural, and material properties as a graft composed of a double loop of semitendinosus and gracilis tendons from humans. To satisfy this objective, grafts were constructed from each tissue source. The cross-sectional area was measured using an area micrometer, and each graft was then pulled using a materials testing system while submerged in a saline bath. Using two groups of tendon grafts n=10, viscoelastic tests were conducted over a three-day period during which a constant displacement load relaxation test was followed by a constant amplitude, cyclic load creep test (first day), a constant load creep test (second day), and an incremental cyclic load creep test (third day). Load-to-failure tests were performed on two different groups of grafts n=8. When the viscoelastic behavior was compared, there were no significant differences in the rate of load decay or the final load (relaxation test) and rates of displacement increase or final displacements (creep tests) p>0.115. To compare both the structural and material properties in the toe region (i.e., <250 N) of the load-elongation curve, the tangent stiffness and modulus functions were computed from parameters used in an exponential model fit to the load (stress)—elongation (strain) data. Although one of the two parameters in the functions was different statistically, this difference translated into a difference of only 0.03 mm in displacement at 250 N of load. In the linear region (i.e., 50–75 percent of ultimate load) of the load-elongation curve, the linear stiffness of the two graft types compared closely (444 N/mm for bovine and 418 N/mm for human) p=0.341. At failure, the ultimate loads (2901 N and 2914 N for bovine and human, respectively) and the ultimate stresses (71.8 MPa and 65.6 MPa for bovine and human, respectively) were not significantly different p>0.261. The theoretical effect of any differences in properties between these two grafts on the results of two types of in vitro experiments (i.e., effect of surgical variables on knee laxity and structural properties of fixation devices) are discussed. Despite some statistical differences in the properties evaluated, these differences do not translate into important effects on the dependent variables of interest in the experiments. Thus the bovine tendon graft can be substituted for the human tendon graft in both types of experiments.

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Predictive Factors for Hamstring Autograft Diameter in Anterior Cruciate Ligament Reconstruction

The Journal of Knee Surgery ◽

10.1055/s-0039-1700495 ◽

2019 ◽

Author(s):

Willem M.P. Heijboer ◽

Mathijs A.M. Suijkerbuijk ◽

Belle L. van Meer ◽

Eric W.P. Bakker ◽

Duncan E. Meuffels

Keyword(s):

Anterior Cruciate Ligament ◽

Linear Regression ◽

Multiple Linear Regression ◽

Acl Reconstruction ◽

Cruciate Ligament ◽

Linear Regression Analysis ◽

Multiple Linear Regression Model ◽

Gracilis Tendon ◽

Thigh Circumference ◽

Anterior Cruciate

AbstractMultiple studies found hamstring tendon (HT) autograft diameter to be a risk factor for anterior cruciate ligament (ACL) reconstruction failure. This study aimed to determine which preoperative measurements are associated with HT autograft diameter in ACL reconstruction by directly comparing patient characteristics and cross-sectional area (CSA) measurement of the semitendinosus and gracilis tendon on magnetic resonance imaging (MRI). Fifty-three patients with a primary ACL reconstruction with a four-stranded HT autograft were included in this study. Preoperatively we recorded length, weight, thigh circumference, gender, age, preinjury Tegner activity score, and CSA of the semitendinosus and gracilis tendon on MRI. Total CSA on MRI, weight, height, gender, and thigh circumference were all significantly correlated with HT autograft diameter (p < 0.05). A multiple linear regression model with CSA measurement of the HTs on MRI, weight, and height showed the most explained variance of HT autograft diameter (adjusted R 2 = 44%). A regression equation was derived for an estimation of the expected intraoperative HT autograft diameter: 1.2508 + 0.0400 × total CSA (mm2) + 0.0100 × weight (kg) + 0.0296 × length (cm). The Bland and Altman analysis indicated a 95% limit of agreement of ± 1.14 mm and an error correlation of r = 0.47. Smaller CSA of the semitendinosus and gracilis tendon on MRI, shorter stature, lower weight, smaller thigh circumference, and female gender are associated with a smaller four-stranded HT autograft diameter in ACL reconstruction. Multiple linear regression analysis indicated that the combination of MRI CSA measurement, weight, and height is the strongest predictor.

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Performance After Anterior Cruciate Ligament Reconstruction in National Basketball Association Players

Orthopaedic Journal of Sports Medicine ◽

10.1177/2325967120981649 ◽

2021 ◽

Vol 9 (2) ◽

pp. 232596712098164

Author(s):

Steven F. DeFroda ◽

Devan D. Patel ◽

John Milner ◽

Daniel S. Yang ◽

Brett D. Owens

Keyword(s):

Anterior Cruciate Ligament ◽

Acl Reconstruction ◽

Odds Ratio ◽

Cruciate Ligament ◽

Case Series ◽

National Basketball Association ◽

High Rate ◽

Return To Play ◽

Lower Percentage ◽

Anterior Cruciate

Background: Anterior cruciate ligament (ACL) injury in National Basketball Association (NBA) players can have a significant impact on player longevity and performance. Current literature reports a high rate of return to play, but there are limited data on performance after ACL reconstruction (ACLR). Purpose/Hypothesis: To determine return to play and player performance in the first and second seasons after ACLR in NBA players. We hypothesized that players would return at a high rate. However, we also hypothesized that performance in the first season after ACLR would be worse as compared with the preinjury performance, with a return to baseline by postoperative year 2. Study Design: Case series; Level of evidence, 4. Methods: An online database of NBA athlete injuries between 2010 and 2019 was queried using the term ACL reconstruction. For the included players, the following data were recorded: name; age at injury; position; height, weight, and body mass index; handedness; NBA experience; dates of injury, surgery, and return; knee affected; and postoperative seasons played. Regular season statistics for 1 preinjury season and 2 postoperative seasons were compiled and included games started and played, minutes played, and player efficiency rating. Kaplan-Meier survivorship plots were computed for athlete return-to-play and retirement endpoints. Results: A total of 26 athletes underwent ACLR; of these, 84% (95% CI, 63.9%-95.5%) returned to play at a mean 372.5 days (95% CI, 323.5-421.5 days) after surgery. Career length after injury was a mean of 3.36 seasons (95% CI, 2.27-4.45 seasons). Factors that contributed to an increased probability of return to play included younger age at injury (odds ratio, 0.71 [95% CI, 0.47-0.92]; P = .0337) and fewer years of experience in the NBA before injury (odds ratio, 0.70 [95% CI, 0.45-0.93]; P = .0335). Postoperatively, athletes played a significantly lower percentage of total games in the first season (48.4%; P = .0004) and second season (62.1%; P = .0067) as compared with the preinjury season (78.5%). Player efficiency rating in the first season was 19.3% less than that in the preinjury season ( P = .0056). Performance in the second postoperative season was not significantly different versus preinjury. Conclusion: NBA players have a high rate of RTP after ACLR. However, it may take longer than a single season for elite NBA athletes to return to their full preinjury performance. Younger players and those with less NBA experience returned at higher rates.

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EFFECT OF SKELETAL MATURITY ON INCIDENCE OF ASSOCIATED MENISCAL AND CHONDRAL INJURIES IN ANTERIOR CRUCIATE LIGAMENT INJURED KNEES

Orthopaedic Journal of Sports Medicine ◽

10.1177/2325967121s00105 ◽

2021 ◽

Vol 9 (7_suppl3) ◽

pp. 2325967121S0010

Author(s):

Brett Heldt ◽

Elsayed Attia ◽

Raymond Guo ◽

Indranil Kushare ◽

Theodore Shybut

Keyword(s):

Anterior Cruciate Ligament ◽

Acl Reconstruction ◽

Medial Meniscus ◽

Skeletal Maturity ◽

Cruciate Ligament ◽

Demographic Data ◽

Meniscal Tear ◽

Lateral Meniscus ◽

Meniscus Tears ◽

Anterior Cruciate

Background: Acute anterior cruciate ligament(ACL) rupture is associated with a significant incidence of concomitant meniscal and chondral injuries. However, to our knowledge, the incidence of these concomitant injuries in skeletally immature(SI) versus skeletally mature(SM) patients has not been directly compared. SI patients are a unique subset of ACL patients because surgical considerations are different, and subsequent re-tear rates are high. However, it is unclear if the rates and types of meniscal and chondral injuries differ. Purpose: The purpose of this study is to compare associated meniscal and chondral injury patterns between SI and SM patients under age 21, treated with ACL reconstruction for an acute ACL tear. We hypothesized that no significant differences would be seen. Methods: We performed a single-center retrospective review of primary ACL reconstructions performed from January 2012 to April 2020. Patients were stratified by skeletal maturity status based on a review of records and imaging. Demographic data was recorded, including age, sex, and BMI. Associated intra-articular meniscal injury, including laterality, location, configuration, and treatment were determined. Articular cartilage injury location, grade, and treatments were determined. Revision rates, non-ACL reoperation rates, and time to surgery were also compared between the two groups. Results: 785 SM and 208 SI patients met inclusion criteria. Mean BMI and mean age were significantly different between groups. Meniscal tear rates were significantly greater in SM versus SI patients in medial meniscus tears(P<.001), medial posterior horn tears(P=.001), medial longitudinal tears configuration(P=.007), lateral Radial configuration(P=.002), and lateral complex tears(P=.011). Medial repairs(P<.001) and lateral partial meniscectomies(P=.004) were more likely in the SM group. There was a significantly greater number of chondral injuries in the SM versus SI groups in the Lateral(p=.007) and medial compartments(P<.001). SM patients had a significantly increased number of outerbridge grade 1 and 2 in the Lateral(P<.001) and Medial Compartments(P=.013). ACL revisions(P=.019) and Non-ACL reoperations(P=.002) were significantly greater in the SI patients compared to SM. No other significant differences were noted. Conclusion: SM ACL injured patients have a significantly higher rate of medial meniscus tears and medial longitudinal configurations treated with repair, and a significantly higher rate of radial and/or complex lateral meniscus tears treated with partial meniscectomy compared to the SI group. We also found a significantly higher rate of both medial and lateral compartment chondral injuries, mainly grades 1 and 2, in SM compared to SI patients. Conversely, SI ACL reconstruction patients had higher revision and subsequent non-ACL surgery rates.

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