Anterior Cruciate Ligament Reconstruction Research Articles

Background: Anterior Cruciate Ligament (ACL) reconstruction is a common orthopaedic procedure, the success of which is ultimately affected by the graft healing process. Quantification of graft healing can be performed non-invasively, using signal-intensity (SI) or signal noise quotient (SNQ) on MRI, however, the variable factors affecting graft healing are still being studied. Objectives: To non-invasively evaluate the normal morphology of the ACL graft on MRI and assess factors affecting graft healing post-arthroscopic ACL reconstruction. Method: A single-centre cross-sectional study was performed using MRI scans for assessment of the ACL graft at 6 months to 2 years post-surgery. Signal noise quotient was correlated with tibial tunnel diameter, femoral tunnel diameter, tibial tunnel location (antero-posterior and medio-lateral), femoral tunnel location (high-low and deep-shallow), graft bending angle (GBA) and notch volume. Results: Twenty-four of 42 patients had normal grafts (mean ± standard deviation post-operative time: 10.15 ± 4.38 months). The SNQ levels were highest at the proximal part of the graft. Graft SNQ correlated positively with tibial (p = 0.020) and femoral (p ≤ 0.001) tunnel diameters, tibial tunnel location in the medio-lateral direction (P ≤ 0.001), femoral tunnel location in the high-low direction (p ≤ 0.001) and patients having complications. Graft SNQ correlated negatively with tibial tunnel location in the antero-posterior (AP) direction (p ≤ 0.001). Univariate analysis revealed a significant correlation between SNQ and tibial and femoral tunnel diameter, tibial tunnel location in both AP and medio-lateral directions, femoral tunnel location in high-low direction and patients having complications. Multivariate analysis showed the tibial tunnel location (medio-lateral) and the femoral tunnel location (high-low) as the significant independent factors. Conclusion: Intraoperative factors, predominantly the positions of the tibial and femoral tunnels, are the major factors affecting graft healing. Contribution: This study provides greater awareness regarding the factors affecting graft healing, helps establish MRI as an effective non-invasive post-operative imaging modality, and helps surgeons in providing a better individualised approach to surgery.

To identify factors associated with knee extension loss prior to anterior cruciate ligament (ACL) reconstruction (ACLR). Patients without concomitant ligament injuries who underwent primary ACLR at the Capio Artro Clinic, Stockholm, Sweden, between 1 January 2002 and 31 December 2023, were eligible for inclusion. The outcome of the study was the presence of preoperative extension loss, defined as a deficit of ≥5 degrees prior to ACLR. Univariable and multivariable logistic regression analyses were conducted to assess associations between the study outcome and the following variables: age at surgery, sex, time from injury to surgery, preinjury Tegner activity level, cartilage injury, medial meniscus or lateral meniscus injury, and physiologic contralateral knee extension deficit (≥5 degrees). A total of 10,692 patients were included. The overall incidence of extension loss prior to ACLR was 6.3% (677/10,692). Multivariable logistic regression analysis showed that early surgery (≤3 months) (odds ratio [OR]: 2.94; 95% confidence interval [CI]: 2.43-3.57; p < 0.001), medial meniscus injury (OR: 1.30; 95% CI: 1.07-1.57; p = 0.01), lateral meniscus injury (OR: 1.23; 95% CI: 1.01-1.48; p = 0.04) and physiologic contralateral knee extension deficit (OR: 34.38; 95% CI: 25.36-46.61; p < 0.001) were associated with increased odds of extension loss prior to ACLR. No associations were found between preoperative extension loss and age at surgery, sex, preinjury Tegner activity level, or the presence of a cartilage injury. Preoperative extension loss was observed in 6.3% of the patients undergoing ACLR. Early surgery (≤3 months), medial or lateral meniscal injury, and physiologic contralateral knee extension deficit were associated with increased odds of preoperative extension loss. Awareness of these factors may assist clinicians identify patients at risk for extension loss and optimise preoperative management strategies prior to ACLR. Level III.

To investigate the graft survival rates of bilateral anterior cruciate ligament reconstruction (ACLR) and to evaluate whether the graft failure rate of bilateral ACLR is different from that of unilateral ACLR. The graft survival rate of bilateral ACLR is lower than that of unilateral ACLR. All ACLRs followed up in our institution from 1997 to 2022 were retrospectively identified. ACLRs were divided into the bilateral and unilateral ACLR groups. Each ACLR was classified as bilateral group if contralateral knee had undergone ACLR; otherwise, it was classified as unilateral ACLR group. Simultaneous ACLRs were excluded. Given the demographic heterogeneity between the groups, propensity score matching was performed with the following covariates: age, sex, body mass index, graft, meniscus lesion and follow-up period. Before and after propensity score matching, the survival rates of the two groups were compared using Kaplan-Meier survival analysis. Survival analysis was performed separately for each ACLR. In addition, clinical outcomes determined by the Lysholm score and the International Knee Documentation Committee (IKDC) score of the last outpatient visit were compared between groups. Graft failure was defined as cases that underwent revision ACLR or were recommended for revision ACLR due to objective instability on physical examination and confirmed graft rupture on MRI. In total, 979 cases of ACLRs met the inclusion and exclusion criteria, of which 94 were bilateral and 885 were unilateral ACLRs. Kaplan-Meier survival analysis showed a significantly lower survival rate in the bilateral ACLR group than that of the unilateral ACLR (log-rank test, p = 0.035). After matching for baseline characteristics, which left 94 ACLRs per group, the survival rate was significantly lower in the bilateral group (log-rank test, p = 0.033). Regarding clinical outcomes, the mean Lysholm and IKDC scores were significantly lower in the bilateral ACLR group compared with the unilateral ACLR group both before (85.3 ± 16.1 vs. 93.8 ± 8.1, p < 0.001; Lysholm, 73.0 ± 17.0 vs. 84.1 ± 11.4, p < 0.001; IKDC) and after matching (85.7 ± 15.9 vs. 91.6 ± 9.4, p = 0.014; Lysholm, 73.4 ± 16.7 vs. 73.4 ± 16.7, p = 0.008; IKDC). Bilateral ACLR is more vulnerable to graft failure than unilateral ACLR. In addition, bilateral ACLR is associated with worse clinical outcomes. Thus, bilateral ACL injury should not be regarded as merely the result of two independent unilateral ACL injuries. Rather, the two conditions should be considered distinct clinical entities. When treating bilateral ACL injury, greater efforts should be made to manage factors known to affect graft survival and more cautious rehabilitation protocol should be adopted. Level III, case-control study.

Patients with prior anterior cruciate ligament reconstruction (ACLR) are at increased risk of early medial osteoarthritis. Medial mobile-bearing (MB) unicompartmental knee arthroplasty (UKA) offers a minimal-invasive and joint-preserving alternative to total knee arthroplasty (TKA), yet evidence in ACLR patients remains limited. This study compared survivorship, reoperation causes and functional outcomes of medial MB UKA in ACLR patients versus matched controls. This retrospective 1:2 matched case-control study included 106 medial MB UKAs after ACLR (mean age 61 ± 9 years; body mass index [BMI]: 29 ± 5 kg/m2; follow-up 5 ± 2 years) and 208 matched controls (n = 4 with only one match) with a minimum follow-up of 2 years. Kaplan-Meier analysis estimated 9-year survival for reoperation, implant revision (femur and/or tibia) and conversion to TKA. Reoperation causes and PROMs (Oxford Knee Score [OKS] and UCLA Activity Score) were compared. Cumulative 9-year reoperation-free survival was significantly lower (p = 0.026) in the ACLR group (81.2%; 95% confidence interval [CI]: 71.8-90.6) compared with matched controls (92.1%; 95% CI: 88.2-96.0). Cumulative 9-year implant revision-free survival was also significantly lower (p = 0.004) in the ACLR group (89.8%; 95% CI: 81.8-97.8) compared with matched controls (98.4%; 95% CI: 96.6-100.0). For conversion to TKA, survival rates were 92.7% (95% CI: 85.3-100.0) and 98.2% (95% CI: 96.2-100.0), respectively (p = 0.071). The risk for bearing dislocation was eightfold higher in the ACLR group compared with controls (3.8% vs. 0.5%; p = 0.046). The mean postoperative OKS in the ACLR group was 42.5 ± 6.2 and 42.3 ± 6.1 in controls; the UCLA Activity Score was 6.3 ± 1.2 and 6.1 ± 1.2, respectively. Despite excellent functional outcomes, ACLR patients undergoing MB UKA face a significantly higher risk for reoperation and inferior implant survival compared with matched controls. The increased risk for additional surgery in patients with prior ACLR, particularly for bearing dislocation, should be acknowledged when indicating medial UKA, and the usage of fixed-bearing implants reduces this risk. Level III.

This study aimed to evaluate the effectiveness of an 8-week prehabilitation programme combined with standardized post-operative rehabilitation in improving functional recovery, pain control and structural healing following anterior cruciate ligament reconstruction (ACLR). A prospective randomized controlled trial was conducted with 90 male patients undergoing primary unilateral ACLR, randomly assigned to either a prehabilitation group (45 patients) or a non-preoperative rehabilitation group (45 patients). The prehabilitation group participated in an 8-week programme including neuromuscular training, strength exercises and education; another group received a home-based exercise programme for 8 weeks, while both groups received identical post-operative rehabilitation. Primary outcomes were measured using the International Knee Documentation Committee (IKDC) score at 12 months, with secondary outcomes including pain levels assessed by the visual analogue scale, Knee injury and Osteoarthritis Outcome Score, functional performance tests and structural assessments through magnetic resonance imaging (MRI). Statistical analyses included repeated-measures analysis of variance, multiple linear regression and Cox proportional hazards models. At 12-month follow-up, the prehabilitation group demonstrated significantly better outcomes compared to the non-preoperative group: IKDC scores improved by 11.3 points (92.4 vs. 77.1), pain scores were lower (0.0 vs. 1.0) and thigh muscle asymmetry was reduced (0.8 cm vs. 1.5 cm). MRI results also showed better structural healing in the preoperative rehabilitation group. The programme was identified as the strongest predictor of improved knee function and reduced recovery time by 2.6 weeks (7.2 weeks vs. 9.8 weeks). Preoperative rehabilitation is essential for better recovery after ACLR. These findings support incorporating preoperative rehabilitation into standard treatment protocols. Further research should investigate these effects in broader patient populations and examine underlying biological mechanisms. N/A.

Strategies for optimal rehabilitation after anterior cruciate ligament (ACL) reconstruction (ACLR) continue to evolve, as the incidence of contralateral ACL injuries and ACL failures varies widely in the literature, highlighting the need for optimising rehabilitation protocols. Early and intermediate rehabilitation build the crucial foundation on which later stages of rehabilitation can successfully be based, ideally leading to satisfactory outcomes and return to preinjury sports performance. However, guidelines for optimal pre- and postoperative rehabilitation management following ACLR remain conflicting, complicating evidence-based decision-making for rehabilitation following ACLR in clinical practice. Furthermore, a standardised rehabilitation protocol, adopted across different institutions, could enable more reliable comparisons of outcomes across studies focusing on surgical aspects, such as graft selection and fixation methods. An international, multidisciplinary group of experts was convened at the 2024 Freddie Fu Panther Sports Medicine Symposium to discuss and debate recent advances and future directions of rehabilitation and return to sport following ACLR. While this part of the series explores the preoperative and early to intermediate phases of rehabilitation, Part 2 highlights the complexity of return to sport and adjunct technologies after ACLR. Early recovery of knee extension, quadriceps function and early focus on movement quality are key components for achieving satisfactory outcomes after ACLR. This summary of key concepts aims to give an overview of recent evidence and current concepts of early and intermediate rehabilitation after ACLR from a multidisciplinary expert perspective and how it needs to be tailored to the individual based on graft type and patient demographics in clinical practice. LEVEL OF EVIDENCE: Level IV, expert opinion.

Background and study aimExcessive posterior tibial slope (PTS) has been identified as a biomechanical factor contributing to the risk of anterior cruciate ligament (ACL) injuries and graft failures. Notably, medial and lateral PTS (MPTS and LPTS) may have distinct influences on these outcomes. This study aims to investigate the impact of MPTS and LPTS on the likelihood of ACL graft failure.Patients and methodsThis retrospective study included 43 patients who underwent revision ACL reconstruction between 2011 and 2018 due to graft failure within two years of primary surgery. These patients were matched with a control group of 43 individuals who underwent ACL reconstruction without graft failure. Medial and lateral posterior tibial slope (MPTS and LPTS) were measured using the Hudek method on magnetic resonance imaging (MRI) and compared between the two groups. Clinical evaluation included the preoperative Tegner activity score, pivot-shift test, Lachman test, and Lysholm score, as well as the postoperative pivot-shift test, Lachman test, and Lysholm score assessed at the two-year follow-up.ResultsThe mean LPTS was significantly higher in the ACL revision reconstruction (RR) group compared to the primary reconstruction (PR) group (6.8 ± 3.6 vs. 3.2 ± 5.7, p < 0.05). However, no significant difference was observed in MPTS between the groups (3.0 ± 3.5 in the RR group vs. 2.4 ± 4.5 in the PR group, p = 0.56). Receiver operating characteristic (ROC) analysis determined an LPTS cut-off value of 6.0°. The Lachman test was positive in all patients preoperatively and became negative postoperatively in both groups. There was a significant improvement in pivot-shift grades from preoperative to postoperative evaluations in both groups. Both groups demonstrated significant improvement in Lysholm scores from preoperative to postoperative assessments, with no significant differences between the groups in either preoperative or postoperative scores.ConclusionAn increased LPTS (> 6.0°) is a significant risk factor for early ACL graft failure. Therefore, routine preoperative measurement of LPTS is recommended to identify patients at higher risk.

Pivot Shift Grade and Patient-Reported Outcomes After Repair of Lateral Meniscus Posterior Root Tears Combined With Anterior Cruciate Ligament (ACL) Reconstruction Versus Those After Isolated ACL Reconstruction at Two-Year Follow-Up

Abstract Anterior cruciate ligament (ACL) injuries are common and often require surgical reconstruction. Autografts remain the clinical standard for ACL reconstruction (ACLR) but are limited by donor site morbidity, inconsistent outcomes, and supply constraints. Here, we report the development of electrospun ligament (ES-Lig), a fully degradable, electrospun scaffold composed of poly(ε-caprolactone) (PCL) designed to mimic the extracellular matrix (ECM) of the native ACL. A scalable manufacturing process was established, incorporating electrospinning, filament stretching, alignment, and braiding. ES-Lig demonstrated controlled in vitro degradation over 12 months while retaining sufficient mechanical strength for early-stage healing. Mechanical characterisation revealed tensile properties and fixation stability comparable to autografts. In vitro biocompatibility was confirmed through cytotoxicity assays, patient-derived ACL explants, and direct cell growth onto the material. In an ovine ACLR model, ES-Lig enabled functional recovery, tissue infiltration throughout its length, and joint stability within 10 weeks post-implantation. Histological and imaging analyses confirmed graft-bone integration, vascularisation, and early ligamentisation. These findings establish ES-Lig as a promising, clinically translatable scaffold for next-generation ACL repair. Graphical abstract

Optimizing return to sports after anterior cruciate ligament reconstruction: A multi-factorial umbrella review on rehabilitation strategies.

Background and Aims Anterior cruciate ligament (ACL) tears compromise knee stability and function despite surgical reconstruction and rehabilitation and predispose patients to long‐term osteoarthritis, reduced activity levels, and persistent neuromuscular deficits. Incorporating targeted neuromuscular training into post-ACL reconstruction programs may optimize sensorimotor control, correct aberrant biomechanics, and thereby enhance performance and reduce the risk of reinjury. Therefore, this study aimed to investigate the effect of neuromuscular training on moments and knee angles during single-leg landing and kinesiophobia in individuals with ACL reconstruction. Methods In this study, 30 people with ACL reconstruction participated and were randomly divided into two groups: Control and experimental. Only the experimental group received the neuromuscular training program. Kinesiophobia was assessed with the Tampa Scale for Kinesiophobia, which has 17 items pertaining to the fear of movement and reinjury. Kinetic and kinematic data were measured using a force plate and motion analysis. The neuromuscular training program consisted of nine different exercises in 16 sessions (two sessions per week for eight weeks, each session lasting approximately one hour) that focused on increasing and coordinating dynamic flexion of lower limb joints, increasing trunk stability, and optimizing landing mechanics. A repeated measures analysis of variance (ANOVA) was used to examine the effect of training. Results The results showed that neuromuscular training had a significant effect on knee flexion angle, knee flexion torque, knee abduction angle, knee abduction torque, knee internal rotation angle, knee internal rotation torque, ground reaction force during single-leg landing, and kinesophobia in participants with ACL reconstruction (P&lt;0.05). Conclusion Neuromuscular training improves landing biomechanics and kinesiophobia in patients after ACL reconstruction. Neuromuscular training reduces the risk factors for ACL re-injury and should be emphasized during and after traditional postoperative rehabilitation.

Background: To date, no targeted pharmacological agents have been clinically available specifically for postoperative management after anterior cruciate ligament reconstruction (ACLR). Purpose: To elucidate the role of macrophage senescence in the tendon-bone interface microenvironment and assess whether targeting CD14 can mitigate senescence, thereby enhancing tendon-bone healing. Study Design: Controlled laboratory study. Methods: A murine ACLR model was used to evaluate the tendon-bone healing. Healing was assessed 8 weeks postsurgery through histological staining, micro–computed tomography analysis of neoplastic bone formation within bone tunnels, and biomechanical testing of tendon grafts. Cellular senescence was evaluated using β-galactosidase staining, while immunofluorescence and immunohistochemistry were used to analyze protein expression levels. Macrophage heterogeneity at the tendon-bone interface was assessed via t-distributed stochastic neighbor embedding projection, and senescent macrophage characteristics were investigated using CellChat, KEGG, and GO analyses. Alkaline phosphatase and Alizarin Red S staining were used to evaluate osteogenic differentiation of bone marrow mesenchymal stem cells. Results: Early inflammatory responses triggered by apoptotic cells at the tendon-bone interface resulted in macrophage senescence, activation of inflammatory pathways, increased secretion of pro-inflammatory factors, and elevated CD14 expression. Targeting CD14 reduced macrophage senescence and the inflammatory response at the tendon-bone interface, thereby increasing tendon-bone healing. Conclusion: The findings indicate that excessive inflammation within the tendon-bone interface microenvironment promotes macrophage senescence, thereby impairing tendon-bone healing. Targeting CD14 effectively prevents macrophage senescence, facilitating improved tendon-bone healing. Clinical Relevance: Currently, targeted therapeutics to enhance tendon-bone healing post-ACLR are lacking in clinical practice. The findings demonstrate that microenvironmental inflammation leading to macrophage senescence is a critical factor contributing to impaired tendon-bone healing. CD14-targeted therapy may inhibit macrophage senescence, accelerate tendon-bone healing, and offer significant translational potential for clinical application.

Background: The femoral attachment of the anterolateral ligament (ALL) reported by anatomic studies is posterior and proximal to the lateral femoral epicondyle. Purpose: To assess the femoral positioning of the ALL graft while performing a percutaneous technique and evaluate the correlation between this positioning and the graft rupture rate, as well as clinical and functional outcomes. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 211 patients undergoing combined anterior cruciate ligament (ACL) and ALL reconstruction were included. Radiological measurements, Knee injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC) score, and graft failure rate were collected at 24 months after surgery. Results: The rate of anatomic positioning of ALL femoral anchors was 79.1% (n = 167). The mean proximal and posterior distances relative to the ALL anatomic femoral position were 1.4 ± 2.8 mm and 0.2 ± 0.2 mm, respectively. The rate of outliers, defined as >5 mm from the anatomic position, was 20.85% (n = 44). The mean KOOS and IKDC score were 84 ± 10.9 and 80.1 ± 11.3, respectively. No statistically significant difference in KOOS and IKDC score was observed between the group of patients with anatomic positioning and the group of outliers (P = .1). The rate of ACL rerupture for all patients was 3.79% (n = 8). Of these, 87.5% (n = 7) were outliers. The correlation between ALL femoral malpositioning and ACL rerupture was statistically significant (P < .00001). Conclusion: Independent ALL reconstruction while performing a percutaneous technique enabled anatomic positioning of the ALL graft in 79% of cases. The femoral malpositioning was correlated with a higher ACL graft rerupture rate but not with a decrease in the functional outcomes.

Background:An alternative single-bundle anatomic anterior cruciate ligament (ACL) reconstruction (ACL-R) devised by the senior author comprised an anterolateral reinforcement using an iliotibial band (ITB) autograft. The knee biomechanics of this technique have not been compared with standard ACL-R methods.Purpose:To compare the knee kinematics of ACL-R using bone–patellar–tendon bone graft with lateral extra-articular tenodesis (BTB+LET) versus ITB ACL-R with anterolateral reinforcement.Study Design:Controlled laboratory study.Methods:A total of 20 unpaired fresh-frozen human cadaveric knees (mean age, 41.4 years) were tested using a robotic system under 3 loads: (1) 89-N anterior tibial (AT) load (at 0°-90° of flexion); (2) 5-Nm internal rotation (IR) tibial torque (0°-90° of flexion); and (3) a simulated pivot-shift (PS) load, as a combined 7-Nm valgus moment and 5-Nm IR torque (at 0°, 15°, and 30° of flexion). All knees were tested with the ACL intact; one ACL-R group (n = 10) was tested with ITB reconstruction, and the other group (n = 10) was tested with BTB graft reconstruction, both with (BTB+LET) and without a LET procedure.Results:Significantly less AT translation, IR, and tibial displacement during simulated PS were detected at all knee flexion angles in the ITB, BTB, and BTB+LET states compared with the ACL-deficient state (P < .05). There was no statistically significant difference during AT loading, IR torque, and simulated PS between BTB and ITB states at all knee flexion angles (P .05). In response to AT loading, significantly less translation was detected in the BTB+LET state compared with the ITB state at 15° (mean difference [MD], 1.6 ± 0.7 mm; P = .048), 30° (MD, 1.8 ± 0.7 mm; P = .03), and 60° (MD, 1.5 ± 0.6 mm; P = .03) of knee flexion. In response to IR torque, the only statistically significant difference between ITB and intact state was at 0° of knee flexion. In response to simulated PS, significantly less tibial displacement was detected in the BTB+LET state compared with the intact state at 15° (MD, 1.7 ± 0.5 mm; P = .04) of knee flexion.Conclusion:BTB and ITB ACL-R both improved knee stability compared with the ACL-deficient state in response to AT, IR, and simulated PS loading; however, no method restored the intact ACL behavior. BTB+LET caused overconstraint at 15° of knee flexion during simulated PS loading.Clinical Relevance:ITB ACL-R provides an alternative technique to improve stability of the ACL-deficient knee.

Older age at anterior cruciate ligament reconstruction associates with a lower systemic inflammation response index after surgery.

Anterior cruciate ligament reconstruction is frequently performed to allow athletes to return to their pre-injury levels of sports participation. A relatively low proportion of athletes successfully achieving this goal, and high rates of secondary injuries after clearance for return to sport highlight the need for optimised rehabilitation and return to sports protocols. A lack of evidence and general consensus on optimal return to sport milestones has caused substantial variability across currently applied concepts, emphasising the need for interdisciplinary approaches to bridge the gap between research findings and clinical application. This summary of key concepts aims to provide a comprehensive framework for optimising return to sport outcomes following anterior cruciate ligament reconstruction in athletes from a multidisciplinary expert perspective. An international, multidisciplinary group of experts was convened at the 2024 Freddie Fu Panther Sports Medicine Symposium to discuss and debate recent advances, future directions and emerging technological innovations of rehabilitation and return to sport following anterior cruciate ligament reconstruction. While Part 1 addressed recent evidence and strategies for early and intermediate phases of rehabilitation after anterior cruciate ligament reconstruction, Part 2 of this series explores the complexity of return to sport conceptualised as a continuum by evaluating key aspects such as functional testing, psychological readiness, and prevention of re-injury while also discussing emerging technologies that promise to enhance the future of rehabilitation and return to sports after anterior cruciate ligament reconstruction. LEVEL OF EVIDENCE: Level IV. (expert opinion).

Following anterior cruciate ligament reconstruction (ACLR), neuromuscular deficits such as impaired proprioception, altered muscle activation timing, and inter-limb loading asymmetries commonly persist and may increase the risk of ACL reinjury. Visual biofeedback has been widely used to remediate these deficits by providing task-relevant information to reduce high-risk kinematic and kinetic deviations. This narrative review synthesizes clinical applications of visual biofeedback following ACLR across three domains: (1) balance and postural control, (2) quadriceps strength and inter-limb loading symmetry, (3) landing/cutting mechanics related to reinjury risk. Evidence indicates that visual biofeedback improves postural stability and joint position sense, and it can enhance engagement with balance tasks. During weight-bearing exercise, real-time displays of vertical ground reaction force (vGRF) or center of pressure (COP) reduce loading asymmetry and may facilitate quadriceps recruitment in the surgical limb. Visual biofeedback also reduces knee abduction moment and valgus angle, and improves vGRF symmetry during landing or cutting. However, squat-based visual biofeedback does not improve peak knee extension moment symmetry during landing, indicating limited transfer of squat-based visual biofeedback to landing mechanics. These findings show that visual biofeedback can help improve deficits associated with post-ACLR when the feedback variable and training task are aligned with the intended clinical outcome. Future work, including task-specific visual biofeedback protocols that incorporate jump landing and cutting, appears necessary to facilitate correction of inter-limb loading asymmetry during high-demand tasks following ACLR.

Changes in MRI T2 mapping value in quadriceps tendon harvest donor site after anterior cruciate ligament reconstruction reflects tendon maturation and correlates with clinical scores.

An adolescent with a knee sprain was submitted to meniscoplasty for a discoid meniscus with anterior horn detachment and posterior horn rupture, achieving a pain-free full range of motion at 5 months. However, he developed knee pain and extension deficit after a year. An MRI indicated anterior arthrofibrosis despite an intact ACL (anterior cruciate ligament), confirmed and treated with arthroscopic debridement. The patient fully recovered.This case underscores the rare incidence of anterior arthrofibrosis post-meniscal repair, indicating it can develop even without ACL reconstruction (ACLR). Its formation may be related to the surgical creation of an anterior working space, similar to that in ACLR procedures, and highlights the importance of considering anterior arthrofibrosis in differential diagnoses for postoperative knee pain and extension loss. Effective management and awareness of potential risk factors are crucial for preventing such lesions.

BackgroundWe aimed to evaluate longitudinal changes in ultrashort echo time (UTE) two-component biomarkers reflecting graft ligamentization after anterior cruciate ligament (ACL) reconstruction and to identify associated clinical factors.Materials and methodsPatients who underwent ACL reconstruction were prospectively included to perform 3-T three-dimensional double-echo UTE sequence at 3, 6, and 12 months postoperatively. Mean values of short T2* (T2*s), long T2* (T2*l), and fast fraction (FF), i.e., the signal proportion attributed to the T2*s component, were calculated by fitting a biexponential model. Changes were analyzed using repeated measures analysis of variance−ANOVA. Multiple linear regression was used to assess associations between clinical factors and UTE parameters at 12 months.ResultsForty-two patients (20 males), aged 32.7 ± 15.0 years (mean ± standard deviation), were enrolled. T2*s and T2*l increased from 3 to 6 months (T2*s, 5.3 to 5.7 ms; p = 0.017; T2*l, 21.1 to 23.3 ms; p < 0.001), then decreased from 6 to 12 months (T2*s, 5.7 to 5.0 ms; T2*l, 23.3 to 21.1 ms; both p < 0.001). FF followed the opposite trend, decreasing from 0.29 to 0.25, then increasing to 0.30 (both p < 0.001). At 12 months, a higher body mass index (BMI) was associated with elevated T2*s (p = 0.005), while semitendinosus-gracilis (STG) grafts (p = 0.018) and remnant preservation (p = 0.004) were associated with lower T2*s values.ConclusionUTE two-component analysis captures temporal changes in graft after ACL reconstruction, suggesting collagen regeneration. Higher BMI may hinder, while STG grafts and remnant preservation may promote ligamentization.Relevance statementUTE two-component analysis serves as an imaging biomarker for ACL graft ligamentization, with higher BMI being associated with impaired ligamentization, while the use of STG grafts and remnant preservation may be associated with more favorable graft maturation at 12 months as assessed by UTE two-component MRI. These findings may help tailor rehabilitation protocols and guide graft selection.Trial registrationThis study was prospectively registered with the University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR) under the identification number UMIN000045710 in October 2021.Key PointsUltrashort echo time two-component analysis noninvasively evaluates ligamentization of reconstructed ACL.Graft short T2* significantly decreased between 6 and 12 months postoperatively.Body mass index, graft type, and remnant status may influence graft maturation at 12 months.Graphical