Search Results (171)

Background/Objectives: Diagnosing periprosthetic joint infection (PJI) after megaprosthetic reconstruction may be difficult due to altered inflammatory responses, extensive prior surgery, and the limited performance of conventional criteria such as the 2018 ICM score. Synovial calprotectin is a rapid neutrophil-derived biomarker that may improve diagnostic accuracy in this challenging setting. The primary aim of this study was to evaluate the diagnostic performance of synovial calprotectin in detecting periprosthetic infection in patients treated with tumor megaprostheses; secondary aims included comparison with ICM classification, assessment in infection classification-inconclusive cases, and exploratory performance in patients with low CRP. Methods: This prospective study included 20 consecutive megaprosthesis patients evaluated for suspected PJI at ATTIKON University Hospital, Athens, with a minimum follow-up of 1 year after biomarker testing. Synovial calprotectin was measured using a lateral-flow assay (positive ≥ 50 mg/L) and compared with a predefined infection reference standard. ICM final status (0 = aseptic, 1 = inconclusive, 2 = infected) was recorded for all cases. Other synovial biomarkers (α-defensin, leukocyte esterase, synovial D-dimer) were not routinely available. The cohort had a mean age of 52.9 ± 22.5 years, 70% were male, and reconstructions involved the knee (80%), hip (15%), and humerus (5%). Preoperative cultures were positive in 40%, the median systemic WBC was 7100/μL, and the median time from last surgery to testing was 1.0 years (IQR 0.46–2.0). Among infected cases, the most common microorganisms were coagulase-negative staphylococci (61.5%) and Staphylococcus aureus (23.1%), with 30.8% demonstrating polymicrobial infection. Results: Thirteen of 20 patients (65%) were classified as infected. Using the ≥50 mg/L threshold, synovial calprotectin demonstrated high apparent diagnostic accuracy in this exploratory cohort, and no false positives, yielding a sensitivity of 92.3%, specificity of 100%, PPV of 100%, NPV of 87.5%, LR+ = ∞, and LR− = 0.08. The AUC for continuous values was 1.00. Agreement with the ICM final classification was substantial (κ = 0.76), with no directional discordance (McNemar p = 1.00). Among the three ICM-inconclusive cases, calprotectin correctly reclassified two (66.7%). In patients with low CRP (<10 mg/L), a clinically difficult subgroup, calprotectin maintained strong performance (sensitivity 75%, specificity 100%, NPV 85.7%). Conclusion: Synovial calprotectin demonstrated promising diagnostic performance for PJI in megaprosthesis patients, with high sensitivity and specificity, and substantial agreement with the 2018 ICM criteria. It successfully clarified most ICM-inconclusive cases and remained reliable even in patients with low CRP. These findings support calprotectin as a valuable adjunctive biomarker in the complex diagnostic environment of megaprosthetic reconstruction and justify further validation in larger cohorts. Full article

Background/Objectives: To evaluate the short-term clinical and radiological outcomes of using custom-designed additive-manufactured acetabular components (CDAMACs) in revision total hip arthroplasty for patients with Paprosky type IIIA-IIIB acetabular defects. Materials and Methods: A retrospective single-center case series was conducted. Between 2020 and 2025, 19 patients with massive Paprosky type IIIA-IIIB acetabular defects underwent revision hip arthroplasty with CDAMACs. Preoperative planning was based on multislice computed tomography data, followed by 3D modeling and implant design. Perioperative parameters, functional outcomes (Harris Hip Score [HHS], WOMAC, Visual Analog Scale [VAS] for pain), and radiographic parameters (restoration of the center of rotation, component stability) were assessed. Minimum follow-up was 12 mo. Results: The mean operative time was 155 ± 24 min, and the mean blood loss was 718 ± 288 mL. At 12 mo, significant functional improvements were observed: the mean HHS increased from 37.5 ± 5.2 to 74.5 ± 8.6 points, WOMAC decreased from 74.5 ± 9.2 to 40.3 ± 7.6 points, and VAS decreased from 7.6 ± 1.0 to 2.8 ± 0.7 points (p < 0.001 for all). Restoration of the hip center of rotation was determined. Minimum follow-up was 12 mo. No component migration or progressive radiolucent lines were observed. Complications occurred in two patients (10.5%), with only one case directly related to the acetabular component. Conclusions: The use of CDAMACs in revision hip arthroplasty for severe Paprosky type IIIA-IIIB acetabular defects is associated with satisfactory short-term clinical, functional, and radiological outcomes. This technique enables restoration of the center of rotation and provides stable component fixation in complex anatomical conditions. Full article

Background and Objectives: Total femoral replacement (TFR) was originally developed for limb salvage following the resection of malignant tumors. Over time, its indications have expanded, now serving as a reconstructive option for failed endoprosthetic replacements and severe trauma cases. Despite its advantages, TFR is a highly complex surgical procedure associated with significant complication rates. This study aims to analyze the management of complications and propose strategies to mitigate associated risks. Materials and Methods: This is a retrospective study conducted on patients from two independent hospitals who underwent TFR for different reasons. Results: Nineteen patients were included: eight underwent TFR for oncological indications, while 11 had the procedure as a revision following failed endoprosthetic arthroplasty or trauma. Postoperative complications were observed in 10 patients (53%), including hip dislocation (21%), mechanical implant failure (11%), infection (21%), wound healing complications (26%), and metal allergy symptoms (5%). Revision surgery was required in six patients (32%), but no cases necessitated amputation. Conclusions: TFR is associated with a high risk of complications, with infection and wound healing issues being the most prevalent. In our experience effective complication management strategies should include early intervention, considering TFR at an earlier stage in non-oncological patients to minimize multiple revision surgeries; allergy screening, assessing for potential metal hypersensitivity preoperatively; dislocation prevention, implementing dual mobility bearings to reduce instability; infection control, utilizing intraoperative local antibiotic therapy in revision cases; and wound management, applying vacuum-assisted closure (VAC) therapy postoperatively to enhance wound healing. Implementing these strategies may improve patient outcomes and reduce the burden of complications associated with TFR. Full article

Introduction: An incomplete high anterior column fracture of the acetabulum is commonly considered to require completion of the fracture. However, reduction may become more difficult after completing the incomplete fracture due to plastic deformation. This study describes a surgical technique of compression osteosynthesis without completing the incomplete fracture and evaluates the clinical and radiographic outcomes. Materials and Methods: In this retrospective study, 25 patients with incomplete high anterior column fractures met the inclusion criteria. The fracture was reduced and stabilized by compression osteosynthesis through the anterior iliac approach without completing the incomplete fracture in the iliac wing. Patient demographics, the mechanism of injury, associated injuries, time to surgical reconstruction, operation time, and postoperative complications were analyzed. The quality of reduction and outcome were evaluated according to Matta’s criteria. Results: The mean operation time was 110 ± 23 min (range, 75–160). All fractures achieved bone union at a mean of 10.2 ± 1.4 weeks (range, 8–14). The quality of fracture reduction was graded as anatomical in 22 hips, imperfect in one and poor in two. Clinical results were excellent in 19 patients and good in six, and radiographic results were excellent in 22 patients and good in three. No statistically significant differences were observed between patients with and without quadrilateral plate fractures. Lateral femoral cutaneous nerve injury occurred in 13 patients (52%), mostly without significant symptoms. One patient experienced vascular injury. Conclusions: Incomplete high anterior column fractures can be effectively reduced and stabilized by compression osteosynthesis through the anterior iliac approach without completing the incomplete fracture in the iliac wing. This case series demonstrated favorable clinical and radiographic outcomes using this surgical technique. However, because this study was a retrospective case series with a small sample size and no comparative control group, further studies are required to confirm these findings. Full article

Background: In children with cerebral palsy, bony acetabular deficiencies are common and may be associated with progressive hip subluxation, abnormal joint loading, and ultimately hip dislocation. Hip reconstruction surgery is typically performed to prevent dislocation, and this includes acetabular reshaping using acetabuloplasty. The location of acetabular deficiency may vary among individuals; however, only radiographs are used for planning and intraoperative correction in many centers. Precise reconstruction and preop planning are necessary for the accurate correction of acetabular coverage. This study compares conventional hip reconstruction with a 3D-guided technique using individual preop 3D planning and 3D-printed guides during surgery to determine which method allows for a more accurate correction. We hypothesize that the patient-specific 3D planning leads to more precise anatomical correction of acetabular coverage compared to conventional freehand osteotomy. Methods: This study was registered in the German Clinical Trial Register (DRKS-ID: DRKS00031356) on 14 July 2023. In a randomized controlled trial, various imaging-based parameters were used to assess the bony anatomy preoperatively and postoperatively. Preoperative and 6-week postoperative computed tomography (CT) scans are part of routine clinical care. Additionally, an immediate postoperative CT scan was performed. One hip was operated on using individualized 3D preoperative planning, while the other hip was corrected using a conventional surgical approach. A standardized subtrochanteric osteotomy was performed for the varisation, derotation, and shortening of the proximal femur. This osteotomy was followed by acetabuloplasty under fluoroscopic control. For the 3D-planned operation, patient-specific cutting and repositioning guides were produced based on preoperative CT imaging. Patients with bilateral cerebral palsy (GMFCS levels I–V), aged 4–18 years, with an open triradiate growth plate and a migration index ≥ 40% in at least one hip were included. In a preliminary retrospective part, this project reproduces the existing three-dimensional acetabular index (3-DAI) and compares it with established radiographic methods to determine the utility and reliability of a reconstructed 3D CT measurement technique. A further component of the retrospective part is the creation of an age-adjusted database of typically developed hips and the development of a 3D head coverage index (3D-HCI) as a new 3D parameter to express acetabular coverage; therefore, it will be used as a secondary parameter and correlated to the 3DAI in the prospective part. Conclusions: Improved precision may have meaningful clinical implications for long-term joint congruency, load distribution, pain, and mobility outcomes. Full article

(1) Background: Postoperative anterior cruciate ligament reconstruction often involves quadriceps strength asymmetry, leading to abnormal lower limb biomechanics during running. While previous studies have examined the relationship between isokinetic strength and walking or jumping, the association between running, a key criterion for return to sport, and lower limb biomechanics remains unclear, particularly regarding isokinetic strength asymmetry at different angular velocities. (2) Methods: Isokinetic quadriceps strength, running kinematic, and kinetic data were collected from 39 ACLR individuals. Paired t-tests compared bilateral differences, and Pearson correlation analysis assessed associations between biomechanical parameters and muscle strength. (3) Results: The injured leg showed significantly weaker Qc at 60°/s, 180°/s, and 300°/s (p < 0.05). Compared to the uninjured leg, the injured leg demonstrated a significantly greater hip flexion angle at initial contact (p < 0.05); the injured leg exhibited significantly reduced knee flexion angle at the time of peak vertical ground reaction force and peak knee flexion angle (p < 0.05); the injured leg exhibited significantly reduced knee flexion moment at PVGRF, peak knee flexion moment, peak knee extension moment (p < 0.05). Both the 60°/s Qc and Qe showed moderate negative correlations with knee flexion angles, and 180°/s Qc correlated with knee flexion moment at PVGRF (p < 0.05). (4) Conclusions: ACLR patients show quadriceps strength asymmetry and abnormal sagittal knee and hip biomechanics during running. Strength symmetry moderately correlates with knee kinematics and kinetics in a velocity-dependent manner. Rehabilitation should focus on multi-speed and eccentric training with neuromuscular and hip–knee coordination exercises to optimize movement and support safe return to sports. Full article

Tibial torsion significantly influences knee biomechanics, yet its interaction with ACL reconstruction history in elite alpine skiers remains under-investigated. In this cross-sectional observational study, we analyzed 20 elite alpine skiers (7 ACL-reconstructed, 13 non-injured) using a markerless motion capture system during dynamic tasks (Squat, Single-Leg Squat, Lunge). Static tibial torsion was assessed via the Transmalleolar Axis and Thigh–Foot Angle. The results revealed a critical divergence in biomechanical strategies based on tibial alignment (p < 0.05). Skiers with rotational deformity adopted a pattern we describe as a “Stiffness Strategy”, characterized by suppressed knee valgus and hip rotation, but relied on excessive ankle dorsiflexion (39.5°)—a compensatory mechanism that may become limited when constrained by rigid ski boots. In contrast, ACL-reconstructed skiers with normal alignment exhibited what we term an “Instability Strategy”, showing dynamic valgus collapse and persistent asymmetry. These findings suggest that “one-size-fits-all” rehabilitation may be insufficient. We propose that injury prevention protocols may benefit from incorporating anatomical screening, focusing on decoupling mobility for skiers with tibial torsion and enhancing dynamic stability for those with normal alignment. Full article

Background/Objectives: Hip displacement is a common problem in children with cerebral palsy (CP). Typically, the recommended hip surveillance imaging for these children consists of an anteroposterior pelvic radiograph, from which we calculate the migration percentage (MP) to determine treatment plans (conservative/preventive therapy, femoral osteotomy, femoral and pelvic osteotomies, and salvage surgery). However, little is known about the accuracy of MP for treatment planning. We aim to compare treatment plans based on MP thresholds with plans determined by an orthopedic surgeon following review of the hip CTs. Methods: We retrospectively identified hip CTs performed in children who were ≤18 years old with CP (11/2018—07/2024). The inclusion criteria were: (1) a pelvic radiograph performed 6 months prior to the hip CT; and (2) no surgeries between the pelvic radiograph and the hip CT. These hip CTs were randomized and blindly reviewed by an orthopedic surgeon to determine each child’s treatment plan (CT-treatment). Separately, a pediatric radiologist blindly reviewed the randomized pelvic radiographs and measured each hip’s MP to determine each child’s treatment plan (XR-treatment). We used kappa-agreement and Bland–Altman analyses to compare XR- and CT-treatments. Results: Our study cohort consisted of 139 children (mean age = 9.3 ± 3.8 years; male = 90) with 278 hips. The proportion of agreement and unweighted kappa between XR- and CT-treatment were both low: 0.532 (148/278) and 0.339, respectively. Bland–Altman analyses showed that XR-treatment and CT-treatment were exchangeable when MP ≤ 10% but were not exchangeable otherwise. Conclusions: We should be cautious about relying exclusively on pelvic radiographs and subsequent MP calculation in making treatment decisions for hip displacement in children with CP since many anatomic details become evident on 3D imaging. Full article

The aims of this research were to characterize neuromuscular control features within the gait cycle in Parkinson’s disease (PD) from the perspectives of muscle synergies and cross-modal coupling and to propose a joint representation of the relationship between muscle activation patterns and kinematic dynamic outputs. PD participants (n = 19) were included. Lower-limb surface electromyography (EMG) and kinematic dynamic channels, including pelvic/hip, knee, and ankle angular acceleration, were collected during level-ground natural walking. EMG signals were first decomposed using non-negative matrix factorization (NMF) to extract muscle synergies, and the number of synergies was evaluated using reconstruction performance (R²). Multimodal matrix factorization (MMF) was then applied to jointly decompose the EMG and angular-acceleration channels, yielding a cross-modal synergy representation comprising a shared temporal structure (H) and modality-specific weight structures (W): non-negativity was imposed on EMG weights, whereas kinematic weights were allowed to take positive and negative values to encode directional contributions. Under the current task and muscle set, NMF achieved high EMG reconstruction performance with four synergies (R² = 0.882). The synergy weights showed an ankle-dominant pattern: tibialis anterior (TA) consistently carried high weights across multiple synergies, while lateral gastrocnemius (LG) and soleus (SOL) contributed prominently to another synergy. The synergy activation profiles exhibited phase-dependent fluctuations with multiple rises and falls across the gait cycle, suggesting that synergy output was primarily characterized by continuous modulation rather than single-peak recruitment. MMF further identified eight cross-modal synergies, simultaneously capturing the shared contributions of key muscle groups (e.g., RF, TA, and SOL) and pelvic/hip and knee/ankle angular-acceleration channels within the same decomposition framework and summarizing their descriptive co-variation through the shared temporal structure (H). Overall, A low-dimensional synergy analysis combining EMG-only NMF with cross-modal MMF enables simultaneous characterization of cohort-level modular organization of muscle activity during gait and its descriptive association with pelvis-to-lower-limb dynamic output. This joint framework provides a methodological basis for quantitatively describing gait-related modular organization and temporal modulation patterns in this PD cohort under natural level-ground walking and lays the groundwork for subsequent testing of associations between synergy features and gait phenotypes, clinical severity, and rehabilitation responses. Full article

Background/Objectives: Neurogenic heterotopic ossification (HO) is an abnormal formation of lamellar bone in soft tissues, frequently developing near major joints in patients with spinal cord injury. While imaging provides valuable diagnostic insights, large and anatomically complex HO often requires advanced preoperative planning to minimize surgical risks. This study presents the development and clinical application of a structured six-stage workflow integrating three-dimensional (3D) technologies for the preoperative planning and surgical resection of giant iliofemoral HO. Materials and Methods: A workflow was developed comprising: (1) 3D imaging acquisition, (2) creation of a virtual model, (3) production of a life-size physical model, (4) preoperative simulation, (5) surgical resection, and (6) postoperative imaging validation. The workflow was applied to a 50-year-old male with paraplegia after a T12 fracture who developed a 26 cm iliofemoral bony bridge, confirmed by computed tomography and 3D reconstruction. Results: The physical model provided a precise anatomical reference, enabling detailed surgical rehearsal and safe planning of neurovascular dissection. Resection was performed using combined orthopedic and vascular techniques. The hip joint was preserved, and postoperative rehabilitation achieved improved range of motion and patient handling without major complications. Conclusions: This structured 3D-assisted workflow enhanced anatomical understanding and surgical precision in this complex case. The framework is applicable to other extensive ossifications with intricate anatomical relationships and warrants further evaluation in larger series. Full article

Background. Accurate assessment of lower limb alignment is critical in diagnostic decision-making for musculoskeletal disorders. This study aimed to validate the PAViR (Posture Analyzing and Virtual Reconstruction) system, a non-invasive device based on artificial vision and 2D photogrammetry, for measuring the Hip–Knee–Ankle (HKA) angle. Method. A total of sixty-one adult participants were evaluated using the PAViR system, and the results were compared against Kinovea, a validated open-source software commonly used for 2D kinematic and angular analysis in clinical and sports biomechanics. Statistical analyses included the Shapiro–Wilk test, Pearson correlation, and Bland–Altman plots. Results. The correlation between both systems was perfect (r = 0.999; p < 0.001). The Bland–Altman analysis showed differences of 0.03° (left) and 0.04° (right), with limits of agreement between −0.25° and +0.75°, within the clinically acceptable margin of ±2°. These findings demonstrate that the PAViR system shows excellent agreement with a validated 2D photogrammetry reference method for measuring the Hip-Knee-Ankle angle in asymptomatic adults. The narrow limits of agreement (−0.25° to +0.75°) and minimal systematic bias (0.03–0.04°) support the technical validity of PAViR for static coronal plane alignment assessment under controlled conditions. Conclusions. Further validation studies in clinical populations and dynamic contexts are necessary to establish broader applicability and clinical utility. Its integration could enhance lower limb assessment in orthopedic, sports, and preventive care. Further validation studies in clinical populations with musculoskeletal pathology, dynamic functional contexts, and direct comparison with radiographic gold standards are necessary to establish broader applicability and clinical utility. Full article

Modified Spitzy shelf acetabuloplasty is a joint-preserving surgical procedure for acetabular dysplasia that aims to enhance bony coverage of the hip joint. Although prior studies have primarily relied on two-dimensional (2D) radiographic evaluations, comprehensive three-dimensional (3D) assessments remain limited. The purpose of this retrospective study was to evaluate changes quantitatively in acetabular coverage following modified Spitzy shelf acetabuloplasty using 3D models reconstructed from computed tomography (CT) images. We retrospectively analyzed 11 hips in 11 patients who underwent staged bilateral modified Spitzy shelf acetabuloplasty. Preoperative and postoperative CT data were used to construct 3D pelvic models, which were registered using anatomical landmarks. Bone graft dimensions, insertion angle, and placement location were evaluated. Acetabular sector angles (ASA), representing circumferential coverage of the femoral head, were measured at 15° intervals on the functional pelvic plane and the anterior pelvic plane. The mean bone graft dimensions were 26.3 ± 3 mm (anteroposterior length) and 12.7 ± 2.7 mm (mediolateral length), providing coverage of 49.5° ± 9.1°. Postoperative ASA increased significantly from 34.5° to 60° on the functional pelvic plane and from 0° to 45° on the anterior pelvic plane (both p < 0.05). 3D analysis demonstrated that modified Spitzy shelf acetabuloplasty effectively enhanced anterosuperior acetabular bony coverage. Although this is a report of a few cases (11 hips), the above findings highlight the value of 3D evaluation in identifying postoperative changes that may not be detected using conventional 2D assessments. Also, further research analyzing the three-dimensional bone graft model revealed in this study may help inform the development of a more ideal biomimetic approach, not only in terms of shape but also function. Full article

Background: This study aimed to investigate the association between femoroacetabular impingement (FAI) morphology and femoral head bone marrow edema of unknown etiology on hip magnetic resonance imaging (MRI), and to assess the added value of computed tomography-based three-dimensional maximum intensity projection (CT-MIP) measurements in identifying a predisposition to acetabular overcoverage. Methods: Hip MRI examinations performed between January 2007 and 2025 were retrospectively reviewed. Cases with bone marrow edema attributable to identifiable etiologies were excluded. Twenty-six patients with available hip or pelvis computed tomography (CT) examinations obtained within one year were included, along with an age- and sex-matched control group imaged for indications unrelated to hip pain. A total of 104 hip joints were evaluated. Alpha angles were measured on axial oblique CT reformations. Virtual pelvic radiographs generated from CT-based three-dimensional reconstructions were used for lateral center-edge angle (LCEA) measurements, and acetabular coverage was quantified using the acetabular coverage index derived from CT-MIP images. Appropriate statistical analyses were performed, with p < 0.05 considered statistically significant. Results: FAI was identified in 82.7% of cases with bone marrow edema of unknown etiology on MRI (p < 0.001), with pincer-type morphology being the most prevalent subtype (55.8%). Bone marrow edema was significantly more common in pincer-type FAI compared with other subtypes (p < 0.001) and predominantly involved the posterolateral femoral head. Mean alpha angle, LCEA, and acetabular coverage index values were significantly higher in the case group than in controls (p < 0.001). For the detection of pincer-type FAI, CT-MIP-based acetabular coverage index demonstrated superior diagnostic performance compared with LCEA (AUC, 0.917 vs. 0.855; p = 0.017), with an optimal cutoff value of 0.93 yielding high specificity and accuracy. All measurements showed excellent intraobserver and interobserver reliability. Conclusions: Femoral head bone marrow edema of unknown etiology may serve as a radiologic clue to underlying pincer-type FAI, while CT-MIP-based analyses may provide incremental value beyond conventional angular measurements in characterizing acetabular overcoverage. Full article

Human mobility is commonly assessed in the laboratory environment, but accurate and robust joint motion measurement and task classification in the home setting are rarely undertaken. This study aimed to develop a digital twin model of a home to measure, visualize, and classify joint motion during activities of daily living. A fully furnished single-bedroom apartment was digitally reconstructed using 3D photogrammetry. Ten healthy adults performed 19 activities of daily living over a 2 h period throughout the apartment. Each participant’s upper and lower limb joint motion was measured using inertial measurement units, and body spatial location was measured using an ultra-wide band sensor, registered to the digital home model. Supervised machine learning classified tasks with a mean 82.3% accuracy. Hair combing involved the highest range of shoulder elevation (124.2 ± 21.2°), while sit-to-stand exhibited both the largest hip flexion (75.7 ± 10.3°) and knee flexion (91.8 ± 8.6°). Joint motion varied from room to room, even for a given task. For example, subjects walked fastest in the living room (1.0 ± 0.2 m/s) and slowest in the bathroom (0.78 ± 0.10 m/s), while the mean maximum ankle dorsiflexion in the living room was significantly higher than that in the bathroom (mean difference: 4.9°, p = 0.002, Cohen’s d = 1.25). This study highlights the dependency of both upper and lower limb joint motion during activities of daily living on the internal home environment. The digital twin modeling framework reported may be useful in planning home-based rehabilitation, remote monitoring, and for interior design and ergonomics. Full article

Approximately two-thirds of athletes who are submitted to Anterior Cruciate Ligament Reconstruction (ACLR) never return to their preinjury level of performance, potentially due to muscle strength deficiencies or altered loading patterns during landing or jumping tasks. This study aimed to estimate individual muscle forces during a double-leg drop jump task, and assess sagittal plane between-limb asymmetries in muscle forces and ground reaction forces using a musculoskeletal modelling approach, in athletes who underwent ACLR. Thirty male field-sport athletes (age: 18–35 years; mass: 84.3 ± 12.3 kg; height: 180.2 ± 8.4 cm) post-ACLR (39.8 ± 3.9 weeks) using patellar or quadriceps tendon grafts were tested. Scaled musculoskeletal models were implemented in OpenSim, and muscle forces were estimated using the Computed Muscle Control optimization method. The contralateral limb exhibited greater vertical ground reaction forces across most of the rebound phase (d = 2.01). Compared with the contralateral limb, the ACLR limb showed reduced quadriceps (d = 1.72), soleus (d = 0.95), and gluteus maximus (d = 0.83) forces, indicating deficits in knee extensor, plantarflexor, and hip extensor neuromuscular function. Smaller asymmetries were found for the gluteus medius (d = 0.60) and hamstrings (d = 0.72), while other muscles showed symmetrical activation patterns. These results reveal persistent between-limb asymmetries in muscle recruitment and loading up to nine months post-ACLR, emphasizing the importance of targeted rehabilitation to restore symmetrical neuromuscular control during explosive movements. Full article