Search Results (422)

Genu valgum (GV) is a common lower limb deformity that may increase the risk of anterior cruciate ligament (ACL) injury. This study used OpenSim musculoskeletal modeling and kinematic analysis to investigate the mechanical responses of the ACL under fatigue in females with GV. Eight females with GV and eight healthy controls completed a running-induced fatigue protocol. Lower limb kinematic and kinetic data were collected and used to simulate stress and strain in the anteromedial ACL (A–ACL) and posterolateral ACL (P–ACL) bundles, as well as peak joint angles and knee joint stiffness. The results showed a significant interaction effect between group and fatigue condition on A–ACL stress. In the GV group, A–ACL stress was significantly higher than in the healthy group both before and after fatigue (p < 0.001) and further increased following fatigue (p < 0.001). In the pre-fatigued state, A–ACL strain was significantly higher during the late stance phase in the GV group (p = 0.036), while P–ACL strain significantly decreased post-fatigue (p = 0.005). Additionally, post-fatigue peak hip extension and knee flexion angles, as well as pre-fatigue knee abduction angles, showed significant differences between groups. Fatigue also led to substantial changes in knee flexion, adduction, abduction, and hip/knee external rotation angles within the GV group. Notably, knee joint stiffness in this group was significantly lower than in controls and decreased further post-fatigue. These findings suggest that the structural characteristics of GV, combined with exercise-induced fatigue, exacerbate A–ACL loading and compromise knee joint stability, indicating a higher risk of ACL injury in fatigued females with GV. Full article

Quadricep weakness is frequently observed in patients following anterior cruciate ligament (ACL) injury or in those with knee osteoarthritis, often contributing to functional impairments and persistent symptoms. While high-intensity resistance training has been shown to effectively improve muscle strength, its application may be limited in certain populations due to pain or the risk of surgical complications. In recent years, blood flow restriction (BFR) training has emerged as a promising alternative. Growing evidence indicates that low-load BFR exercise can significantly improve muscle strength, induce hypertrophy, and enhance knee function, with outcomes comparable to those of high-intensity resistance training. When implemented using appropriate protocols, BFR training appears to be a safe and efficacious rehabilitation strategy for individuals with knee pathology. Full article

Background/Objectives: Serum 25-hydroxyvitamin D (25(OH)D) concentrations are decreased with metabolic syndrome (MetSy), and low serum 25(OH)D concentrations are associated with poor outcomes following anterior cruciate ligament (ACL) reconstruction (ACLR). It is unknown whether serum 25(OH)D concentrations are decreased in patients with MetSy following ACLR. The purpose of this study was to investigate whether serum 25(OH)D concentrations are decreased with MetSy following ACLR. Methods: This retrospective case–control study consisted of patients (≥18 years) who underwent ACLR. MetSy was defined as meeting any three of the five criteria (cases): (1) body mass index ≥ 30 kg/m², (2) triglycerides ≥ 150 mg/dL, (3) HDL < 40 mg/dL in men and <50 mg/dL in women, (4) systolic blood pressure ≥ 130 mmHg or diastolic blood pressure ≥ 85 mmHg, or (5) estimated (from hemoglobin A1c% [HbA1c]) fasting glucose ≥ 100 mg/dL. Participants without MetSy (meeting <3 criteria) served as controls. The first blood lipid, HbA1c, and 25(OH)D assessed ≥90 d after ACLR were included in this study. Results: The final analysis consisted of 219 patients (cases (with MetSy), n = 84; controls (without MetSy), n = 135). Serum 25(OH)D was significantly (p < 0.01) decreased (15.8%) in cases (mean [SD]; 25.1 [11.3] ng/mL) compared to controls (29.8 [14.8] ng/mL). An increasing number of MetSy components was associated with a decreased prevalence of vitamin D sufficiency (p < 0.01). Conclusions: We conclude that serum 25(OH)D concentrations are significantly lower with MetSy. These preliminary findings could provide justification for assessing serum 25(OH)D following ACLR in patients with MetSy and assist with risk stratification. Full article

Tendinopathies are a significant challenge in musculoskeletal medicine, with current treatments showing variable efficacy. Electromagnetic transduction therapy (EMTT) has emerged as a promising therapeutic approach, but its biological effects on tendon cells remain largely unexplored. Here, we investigated the effects of EMTT on primary cultured human tenocytes’ behavior and functions in vitro, focusing on cellular responses, senescence-related pathways, and molecular mechanisms. Primary cultures of human tenocytes were established from semitendinosus tendon biopsies of patients undergoing anterior cruciate ligament (ACL) reconstruction (n = 6, males aged 17–37 years). Cells were exposed to EMTT at different intensities (40 and 80 mT) and impulse numbers (1000–10,500). Cell viability (MTT assay), proliferation (Ki67), senescence markers (CDKN2a/INK4a), migration (scratch test), cytoskeleton organization (immunofluorescence), and gene expression (RT-PCR) were analyzed. A 40 mT exposure elicited minimal effects, whereas 80 mT treatments induced significant cellular responses. Repeated 80 mT exposure demonstrated a dual effect: despite a moderate decrease in overall cell vitality, increased Ki67 expression (+7%, p ≤ 0.05) and significant downregulation of senescence marker CDKN2a/INK4a were observed, suggesting potential senolytic-like activity. EMTT significantly enhanced cell migration (p < 0.001) and triggered cytoskeletal remodeling, with amplified stress fiber formation and paxillin redistribution. Molecular analysis revealed upregulation of tenogenic markers (Scleraxis, Tenomodulin) and enhanced Collagen I and III expressions, particularly with treatments at 80 mT, indicating improved matrix remodeling capacity. EMTT significantly promotes tenocyte proliferation, migration, and matrix production, while simultaneously exhibiting senolytic-like effects through downregulation of senescence-associated markers. These results support EMTT as a promising therapeutic approach for the management of tendinopathies through multiple regenerative mechanisms, though further studies are needed to validate these effects in vivo. Full article

Background and Objectives: Anterior cruciate ligament (ACL) injury rates remain high and have a significant impact on female football players. This study aims to evaluate knee kinematics and lower limb muscle activity in players at risk of ACL injury compared to healthy players through three side-cutting tests. It also investigates how the amplitude of a change in direction influences stabilization parameters. Materials and Methods: A cross-sectional case–control study was conducted with 16 second division female futsal players (23.93 ± 5.16 years), divided into injured (n = 8) and healthy groups (n = 8). Injured players had a history of non-contact knee injury involving valgus collapse, without undergoing surgical intervention. Three change of direction tests, namely the Change of Direction and Acceleration Test (CODAT), Go Back (GOB) test, and Turn (TURN) test, were used for evaluation. The peak and range of knee joint angles and angular velocities across three planes, along with the average rectified and peak envelope EMG signals of the Biceps Femoris (BF), Semitendinosus (ST), Vastus Medialis (VM), and Lateral Gastrocnemius (LG), were recorded during the preparation and load phases. Group differences were analyzed using two-factor mixed-model ANOVA with pairwise comparisons. Statistical significance was set at p < 0.05. Results: Injured players demonstrated lower external tibial rotation angular velocity and a greater range of motion in tibial external rotation compared to healthy players. Additionally, the injured group showed significantly higher average rectified muscle activity in VM and LG both increased by 4% during the load phase. The CODAT and TURN tests elicited higher BF and VM muscle activity, compared to the GOB test. The TURN test also showed greater extension angular velocity in the sagittal plane. Conclusions: The results revealed differences in knee kinematics and muscle activity between players at risk of ACL injury and healthy players, influenced by the amplitude of directional changes. Players altered transverse plane mechanics and increased VM and LG activation during LOAD may reflect a dysfunctional motor pattern, while the greater sagittal plane angular velocity and VM and BF activation from the CODAT and the TURN test highlight their higher potential to replicate ACL injury mechanisms compared to the GOB test. Full article

Knee rotational stability is crucial for anterior cruciate ligament (ACL) procedures, yet, current clinical assessments are subjective and lack precision. This study evaluates the accuracy and repeatability of the GATOR system, developed by PreciX Pte Ltd. and integrating ultrasound with inertial measurement units (IMUs), against a reference IMU (Xsens DOTS) for measuring knee flexion and rotation in six cadaveric specimens secured in an Oxford Knee Jig. Two experiments were conducted: (A) knee flexion from 0° to 120°, and (B) internal/external rotation at 0°, 30°, 60°, 90°, and 120° flexion. Analysis using Bland–Altman plots, root mean square error (RMSE: 3.93° for internal rotation, 6.90° for external rotation), mean biases, and paired t-tests (Bonferroni corrected) revealed that GATOR recorded lower peak flexion angles (91.49–114.65°) compared to the reference (110.31–118.49°). For rotation, internal rotation showed narrower limits of agreement than external rotation (biases: 1.91–6.88°). Over 60% of trials had errors < 5°, and 80% < 10°, indicating good agreement. Despite no isolated comparison of GATOR’s ultrasound component, findings suggest reduced soft tissue artifact due to bone-referenced sensor alignment. With optimal placement (10–15 cm from the knee center), GATOR shows promise in ACL assessment and remote rehabilitation. Full article

Anterior cruciate ligament (ACL) injury (ACLI) is a prevalent sports injury. Genetic factors play a crucial role in determining the risk of ACLI. This systematic review aimed to identify the association between the COL5A1 rs13946 polymorphism and susceptibility to ACLI. Methods: Searches were performed in PubMed Central, Web of Science, EBSCOhost, Scopus, and CNKI. The Newcastle–Ottawa Scale (NOS) was used to assess potential bias, and data from the included studies were analyzed using RevMan 5.4. The odds ratio (OR) and 95% confidence intervals (95% CI) were calculated to determine the strength of the association between COL5A1 rs13946 and the risk of anterior cruciate ligament injury. A p value < 0.05 was considered statistically significant. Seven studies met the inclusion criteria for screening the association between COL5A1 rs13946 and ACL injury and were included in this meta-analysis. The meta-analysis revealed no significant heterogeneity across five genetic models. Statistically significant findings were observed in the recessive (OR = 1.29, 95% CI [1.06, 1.58], p = 0.01) and allele models (OR = 0.85, 95% CI [0.73, 1.00], p = 0.04). The TT genotype or T allele of rs13946 showed a distinct susceptibility to ACLI under the recessive model, particularly in Caucasians. This study supports the association between COL5A1 rs13946 and the risk of ACLI, particularly in Caucasians. More specifically, the C/- genotype of rs13946 provides protection against ACLI in Caucasians. Further research with larger sample sizes and well-balanced gender-specific cohorts is necessary to validate this association and strengthen our findings. Full article

Background: The quadriceps femoris (QF) muscle is traditionally described as a four-headed structure (QF4), yet recent anatomical studies have identified significant morphological variations, including accessory heads and complex quadriceps femoris tendon (QFT) layering. These anatomical differences are especially relevant when harvesting the QFT for anterior cruciate ligament (ACL) reconstruction, where graft quality and structure are critical to surgical success. This study aimed to systematically review and quantitatively synthesize available data on QF variants, with a focus on accessory heads and tendon architecture. Methods: This systematic review and meta-analysis followed PRISMA 2020 and Evidence-Based Anatomy Workgroup guidelines. Cadaveric studies reporting QF variants were identified through searches of multiple databases and anatomical journals. Pooled prevalence estimates and mean QFT lengths were calculated using random-effects models. Heterogeneity and publication bias were also assessed. Results: Eighteen studies encompassing 1066 lower limbs met inclusion criteria. The five-headed QF (QF5) was the most common variant (54.11%), followed by the classical four-headed form (QF4) (40.74%). Rare morphologies with six to eight heads (QF6–QF8) were also documented. Among accessory heads, the vastus lateralis (VL) type was most prevalent (21.35%), while an independent tensor vastus intermedius (TVI) occurred in 13.54% of limbs. The QFT most frequently displayed a trilaminar structure (47.73%), with quadrilaminar architecture observed in 42.49%. The mean QFT length was 78.63 mm. Conclusions: This meta-analysis confirms that the QF often deviates from classical anatomical descriptions, frequently exhibiting supernumerary heads and multilayered tendon architecture. These findings highlight the importance of detailed preoperative imaging and personalized surgical planning to minimize complications and optimize graft selection in ACL reconstruction. Full article

Background: The intercondylar notch (IN) houses the central ligaments of the knee joint, namely the anterior and posterior cruciate ligaments (ACL and PCL) as well as the anterior and posterior meniscofemoral ligaments (aMFL and pMFL). As not only the available intercondylar space directly influences the encased ligaments, but also the ligaments themselves may influence each other, the purpose of this study was to evaluate the influence of osteoarthritis on central ligament morphology. Methods: Imaging data from the osteoarthritis initiative was used to assess 415 randomly selected patients, equally distributed across five groups based on osteoarthritis severity using the Kellgren and Lawrence classification. MRI scans were used to measure ligament structures in the coronal, axial and sagittal planes. The ACL was evaluated and classified into healthy, pathologic and ruptured. The relationship between osteoarthritis severity and the shape of the IN (A-shape, inverse-U-shape and Ω-shape) was analyzed in relation to ligament morphometrics and ACL condition. Results: The morphology of the ligaments is directly influenced by the development of osteoarthritis. In particular, the Ω-shape, which is associated with severe-grade osteoarthritis, is a risk factor for the development of ACL rupture (p < 0.001). But also, the condition of the ACL influenced the morphometrics of the posterior ligaments, and the PCL as well as the MFLs influenced each other. Conclusions: Statistically significant morphological changes to the encased ligaments in the intercondylar space in osteoarthritis were reported. In particular, the ACL shows a higher risk for pathological changes during ongoing joint degeneration due to osteoarthritis. The other evaluated ligaments—MFLs and PCL—are influenced by the condition of the osseous structures and the shape of the IN as well as by the condition and continuity of the ACL. Full article

Background and Objectives: This study aimed to evaluate the influence of the angle and position of the tibial tunnel in the coronal and sagittal planes on short-term postoperative clinical outcomes following arthroscopic anterior cruciate ligament reconstruction (ACLR). Materials and Methods: This retrospective study included 40 patients who underwent anatomical ACLR between 1 January 2023 and 31 December 2023 and had a follow-up period of at least 4 months. The angle of the tibial tunnel on the AP radiograph and both the angle and anteroposterior position on the lateral radiograph were measured. Clinical evaluations were conducted using the Visual Analogue Scale (VAS), the International Knee Documentation Committee (IKDC) score, and the Lysholm Knee Score, along with measurements of knee flexion and extension, to assess short-term outcomes at 1, 2, and 4 months postoperatively. Results: In patients whose tibial tunnels were positioned at 40–50° in the coronal plane, Lysholm scores were significantly higher at the 2nd and 4th months compared to other angles. In the sagittal plane, a tunnel angle between 30° and 40° was associated with significantly increased IKDC scores at both the 2nd and 4th months. Additionally, tunnels with an anterior–posterior ratio of 0.4–0.6 in the sagittal plane were associated with limitations in flexion and extension at the 4th month. There was no significant difference in VAS scores between the groups. Conclusions: Our findings suggest that optimizing the tibial tunnel angle in both the coronal and sagittal planes may play a crucial role in early postoperative knee function. Specifically, tibial tunnels placed between 40° and 50° in the coronal plane and 30° and 40° in the sagittal plane were associated with higher functional scores. However, tunnels positioned with an anterior–posterior ratio of 0.4 to 0.6 were linked to greater joint motion limitation. These findings indicate that angular and positional optimization of the tibial tunnel may have contributed to improved functional recovery following ACL reconstruction. Full article

Youth sport participation provides undeniable physical, emotional, and social benefits. However, the current landscape of pediatric athletics has shifted toward early sports specialization (ESS), year-round training, and heightened competitive pressures. This has led to an increased prevalence of overuse-related traumatic injuries in adolescent patients, as well as increased risk of worsening mental health due to burnout, depression, suicide, and general psychological distress. There are numerous innovations and solutions aimed at addressing the increased risk of injury associated with current sporting trends, such as neuromuscular training programs, delayed specialization, promotion of free play, and pediatric specific surgical techniques mindful of future growth, such as those seen for anterior cruciate ligament reconstruction (ACL-R). However, the social factors associated with an injury remain problematic and are not adequately addressed; these include social isolation, depression, anxiety, and academic decline. Sport psychology is a promising solution to address many risk factors associated with poor performance, address the challenges associated with injury, and increase return-to-play in adolescent sports medicine. Integrating sport psychology into pediatric sports medicine offers the ability to directly address the emotional and cognitive demands of injury and recovery. Emphasizing mental health support and redefining success in youth sports—prioritizing enjoyment, personal growth, and long-term health over scholarships and professional aspirations—are key steps in preserving the overall benefits of pediatric sport participation. Yet sport psychology remains often underutilized and has been slow to gain traction, particularly in youth sports. This editorial serves to highlight the current state of mental health advocacy in pediatric sports medicine and how sport psychology can help young athletes manage the mental stress of high-performance athletics and mitigate the detrimental effect of injury and delayed return to sport. Full article

The knee is one of the most frequently injured joints, involving various structures. To prevent reinjury after rehabilitation, braces are commonly used. However, most studies on knee supports focus on subjects with anterior cruciate ligament (ACL) injuries and do not account for muscle fatigue, which typically occurs during prolonged intense training and can significantly increase the risk of injury. Hence, this study investigates the acute effects of wearing a knee brace on biomechanics in subjects with a history of various unilateral knee injuries or pain under muscle fatigue. In total, 50 subjects completed an intense fatigue protocol and then performed counter-movement jumps and running tests on a force plate while tracking kinematics with a marker-based 3D motion analysis system. Additionally, subjects filled out a visual analog scale (VAS) to assess knee pain and stability. Tests were conducted on the injured leg with and without a knee brace (Sports Knee Support, Bauerfeind AG, Zeulenroda-Triebes, Germany) and on the healthy leg. Results indicated that wearing the knee brace stabilized knee movement in the frontal plane, with a significant reduction in maximal medio-lateral knee acceleration and knee abduction moment during running and jumping. The brace also normalized loading on the injured leg. We observed higher maximal knee flexion moments, which were associated with increased vertical ground reaction forces, segment velocities, and knee flexion angles. Subjects reported less pain and greater stability while wearing the knee brace. Therefore, we confirm that wearing a knee brace on the injured leg improves joint biomechanics by enhancing stability and kinematics and reducing pain during running and jumping, even with muscle fatigue. Consequently, wearing a knee brace after a knee joint injury may reduce the risk of reinjury. Full article

Objective: The resistive knee orthosis, as a novel rehabilitation device, is designed to provide resistance to joint movement during continuous walking, thereby enhancing the postoperative recovery effect. This study aims to explore the impact of such orthoses on the joint coordination patterns of martial artists after anterior cruciate ligament (ACL) reconstruction. Methods: A total of 44 martial artists who underwent ACL reconstruction were recruited and divided into an experimental group (EG, n = 22, using resistive braces) and a control group (CG, n = 22, using conventional braces). Assessments were conducted preoperatively (T0) and at 15 days (T1), 30 days (T2), and 60 days (T3) postoperatively. The changes in joint coordination patterns during the gait cycle were analyzed, and the ACL force was estimated using a musculoskeletal model. Results: At T2 and T3, compared with the CG, the EG exhibited a significantly larger peak knee flexion angle (p < 0.05). At T3, the EG showed higher hip–ankle in-phase coordination (p < 0.05), increased proximal hip–knee coordination (p < 0.05), and decreased knee–ankle anti-phase coordination (p < 0.05). In addition, the ACL force in the EG was significantly lower. Conclusions: The resistive knee orthosis can effectively improve the joint coordination of martial artists after ACL reconstruction and reduce the ACL force. Full article

Background: Anterior cruciate ligament (ACL) injury is more prevalent in young athletes and women. A deficit of knee flexor strength and a H/Q strength ratio below 0.6 in athletes are risk factors. Therefore, the main objective of this study is to determine if there are differences in the strength of the knee musculature, joint work, and H/Q ratio between professional and junior elite basketball players and sexes, since there are differences in the incidence of ACL injuries between these groups. Methods: Forty-three professional (27 male and 16 female) and 42 junior elite (28 male and 14 female) basketball players were evaluated. Dynamometric knee flexion and extension measurements were performed on both lower limbs at three angular velocities: 30°/s, 120°/s, and 180°/s. Concentric knee flexion and extension strength variables were measured in Newtons, the strength ratio between flexors and extensors in H/Q ratio, and muscle work (product of force times displacement) in Joules. Comparisons of the measured variables were made between categories and sexes. Results: Significant differences (p < 0.05) were found between categories (professional and junior) in all measured strength parameters as well as in joint work. No differences were found between categories in the H/Q ratios. Significant differences (p < 0.05) were found between sexes in most measured strengths and joint work. However, no differences were found in most of the H/Q ratios. Female basketball players have lower values of strength and muscle work than male players, however, in the H/Q ratio data there are no differences between the two groups. The same occurs between junior and professional athletes. Conclusions: The authors conclude that flexor and extensor strength values should be analyzed in isolation and not in terms of the H/Q ratio. Full article

Objectives: Some following up patients have poor clinical outcomes when they experience anterior cruciate ligament reconstruction. The patient will undergo progression of knee joint osteoarthritis or several secondary knee procedures such as high tibial osteotomy, total knee arthroplasty, menisectomy, meniscus repair, or meniscus transplantation on their knees after anterior cruciate ligament reconstruction. This may be related to the remaining instability of the knee joint, changes in the knee joint biomechanics, and progression of osteoarthritis. This study aims to determine which secondary knee procedures are performed over time after anterior cruciate ligament reconstruction. Methods: The National Health Insurance Service-Health Screening database analyzed 146,122 patients who underwent ACL reconstruction surgery between 1 January 2002 and 31 December 2021. Secondary knee procedures were investigated by categorizing them into revisional reconstruction, high tibial osteotomy, total knee arthroplasty, menisectomy, meniscus repair, and meniscus transplantation, respectively. Multivariable Cox Proportional Hazard model analysis was used. The significant predictors for complications (p < 0.05) were as follows. Results: Among a total of 146,122 patients with anterior cruciate ligament reconstruction, 1073 (0.7%) patients underwent HTO, 908 (0.6%) patients underwent TKA, 15,218 (10.4%) patients underwent meniscectomy, 7169 (4.9%) patients underwent meniscus repair, and 938 (0.6%) patients underwent meniscus transplantation. The hazard ratio differed according to graft type, gender, and age group. Conclusions: Patients who undergo ACL reconstruction may experience poor clinical outcomes, such as progression of osteoarthritis and undergoing secondary knee procedures several years after ACL reconstruction. It is important for decision-making, ongoing monitoring, and follow-up care for patients undergoing ACL reconstruction. Full article