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PubMed2026

Could creatine supplementation combined with physical rehabilitation accelerate return to play in athletes with patellar tendinopathy?

BACKGROUND: Several dietary supplements have been proposed to positively influence the rehabilitation process following injury. However, to date, no studies have specifically examined the effects of scientifically supported ergogenic aids on recovery outcomes when combined with physical performance interventions. Therefore, the aim of this study was to analyze the ergogenic effects of creatine supplementation on neuromuscular performance, tendon thickness, pain, and body composition in athletes diagnosed with patellar tendinopathy (PT). METHODS: Using a triple-blind experimental design, 20 federated athletes (age: 33.7 ± 9.84 years) with PT were randomly assigned to either a creatine supplementation group (CR; n = 9) or a placebo group (PLA; n = 11). All participants followed a physical rehabilitation intervention that included daily eccentric training combined with stretching exercises, along with one session every 10 days of extracorporeal shock wave therapy (ESWT) and manual therapy targeting the tendon and surrounding muscle tissue. At the end of each eccentric training session, the participants ingested 3 capsules of creatine monohydrate - Creapure® (CR) or sucrose (PLA). At the beginning (PRE), after 4 weeks (MID), and after 8 weeks (POST), the pain level (Victorian Institute for Sports Assessment-Patella, VISA-P), tendon thickness (echography), body composition (bioelectrical impedance system), and neuromuscular performance using a countermovement jump test (CMJ) and a strength test (5-RM) of knee extension in the injured leg. RESULTS: A significant main effect of time was observed for VISA-P scores (p < 0.001; η2 p = 0.626), indicating a reduction in pain over time in both the creatine (CR) and placebo (PLA) groups. At POST, both groups showed significant improvements compared to PRE (CR: 78.0 points [69.2-86.8] vs. 60.6 points [53.4-67.7]; p = 0.002; PLA: 75.2 points [66.3-84.0] vs. 60.0 points [52.5-67.5]; p = 0.003). However, only the CR group showed a statistically significant improvement in the MID compared to PRE (MID: 70.2 points [60.0-80.5]; p = 0.027). A significant main effect of time was observed for both tendon thickness (p < 0.001; η2 p = 0.629) and the 5-RM leg extension test (p < 0.001; η2 p = 0.739), with both groups showing progressive improvements over time. Nevertheless, as trend toward a statistically significant time·supplementation interaction was observed (p = 0.099; η2p = 0.126), with an increase in performance only in CMJ in MID vs PRE (36.8  cm (33.8-39.7) vs 34.3  cm (30.8-37.7); p = 0.019) and POST vs MID (POST: 37.6  cm (33.5-41.8); p = 0.015). CONCLUSIONS: A physical rehabilitation program involving eccentric training, stretching, and ESWT is effective in reducing tendon thickness and increasing muscle strength. However. It seems that the addition of CR induces an earlier reduction of pain and a positive effect on CMJ performance. Therefore, CR could be considered as an ergogenic recovery aid in athletes with PT.

Humans↗

PubMed2026

Adductor Canal Block and Local Anesthetic Versus Local Anesthetic Alone in ACL Reconstruction: A Double-Blind Randomized Controlled Trial.

BACKGROUND: Effective postoperative analgesia is crucial for early recovery after anterior cruciate ligament reconstruction (ACLR). Local infiltration analgesia (LIA) and adductor canal block (ACB) are common regional techniques, but their combined efficacy remains unclear. PURPOSE: To compare the effectiveness of LIA alone versus LIA combined with ACB in patients undergoing ACLR, with primary outcomes including postoperative opioid consumption and quadriceps function. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: A double-blind randomized controlled trial enrolled 100 patients undergoing ACLR under general anesthesia. Patients were randomized into 2 groups: LIA + sham (saline injection) (n = 50) and LIA + ACB (n = 50). The primary outcome was postoperative opioid consumption in the first 24 hours. Secondary outcomes included visual analog scale (VAS) pain score, quadriceps function assessed by straight leg raise (SLR) at 3 hours, Quality of Recovery-15 (QoR-15) score, and Knee Injury and Osteoarthritis Outcome Score (KOOS) at 1 week. Statistical analysis was performed using t tests and chi-square tests with a P value <.05 considered significant. RESULTS: There was no significant difference in 24-hour opioid consumption between the LIA + ACB and LIA-only groups (P = .109). Similarly, VAS pain scores at 24 hours postoperatively showed no significant differences between the groups (P = .0804). Early functional recovery, assessed by SLR performance at 3 hours, was equivalent between groups (P = .6711). Additionally, QoR-15 scores on postoperative day 1 and KOOS values at 1 week demonstrated no significant differences (P = .6486 and P = .9054, respectively). Intraoperative opioid consumption was not different between the groups (P = .127). CONCLUSION: These findings indicate that the addition of ACB to LIA does not yield postoperative analgesic in ACLR. Consequently, LIA alone suffices for routine ACLR, potentially enabling clinicians to optimize perioperative workflows without incurring the additional time, financial burden, and resources associated with routine ACB administration. TRIAL REGISTRATION: ClinicalTrials.gov; NCT04721119.

Humans↗

PubMed2026

The knee-ankle link: impact of knee varus severity on distal joint malalignment and concomitant pathologies.

BACKGROUND: Knee varus deformity is traditionally managed as an isolated joint pathology; however, persistent distal symptoms following proximal realignment suggest a more extensive kinetic chain dysfunction. The degree to which knee varus severity dictates distal malalignment and secondary pathologies remains poorly quantified in the current literature. METHODS: This systematic review and meta-analysis were conducted in accordance with PRISMA 2020 guidelines (PROSPERO: CRD420261363327). A comprehensive search of PubMed, Embase, Web of Science, and the Cochrane Library was performed from inception to April 2026. Studies examining the relationship between knee varus (HKA angle) and radiographic distal alignment or pathologies were included. Data synthesis utilized random-effects models, with prevalence analyzed via generalized linear mixed models (GLMM). RESULTS: Fourteen studies were included in the final synthesis. While pooling of continuous radiographic parameters was limited by high statistical heterogeneity in Talar Tilt (I2 = 96.5%), individual large-cohort data (Huang et al.) indicated that severe knee varus (HKA > 10°) was associated with increased odds of concomitant ankle osteoarthritis (OR 2.29; 95% CI 1.28-4.11) and a specific cohort prevalence of 37.1%. Furthermore, single-arm prevalence data revealed divergent trends across different study populations, with compensatory hindfoot valgus reaching 69.9% in some cohorts and rigid varus up to 63.9% in others. CONCLUSIONS: Severe genu varum is associated with distal kinetic chain alterations and concomitant ankle pathologies. However, due to the extreme heterogeneity and divergent distal adaptations observed across different cohorts, standardized knee-centric protocols may be insufficient. Further longitudinal and interventional studies are required to establish phenotype-specific rehabilitation guidelines.

Humans↗

PubMed2026

Alignment strategies in total knee arthroplasty and the patellofemoral joint: A systematic review.

BACKGROUND: Different alignment strategies in total knee arthroplasty (TKA) may affect the patellofemoral joint. Mechanical alignment (MA) is commonly used but may alter native anatomy. Newer strategies such as kinematic alignment (KA), restricted kinematic alignment (rKA), and functional alignment (FA) aim to better restore native joint mechanics. This study provides an overview of the effects of alignment strategies on patellofemoral outcomes after TKA. METHODS: A literature search in July 2025 identified studies comparing patellofemoral outcomes in TKA using different alignment strategies. Of 166 studies screened, eight met inclusion criteria. Three studies were considered medium quality and five studies low quality. RESULTS: KA and rKA more closely restored native trochlear morphology than MA and FA, reducing outliers in the anterior trochlear line compared with MA and FA. MA showed greater trochlear translation, suggesting worse patellar tracking. Trochlear angles were more anatomical in KA and rKA. However, KA was associated with increased internal femoral component rotation and more outliers beyond safe thresholds. FA showed more consistent rotational positioning, generally within safe limits. Lateral patellar shift and intraoperative lateral release rates did not differ significantly between KA and MA. Only one study reported patella-specific clinical outcome scores, finding no difference between FA and adjusted MA. CONCLUSION: KA and rKA better restore trochlear morphology, but risk excessive internal femoral component rotation. FA provides a more balanced approach. MA, while widely used, is linked to altered trochlear shape and worse patellar tracking. The clinical impact of these radiological differences remains unclear, and higher-quality studies are needed.

Humans↗

PubMed2026

Association of Early Knee Extension Range of Motion Deficits With Cartilage T2 Relaxation Following Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Anterior cruciate ligament (ACL) injury significantly increases the risk for developing knee osteoarthritis (OA), yet the early contributors to cartilage degeneration remain poorly understood. While range of motion (ROM) deficits after ACL reconstruction (ACLR) are associated with long-term development of radiographic OA, the association between early ROM recovery and cartilage composition has not been established. HYPOTHESIS: Knee extension ROM deficits at 2 months after ACLR would be associated with worsening tibiofemoral and patellofemoral cartilage T2 relaxation times at 6 months. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: A total of 30 participants (15-35 years) were enrolled within 1 month of ACL injury and before ACLR. At 2 months post-ACLR, active knee extension ROM was measured in the supine position using a goniometer. An extension deficit was considered >3° less extension in the injured knee compared to the uninjured side. Quantitative magnetic resonance imaging-based T2 relaxometry of the injured knee was performed preoperatively and at 6 months post-ACLR to measure percent change in mean T2 relaxation times in predefined tibial and femoral cartilage regions. Independent t tests were used to compare changes in T2 values between participants with and without an extension deficit. RESULTS: The mean age of the participants was 18.8 ± 3.9 years, and 63.3% were female. Fifteen (50.0%) participants exhibited an extension deficit at 2 months. Those with an extension deficit demonstrated a greater increase in T2 relaxation time in the anterior (mean difference, 10.21% [95% CI, 3.67%-16.76%]; P = .003) and weightbearing (mean difference, 6.14% [95% CI, 2.19%-10.09%]; P = .004) cartilage of the medial femoral condyle. No significant group differences were observed in other cartilage regions (all P > .05). CONCLUSION: Knee extension ROM deficits at 2 months post-ACLR are associated with early compositional changes in the medial femoral cartilage, indicating a potential relationship between limited extension and OA risk.

Humans↗

PubMed2026

Sensor-based measures of knee brace adherence have low agreement with self-report methods: A multi-measure study among knee osteoarthritis patients.

OBJECTIVE: To explore agreement between self-report and objectively measured adherence to brace wearing by patients with knee osteoarthritis. METHOD: A single-arm observational analysis nested within the PROP OA randomised controlled trial (ISRCTN28555470). Of 237 adults with symptomatic knee osteoarthritis randomised to brace treatment, 60 were included in this sub-study investigating three different methods of assessing knee brace wear time over 26 weeks: 1. Self-report questionnaires (SRQ) at 12 weeks and 26 weeks; 2. Short message service (SMS) questions (days worn in past week, typical hours per day when worn) administered from week 1 to week 24; 3. A skin temperature sensor embedded in the brace, sampling every 10 min for 26 weeks. The presence and reason for the sensor were concealed from participants. The estimated proportion of participants meeting "minimum brace use", defined a priori as ≥1 h on ≥2 days in past week, was described for each measurement method, overall and by brace type (unloader, neutral). For temperature sensor measurements, time spent above 24°C and time spent above 25°C were used. Agreement between the measures was summarised by percentage agreement and kappa (ĸ). RESULTS: The estimated proportions of participants meeting "minimum brace use" at 12 weeks were 83% (SRQ), 83% (SMS), 60% and 58% (temperature sensor, 24°C and 25°C thresholds, respectively). At 26 weeks, the corresponding estimates reduced to 72%, 71% (SMS at 24 weeks), 43% and 37%. Sensor data suggested the sharpest decline in brace use occurred within the first 12 weeks. Agreement between self-report measures was higher than between self-report measures and sensor (SRQ vs SMS at 12 weeks: 92% agreement, ĸ=0.67 (95%CI: 0.34, 1.00); SRQ vs Sensor at 12 weeks: 74%, 0.35 (0.10, 0.60); SMS vs Sens at 12 weeks: 76%, 0.36 (0.05, 0.66). Agreement between all measurement methods reduced at 26 weeks. CONCLUSIONS: This novel use of a temperature sensor to monitor brace adherence in knee osteoarthritis indicates that self-report adherence substantially overestimates knee brace wearing time, with implications for clinical trials and practice.

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PubMed2026

Weight-bearing locomotion mitigates the progression of post-traumatic knee osteoarthritis in male rodents: A systematic review and meta-analysis.

OBJECTIVE: Although knee post-traumatic osteoarthritis (PTOA) has been associated with altered loading, how weight-bearing (WB) activities should be modulated post-injury to preserve knee health remains unknown. This systematic review and meta-analysis examined the effects of WB locomotion on knee PTOA in rodents to provide insight into potential clinical implications. DESIGN: Studies published in PubMed, Cochrane Library, Embase, and CINAHL through 02/2025 and meeting the following criteria were included: 1) rodents with knee PTOA, 2) compared locomotor exercises (treadmill/wheel) to no exercise, 3) outcome measures of PTOA (OARSI/Mankin OA scores, bone quality, osteophyte condition, cartilage quality/morphology). If significant heterogeneity across studies was observed, locomotion speed, time/number of intervention sessions, frequency and duration of intervention, exercise initiation, follow-up time, animal species, PTOA model were analyzed as potential moderator variables that may influence findings. RESULTS: Twenty-two studies met the criteria, resulting in a total of 156 effect sizes (ESs) for meta-analysis (all males). A positive ES denotes less PTOA. Based on the CAMARADES checklist, 5 studies were ranked low risk of bias and 14 studies were ranked moderate risk of bias. Locomotion significantly reduced PTOA severity evaluated using OARSI/Mankin scores (ES=0.927, 95% CI: [0.590, 1.264]) and improved bone quality (ES=0.379, 95% CI: [-0.023, 0.780]) with substantial heterogeneity across studies. Follow-up analyses indicated that greater ESs for reducing OA scores were associated with a shorter duration of each training session, more training sessions, longer intervention duration, and longer follow-up time (all P≤0.004). Greater ESs for improving bone quality were associated with a longer follow-up time and later exercise initiation post-injury (both P≤0.014). Locomotion resulted in small to moderate but non-significant positive effects for isolated measures assessing osteophyte condition (ES=0.379, 95% CI: [-0.023, 0.780]), cartilage quality (ES=0.430, 95% CI: [-0.034, 0.893]), and cartilage morphology (ES=0.464, 95% CI: [-0.006, 0.934]). CONCLUSION: WB locomotion reduced the overall degree of knee PTOA in male rodents. Composite knee OA scores may be more responsive to exercise interventions than isolated cartilage/osteophyte measures. The benefits of locomotion may be more prominent with a longer follow-up time or with exercise protocols consisting of shorter but more individual sessions and longer overall intervention durations.

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PubMed2026

Discrepancies in CPAK classification between CT and long-leg radiography: a systematic review and meta-analysis.

OBJECTIVE: To determine whether substantial differences in coronal plane alignment of the knee phenotype distribution, as well as systematic angular measurement discrepancies, exist between CT and long-leg radiography. MATERIALS AND METHODS: From February 2021 to April 2025, we searched PubMed, Embase, and the Cochrane Central Register of Controlled Trials for studies comparing CT- and long-leg radiography-derived coronal plane alignment classifications of the knee in patients with osteoarthritis. The primary outcome was distribution of coronal plane alignment phenotypes. Secondary outcomes included differences in medial proximal tibial angle, lateral distal femoral angle, arithmetic hip-knee-ankle angle, and joint line obliquity. RESULTS: Four studies (1,134 knees) were included. Compared with long-leg radiography-derived classification, CT-derived classification increased type I phenotypes (risk difference: 0.10; 95% confidence interval: 0.01-0.20; P = 0.040) and decreased type III (risk difference: -0.04; 95% confidence interval: -0.07 to -0.01; P = 0.020) and type V phenotypes (risk difference: -0.04; 95% confidence interval: -0.07 to -0.01; P = 0.004). CT yielded significantly lower medial proximal tibial angle (weighted mean difference: - 1.18°; P < 0.001), arithmetic hip-knee-ankle angle (weighted mean difference: - 0.95°; P < 0.001), and joint line obliquity (weighted mean difference: - 1.40°; P < 0.001) than long-leg radiography. Heterogeneity was high for type I phenotype (I2 = 81%), lateral distal femoral angle (I2 = 70%), and joint line obliquity (I2 = 69%). CONCLUSION: Discrepancies between CT-based software-generated and long-leg radiography-derived measurements substantially affect coronal plane alignment classification and angular parameters. Surgeons should consider these modality-specific variations and employ compensatory verification strategies to ensure optimal alignment.

Humans↗

PubMed2026

A single session of high-definition transcranial direct current stimulation does not modulate effects of knee two-point discrimination training or sensorimotor function in healthy adults: Double-blind randomised controlled trial.

BACKGROUND: Benefits of sensory-training interventions on sensorimotor outcomes are inconsistent, and it is unclear whether transcranial direct current stimulation (tDCS) can enhance proprioception, which is fundamental to neuromuscular control. Existing evidence is dominated by upper-limb studies, so transferability to the knee is unclear. This study investigated whether a single session of anodal high-definition (HD)-tDCS, alone or combined with brief two-point discrimination (TPD) training, enhances knee sensorimotor function and performance in healthy adults. METHODS: In a double-blind randomised-controlled trial, 57 healthy participants received (1) 20-min, 1 mA anodal HD-tDCS over the knee primary somatosensory (S1) map or sham stimulation, and (2) 15-min knee TPD training or no training. Knee somatosensory, sensorimotor, and functional performance measures were assessed pre- and immediately post-intervention. Three-way mixed-design ANOVAs, equivalence testing (smallest effect size of interest η2 = 0.02), Bayes factors, and linear mixed-effects models quantified effects. RESULTS: HD-tDCS, TPD training, and their sequential combination had no effect on any outcome measure (p ≥ 0.05; η2 ≤ 0.015). Confidence intervals spanned equivalence bounds, and equivalence testing results were non-significant (p ≥ 0.05). Bayes factors (<0.33) showed moderate evidence for the null (no effect). Mixed-effects modelling attributed ≤8% of total variance to intervention fixed effects, with the remainder captured by participant-level random effects. CONCLUSION: A single 20-minute session of 1 mA HD-tDCS, with or without brief TPD training, does not acutely modify knee somatosensory, sensorimotor, or functional performance in healthy adults. Existing evidence at the hand may not translate to the lower limb. Future work should investigate higher-dose, multi-session, task-concurrent, or network-targeted strategies in clinical populations.

Humans↗

PubMed2026

Risk prediction models for blood transfusion in patients undergoing total hip and knee arthroplasty: a systematic review and meta-analysis.

OBJECTIVE: To systematically review and evaluate published risk prediction models for perioperative blood transfusion in patients undergoing total hip or knee arthroplasty (THA/TKA). METHODS: We systematically searched PubMed, Web of Science, the Cochrane Library, and Embase from inception to May 31, 2025. Two researchers independently screened the literature, extracted data, and assessed the risk of bias and applicability using the Prediction model Risk Of Bias Assessment Tool (PROBAST). The area under the receiver operating characteristic curve (AUC) values were pooled via a meta-analysis using Stata 18.0. RESULTS: d Fourteen studies containing 36 prediction models were included. The incidence of blood transfusion among THA/TKA patients ranged from 3.2% to 30.8%. Preoperative hemoglobin (Hb) level, tranexamic acid (TXA) use, operative duration, intraoperative blood loss, and age were the most frequently incorporated predictors. Model sensitivity ranged from 58% to 94.5%, and specificity ranged from 71.3% to 94%. Meta-analysis showed that the pooled AUC value of the 13 validated models was 0.87 (95% CI: 0.85-0.90), suggesting good discriminatory performance. All models were rated as having a high risk of bias. The applicability of four studies was rated as unclear. CONCLUSION: Although the included studies demonstrated promising discriminative ability of prediction models for blood transfusion in THA/TKA, all were assessed as having a high risk of bias using the PROBAST tool. Therefore, future research should prioritize the development of models with larger sample sizes, rigorous study designs, and multicenter external validation.

Humans↗

PubMed2026

Intramuscular Fat Infiltration and Knee Osteoarthritis: A Systematic Review and Meta-Analysis.

BACKGROUND: Intramuscular fat infiltration (IMFI) is considered to be closely associated with knee osteoarthritis (KOA); however, its overall association, muscle-specific involvement, and clinical relevance remain unclear. OBJECTIVE: To quantify the association between IMFI and KOA, identify affected muscle groups, and evaluate prognostic value. METHODS: We searched PubMed, Web of Science, Scopus, and Embase up to December 2025 for observational studies. Two reviewers independently screened, extracted data, and assessed bias (NOS/JBI). Pooled standardized mean differences (SMDs) were calculated using random-effects models, with subgroup and sensitivity analyses. RESULTS: Seventeen studies were included. IMFI was significantly higher in KOA patients than controls (SMD = 0.63, 95% CI 0.41-0.85, I2 = 84.7%). Anatomically, the anterior thigh muscles (rectus femoris, vastus lateralis, vastus medialis) demonstrated a significant pooled effect (SMD = 0.96, 95% CI 0.66-1.25, I2 = 3.2%) and showed the strongest pooled association, whereas posterior, medial, and composite measures did not demonstrate significant associations. At the individual muscle level, a single study reported a notable association for the semimembranosus (SMD = 1.25, 95% CI 0.57-1.93); however, this finding is based on limited evidence and requires confirmation in future studies. Subgroup by imaging modality: CT demonstrated a significant association (SMD = 0.59, 95% CI 0.28-0.90), while MRI and ultrasound did not show significant associations. Elevated IMFI was also associated with reduced muscle strength, higher KOA incidence, structural progression, and increased knee replacement risk. CONCLUSION: A moderate positive association exists between IMFI and KOA, with notable muscle-specific heterogeneity. Anterior thigh muscles show the strongest pooled association, whereas individual muscle findings require further confirmation. These findings suggest that IMFI may represent a promising potential marker warranting further prospective investigation for risk stratification, though causality and its role in modifying disease progression remain to be established.

Humans↗

PubMed2026

Factors associated with periprosthetic joint infection following total knee arthroplasty: an updated systematic review and meta-analysis.

BACKGROUND: This study aimed to systematically evaluate factors associated with periprosthetic joint infection (PJI) following total knee arthroplasty (TKA), and thereby to provide evidence-based references for clinical prevention and perioperative risk stratification. METHODS: Computerized searches were conducted in the following databases from their inception until May 26, 2025: PubMed, Web of Science, Embase, the Cochrane Library, CINAHL, China National Knowledge Infrastructure, Wanfang Database, Chinese Scientific Journal Database, and Chinese Biomedical Literature Database. Two researchers independently screened the literature, extracted data, and assessed study quality. The methodological quality was assessed using the Newcastle-Ottawa Scale. Quantitative synthesis was performed when at least two studies reported comparable exposure definitions and sufficient comparator information; otherwise, narrative synthesis was used. Review Manager 5.4 software was used for the primary analysis. This study is registered on PROSPERO (CRD420251079339). RESULTS: A total of 25 observational studies were included in the qualitative synthesis, of which 24 contributed to the primary quantitative synthesis. Quantitatively pooled factors associated with PJI included male sex (OR = 1.39, 95% CI 1.27-1.51), BMI ≥30 kg/m2 (OR = 5.72, 95% CI 2.65-12.36), prolonged operative time, type 2 diabetes mellitus (OR = 2.09, 95% CI 1.45-3.01), rheumatoid arthritis (OR = 2.64, 95% CI 1.38-5.02), smoking (OR = 1.65, 95% CI 1.34-2.04), blood transfusion (OR = 2.27, 95% CI 1.59-3.25), American Society of Anesthesiologists score ≥3 (OR = 2.73, 95% CI 1.02-7.32), history of hormone therapy (OR = 4.88, 95% CI 2.90-8.22), postoperative urinary tract infection (OR = 3.59, 95% CI 1.15-11.21), intraoperative blood loss >200 ml (OR = 1.51, 95% CI 1.03-2.22), postoperative drainage tube placement duration ≥24 h (OR = 2.23, 95% CI 1.50-3.32), preoperative anemia (OR = 1.82, 95% CI 1.67-1.99), and combined pulmonary disease (OR = 5.54, 95% CI 1.93-15.96). Age was narratively summarized because its classification differed substantially across studies. CONCLUSION: Multiple demographic, comorbidity-related, and perioperative factors were associated with PJI after TKA. However, because the included studies were observational and clinically heterogeneous, these findings should be interpreted as associations rather than causal effects. Optimization of modifiable factors may help reduce the burden of PJI, but further prospective studies using standardized PJI definitions and adjusted effect estimates are required.

Humans↗

PubMed2026

Effect of knee and hip joint positions on passive stiffness of the rectus femoris and vastus lateralis in healthy individuals.

Passive muscle stiffness is a key determinant of musculoskeletal function and is influenced by structural components such as titin, connective tissue, and fascia. However, the effects of joint position, muscle depth, and sex on quadriceps passive stiffness remain unclear. To investigate the passive stiffness of the rectus femoris (RF) and vastus lateralis (VL) under different joint configurations, muscle depths, and between sexes using shear wave elastography (SWE). Thirty-six healthy young adults (18 men and 18 women) participated in this randomized crossover study. Passive stiffness was assessed in four positions of knee flexion: supine with 60° (SUP60), supine with 20° (SUP20), sitting with 60° (SIT60), and sitting with 20° (SIT20). SWE measurements (m/s) were obtained from 30 regions of interest (ROIs) per muscle, categorized into superficial, intermediate, and deep levels. Data were analyzed using Generalized Estimating Equations (GEE). A significant effect of position was observed, with higher stiffness values in the SUP60 condition for both RF and VL (p < 0.001). Superficial regions consistently exhibited greater stiffness compared to intermediate and deep regions across all positions (p < 0.001). Additionally, men demonstrated significantly higher stiffness values than women (p < 0.001). Significant interactions were found between position and muscle, as well as position and depth. Quadriceps passive stiffness is influenced by joint position, muscle depth, and sex. The SUP60 position elicits the highest stiffness, while superficial muscle regions are consistently stiffer. These findings highlight the non-uniform mechanical behavior of the quadriceps and may have implications for clinical assessment, rehabilitation, and exercise prescription. Clinical trial registration: This study was registered at Clinicaltrials.gov in June 06th, 2023. Register number NCT05905406. Link to access https//clinicaltrials.gov/study/NCT05905406.

Humans↗

PubMed2026

Sex-stratified analyses of femoral intercondylar notch morphology and ACL injury risk: a systematic review and meta-analysis.

BACKGROUND: Anterior cruciate ligament (ACL) injury is more common in females. Although ACL injury risk is multifactorial, involving neuromuscular, hormonal, and biomechanical factors, femoral intercondylar notch morphology is a proposed non-modifiable anatomical contributor that may help explain this disparity. This review synthesizes evidence on its association with ACL injury risk, analyses stratified by male and female sex. METHODS: A literature search of PubMed, Web of Science, and Scopus was conducted through January 2026. After duplicate removal, 527 unique records were screened and 134 full texts assessed for eligibility. Twenty-four studies met inclusion criteria, with 22 providing quantitative data. Data were extracted on ACL-injured (ACLi) and control (ACLc) knees, stratified by sex. RESULTS: ACLi knees had narrower notch widths than ACLc knees in both females (MD -1.74 mm, 95% CI -2.54 to -0.95) and males (MD -1.31 mm, 95% CI -1.94 to -0.68), with substantial heterogeneity (I2 81-95%). NWI differences were significant in males (MD -0.01, 95% CI -0.02 to 0.00) but not females. Limited notch shape data suggested higher ACL injury odds with A-shaped notches in females (OR 2.85, 95% CI 0.07-110.66) and males (OR 1.67, 95% CI 0.00-3.98 × 105). CONCLUSION: Narrower femoral intercondylar notch width was consistently associated with ACL injury in both sexes, whereas findings for NWI and notch shape were limited by heterogeneity and sparse data. These results provide a structured synthesis of sex-specific anatomical risk factors and support femoral notch narrowing as a shared contributor, while highlighting the need for prospective, standardized studies in the future.

Humans↗

PubMed2026

All-inside repair is an effective treatment for medial meniscus posterior root tears: a systematic review and meta-analysis of biomechanical and clinical evidence.

BACKGROUND: Medial meniscus posterior root tears (MMPRTs) reproduce the biomechanics of subtotal meniscectomy. Repair is favored, but the role of all-inside repair (AR) remains unclear relative to transtibial pull-out (TP). This study aimed to review the biomechanical and clinical evidence on AR for MMPRTs. METHODS: A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and registered in the International Prospective Register of Systematic Reviews (PROSPERO). MEDLINE, Embase, Scopus, and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched. Outcomes included patient-reported outcome measures (PROMs), magnetic resonance imaging (MRI), and biomechanical performance. When available, random-effects meta-analysis was performed. RESULTS: Thirteen studies were included. AR restored contact mechanics and showed load to failure comparable to TP, with lower stiffness. Meta-analysis showed lower conversion to total knee arthroplasty with AR versus non-repair (RR 0.18, 95% CI 0.05-0.58), and no significant PROM differences between AR and TP. CONCLUSIONS: AR showed favorable biomechanical properties and improved outcomes versus non-repair. Compared with TP, no significant clinical differences were observed. AR may represent a reasonable option in selected scenarios.

Humans↗

PubMed2026

Meniscal preservation in the age of biologics: toward a quantitative decision algorithm for personalized repair.

BACKGROUND: Despite advances in arthroscopic repair and biologic augmentation, surgical indication for meniscal tears remains heterogeneous. No standardized framework currently integrates biomechanical, clinical, and biological determinants to guide repair versus resection. PURPOSE: To develop a quantitative decision model-the Meniscal Preservation Score (MPS)-that unifies biomechanical and biological evidence to stratify reparability potential and standardize treatment selection in meniscal surgery. METHODS: A systematic evidence synthesis conducted in accordance with PRISMA 2020 reporting standards of studies published from 2000 to 2025 in PubMed, Embase, and Scopus identified key determinants of meniscal healing. Five consistent predictors-patient age, vascularity, tear morphology, associated pathology, and activity profile-were weighted through a two-round modified Delphi consensus among ten experienced knee surgeons. The resulting 0-9-point MPS was incorporated into a stepwise decision tree linking lesion morphology, biological context, and surgical strategy. Conceptual validation used 50 simulated cases and a retrospective cohort of 45 patients to test agreement between algorithm recommendations and expert surgical decisions. RESULTS: The MPS achieved 86% concordance with expert judgment in simulation and 84% agreement in clinical validation. In this retrospective exploratory cohort, cases in which surgical management was concordant with MPS recommendations demonstrated higher mean IKDC scores at 24 months and lower observed reoperation rates. These findings should be interpreted as associative rather than causal, as treatment allocation was not controlled and discordant cases may have represented inherently more complex pathology. CONCLUSION: The MPS represents an evidence-informed decision-support framework designed to systematize reparability assessment. While exploratory analyses suggest structural coherence with expert reasoning, prospective implementation and external validation are required before clinical adoption as a predictive tool. LEVEL OF EVIDENCE: conceptual model with exploratory validation.

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PubMed2026

Predicting ACL injury risk in athletes: A systematic review of machine learning-based models.

BACKGROUND: Early ACL injury risk identification in athletes is essential. This systematic review examines machine learning (ML) models for predicting ACL injuries, evaluating their methodological quality, performance, and reliability. METHOD: A comprehensive electronic search was conducted across PubMed, Scopus, Web of Science, and IEEE Xplore databases, supplemented by Google Scholar for grey literature, covering articles published between January 1, 2015, and August 30, 2025. Eligible studies were appraised using the Prediction Model Study Risk of Bias Assessment Tool (PROBAST) for methodological quality and risk of bias, and the Transparent Reporting of a Multivariable Prediction Model for Individual Prognosis or Diagnosis (TRIPOD) guidelines for quality of evidence. RESULTS: Ten studies were included. PROBAST showed eight studies had moderate risk of bias and two low risk. TRIPOD found only two studies met quality criteria. ML models included logistic regression (n = 5), support vector machines (n = 4), k-nearest neighbor (n = 3), decision trees (n = 3), random forests (n = 5), neural networks (n = 2), linear discriminant analysis (n = 1), and pre-trained CNNs (n = 1). AUC ranged from 0.63 to 0.98. Accuracy (reported in six studies) ranged from 26% to 95%; however, these values should be interpreted with caution due to the absence of confidence intervals, lack of class imbalance handling, and limited external validation across studies. Tree-based ensemble methods such as random forest achieved competitive accuracy (74-86%), while SVM, a non-ensemble classifier, reported accuracy ranging from 71% to 95%; however, the highest values were obtained in studies with notably small sample sizes (n = 12 to n = 39), raising concerns about overfitting and generalizability. CONCLUSION: Current ML algorithms show promise for identifying athletes at high ACL injury risk and detecting relevant risk factors. Although study quality was generally satisfactory, future research should prioritize external validation and model interpretability to support clinical translation.

Humans↗

PubMed2026

Skeletal Muscles Do Not Compete for Growth: Activating Additional Muscle Mass Does Not Compromise Changes in Muscle Size.

Kataoka, R, Yamada, Y, Hammert, WB, Sallberg, RW, Kang, A, Song, JS, Kassiano, W, Metcalf, EE, and Loenneke, JP. Skeletal muscles do not compete for growth: Activating additional muscle mass does not compromise changes in muscle size. J Strength Cond Res 40(9): 1043-1049, 2026-This study investigated whether the magnitude of muscle size and strength differed based on the amount of muscle recruited during training sessions. One hundred five untrained individuals were randomly assigned to 1 of 3 groups: low-load unilateral elbow flexion exercise (a) to failure (LL-Failure, n = 36), (b) to failure and low-load knee extension exercise to failure (LL-Failure + Legs, n = 33), or (c) a time-matched nonexercise control (CON, n = 36). Training groups completed 18 supervised sessions over 6 weeks (2 sets at 30% 1 repetition maximum [1RM] to failure). LL-Failure + Legs group performed 4 additional sets of knee extension exercise in each leg (20-30 RM). Muscle thickness on the anterior upper arm (60 and 70% sites) and elbow flexor 1RM strength of the trained arm were measured at pretesting and posttesting. Changes were compared using the ANCOVA function of Bayes Factors for Informative Hypotheses (prevalues as the covariate). Specific hypotheses were evaluated by comparing Bayes factors and the posterior probabilities between models. Six weeks of training led to increases in muscle size and strength. However, performing additional leg exercise did not attenuate the muscle growth in the anterior upper arm (0.19 cm) compared with performing only arm exercise to failure (0.18 cm). Changes in 1RM strength also did not differ between training groups (0.32 and 0.25 kg for LL-Failure and LL-Failure + Legs, respectively). Overall, there was no evidence for competition of adaptations in muscle size and strength under uncontrolled nutritional conditions. Whether greater training volume or limited nutrient intake induces a competition for resources warrants further investigation.

Humans↗