The predictors to self-reported and performance-based physical function in knee osteoarthritis patients: a cross-sectional study.

Background: Osteoarthritis (OA) knee patients have limited ability in physical function, or difficulties with physical tasks and activities may develop disability. This study aimed to observe the predictors of self-reported and performance-based physical function in patients with knee OA by analyzing the impacts of demographic, pathological, and muscle impairment factors. Methods: 135 knee OA patients participated in this study to complete self-reported questionnaires using Knee Injury and Osteoarthritis Outcome Score (KOOS). When measuring performance-based physical function, a 6-meter gait speed (6MGS) test was measured to evaluate their mobility, and a 5-time Sit-to-Stand test (5STS) was assessed to evaluate their balance. Pain intensity, knee extensor and flexor muscle strength, age, body mass index (BMI), durations of symptoms, and radiographic severity were also collected. Spearman correlation and stepwise multiple linear regression were used to explore the association and predictors in self-reported and performance-based physical function. Results: BMI and durations of symptoms did not indicate any significant correlation with either self-reported or performance-based physical function. Age is significantly negatively associated with 6MGS (r 2 = -0.383, p < 0.01), while knee extensor muscle strength has a moderate correlation with 5STS (r 2 = -0.528, p < 0.01). In the stepwise multiple linear regression models, pain intensity (ß = 0.712, p < 0.001), knee flexor muscle strength (ß = 0.112, p = 0.042) were significantly associated with self-reported physical function in daily activities and contributed to 55.0% of the variance in KOOS-PF score. Knee muscle strength, including knee extensor (5STS: ß = -0.428, p < 0.001) and flexor muscle strength (6MGS: ß = 0.367, p < 0.001), were the main predictors with performance-based physical function. Conclusion: Pain intensity was the leading risk factor of self-reported physical function, and knee flexor muscle strength contributed as well. The severity of knee OA, durations of symptoms and BMI did not contribute to physical function. However, knee extensor and flexor muscle strength were the main predictors of performance-based performance. Our results show that strengthening of weak knee muscles in both quadriceps and hamstring muscle strength should be considered a priory consideration in knee OA no matter if people are in the early or end-stage of knee OA.

Effects of volume-matched once-weekly and thrice-weekly high-intensity interval training (HIIT) on body adiposity in adults with central obesity: Study protocol for a randomized controlled trial.

Objective: This study aims to examine the comparative effects of 75 min of volume-matched once-weekly and thrice-weekly high-intensity interval training (HIIT) on body adiposity in adults with central obesity. Methods: This assessor-blinded, three-arm, randomized controlled trial will recruit 315 physically inactive adults with central obesity (aged ≥18 years, body mass index ≥23, waist circumference ≥90 cm for men and ≥80 cm for women). Participants will be randomly allocated to the once-weekly HIIT, thrice-weekly HIIT or usual care control group. Participants in the HIIT groups will receive weekly exercise training sessions for 16 weeks, prescribed either once or three times weekly. Each HIIT session will consist of a supervised program of four 4-min high-intensity intervals at 85%-95% peak heart rate (HRpeak) interspersed with 3-min active recovery intervals at 50%-70% HRpeak. Participants in the once-weekly HIIT group will perform the 25-min HIIT bout three times with a break between each 25-min HIIT bout. The usual care control group will receive bi-weekly health education classes. The outcome assessments will be conducted at baseline, 16 weeks (post-intervention) and 32 weeks (follow-up). The primary outcome will be total body adiposity assessed by dual-energy X-ray absorptiometry (DXA). The secondary outcome measures will include markers of cardiovascular and metabolic health (body composition, cardiorespiratory fitness, blood pressure, and blood lipids), mental health, cognitive performance, health-related quality of life, sleep quality, habitual physical activity, diet, medication, adverse events and adherence to the intervention. Impact of the project: The findings from this study are expected to consolidate the therapeutic efficacy of HIIT for the management of central obesity and inform the comparative compliance, feasibility and suitability of once-weekly and thrice-weekly HIIT as exercise strategies to manage obesity. In particular, the present study is expected to provide a novel perspective on the utility of low-frequency HIIT (i.e., once-weekly) as an effective and sustainable exercise strategy to tackle the obesity pandemic. The anticipated findings will hold substantial translational value by informing public health policies and enhancing exercise compliance in the physically inactive obese population. Trial registration: ClinicalTrials.gov (NCT04887454).

The emerging role of Piezo1 in the musculoskeletal system and disease.

Piezo1, a mechanosensitive ion channel, has emerged as a key player in translating mechanical stimuli into biological signaling. Its involvement extends beyond physiological and pathological processes such as lymphatic vessel development, axon growth, vascular development, immunoregulation, and blood pressure regulation. The musculoskeletal system, responsible for structural support, movement, and homeostasis, has recently attracted attention regarding the significance of Piezo1. This review aims to provide a comprehensive summary of the current research on Piezo1 in the musculoskeletal system, highlighting its impact on bone formation, myogenesis, chondrogenesis, intervertebral disc homeostasis, tendon matrix cross-linking, and physical activity. Additionally, we explore the potential of targeting Piezo1 as a therapeutic approach for musculoskeletal disorders, including osteoporosis, muscle atrophy, intervertebral disc degeneration, and osteoarthritis.

Upregulation of FABP4 induced inflammation in the pathogenesis of chronic tendinopathy.

Objectives: Excessive inflammation contributes to the pathogenesis of tendinopathy. Fatty acid binding protein 4 (FABP4) is a pro-inflammatory adipokine mediating various metabolic and inflammatory diseases. This study aimed to examine the expression of FABP4 and its association with the expressions of inflammatory cytokines in tendinopathy. The effects of a single injection of FABP4 on tendon pathology and inflammation were examined. The effect of FABP4 on the expressions of inflammatory cytokines and the effect of IL-1ß on the expression of FABP4 in tendon-derived stem/progenitor cells (TDSCs) were also investigated. Methods: 1) Clinical patellar tendinopathy samples, healthy hamstring tendon samples, and healthy patellar tendon samples, 2) rotator cuff tendinopathy samples and healthy hamstring tendon samples; and 3) Achilles tendons of mice after saline or collagenase injection (CI) were stained for FABP4, IL-1ß, IL-6, TNF-α and IL-10 by immunohistochemistry (IHC). For the rotator cuff tendinopathy samples, co-localization of FABP4 with IL-1ß and TNF-α was done by immunofluorescent staining (IF). Mouse Achilles tendons injected with FABP4 or saline were collected for histology and IHC as well as microCT imaging post-injection. TDSCs were isolated from human and mouse tendons. The mRNA expressions of inflammatory cytokines in human and mouse TDSCs after the addition of FABP4 was quantified by qRT-PCR. The expression of FABP4 in TDSCs isolated from rotator cuff tendinopathy samples and healthy hamstring tendon samples was examined by IF. Mouse Achilles TDSCs were treated with IL-1ß. The mRNA and protein expressions of FABP4 were examined by qRT-PCR and IF, respectively. Results: There was significant upregulation of FABP4 in the patellar tendinopathy samples and rotator cuff tendinopathy samples compared to their corresponding controls. FABP4 was mainly expressed in the pathological areas including blood vessels, hypercellular and calcified regions. The expressions of IL-1ß and TNF-α increased in human rotator cuff tendinopathy samples and co-localized with the expression of FABP4. Collagenase induced tendinopathic-like histopathological changes and ectopic calcification in the mouse Achilles tendinopathy model. The expressions of inflammatory cytokines (IL-1ß, IL-6, TNF-α, IL-10) and FABP4 increased in hypercellular region, round cells chondrocyte-like cells and calcified regions in the mouse Achilles tendons post-collagenase injection. A single injection of FABP4 in mouse Achilles tendons induced histopathological changes resembling tendinopathy, with increased cell rounding, loss of collagen fiber alignment, and additionally presence of chondrocyte-like cells and calcification post-injection. The expressions of IL1-ß, IL-6, TNF-α and IL-10 increased in mouse Achilles tendons post-FABP4 injection. FABP4 increased the expressions of IL10, IL6, and TNFa in human TDSCs as well as the expressions of Il1b, Il6, and Il10 in mouse TDSCs. Human tendinopathy TDSCs expressed higher level of FABP4 compared to healthy hamstring TDSCs. Besides, IL-1ß increased the expression of FABP4 in mouse TDSCs. Conclusion: In conclusion, an upregulation of FABP4 is involved in excessive inflammation and pathogenesis of tendinopathy. TDSCs is a potential source of FABP4 during tendon inflammation. Translation potential of this article: FABP4 can be a potential treatment target of tendinopathy.

Skilled reaching test for shoulder function assessment in a rat model of rotator cuff tear: a pilot study.

BACKGROUND: Functional assessments are crucial to evaluate treatment outcomes in clinical and animal studies on rotator cuff injuries. While gait analysis is commonly used to assess animal models of rotator cuff tears, it is less relevant for human patients as the human shoulder is typically assessed in a non-weight-bearing condition. The present study introduces the skilled reaching test as a shoulder functional assessment tool for rats, which allows for evaluation without weight bearing. METHODS: In the control group, 8 male Sprague-Dawley rats received rotator cuff tear surgery without repair. In the rotator cuff repair group, 20 rats received rotator cuff repair at 4 weeks post rotator cuff tear. For the skilled reaching test, rats were trained to extend their forelimbs to fetch food pellets, and the number of trials, number of attempts and the success rate were recorded. The gait analysis and skilled reaching test were performed at baseline, 4 weeks post-tear, 1, 2, 4, and 8 weeks post-repair. The repeated measures analysis of variance was used to evaluate the effects of time on the shoulder function. The significance level was set at 0.05. RESULTS: The skilled reaching test required 216 h to conduct, while the gait analysis took 44 h. In the rotator cuff repair group, gait performance significantly deteriorated at 1 week post-repair and restored to 4 weeks post-tear levels at 4 weeks post-repair. Regarding the skilled reaching test, the number of attempts, number of trials and the success rate decreased at 1 week post-repair. Subsequently, there was a brief rebound in performance observed at 2 weeks post-repair, followed by a continued decline in the number of attempts and trials. By 8 weeks post-repair, only the success rate had restored to levels similar to those observed at 4 weeks post-tear. CONCLUSION: The skilled reaching test can detect functional deficiencies following rotator cuff tear and repair, while it requires high time and labour costs.

Intra-articular sustained-release of pirfenidone as a disease-modifying treatment for early osteoarthritis.

Osteoarthritis (OA) is a major clinical challenge, and effective disease-modifying drugs for OA are still lacking due to the complicated pathology and scattered treatment targets. Effective early treatments are urgently needed to prevent OA progression. The excessive amount of transforming growth factor ß (TGFß) is one of the major causes of synovial fibrosis and subchondral bone sclerosis, and such pathogenic changes in early OA precede cartilage damage. Herein we report a novel strategy of intra-articular sustained-release of pirfenidone (PFD), a clinically-approved TGFß inhibitor, to achieve disease-modifying effects on early OA joints. We found that PFD effectively restored the mineralization in the presence of excessive amount of TGFß1 (as those levels found in patients' synovial fluid). A monthly injection strategy was then designed of using poly lactic-co-glycolic acid (PLGA) microparticles and hyaluronic acid (HA) solution to enable a sustained release of PFD (the "PLGA-PFD + HA" strategy). This strategy effectively regulated OA progression in destabilization of the medial meniscus (DMM)- induced OA mice model, including preventing subchondral bone loss in early OA and subchondral bone sclerosis in late OA, and reduced synovitis and pain with cartilage preservation effects. This finding suggests the promising clinical application of PFD as a novel disease-modifying OA drug.

Comparison of the in vivo kinematics between robotic-assisted Bi-cruciate retaining and Bi-cruciate stabilised total knee arthroplasty.

BACKGROUND: Up to 20% of patients remain unsatisfied after total knee arthroplasty (TKA), prompting the development of new implants. Bi-Cruciate Retaining (BCR) TKA preserves both the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL), with the ACL beneficial for its proprioceptive qualities. The Bi-Cruciate Stabilised (BCS) TKA substitutes the ACL and PCL with a unique dual cam-post mechanism. Robotics improve accuracy and facilitate technically demanding TKA. METHODS: This was a retrospective case-control study recruited from two centres. Measured outcomes included kinematic analysis, proprioception, and functional outcomes. RESULTS: There was a significantly larger maximum flexion angle and range of flexion to extension in sit-to-stand and stairs in BCR when compared to BCS. Further analysis revealed more similarities between BCR and normal native knees. Proprioception and functional scores did not have any statistical difference. CONCLUSION: BCR TKA demonstrated better knee flexion in weight-bearing active range of motion and showed similarities with normal knee kinematics.

4D bioprinting of programmed dynamic tissues.

Setting time as the fourth dimension, 4D printing allows us to construct dynamic structures that can change their shape, property, or functionality over time under stimuli, leading to a wave of innovations in various fields. Recently, 4D printing of smart biomaterials, biological components, and living cells into dynamic living 3D constructs with 4D effects has led to an exciting field of 4D bioprinting. 4D bioprinting has gained increasing attention and is being applied to create programmed and dynamic cell-laden constructs such as bone, cartilage, and vasculature. This review presents an overview on 4D bioprinting for engineering dynamic tissues and organs, followed by a discussion on the approaches, bioprinting technologies, smart biomaterials and smart design, bioink requirements, and applications. While much progress has been achieved, 4D bioprinting as a complex process is facing challenges that need to be addressed by transdisciplinary strategies to unleash the full potential of this advanced biofabrication technology. Finally, we present future perspectives on the rapidly evolving field of 4D bioprinting, in view of its potential, increasingly important roles in the development of advanced dynamic tissues for basic research, pharmaceutics, and regenerative medicine.

Vitamin D as an intervention for improving quadriceps muscle strength in patients after anterior cruciate ligament reconstruction: study protocol for a randomized double-blinded, placebo-controlled clinical trial.

BACKGROUND: The goal of anterior cruciate ligament reconstruction (ACLR) is to restore the preinjury level of knee function to return to play (RTP). However, even after completing the rehabilitation programme, some patients may have persistent quadriceps muscle weakness affecting knee function which ultimately leads to a failure in returning to play. Vitamin D has been long recognized for its musculoskeletal effects. Vitamin D deficiency may impair muscle strength recovery after ACLR. Correcting vitamin D levels may improve muscle strength. METHODS: This is a double-blinded, randomized controlled trial to investigate the effects of vitamin D supplementation during the post-operative period on quadriceps muscle strength in anterior cruciate ligament (ACL)-injured patients. Patients aged 18-50 with serum vitamin D < 20 ng/ml, unilateral ACL injury, > 90% deficit in total quadriceps muscle volume on the involved leg compared with uninvolved leg, Tegner score 7 + , and no previous knee injury/surgery will be recruited. To assess patient improvement, we will perform isokinetic and isometric muscle assessments, ultrasound imaging for quadriceps thickness, self-reported outcomes, KT-1000 for knee laxity, biomechanical analysis, and Xtreme CT for bone mineral density. To investigate the effect of vitamin D status on quadriceps strength, blood serum samples will be taken before and after intervention. DISCUSSION: Patients with low vitamin D levels had greater quadriceps fibre cross-sectional area loss and impaired muscle strength recovery after ACL. The proposed study will provide scientific support for using vitamin D supplementation to improve quadriceps strength recovery after ACLR. TRIAL REGISTRATION: ClinicalTrials.gov NCT05174611. Registered on 28 November 2021.

Tracking and predicting the treatment adherence of patients under rehabilitation: a three-wave longitudinal validation study for the Rehabilitation Adherence Inventory.

This study aimed to develop and validate a new measurement tool, the Rehabilitation Adherence Inventory (RAI), to measure patients' rehabilitation adherence. We recruited 236 patients with anterior cruciate ligament (ACL) ruptures from the United Kingdom (Mage = 33.58 ± 10.03, range = 18 to 59; female = 46.2%). Participants completed a survey, that measured their rehabilitation adherence, rehabilitation volume, psychological needs support, autonomous motivation, and intention at baseline, and at the 2nd and 4th month. Factorial, convergent, discriminant, concurrent, predictive, ecological validity and test-retest reliability of the RAI were tested via exploratory factor analysis (EFA), confirmatory factor analysis (CFA), and structural equation modelling (SEM). All the EFAs, CFAs, and SEMs yielded acceptable to excellent goodness-of-fit, χ2 = 10.51 to 224.12, df = 9 to 161, CFI > 0.95, TLI > 0.95, RMSEA <0.09 [90%C I < 0.06 to 0.12], SRMR <0.04. Results fully supported the RAI's factorial, convergent, discriminant, and ecological validity, and test-retest reliability. The concurrent and predictive validity of the RAI was only partially supported because the RAI scores at baseline was positively associated with rehabilitation frequency at all time points (r = 0.34 to 0.38, p < 0.001), but its corresponding associations with rehabilitation duration were not statistically significant (p = 0.07 to 0.93). Overall, our findings suggest that this six-item RAI is a reliable and valid tool for evaluating patients' rehabilitation adherence.

Establishment of a Mouse Degenerative Model of Patellar Tendinopathy with Upregulation of Inflammation.

There is no mouse model of patellar tendinopathy. This study aimed to establish a mouse inflammatory and degenerative patellar tendon injury model, which will facilitate research on patellar tendinopathy using advanced molecular tools including transgenic models. Collagenase at different doses (low dose (LD), medium dose (MD), high dose (HD)) or saline was injected over the mouse patellar tendon. At weeks 1, 2, 4, and 8 post-injection, the tendons were harvested for histology and further examined by micro-computed tomography (microCT) imaging at week 8. The optimal dose group and the saline group were further evaluated by immunohistochemical staining, gait pattern, and biomechanical properties. The histopathological score increased dose-dependently post-collagenase injection. Ectopic mineralization was observed and increased with collagenase dose. The LD group was selected for further analysis. The expression of IL-10, TNF-α, and MMP-1 significantly increased post-injection. The changes of limb idleness index (ΔLII) compared to preinjury state were significantly higher, while the ultimate load, stiffness, ultimate stress, and maximum Young's modulus were significantly lower in the LD group compared to the saline group. A mouse inflammatory degenerative model of patellar tendon injury resembling tendinopathy was established as indicated by the dose-dependent increase in tendon histopathology, ectopic calcification, decrease in biomechanical properties, and pain-associated gait changes.

Musculoskeletal Organs-on-Chips: An Emerging Platform for Studying the Nanotechnology-Biology Interface.

Nanotechnology-based approaches are promising for the treatment of musculoskeletal (MSK) disorders, which present significant clinical burdens and challenges, but their clinical translation requires a deep understanding of the complex interplay between nanotechnology and MSK biology. Organ-on-a-chip (OoC) systems have emerged as an innovative and versatile microphysiological platform to replicate the dynamics of tissue microenvironment for studying nanotechnology-biology interactions. This review first covers recent advances and applications of MSK OoCs and their ability to mimic the biophysical and biochemical stimuli encountered by MSK tissues. Next, by integrating nanotechnology into MSK OoCs, cellular responses and tissue behaviors may be investigated by precisely controlling and manipulating the nanoscale environment. Analysis of MSK disease mechanisms, particularly bone, joint, and muscle tissue degeneration, and drug screening and development of personalized medicine may be greatly facilitated using MSK OoCs. Finally, future challenges and directions are outlined for the field, including advanced sensing technologies, integration of immune-active components, and enhancement of biomimetic functionality. By highlighting the emerging applications of MSK OoCs, this review aims to advance the understanding of the intricate nanotechnology-MSK biology interface and its significance in MSK disease management, and the development of innovative and personalized therapeutic and interventional strategies.

Reconsidering "Critical" Bone Loss in Shoulder Instability: 17-Year Follow-Up Study following Arthroscopic Bankart Repair.

Background: Glenoid bone loss is a risk factor leading to the failure of arthroscopic Bankart repair. While 20-25% glenoid bone loss has long been considered the level to necessitate bony augmentation, recent studies indicate that 13.5% has a "subcritical" glenoid bone loss level, which is associated with decreased short- and medium-term functional scores. Few researchers worked on the long-term effect of "subcritical" or even less severe degrees of glenoid bone loss on redislocation rates and functional outcomes after arthroscopic Bankart repair. This study aimed to evaluate the effect of subcritical or less severe glenoid bone loss on redislocation rates and function after arthroscopic Bankart repair. Methods: A patient cohort who had undergone computed tomography (CT) of glenoid bone loss and arthroscopic Bankart repair over 15 years ago was reviewed. Western Ontario Shoulder Instability (WOSI) score, Single Assessment Numeric Evaluation (SANE) score, redislocation after operation, mechanism of recurrence, and revision details were reviewed. Results: Seventy-five patients were reassessed 17.6 ± 1.9 years following initial surgery. The age at enrolment was 26.8 ± 8.3 years. Twenty-two (29%) patients of the 75 patients had a redislocation on long-term follow-up, though this was not related to glenoid bone loss severity. The impaired functional score was found in patients with initial glenoid bone loss of 7% or more on long-term follow-up: WOSI (physical symptoms): 0.98 ± 2.00 vs 2.25 ± 4.01, p=0.04 and WOSI (total): 0.79 ± 1.43 vs 1.88 ± 3.56, p=0.04. Conclusions: At a mean of 17.5 years following arthroscopic Bankart repair, redislocation occurs in over a quarter of 75 patients, and they are not related to initial glenoid bone loss severity. Impaired functional outcome is apparent in patients with initial glenoid bone loss of >7%, though this impairment does not seem sufficiently severe to warrant an alternative treatment approach.

Serum vitamin D insufficiency is correlated with quadriceps neuromuscular functions in patients with anterior cruciate ligament injury: A preliminary study.

Background: This study aimed to investigate the correlations of serum vitamin D insufficiency with quadriceps neuromuscular function in patients with anterior cruciate ligament (ACL) injury. Methods: A cross-sectional study was conducted. Eighteen patients with a primary, unilateral ACL injury who had insufficient serum vitamin D concentrations (<30 ng/ml) were recruited for the study. Bilateral quadriceps neuromuscular function, including maximal strength, the speed of rapid contraction, and inhibition, were measured on an isokinetic dynamometer with the hip and the knee joint flexion at 90° and 45°, respectively. Quadriceps strength was measured by maximal voluntary isometric contractions (MVIC); the speed of rapid contraction was quantified by the rate of torque development (RTD), which was divided into the early (RTD0-50) and the late phase (RTD100-200); quadriceps inhibition was quantified by the central activation ratio (CAR). Serum vitamin D concentration was quantitatively determined by serum 25(OH)D concentration measured by the 25(OH)D ELISA kit. The Spearman rank correlation analysis was used to examine the correlation between the vitamin D concentration and bilateral quadriceps MVIC, RTD0-50, RTD100-200, and CAR, respectively. Results: The results of Spearman rank correlation analyses showed that the serum 25(OH)D concentration was significantly correlated with bilateral quadriceps MVIC (injured: r = 0.574, p = 0.013; uninjured: r = 0.650, p = 0.003) and RTD0-50 (r = 0.651, p = 0.003), and CAR (r = 0.662, p = 0.003) on the uninjured limb. However, no significant correlations were found between the serum 25(OH)D concentration and the other outcomes. Conclusions: The serum vitamin D concentration correlates with quadriceps neuromuscular function in patients with ACL injury who had vitamin D insufficiency.

Optimized design of an enthesis-mimicking suture anchor-tendon hybrid graft for mechanically robust bone-tendon repair.

Repair of functionally graded biological interfaces requires joining dissimilar materials such as hard bone to soft tendon/ligament, with re-injuries/re-tears expected to be minimized by incorporating biomimicking, stress-reducing features within grafts. At bone-tendon interfaces (entheses), stress can be reduced via angled insertion, geometric flaring, mechanical gradation, and interdigitation of tissues. Here, we incorporated enthesis attributes into 3D in silico and physical models of a unique suture anchor-tendon hybrid graft (SATHG) and investigated their effects on stress reduction via finite element analyses (FEA) studies. Over 20 different simulations altering SATHG angulation, flaring, mechanical gradation, and interdigitation identified an optimal design, which included 90° angulation, 25° flaring, and a compliant (ascending then descending) mechanical gradient in SATHG's bone-to-tendon-like transitional region. This design reduced peak stress concentration factor (SCF) by 43.6 % relative to an ascending-only mechanical gradient typically used in hard-to-soft tissue engineering. To verify FEA results, SATHG models were fabricated using a photocrosslinkable bone-tendon-like polyurethane (QHM polymer) for ex vivo tensile assessment. Tensile testing showed that ultimate load (132.9 N), displacement-at-failure (1.78 mm), stiffness (135.4 N/mm), and total work-to-failure (422.1 × 10-3 J) were highest in the optimized design. Furthermore, to assess envisioned usage, SATHG pull-out testing and 6-week in vivo implantation into large, 0.5-cm segmental supraspinatus tendon defects was performed. SATHG pull-out testing showed secure bone attachment while histological assessment such as hematoxylin and eosin (H&E) together with Safranin-O staining showed biocompatibility including enthesis regeneration. This work demonstrates that engineering biomaterials with FEA-optimized, enthesis-like attributes shows potential for enhancing hard-to-soft tissue repair. STATEMENT OF SIGNIFICANCE: Successful repair of hard-to-soft tissue injuries is challenging due to high stress concentrations within bone-tendon/ligament grafts that mechanically compromise repair strength. While stress-reducing gradient biomaterials have been reported, little-to-no attention has focused on other bone-tendon/ligament interface (enthesis) features. To this end, a unique bone-tendon graft (SATHG) was developed by combining two common orthopaedic devices along with biomimetic incorporation of four enthesis-like features to reduce stress and encourage widespread clinician adoption. Notably, utilizing designs based on natural stress dissipation principles such as anchor insertion angle, geometric flaring, and mechanical gradation reduced stress by 43.6 % in silico, which was confirmed ex vivo, while in vivo studies showed SATHG's ability to support native enthesis regeneration. Thus, SATHG shows promise for hard-to-soft tissue repairs.

In Vivo Effect of Single Intra-Articular Injection of Tranexamic Acid on Articular Cartilage and Meniscus: Study in a Rat Model.

BACKGROUND: Tranexamic acid (TXA) has been increasingly used in arthroscopic surgery to prevent hemarthrosis. Despite its effectiveness, safety concerns have been raised regarding its potential cytotoxicity to articular cartilage and meniscus following intra-articular injection. METHODS: To evaluate the impact of TXA on cartilage and meniscus, a rat model of knee instability was utilized wherein anterior cruciate ligament (ACL) transection surgery was followed by a single intra-articular injection of TXA at varying concentrations (0, 20, 50, 100, and 150 mg/mL) in saline solution. Cell viability assessment of the cartilage and meniscus (n = 6 per group) was conducted at 24 hours, and gross observation and histological analysis of the medial tibial plateau and medial meniscus were conducted at 2, 4, and 8 weeks (n = 6 per group and time point). RESULTS: The chondrocyte viability was significantly decreased in the 50, 100, and 150 mg/mL TXA groups compared with the specimens injected with saline solution only (saline group) (p = 0.001, p < 0.001, p < 0.001, respectively), as was meniscal cell viability (p = 0.042, p < 0.001, p < 0.001, respectively). At week 8, the saline and 20 and 50 mg/mL groups showed relatively normal appearances, whereas the 100 and 150 mg/mL groups exhibited increased and varying severity of cartilage and meniscal degeneration. In the 150 mg/mL group, the mean Osteoarthritis Research Society International score was significantly higher than that in the saline and 20 mg/mL groups (p = 0.010 and p = 0.007). Additionally, the mean meniscus score in the 150 mg/mL group was significantly higher than that in the saline, 20 mg/mL, and 50 mg/mL groups (p = 0.020, p = 0.021, p = 0.031, respectively). CONCLUSIONS: Our findings indicate that concentrations of TXA at or above 100 mg/mL can lead to decreased cell viability in both cartilage and meniscus, resulting in significant cartilage degeneration in rats with ACL transection. Furthermore, the use of 150 mg/mL of TXA led to significant meniscal degeneration. CLINICAL RELEVANCE: It is prudent to avoid using concentrations of TXA at or above 100 mg/mL for intra-articular injection, as such concentrations may result in adverse effects on the cartilage and meniscus.

Effect of eccentric isokinetic exercise on muscle strength and functional recovery after anterior cruciate ligament reconstruction.

Background: Previous studies have shown isokinetic exercise forms an important part in reconditioning the patients after anterior cruciate ligament reconstruction (ACLR) in regaining muscle strength and knee function. Although eccentric isokinetic training has been shown to enhance quadriceps muscle strength, the application toward benefiting patients after ACLR remains controversial. The present study aims to investigate the benefits of eccentric over concentric isokinetic exercises on knee muscle strength and its value in later stage of rehabilitation, including the return-to-sport. Methods: Thirty-six patients who had undergone ACLR for 4-to-6 months were assigned to receive either eccentric or concentric isokinetic training weekly for six weeks on top of their standardized post-operative exercise programme. The assessments include isokinetic test on the peak torques of quadriceps and hamstrings, single-leg hop test and ability to return-to-sport. Results: Both groups demonstrated significant gains on peak torques in quadriceps and hamstrings after training. At post-intervention, the peak torques for both quadriceps (p = 0.005) and hamstrings (p = 0.017) of the ACL-reconstructed limb from eccentric training were significantly higher than concentric training. The significant improvement was similarly demonstrated in the limb symmetry index (LSI) in hamstrings (p = 0.016) of the ACL-reconstructed limb from eccentric training. Moreover, eccentric group performed significantly better in single-leg hop tests (p = 0.042). Most importantly, eccentric group have higher percentages of return-to-sport (55.6 %) than concentric group (27.8 %). Conclusion: A 6-week course of eccentric isokinetic training was more effective than concentric isokinetic training in increasing quadriceps and hamstrings strength in terms of peak torques. Importantly, the better functional performance after the eccentric isokinetic exercise account for higher return-to-sport ratio.

Prevalence of dance-related injuries and associated risk factors among children and young Chinese dance practitioners.

While Chinese dance is a popular dance genre among Chinese teenagers and adults, little is known regarding the prevalence of dance-related injuries or factors associated with such injuries among Chinese dance practitioners. The current cross-sectional study aimed to determine the prevalence of dance-related injuries and their associated risk factors among young Chinese dance practitioners in Hong Kong. Online surveys were distributed to dancers through local dance associations, while paper-based surveys were distributed to young Chinese dance performers during the 54th School Dance Festival in Hong Kong. Self-reported hours of dancing, injuries in the last 12 months, injury sites, and related factors were collected. The injury rate, 12-month prevalence of dance-related injuries were determined. Risk factors for common dance injuries were analyzed using separate multivariate regression models. A total of 175 children (aged 10-14 years) and 118 young (aged 15-24 years) Chinese dance practitioners provided their dance injury information. Young dancers had a significantly higher injury rate (6.5 injuries vs 4.6 injuries/1000 dance hours) and 12-month prevalence (52.5% vs 19.4%) than their child counterparts. The most commonly injured sites were the knee (children:7.4%; young:15.3%), lower back (children: 4.6%; young: 9.5%), and ankles (children: 5.1%; young: 16.9%). Age was a significant independent risk factor for dance-related injuries to the upper back, lower back, and pelvis/buttock (odds ratios ranging from 1.2 to 1.3/additional years). Additionally, height was a significant independent risk factor for lower limb injury (odds ratios ranging from 1.0-1.1/additional centimeter). Collectively, young Chinese dance practitioners are more vulnerable to dance-related injuries than are child dancers. Older age increases the risk of trunk injuries, whereas taller dancers are more likely to sustain lower-limb injuries. Future research should determine the mechanisms underlying dance-related injuries among these dancers.

Surgical accuracy of image-free versus image-based robotic-assisted total knee arthroplasty.

BACKGROUND: This study investigated the accuracy in achieving proper lower limb alignment and component positions after total knee replacement (TKR) with image-free and image-based robotic-assisted TKR. METHODS: A total of 129 patients (166 knees) suffering from end-stage knee arthritis who underwent TKA operated by robotic-assisted surgery between the years 2018 and mid-2021 were recruited. Radiological outcomes were compared between image-free and image-based robotic-assisted surgical systems. RESULTS: There were significant differences between the two robotic systems when comparing the mean planned component alignment and the mean measured alignment on radiographs, in which the image-free robotic-assisted system was more varus, whereas the image-based robotic-assisted system was more valgus for both the mean femoral and tibial component coronal alignment (p < 0.001). For tibial component sagittal alignment, the image-based group had a larger deviation from the planned posterior slope (p < 0.001). CONCLUSION: Image-free and image-based robotic assisted TKR had differing accuracy in femoral and tibial alignment.