Wound complications after cast immobilization compared to early functional treatment in surgical fixation of ankle fractures: A systematic review and meta-analysis of randomized controlled trials.

Arthrofibrosis (AF) is a common pathological condition characterized by joint dysfunction. However, traditional non-invasive external fixation methods are difficult to maintain on the small limbs of rats. This study aimed to develop a novel, non-invasive, and stable rat model of knee arthrofibrosis using a thermoplastic polymer resin. Sixty male Sprague-Dawley rats were randomly assigned into a Sham group and immobilization groups (1, 2, 4, and 6 weeks). Utilizing the material's property of being malleable at high temperatures and rigid at room temperature, a custom-fitted "thigh-crus-trunk" external fixation device was fabricated to immobilize the knee at 135° of flexion. Total, arthrogenic, and myogenic contractures were assessed by measuring the range of motion (ROM). Histopathological changes were evaluated using H&E and Masson's trichrome staining. The expression of fibrotic markers (α-smooth muscle actin,α-SMA and collagen type I alpha 1 chain,COL1A1) in synovial tissues was detected via immunohistochemistry, RT-qPCR, and Western blotting. Biosafety was assessed through histological and serum biochemical analyses of major organs. Prolonged immobilization resulted in a significant decrease in knee ROM, while joint capsule thickness, synovial hyperplasia, and collagen deposition increased, stabilizing after 4 weeks. Analysis revealed that myogenic contracture predominated in the first 2 weeks, whereas arthrogenic contracture became dominant in the later stage. Molecular analysis confirmed a time-dependent upregulation of α-SMA and COL1A1 in synovial tissues. Furthermore, no abnormalities were observed in major organs or serum biochemical indices, indicating favorable biosafety. A novel non-invasive rat model of knee arthrofibrosis was successfully established using thermoplastic polymer resin. This device is cost-effective, user-friendly, stable, and biocompatible. It effectively simulates immobilization-induced joint contracture without surgical trauma, serving as a valuable model for future arthrofibrosis research.

Immobilization versus Early Active Mobilization after Zone 5-6 extensor tendon repair.

After rotator cuff repair, immobilization (IM) is routinely employed to limit mechanical loading at the repaired enthesis and reduce the risk of reinjury. However, prolonged IM can lead to stiffness, muscle atrophy, and impaired healing, including fatty degeneration and abnormal matrix remodeling. The purpose of this study was to determine whether adjunctive electrical stimulation (ES) during postoperative IM mitigates disuse-related impairments and promotes tendon-to-bone healing and functional recovery after rotator cuff repair in a rat model. ES applied during IM would mitigate IM-related impairments, enhance tendon-bone healing, and accelerate functional recovery. Controlled laboratory study. A total of 45 adult male Sprague-Dawley rats underwent unilateral supraspinatus repair and were randomized to the control, IM, or IM with ES (IM/ES) groups. IM was achieved by forelimb fixation, and the IM/ES group received daily transcutaneous ES. Outcomes at 2 and 4 weeks included histology, magnetic resonance imaging mapping, biomechanical testing, and gait analysis. Rats that underwent IM/ES exhibited a more mature tendon-bone interface with increased proteoglycan deposition and collagen organization compared with the control and IM groups (P < .001). Chondrogenic marker expression was upregulated, whereas fatty infiltration (FABP4) was suppressed. At 4 weeks, the IM/ES group demonstrated lower T2 relaxation times (140.2 ± 24.4 ms) and higher ultimate failure load (27.7 ± 2.1 N) versus the IM (16.6 ± 1.7 N) and control groups (13.9 ± 1.3 N) (P < .0001). Gait analysis confirmed superior functional recovery. ES administered during IM improved tendon-bone healing by reducing FABP4 and enhancing fibrocartilaginous remodeling, resulting in superior structural, biomechanical, and functional outcomes. These findings suggest that adjunctive ES during the IM after rotator cuff repair may offset the detrimental effects of disuse and promote earlier and stronger tendon-bone healing, supporting its potential translation to postoperative rehabilitation strategies.

Post-operative elbow stiffness is a common and debilitating complication following open reduction and internal fixation for displaced radial head fractures. The relative contributions of post-operative immobilization and intrinsic soft tissue damage remain debated. The purpose of this pilot study was to generate preliminary data on this relationship to inform the design of future, definitive research. This study retrospectively reviewed 45 patients who underwent open reduction and internal fixation for displaced radial head fractures. Pre-operative magnetic resonance imaging was used to identify injuries to the anterior capsule (AC), posterior band of the medial collateral ligament (pMCL), and lateral collateral ligament complex. Primary outcomes were final range of motion. For descriptive purposes, patients were categorized by immobilization duration (<3 weeks vs. ≥3 weeks). To assess independent predictors of final motion, multivariate linear regression analysis was performed, treating immobilization duration as a continuous variable (in days). No statistically significant differences in final range of motion were found between the short and long immobilization groups. Specific soft tissue injuries were strongly associated with motion loss. AC tears were linked to greater extension loss (mean deficit 15.0° vs. 2.0°, P < .001), and pMCL tears were associated with reduced flexion (mean 132.8° vs. 142.7°, P < .001). In the multivariate analysis, an AC tear was the only significant independent predictor of final extension loss (P < .001), and a pMCL tear was the only significant predictor of final flexion (P < .001). Immobilization duration, when analyzed as a continuous variable, was not a significant predictor of either flexion or extension loss. This pilot study provides strong preliminary evidence that specific soft tissue injuries, particularly of the AC and pMCL, are independent predictors of post-operative stiffness, whereas immobilization duration is not. The study was underpowered to definitively rule out a small effect of immobilization. These findings justify the need for a large, multicenter trial to confirm these associations and establish evidence-based post-operative guidelines.

Although the effects of long-term immobilization on muscle function are well documented, the neuromuscular consequences of short-term disuse, particularly in the upper limbs, remain poorly understood. This study investigated the impact of 72h of hand immobilization on muscle strength and the underlying neuromuscular mechanisms. Twenty-eight participants were assigned to either an immobilization group (n=14), who underwent 72h of and hand immobilization followed by a 7-day recovery period, or a control group (n=14). Maximal voluntary contraction, voluntary activation, first dorsal interosseous electromyographic activity, and electrically evoked contractile properties were assessed before, immediately after, and seven days post-immobilization. Immobilization resulted in significant reductions in muscle strength, which persisted after one week of recovery. The strength decline was accompanied by significant reductions in voluntary activation and electromyographic activity, whereas the contractile properties of the muscles remained unchanged. The findings demonstrate that short-term upper-limb immobilization induces rapid and sustained strength loss, primarily driven by diminished neural drive rather than alterations in muscle contractility. The results emphasize the importance of preserving neural function during brief periods of disuse and highlight the utility of short-term upper-limb immobilization protocols for studying the central mechanisms of strength loss.

Exercise Initiation After Surgical Reconstruction for Rat Rotator Cuff Injury Affects Tendon Healing and Muscle Preservation

Background:Pediatric diaphyseal both-bone forearm fractures are increasingly treated with elastic stable intramedullary nailing (ESIN) using titanium nails. However, clear guidelines on the type and duration of splint immobilization are lacking. This study aims to assess the necessity of splint immobilization after ESIN for diaphyseal forearm fractures in children.Methods:A prospective study was conducted on 38 patients with isolated radial and ulnar shaft fractures from 2018 to 2020. Patients were divided into two groups: 14 with splint immobilization for a mean of 3.93 weeks and 24 with only a sling allowing early postoperative movement. The mean ages were 10.3 years (group I) and 10.0 years (group II). Patients were evaluated at 2, 6, 12, and 24 weeks postsurgery. Final range of motion, recovery pace, bone healing, pain, complications, and treatment outcomes were compared.Results:No notable differences were found between splint immobilization and nonsplint groups regarding bone healing time (3.79 vs. 3.13 months), complications (28.6% vs. 29.2%), and final outcomes. Movement recovery was faster in the nonsplint group, but range of motion was similar at the final follow-up. Pain-free rates at 2 weeks postsurgery were higher in the splint group (85.8% vs. 50%). Pain intensity was similarly low in both groups (mean 2.5 vs. 2.67 on the visual analog scale scale).Conclusion:Splint immobilization improves pain control in the first 2 weeks postsurgery, but it offers no additional benefits in terms of healing time and functional outcome. Meanwhile, ESIN is a safe, effective treatment for pediatric forearm shaft fractures.

Fractures of the clavicle primarily occur in young males and constitute 2.6% to 5% of all fractures in adults. Distal clavicle fractures, where the outer end of the collarbone breaks, account for 20% to 25% of all clavicle fractures. These fractures can be called displaced if the ligaments connecting the collarbone to the shoulder blade (coracoclavicular complex) rupture. Such displaced fractures (Neer's type II and V) are currently treated with an operation involving fracture fixation or with sling immobilization. This protocol describes a randomized controlled trial that aims to evaluate the clinical and cost-effectiveness of these two types of treatment which are used for displaced distal clavicle fractures. The DIsplaced DistAl Clavicle Fracture Trial (DIDACT) is a pragmatic, parallel, two-arm individually randomized non-inferiority trial of 214 adult patients with a radiologically confirmed diagnosis of a displaced distal clavicle fracture. Participants will be randomly allocated on 1:1 basis to surgery with locking plate fixation (with or without coracoclavicular (CC) sling, or CC reconstruction alone) or sling immobilization. In the sling immobilization group, if symptomatic nonunion occurs, participants would be offered surgical fixation (typically at the three-month follow-up). The primary outcome and endpoint will be the self-reported Disabilitities of the Arm, Shoulder and Hand questionnaire (DASH) at 12 months. The DASH will also be collected as a secondary outcome at baseline, six weeks, three, and six months after randomization. Other secondary outcomes include shoulder pain, EuroQol five-dimension five-level questionnaire (EQ-5D-5L), complications (e.g. infections, reoperations), fracture healing, healthcare costs, patient treatment preferences, satisfaction with appearance of their shoulder, sensitivity or pain to touch, and range of motion. There is uncertainty around whether a sling immobilization pathway is non-inferior to surgery and which of these two treatments is cost-effective. The DIDACT trial is a sufficiently powered and rigorously designed study to inform clinical decisions for the treatment of adults with this injury.

Hydrogen sulphide (H2S), a gasotransmitter synthesized by cystathionine-γ-lyase (CSE), exhibits antioxidant properties and may mimic exercise-induced muscle protection. However, its mechanistic role in muscle atrophy and exercise intervention remains unclear. Six-month-old male wild-type (WT) and SESN2 knockout (SESN2-/-) C57BL/6J mice were subjected to a 2-week hindlimb immobilization, followed by combined resistance and aerobic exercise or pharmacological intervention using the H2S donor NaHS (30 μmol/kg) or the CSE inhibitor DL-propargylglycine (PAG, 50 mg/kg). Invitro, C2C12 myotubes were treated with H2O2 and NaHS to assess oxidative stress injury. Muscle mass, cross-sectional area (CSA), collagen deposition and oxidative stress markers were evaluated via histology, Western blot and immunofluorescence. Compared with the immobilization (IM) group, mice receiving a 2-week combined exercise intervention (IM + EX) exhibited significantly increased gastrocnemius muscle mass/body weight (10.86 ± 0.62 vs. 8.56 ± 1.61, p < 0.01), enlarged muscle fibre CSA (1628 ± 265 μm2 vs. 905.5 ± 88.52 μm2, p < 0.01) and reduced collagen deposition as indicated by Sirius red staining (collagen-positive area: 2.86% ± 1.12% vs. 7.06 ± 1.18%, p < 0.001). Pharmacological inhibition of CSE with PAG significantly attenuated these exercise-induced improvements (muscle mass/body weight: 10.22 ± 0.59, CSA: 1139 ± 96.21 μm2, collagen area: 5.04 ± 0.66%, all p < 0.05 vs. IM + EX). Conversely, administration of the H2S donor NaHS mimicked the protective effects of exercise, increasing muscle mass/body weight (8.94 ± 0.51), CSA (1474 ± 176.1 μm2) and reducing collagen accumulation (collagen area: 3.04 ± 0.74%, all p < 0.05 vs. IM). Invitro, NaHS treatment (30 μM) significantly reversed H2O2-induced reductions in myotube diameter (19.16 ± 0.91 μm vs. 15.61 ± 0.72 μm, p < 0.01) and improved fusion index (46.47 ± 1.51% vs. 35.28 ± 2.87%, p < 0.05). Western blot analysis showed that NaHS upregulated SESN2 and Nrf2 expression, as well as downstream antioxidant proteins HO-1 and NQO1 (p < 0.05), whereas SESN2 knockdown blocked these effects and abolished NaHS-mediated protection in myotubes. In SESN2-/- mice, NaHS failed to increase muscle mass/body weight (7.24 ± 1.3 vs. WT + NaHS 10.12 ± 0.38, p < 0.001), CSA (699.2 ± 21.51 μm2 vs. WT + NaHS 1189 ± 93.27 μm2, p < 0.001) or antioxidant capacity, confirming the essential role of SESN2 in mediating H2S-dependent muscle protection. H2S protects against disuse-induced muscle atrophy by enhancing antioxidant defences via the SESN2/Nrf2 signalling pathway. These findings identify H2S as a potential exercise-mimetic therapeutic strategy for preserving muscle mass and function.

Identification of novel strain Acinetobacter baumannii H1 and its improvement capacity for nutrient removal after coimmobilized on activated carbon and CaCO3 in real aquaculture wastewater.

Recent years have seen continuous debate over the preferred method of immobilization for ankle fractures, especially between removable braces and cast immobilization. To address this, we conducted a meta-analysis of prospective randomized controlled trials (RCTs) to compare the two approaches and assess the feasibility of using a removable brace as an alternative to cast immobilization. PubMed, Cochrane Library, Embase, and Web of Science were last searched on January 18, 2025, to identify comparative studies evaluating removable braces vs. cast immobilization. Data were extracted and pooled, and a meta-analysis was conducted using Review Manager 5.4 (RevMan 5.4), The Cochrane Collaboration. Functional scores, complications, and time to return to work (RTW) were analyzed to assess the efficacy, safety, and cost of the two groups. We included 11 RCTs with a total sample size of 1,472 participants. There were no significant differences in the Olerud-Molander Ankle Score (OMAS) between the removable brace and cast immobilization groups, both in the short term at 6 weeks [mean differences (MD): 7.18, 95% confidence interval (CI): -5.77 to 20.12, p = 0.28], 12 weeks (MD: 6.02, 95% CI: -0.22 to 12.26, p = 0.06), and in the long term at 24 weeks (MD: 2.25, 95% CI: -2.78 to 7.27, p = 0.38), as well as beyond 1 year (MD: 0.82, 95% CI: -1.75 to 3.39, p = 0.53). Compared to the cast immobilization group, the removable brace group showed similar rates of chronic regional pain [risk ratio (RR): 0.74, 95% CI: 0.14-3.94, p = 0.73], non-union (RR: 0.96, 95% CI: 0.17-5.46, p = 0.96), and thrombosis (RR: 0.46, 95% CI: 0.20-1.10, p = 0.08). Additionally, there was no significant difference in the incidence of wound infections when the brace was applied after primary wound healing (RR: 1.63, 95% CI: 0.87-3.03, p = 0.13). In terms of return to work (RTW), the removable brace group showed a significantly shorter mean time to return to work (MD: -17.17, 95% CI: -33.00 to -1.34, p = 0.03). Subgroup analysis revealed that the brace group achieved a better OMAS score at 12 weeks when early weight-bearing was permitted (MD: 9.00, 95% CI: 1.47-16.53, p = 0.02). Overall, both braces and casts demonstrated comparable effectiveness in postoperative ankle function recovery and wound complications. However, braces offered an advantage in promoting early weight-bearing, which contributed to improved recovery of ankle function. Additionally, the use of braces allowed patients to return to work earlier.

Introduction: Fractures in the distal end of the radius are one of the most common fractures treated by orthopedic surgeons, constituting nearly 18% of all fractures. Displaced, unstable distal end of radius fractures remain a challenging problem for orthopedic surgeons; they tend to heal with malunion if not treated properly. These fractures result in significant anatomic deformity and functional disability if the radial length and angulation are not maintained well in the course of treatment. The purpose of this study is to assess and compare the functional outcome of displaced distal end of radius fractures treated with closed reduction and percutaneous K-wiring vs the conventional method of closed reduction with plaster cast immobilization using the disability of arm, shoulder, and hand (DASH) score. Subjects and methods: A prospective comparative study was conducted among 50 patients who presented to the emergency medicine department and to the orthopedics outpatient department (OPD) at our tertiary care center from July 2022 to October 2023. Patients who had unstable closed distal radius fractures (DRFs), with patient age ranging from 18 to 80 years, and simple extra-articular DRFs (A2, A3), were included in the study. Patients with open fractures, intra-articular DRFs (A1, B, C), neurovascular injuries, pathological fractures, and previous history of distal radius fracture were excluded from the study. A total of 50 patients were divided randomly into two groups, with each group containing 25 patients. One group underwent closed reduction and percutaneous K-wiring, and the other group underwent closed reduction with plaster cast immobilization. Both groups of patients were followed up at the 1st, 3rd, and 6th week. At this stage, fracture union was confirmed radiologically and patients were encouraged to begin wrist movements. Thereafter, both groups of patients were regularly followed up at the 9th, 12th, and 24th week, and at 1 year, and their functional outcome was assessed using the DASH score, Lindstrom grading, and Frykman grading. Statistical analysis used: The data were analyzed using SPSS software version 25.0. Continuous variables were expressed as mean ± standard deviation (SD), and categorical variables were expressed as frequencies and percentages. The Mann–Whitney <i>U</i> test was used to compare the DASH scores between the two groups. The Chi-squared test was used to compare categorical variables. A <i>p</i>-value of <0.05 was considered statistically significant. Results: The average DASH score at 9 weeks was 54 and 68 in the K-wire and cast immobilization groups, respectively. The DASH score was assessed at 9, 12, and 24 weeks in both groups. The Mann–Whitney <i>U</i> test was used to assess the functional outcome. The mean DASH score among the groups, though showing a minor difference (DASH score higher in those with cast immobilization), was not statistically significant. At the end of 9, 12, and 24 weeks, the <i>p</i>-value was 0.059, 0.094, and 0.253, respectively. The postoperative radiological assessment showed a significant difference in both the K-wire fixation and cast immobilization groups. The anatomical outcome was assessed according to Lindstrom and Frykman's criteria. In the K-wire fixation group, 48% had grade I, 40% had grade II, and 12% had grade III outcomes. In the cast immobilization group, an equal proportion (40%) had grade I and grade II, 12% had grade III, and 8% had grade IV outcomes. Conclusion: The results showed that both treatment modalities had significant improvements in radiological and anatomical parameters. However, patients treated with K-wire fixation generally exhibited better functional outcomes, as indicated by lower DASH scores, improved range of motion, and fewer complications such as stiffness and moderate pain. Although the differences were not always statistically significant, the trends suggest that K-wire fixation might offer a slight advantage in terms of overall functional recovery.

Digital function following flexor tendon repair in Zone II: A comparison of immobilization and controlled passive motion techniques.

Objective. Muscle atrophy is frequently observed after anterior cruciate ligament (ACL) reconstruction. The effects of different rehabilitation protocols after ACL reconstruction on muscle atrophy are not well studied. We aimed to examine the effects of joint immobilization and treadmill exercise after ACL reconstruction on muscle atrophy. Methods. After ACL reconstruction, rats were divided into no intervention, joint immobilization, or treadmill exercise (60 min/day, six days/week) groups. Untreated rats were used as controls. At two- or four-weeks post-surgery, muscle atrophy in the rectus femoris and semitendinosus as well as ankle plantar flexors was assessed. Results. ACL reconstruction induced muscle atrophy at two weeks in the rectus femo- ris, semitendinosus, and plantar flexors. Muscle atrophy in the rectus femoris and plantar flexors spontaneously recovered to levels not significantly different from those in the control group at four weeks, while that in the semitendinosus persisted at four weeks. Four weeks of joint immobilization after ACL reconstruction did not affect the muscle atrophy progression until two weeks, but it hindered the recovery of muscle atrophy in the rectus femoris and plantar flexors during the remaining two weeks. Treadmill exercise did not affect muscle atrophy in all examined muscles. Conclusions. Our results suggest that immobilization after ACL reconstruction should be limited to two weeks to avoid inhibition of recovery from muscle atrophy. Exer- cise may not be effective to alleviate muscle atrophy early after ACL reconstruction. However, since the exercise protocol differs from that used in humans, caution is need- ed when interpreting the results.

Objective: To evaluate the impact of early range of motion (ROM) exercises versus initial immobilization on postoperative pain and joint mobility in patients undergoing total hip replacement (THR).Methods: This single-centre, comparative experimental study was conducted at the Orthopaedic Surgery Department, Hayat Memorial Teaching Hospital, affiliated with Continental Medical College, Lahore, from 15th of October, 2024 till 15th of April, 2025. Forty adults, including both genders, aged 40–70 years undergoing unilateral or bilateral THR for advanced (Grade 4) primary osteoarthritis were randomly assigned into two groups: Group A (Early Mobilization, n=20) initiated supervised ROM exercises within 24 hours of surgery, while Group B (Immobilization, n=20) remained immobilized for the first postoperative week before starting the same protocol. Patients undergoing THR for fractures, tumours, infections, or revision surgery, or with comorbidities precluding early mobilization, were excluded. Pain was assessed using the Visual Analogue Scale (VAS), and hip mobility using the ROM subsection of the Harris Hip Score. Assessments were conducted at the 1st, 3rd, and 6th postoperative weeks by a blinded physiotherapist. Statistical analysis was done using SPSS v23, with significance set at p&lt;0.05.Results: Patients in the early mobilization group A demonstrated significantly greater reductions in VAS pain scores (Week 1: 5.0 vs 6.0; Week 3: 3.1 vs 5.0; Week 6: 1.0 vs 4.0; all p&lt;0.05) and superior ROM scores (Week 1: 3.1 vs 2.0; Week 3: 4.1 vs 3.3; Week 6: 4.7 vs 4.0; all p&lt;0.05) compared to the immobilization group B. No adverse events were reported in either group.Conclusion: Early ROM exercises following THR result in faster pain relief and improved hip mobility compared to initial immobilization. Therefore, early mobilization should be incorporated into postoperative rehabilitation protocols to enhance recovery and patient outcomes. Keywords: Total Hip Replacement, , Immobilization, Range of Motion, Visual Analogue Scale, Harris Hip Score, Postoperative Rehabilitation

The management of distal radial fractures (DRFs) in elderly patients remains controversial. Although conservative treatment with cast immobilization is widely accepted, the optimal duration for immobilization is unclear. This study aimed to compare pain control, functional outcomes, and complication rates between 4-week and 6-week immobilization periods in elderly patients treated nonoperatively for displaced DRFs. A single-center randomized controlled trial was conducted, including 150 patients who were ≥65 years of age and had displaced DRFs. Patients were randomized into 2 groups: 4-week immobilization and 6-week immobilization. Pain was assessed using a visual analog scale (VAS) at 10 days after removing the cast and then at 3, 6, and 12 months after injury. Functional outcomes were measured using the Patient-Rated Wrist Evaluation (PRWE) and QuickDASH (the abbreviated version of the Disabilities of the Arm, Shoulder and Hand questionnaire) at 3, 6, and 12 months. Radiographs were reviewed for malunion, and complications and range of motion were also evaluated. In the 135 patients analyzed, no differences were observed in pain or functional outcomes between the 2 groups at any time point. VAS scores 10 days after the cast removal were similar (3.87 for the 4-week immobilization group and 4.00 for the 6-week group; p = 0.67), as were PRWE scores (14.18 for the 4-week group and 15.51 for the 6-week group; p = 0.686) and QuickDASH scores (15.46 for the 4-week group and 17.86 for the 6-week group; p = 0.449) after 1 year. The malunion rates were 29.9% in the 4-week group and 32.8% in the 6-week group (p = 0.85), and there were no significant differences in complications or range of motion between groups. A 4-week immobilization period provided equivalent pain control, functional outcomes, and complication rates as a 6-week immobilization period in elderly patients with displaced DRFs treated nonoperatively. Therefore, a shorter immobilization period may be safely recommended for treating these fractures. Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.

Conservative treatment of the anterior cruciate ligament (ACL) is important for restoring functional activity and preventing secondary degeneration. However, the molecular mechanisms underlying ligament immobilization and its precise role in the healing process remain poorly understood. In this study, we investigated the effect of immobilization on the strength of the healed ACL during acute management. We performed surgery to heal the ACL of rats and immobilized the knees using Kirschner wires. The group in which only the surgery to promote ACL healing was performed was designated as the controlled anterior tibial instability group, whereas the group that underwent both surgery and immobilization was designated as the immobilization (IMM) group. After 1-2weeks of immobilization, histological analyses using hematoxylin-eosin staining and immunohistochemical evaluation of collagen types I and III expression were performed. A comprehensive genetic analysis in the acute phase was performed via RNA sequencing. Furthermore, fibroblasts derived from rat ACL were used to recapitulate inflammation with interleukin-1β, and its effect on elongation stress (110%) was investigated using polymerase chain reaction. Joint immobilization for 2weeks postoperatively increased the mechanical strength of the conservatively connected ligaments. Stretch stimulation of fibroblasts with interleukin-1β also decreased the expression of the extracellular matrix. Furthermore, bioinformatics analyses identified differentially expressed genes associated with the healing process in fixed versus unfixed ligaments. The results demonstrate that acute-phase immobilization, defined as fixation for 2weeks following injury, enhances ligament strength by promoting extracellular matrix synthesis and organized regeneration, providing novel insights into optimizing conservative ACL therapy.

Introduction: Skeletal muscle fibers are generally classified as fast- and slow-twitch fibers, each innervated by distinct motor neurons at the neuromuscular junction (NMJ). Muscle atrophy progresses in a type-specific manner during disuse, which may be associated with NMJ degeneration. Muscle disuse involves a reduction in both mechanical load and neural input onto myofibers, but their respective influences on the NMJ and myofibers are poorly understood. In this study, we aimed to elucidate the association between NMJ degeneration and myofiber atrophy by comparing two different disuse models in mice. Methods: Male C57BL/6J mice (12-13 weeks old) were divided into untreated control (CON), tail suspension (TS), and cast immobilization (IM) groups. TS mice were suspended by their tails to reduce the mechanical load on the hindlimb muscles but were allowed free movement. IM mice were suspended with their hindlimbs immobilized in casts to restrict neuromuscular activity. After 20 days of intervention, the neuromuscular transmission index (the ratio of the 10th to 1st compound muscle action potential amplitude during repetitive sciatic nerve stimulation), the wet weights of lower hindlimb muscles, myofiber size, NMJ morphology, and the expression of proteins and mRNAs related to protein metabolism and NMJ formation were analyzed. Additionally, adeno-associated virus-mediated overexpression of Dok7 and Neurotrophin-4 (NT4), proteins associated with NMJ formation and maintenance, was performed to determine their roles in preventing NMJ degeneration and myofiber atrophy. Results: The wet weight of the gastrocnemius muscle was significantly higher in TS than in IM, whereas that of the soleus was significantly higher in IM than in TS. Type I and IIa fibers in the soleus were significantly smaller in TS than in IM, while type IIb fibers in the plantaris were significantly smaller in IM than in TS. The neuromuscular transmission index was significantly lower in IM than in TS. TS had a significantly lower acetylcholine receptor (AChR) density in type I than in type II fibers in the soleus, whereas IM exhibited a significantly smaller presynaptic nerve terminal area in type II than in type I fibers. The phosphorylation level of RPS6 was significantly lower in TS than in IM, while mRNA expression of atrogin-1 and MuRF-1 was significantly lower in IM than in TS. The protein expression of Dok7, which is involved in AChR clustering, was significantly lower in TS than in IM in the soleus, whereas mRNA expression of NT4 was significantly lower in IM than in TS in the plantaris. Dok7 overexpression had no significant effect on myofiber size but prevented the impairment of neuromuscular transmission and reduction in AChR density in TS. NT4 overexpression prevented the atrophy of type IIb fibers in the plantaris and the degeneration of presynaptic nerve terminals in IM. Conclusions: Our results suggest that reduced mechanical load on myofibers during TS causes degeneration of postsynaptic AChRs and myofiber atrophy in type I fibers. Dok7 overexpression prevented the AChRs degeneration but not myofiber atrophy, which implies that AChRs degeneration does not directly lead to muscle atrophy in this model. Our results also suggest that reduced neural activity during IM causes degeneration of presynaptic nerve terminals and myofiber atrophy in type II fibers. As NT4 overexpression prevented both nerve terminal degeneration and myofiber atrophy, NT4 is a potential key factor in preventing NMJ degeneration and muscle atrophy. Taken together, we found evidence that muscle atrophy induced by different disuse models exhibits different fiber type-specific characteristics, in which neuromuscular interactions are deeply involved. This study was supported by Japan Society for the Promotion of Science and by Yamaha Motor Foundation for Sports. This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

ABSTRACTObjectiveThe treatment of tuberculosis at the craniovertebral junction (CVJ) remains challenging, with significant debate surrounding therapeutic approaches. Halo vest (HV) therapy provides a non‐invasive immobilization alternative, while occipitocervical fusion (OCF) offers a surgical option. However, limited evidence exists comparing the efficacy of HV therapy with OCF for CVJ tuberculosis. This study aimed to evaluate the clinical outcomes and safety of HV immobilization in treating CVJ tuberculosis, compared with OCF.MethodsThis retrospective cohort study was conducted from January 2012 to December 2022 and included 43 patients diagnosed with CVJ tuberculosis. Radiographic and treatment data were meticulously analyzed to compare outcomes between patients treated with HV immobilization (Group H, n = 22) and those undergoing OCF (Group O, n = 21). Interventions comprised at least 28 weeks of HV immobilization for Group H and OCF supplemented with postoperative external fixation for Group O. Outcomes were evaluated using the Visual Analog Scale (VAS‐neck), erythrocyte sedimentation rate (ESR), and radiographic stability (assessed via X‐ray and CT). Statistical analyses included the Student's t‐test (parametric data), Mann–Whitney U test (nonparametric data), and chi‐square test (categorical variables), with a significance level set at p < 0.05.ResultsOver a 24‐month follow‐up, all patients exhibited successful healing of tuberculosis lesions. Group H demonstrated greater improvements in cervical flexion‐extension and rotation function compared with Group O. Both groups showed statistically significant decreases in Visual Analog Scale (VAS‐neck) and Neck Disability Index (NDI) scores, as well as in ESR and C‐reactive protein (CRP) values from pre‐surgery levels (p < 0.01). Notably, differences in VAS‐neck (1 month) and NDI (24 months) between the groups were statistically significant (p < 0.05), while no significant differences were observed in other follow‐up periods (p > 0.05). Additionally, there were no significant differences in ESR and CRP values at any time point between the treatment groups (p > 0.05).ConclusionsThe study yielded satisfactory outcomes for all patients. Short‐term differences in pain relief did not significantly impact the healing of CVJ tuberculosis. Patients receiving HV treatment showed greater improvement in neck function compared with those undergoing occipitocervical fusion. Given the substantial costs and risks associated with open surgery, we advocate for conservative treatment utilizing HV.