Morphological comparative study of canine and feline diaphragms: Effect of bodyweight, body condition score, gender, age and breed.

The canine diaphragm is a muscular and tendinous dome-like plate and is largely involved in digestive and respiratory functions. Very few studies compared morphology of the diaphragm between dogs and cats and no studies have investigated the effects of individual factors on this morphology. So the aim of this study was to (1) study the effects of individual factors on the morphology of the diaphragm and (2) to compare its morphology between cats and dogs. Surface measurements of 86 diaphragms were performed. The tendinous centre (TC), the lumbar part of the peripheral muscular (LP) and the sternal and costal parts of the peripheral muscular (SCPM) were measured. Measurement ratios (surface of anatomical part of the diaphragm/total surface of the diaphragm) were used for statistical analysis (TC%S, LP%S, SCPM%S). The SCPM%S are significantly lower, and the LP%S are significantly higher when bodyweight increases in dogs and cats. The TC%S are significantly lower when the body condition score of dogs increases. The SCPM%S are significantly higher, and therefore, the TC%S and LP%S lower in brachycephalic animals as opposed to mesocephalic animals. The TC%S are significantly higher in dogs than in cats and the SCPM%S are significantly higher in cats than in dogs. This study proposed a cartography of the diaphragm morphology in cats and dogs taking into account individual animal factors. Significant differences in the diaphragm morphology between cats and dogs and between mesocephalic and brachycephalic animals were found. Further studies are necessary to confirm these results and to investigate the consequences of these variations.

Distal hamstrings tendons mechanical properties at rest and contraction using free-hand 3-D ultrasonography.

Tendon properties impact human locomotion, influencing sports performance, and injury prevention. Hamstrings play a crucial role in sprinting, particularly the biceps femoris long head (BFlh), which is prone to frequent injuries. It remains uncertain if BFlh exhibits distinct mechanical properties compared to other hamstring muscles. This study utilized free-hand three-dimensional ultrasound to assess morphological and mechanical properties of distal hamstrings tendons in 15 men. Scans were taken in prone position, with hip and knee extended, at rest and during 20%, 40%, 60%, and 80% of maximal voluntary isometric contraction of the knee flexors. Tendon length, volume, cross-sectional area (CSA), and anteroposterior (AP) and mediolateral (ML) widths were quantified at three locations. Longitudinal and transverse deformations, stiffness, strain, and stress were estimated. The ST had the greatest tendon strain and the lowest stiffness as well as the highest CSA and AP and ML width strain compared to other tendons. Biceps femoris short head (BFsh) exhibited the least strain, AP and ML deformation. Further, BFlh displayed the highest stiffness and stress, and BFsh had the lowest stress. Additionally, deformation varied by region, with the proximal site showing generally the lowest CSA strain. Distal tendon mechanical properties differed among the hamstring muscles during isometric knee flexions. In contrast to other bi-articular hamstrings, the BFlh high stiffness and stress may result in greater energy absorption by its muscle fascicles, rather than the distal tendon, during late swing in sprinting. This could partly account for the increased incidence of hamstring injuries in this muscle.

Aged Tendons Exhibit Altered Mechanisms of Strain-Dependent Extracellular Matrix Remodeling.

Aging is a primary risk factor for degenerative tendon injuries, yet the etiology and progression of this degeneration are poorly understood. While aged tendons have innate cellular differences that support a reduced ability to maintain mechanical tissue homeostasis, the response of aged tendons to altered levels of mechanical loading has not yet been studied. To address this question, we subjected young and aged murine flexor tendon explants to various levels of in vitro tensile strain. We first compared the effect of static and cyclic strain on matrix remodeling in young tendons, finding that cyclic strain is optimal for studying remodeling in vitro. We then investigated the remodeling response of young and aged tendon explants after 7 days of varied mechanical stimulus (stress deprivation, 1%, 3%, 5%, or 7% cyclic strain) via assessment of tissue composition, biosynthetic capacity, and degradation profiles. We hypothesized that aged tendons would show muted adaptive responses to changes in tensile strain and exhibit a shifted mechanical setpoint, at which the remodeling balance is optimal. Interestingly, we found that 1% cyclic strain best maintains native physiology while promoting extracellular matrix (ECM) turnover for both age groups. However, aged tendons display fewer strain-dependent changes, suggesting a reduced ability to adapt to altered levels of mechanical loading. This work has a significant impact on understanding the regulation of tissue homeostasis in aged tendons, which can inform clinical rehabilitation strategies for treating elderly patients.

Regional shear wave speeds track regional axial stress in nonuniformly loaded fibrous soft tissues.

Ligaments and tendons undergo nonuniform deformation during movement. While deformations can be imaged, it remains challenging to use such information to infer regional tissue loading. Shear wave tensiometry is a promising noninvasive technique to gauge axial stress and is premised on a tensioned beam model. However, it is unknown whether tensiometry can predict regional stress in a nonuniformly loaded structure. The objectives of this study were to (1) determine whether regional shear wave speed tracks regional axial stress in nonuniformly loaded fibrous soft tissues, and (2) determine the sensitivity of regional axial stress and shear wave speed to nonuniform load distribution and fiber alignment. We created a representative set of 12,000 dynamic finite element models of a fibrous soft tissue with probabilistic variations in fiber alignment, stiffness, and aspect ratio. In each model, we applied a randomly selected nonuniform load distribution, and then excited a shear wave and tracked its regional propagation. We found that regional shear wave speed was an excellent predictor of the regional axial stress (RMSE = 0.57 MPa) and that the nature of the regional shear wave speed-stress relationship was consistent with a tensioned beam model (R2 = 0.99). Variations in nonuniform load distribution and fiber alignment did not substantially alter the wave speed-stress relationship, particularly at higher loads. Thus, these findings suggests that shear wave tensiometry could provide a quantitative estimate of regional tissue stress in ligaments and tendons.

Acute Patellar Tendon Ruptures: An Update on Management.

Patellar tendon ruptures can be debilitating injuries. When incomplete, partial tears can be managed nonsurgically with immobilization and progressive rehabilitation. Although complete ruptures remain a relatively uncommon injury, they portend a high level of morbidity. Ruptures typically result from an acute mechanical overload to the extensor mechanism, such as with forced quadriceps contraction and knee flexion. However, chronically degenerated tendons are also predisposed to failure from low-energy injuries. Diagnosis can often be made clinically with recognition of a palpable defect to the tendon, localized patellar tendon tenderness, and inability to actively extend the knee. Diagnosis and surgical planning can be established with radiograph, ultrasonography, or magnetic resonance imaging. Surgical repair is the mainstay of treatment, and there have been many recent advances in repair technique, optimal reconstruction strategies, and supplemental fixation. Time to surgery for complete tears remains the most important prognosticator for success. Direct primary repair can be completed with transosseous tunnels, suture anchor repair, or end-to-end repair. Tendon reconstruction can be achieved with or without mechanical or biologic augments. Rehabilitation programs vary in specifics, but return to sport can be expected by 6 months postoperatively.

Investigation of the pressure value while performing biceps tenodesis for superior capsuler reconstruction.

BACKGROUND: To compare the histopathological results of biceps tenodesis (BT) performed with normal, low, and high pressures for superior capsule reconstruction (SCR) in rabbits with massive rotator cuff tears. MATERIALS AND METHODS: Thirty rabbits were divided into three groups. Rabbits 1-10 underwent SCR with BT at the same pressure (Group 1), value measured in the groove; 50% lower (Group 2); 50% higher (Group 3). After the 4-week follow-up, shoulder were en-bloc excised and histopathological evaluation was performed with modified Bonar's scale. Results were compared between the groups, statistically. RESULTS: Extracellular matrix were significantly lower in group 2 compared to the other groups (p < 0.05). Cellularity levels were significantly lower in group 2 compared to the other groups (p < 0.05). Group 2 had no difference between the sides (p > 0.05). Group 2 had lower vascularity levels compared to the other groups (p = 0.01). DICSUSSION: When the biceps tendon was in the bicipital groove and in a more mobile state with lower pressure exposure. BT performed with a tension that creates less pressure than the biceps in the groove is more successful in SCR.

Two-Photon Microscopy for the Study of Tendons.

Two-photon microscopy has emerged as a potent tool for evaluating deep tissue cells and characterizing the alignment of the extracellular matrix (ECM) in various biological systems. This technique relies on nonlinear light-matter interactions to detect two distinct signals: the second harmonic generated (SHG) diffusion signal, which facilitates the visualization of collagen fibers and their orientation, and the near-infrared excitation signal for imaging ultraviolet excited autofluorescence. SHG imaging proves especially effective in visualizing collagen fibers due to the non-centrosymmetric crystalline structure of fibrillar collagen I. Given that tendons are matrix-rich tissues with a limited number of cells, their high collagen content makes them ideal candidates for analysis using two-photon microscopy. Consequently, two-photon microscopy offers a valuable means to analyze and characterize collagen abnormalities in tendons. Its application extends to studying tendon development, injuries, healing, and aging, enabling the comprehensive characterization of tendon cells and their interactions with the ECM under various conditions using two-photon microscopy tools. This protocol outlines the use of two-photon microscopy in tendon biology and presents an adapted methodology to achieve effective imaging and characterization of tendon cells during development and after injury. The method allows the utilization of thin microscopic sections to create a comprehensive image of the ECM within tendons and the cells that interact with this matrix. Most notably, the article showcases a technique to generate 3D images using two-photon microscopy in animal models.

Arthroscopic cuff repair: footprint remnant preserving versus debriding rotator cuff repair of transtendinous rotator cuff tears with remnant cuff.

BACKGROUND: In transtendinous full thickness rotator cuff tears (FTRCT) with remnant cuff, conventionally, cuff remnant of the greater tuberosity (GT) is debrided for better tendon to bone healing. However, larger cuff defect caused overtension on the repaired tendon. The purpose of this study was to compare the clinical outcomes and tendon integrity between remnant preserving and remnant debriding cuff repairs in the transtendinous FTRCT with remnant cuff. METHODS: From March, 2012 to October, 2017, a total of 127 patients who had the transtendinous FTRCT with remnant cuff were enrolled in this study. Rotator cuff tears were repaired arthroscopically, with patients divided into two groups: group I (n = 63), where rotator cuff remnants were preserved during the repair, and group II (n = 64), where the remnants were debrided during the repair. Clinical outcomes were assessed at the last follow-up (minimum 2 years) using the UCLA score, ASES score, SST score, Constant Shoulder score, and range of motion (ROM). The analysis of structural integrity and tendon quality was performed using the Sugaya classification on postoperative MRI scans at 8 months after surgery. RESULTS: At the final follow-up, UCLA, ASES, SST, and CS scores significantly improved from preoperative values to postoperative (all p < 0.05): UCLA (I: 19.6 ± 6.0 to 31.7 ± 3.2, II: 18.0 ± 5.7 to 31.5 ± 3.2), ASES (I: 54.3 ± 10.7 to 86.5 ± 12.5, II: 18.0 ± 5.7 to 85.8 ± 12.4), SST (I: 5.6 ± 2.8 to 10.2 ± 2.0, II: 5.0 ± 2.9 to 10.1 ± 2.5), CS (I: 74.0 ± 17.2 to 87.8 ± 9.7, II: 62.0 ± 19.2 to 88.3 ± 6.2). However, there were no significant differences between the two groups (p > 0.05). Also, remnant preserving cuff repair yielded significantly better tendon quality on postoperative MRI (p < 0.05). The incidence of re-tear (Sugaya's Type IV and V) was not significantly different between the two groups (I:17% vs. II:19%; p = 0.053). CONCLUSIONS: Remnant preserving rotator cuff repairs, which facilitate tendon-to-tendon healing, are superior in terms of tendon quality and are the preferred option for transtendinous FTRCT. TRIAL REGISTRATION: Retrospectively registered.

The subacromial bursa modulates tendon healing after rotator cuff injury in rats.

Rotator cuff injuries result in more than 500,000 surgeries annually in the United States, many of which fail. These surgeries typically involve repair of the injured tendon and removal of the subacromial bursa, a synovial-like tissue that sits between the rotator cuff and the acromion. The subacromial bursa has been implicated in rotator cuff pathogenesis and healing. Using proteomic profiling of bursa samples from nine patients with rotator cuff injury, we show that the bursa responds to injury in the underlying tendon. In a rat model of supraspinatus tenotomy, we evaluated the bursa's effect on the injured supraspinatus tendon, the uninjured infraspinatus tendon, and the underlying humeral head. The bursa protected the intact infraspinatus tendon adjacent to the injured supraspinatus tendon by maintaining its mechanical properties and protected the underlying humeral head by maintaining bone morphometry. The bursa promoted an inflammatory response in injured rat tendon, initiating expression of genes associated with wound healing, including Cox2 and Il6. These results were confirmed in rat bursa organ cultures. To evaluate the potential of the bursa as a therapeutic target, polymer microspheres loaded with dexamethasone were delivered to the intact bursae of rats after tenotomy. Dexamethasone released from the bursa reduced Il1b expression in injured rat supraspinatus tendon, suggesting that the bursa could be used for drug delivery to reduce inflammation in the healing tendon. Our findings indicate that the subacromial bursa contributes to healing in underlying tissues of the shoulder joint, suggesting that its removal during rotator cuff surgery should be reconsidered.

Bioactive fiber-reinforced hydrogel to tailor cell microenvironment for structural and functional regeneration of myotendinous junction.

Myotendinous junction (MTJ) injuries are prevalent in clinical practice, yet the treatment approaches are limited to surgical suturing and conservative therapy, exhibiting a high recurrence rate. Current research on MTJ tissue engineering is scarce and lacks in vivo evaluation of repair efficacy. Here, we developed a three-dimensional-printed bioactive fiber-reinforced hydrogel containing mesenchymal stem cells (MSCs) and Klotho for structural and functional MTJ regeneration. In a rat MTJ defect model, the bioactive fiber-reinforced hydrogel promoted the structural restoration of muscle, tendon, and muscle-tendon interface and enhanced the functional recovery of injured MTJ. In vivo proteomics and in vitro cell cultures elucidated the regenerative mechanisms of the bioactive fiber-reinforced hydrogel by modulating oxidative stress and inflammation, thus engineering an optimized microenvironment to support the survival and differentiation of transplanted MSCs and maintain the functional phenotype of resident cells within MTJ tissues, including tendon/muscle cells and macrophages. This strategy provides a promising treatment for MTJ injuries.

Effects of gait retraining using minimalist shoes on the medial gastrocnemius muscle-tendon unit behavior and dynamics during running.

The effects of a 12-week gait retraining program on the adaptation of the medial gastrocnemius (MG) and muscle-tendon unit (MTU) were investigated. 26 runners with a rearfoot strike pattern (RFS) were randomly assigned to one of two groups: gait retraining (GR) or control group (CON). MG ultrasound images, marker positions, and ground reaction forces (GRF) were collected twice during 9 km/h of treadmill running before and after the intervention. Ankle kinetics and the MG and MTU behavior and dynamics were quantified. Runners in the GR performed gradual 12-week gait retraining transitioning to a forefoot strike pattern. After 12-week, (1) ten participants in each group completed the training; eight participants in GR transitioned to non-RFS with reduced foot strike angles; (2) MG fascicle contraction length and velocity significantly decreased after the intervention for both groups, whereas MG forces increased after intervention for both groups; (3) significant increases in MTU stretching length for GR and peak MTU recoiling velocity for both groups were observed after the intervention, respectively; (4) no significant difference was found for all parameters of the series elastic element. Gait retraining might potentially influence the MG to operate at lower fascicle contraction lengths and velocities and produce greater peak forces. The gait retraining had no effect on SEE behavior and dynamics but did impact MTU, suggesting that the training was insufficient to induce mechanical loading changes on SEE behavior and dynamics.

Engineering Tendon Assembloids to Probe Cellular Crosstalk in Disease and Repair.

Tendons enable locomotion by transferring muscle forces to bones. They rely on a tough tendon core comprising collagen fibers and stromal cell populations. This load-bearing core is encompassed, nourished, and repaired by a synovial-like tissue layer comprising the extrinsic tendon compartment. Despite this sophisticated design, tendon injuries are common, and clinical treatment still relies on physiotherapy and surgery. The limitations of available experimental model systems have slowed the development of novel disease-modifying treatments and relapse-preventing clinical regimes. In vivo human studies are limited to comparing healthy tendons to end-stage diseased or ruptured tissues sampled during repair surgery and do not allow the longitudinal study of the underlying tendon disease. In vivo animal models also present important limits regarding opaque physiological complexity, the ethical burden on the animals, and large economic costs associated with their use. Further, in vivo animal models are poorly suited to systematic probing of drugs and multicellular, multi-tissue interaction pathways. Simpler in vitro model systems have also fallen short. One major reason is a failure to adequately replicate the three-dimensional mechanical loading necessary to meaningfully study tendon cells and their function. The new 3D model system presented here alleviates some of these issues by exploiting murine tail tendon core explants. Importantly, these explants are easily accessible in large numbers from a single mouse, retain 3D in situ loading patterns at the cellular level, and feature an in vivo-like extracellular matrix. In this protocol, step-by-step instructions are given on how to augment tendon core explants with collagen hydrogels laden with muscle-derived endothelial cells, tendon-derived fibroblasts, and bone marrow-derived macrophages to substitute disease- and injury-activated cell populations within the extrinsic tendon compartment. It is demonstrated how the resulting tendon assembloids can be challenged mechanically or through defined microenvironmental stimuli to investigate emerging multicellular crosstalk during disease and injury.

Comparison of Graft Type and Fixation Method in Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis Based on Randomized Control Studies.

BACKGROUND: The anterior cruciate ligament (ACL) is the most commonly injured ligament in the knee. ACL reconstruction (ACLR) proves the standard for treating this injury. However, graft choice and method of fixation remain a heavily debated topic. This study investigates the following: bone-patellar tendon-bone (BPTB) vs. hamstring tendon (HT) autograft, single-bundle vs. double-bundle hamstring graft, and metal vs. bioabsorbable screws in ACLR. METHODS: A systematic review was performed on PubMed and Google Scholar according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Data were collected on patient demographics, complications, and functionality scores including International Knee Documentation Committee (IKDC) and Lysholm scores. A systematic review and meta-analysis were conducted with Review Manager. Outcome measurements were determined using forest plots with significant differences considered p < 0.05. RESULTS: Twenty-five studies were included, accounting for 2,170 patients. No statistically significant difference was appreciated when comparing BPTB to hamstring autografts. Patients who received a double bundle HT autograft exhibited significantly superior outcomes in terms of revision (p = 0.05), failure (p = 0.002), normal pivot shift tests (p = 0.04), and normal IKDC (p = 0.008). When comparing screw types, bioabsorbable screws had a greater Lysholm score (p = 0.01) and lower failure rates for copolymer screws (p = 0.03). CONCLUSION: Overall, the data collected suggested that BPTB and HT autografts display similar postoperative results. However, if an HT autograft is used, the data suggest a double-bundle graft improves both functionality and decreases the possible complications. Finally, bioabsorbable screws prove superior to metal screws when looking at both functionality and failure rates. Further research into the superior graft type is still needed. LEVEL OF EVIDENCE: Level II. See Instructions for Authors for a complete description of levels of evidence.

Ultrasonography-guided percutaneous release of A3 pulley of the fifth finger to treat trigger finger: Description of the technique, with reference to a specific case.

Trigger finger causes pain and a persistent functional limitation of the hand, which can lead to permanent blockage of the flexor tendon. Ultrasonography-guided percutaneous release has been widely reported as a successful technique for trigger finger involving the A1 pulley. This article describes for the first time the use of this technique in an unusual location, the A3 pulley of the fifth finger. A 71-year-old patient presented with a 3-month history of pain and blockage in the fifth finger of the right hand and was diagnosed with a grade III trigger finger, according to the Froimson scale. We performed an ultrasonography-guided percutaneous release technique on the A3 pulley to release the flexor tendon of the fifth finger. Ultrasonography-guided percutaneous polectomy to treat trigger finger in the A1 pulley is an effective alternative treatment to surgery and even has certain advantages over it. The anatomical similarity between the A1 and A3 pulleys was the key factor that supported the use of this technique in this clinical case. Based on past experience in similar cases, we conclude that ultrasonography-guided percutaneous polectomy of the A3 pulley of the fifth finger was a surgical technique which could lead to a satisfactory outcome in the treatment of this condition.

Spatial High-resolution Analysis of Gene Expression Levels in Tendons.

In recent years, many protocols have been developed for high-resolution transcriptomics in many different medical and biology fields. However, matrix-rich tissues, and specifically, tendons were left behind due to their low cell number, low RNA amount per cell, and high matrix content, which made them complicated to analyze. One of the recent and most important single-cell tools is the spatial analysis of gene expression levels in tendons. These RNA spatial tools have specifically high importance in tendons to locate specific cells of new and unknown populations, validate single-cell RNA-seq results, and add histological context to the single-cell RNA-seq data. These new methods will enable the analysis of RNA in cells with exceptional sensitivity and the detection of single-molecule RNA targets at the single-cell level, which will help to molecularly characterize tendons and promote tendon research. In this method paper, we will focus on the available methods to analyze spatial gene expression levels on histological sections by using novel in situ hybridization assays to detect target RNA within intact cells at single-cell levels. First, we will focus on how to prepare the tendon tissue for the different available assays and how to amplify target-specific signals without background noise but with high sensitivity and high specificity. Then, the paper will describe specific permeabilization methods, the different probe designs, and the signal amplification strategies currently available. These unique methods of analyzing transcription levels of different genes in single-cell resolution will enable the identification and characterization of the tendon tissue cells in young and aged populations of various animal models and human tendon tissues. This method will also help analyze gene expression levels in other matrix-rich tissues such as bones, cartilage, and ligaments.

The rat as a novel model for chronic rotator cuff injuries.

Chronic rotator cuff injuries (CRCIs) still present a great challenge for orthopaedics surgeons. Many new therapeutic strategies are developed to facilitate repair and improve the healing process. However, there is no reliable animal model for chronic rotator cuff injury research. To present a new valuable rat model for future chronic rotator cuff injuries (CRCIs) repair studies, and describe the changes of CRCIs on the perspectives of histology, behavior and MRI. Sixty male Wistar rats were enrolled and underwent surgery of the left shoulder joint for persistent subacromial impingement. They were randomly divided into experimental group (n = 30, a 3D printed PEEK implant shuttled into the lower surface of the acromion) and sham operation group (n = 30, insert the same implant, but remove it immediately). Analyses of histology, behavior, MRI and inflammatory pain-related genes expression profiles were performed to evaluate the changes of CRCIs. After 2-weeks running, the rats in the experimental group exhibited compensatory gait patterns to protect the injured forelimb from loading after 2-weeks running. After 8-weeks running, the rats in the experimental group showed obvious CRCIs pathological changes: (1) acromion bone hyperplasia and thickening of the cortical bone; (2) supraspinatus muscle tendon of the humeral head: the bursal-side tendon was torn and layered with disordered structure, forming obvious gaps; the humeral-side tendon is partially broken, and has a neatly arranged collagen. Partial fat infiltration is found. The coronal T2-weighted images showed that abnormal tendon-to-bone junctions of the supraspinatus tendon. The signal intensity and continuity were destroyed with contracted tendon. At the nighttime, compared with the sham operation group, the expression level of IL-1ß and COX-2 increased significantly (P = 0063, 0.0005) in the experimental group. The expression of COX-2 in experimental group is up-regulated about 1.5 times than that of daytime (P = 0.0011), but the expression of IL-1ß, TNF-a, and NGF are all down-regulated (P = 0.0146, 0.0232, 0.0161). This novel rat model of chronic rotator cuff injuries has the similar characteristics with that of human shoulders. And it supplies a cost-effective, reliable animal model for advanced tissue engineered strategies and future therapeutic strategies.

[Early effectiveness of arthroscopic tri-anchor double-pulley suture-bridge repair of medium-size supraspinatus tendon tears].

Objective: To explore the early effectiveness of arthroscopic tri-anchor double-pulley suture-bridge in treatment of medium-size supraspinatus tendon tears. Methods: Between December 2020 and January 2023, 40 patients with medium-size supraspinatus tendon tears were treated with arthroscopic tri-anchor double-pulley suture-bridge. There were 18 males and 22 females, with an average age of 62.6 years (mean, 45-73 years). Among them, 17 patients had trauma history. The main clinical symptom was shoulder pain with hug resistance test (+). The interval from symptom onset to operation was 10.7 months on average (range, 3-36 months). Visual analogue scale (VAS) score, University of California Los Angeles (UCLA) score, American Shoulder and Elbow Surgeons (ASES) score, and shoulder range of motion (ROM) of forward flexion, abduction, and external rotation were used to evaluate shoulder function. MRI was performed to assess the structural integrity and tension of reattached tendon. Patient satisfactions were calculated at last follow-up. Results: All incisions healed by first intention, no complications such as incision infection or nerve injury occurred. All patients were followed up 12-37 months (mean, 18.2 months). At 12 months after operation, VAS score, UCLA score, and ASES score significantly improved when compared with the preoperative scores ( P<0.05). At 3 and 12 months after operation, the ROM of external rotation significantly improved when compared with preoperative one ( P<0.05), and further improved at 12 months after operation ( P<0.05). However, the ROMs of abduction and forward flexion did not improve at 3 months after operation when compared with those before operation ( P>0.05), but significantly improved at 12 months after operation ( P<0.05). Twenty-six patients underwent MRI at 3-6 months, of which 23 patients possessed intact structural integrity, good tendon tension, and tendon healing; 3 patients underwent tendon re-tear. The self-rated satisfaction rate was 92.5% at last follow-up. Conclusion: Arthroscopic tri-anchor double-pulley suture-bridge in treatment of medium-size supraspinatus tendon tears can maximize the tendon-bone contact area, obtain satisfied early effectiveness with high satisfaction rate and low incidence of tendon re-tear. However, the function of abduction is limited at 3 months after operation, and patients need to adhere to rehabilitation training to further improve the joint activity.

Clinical Outcomes of Bipolar Hemiarthroplasty with a Conjoined Tendon-Preserving Posterior Approach for Femoral Neck Fractures.

Background and Objectives: The conventional posterior approach in the lateral decubitus position is widely used for femoral neck fractures in femoral hemiarthroplasty. Postoperative dislocation is the major problem with this approach. The conjoined tendon-preserving posterior (CPP) approach is a less invasive surgical approach than the conventional posterior approach to the hip, maintains posterior stability, and preserves short external rotators and joint capsules. However, the mention was required to avoid muscle damage and whether muscle damage affects postoperative dislocation or not. The current study aimed to evaluate the clinical results of the CPP approach in hemiarthroplasty for femoral neck fractures and identify muscle damage risk factors. Materials and Methods: This study was a retrospective cohort study and included 170 hips in 168 patients. The mean age at the operation was 81.2 years. The preservation rate of the internal obturator muscle and gemellus inferior muscle and factors related to intraoperative short rotator muscle injury were investigated retrospectively. The postoperative complications and the relation between muscle damage and postoperative dislocation were investigated. Results: In the four hips (2.3%) with the obturator internus muscle damage, thirty-eight hips (22.4%) with gemellus inferior muscle damage were detected; in the muscle-damaged cases, the high body mass index (BMI) was significantly higher. The complication occurred in four hips (2.3%), including postoperative posterior dislocation in one hip without muscle damage (0.6%). Postoperative infection occurred in one hip (0.6%), and peroneal or sciatic nerve paralysis was suspected in two hips (1.1%). Conclusions: Compared to the conventional posterior approach in previous reports, the CPP approach reduces postoperative dislocation. A higher BMI is a risk factor for muscle damage, and the gemellus inferior muscle damage has no effect on postoperative dislocation. The CPP approach for BHA appeared to be an effective treatment method.

Cell-Based Therapies for Rotator Cuff Injuries: An Updated Review of the Literature.

This review focuses on non-surgical treatment options for rotator cuff injuries and highlights the potential of mesenchymal stem cells (MSCs) as a potential regenerative approach. MSCs, sourced from various tissues like bone marrow and adipose tissue, exhibit promising mechanisms in vitro, influencing tendon-related gene expression and microenvironment modulation. Animal studies support this, showcasing MSCs' ability to reduce inflammation, improve tissue remodeling, and enhance repaired tendon strength. Human trials, while varied and limited, suggest that MSCs might lower retear rates and enhance post-repair outcomes, but randomized controlled trials yield mixed results, emphasizing the necessity for standardized investigations. Ultimately, while cell-based therapies demonstrate an excellent safety profile, more rigorous clinical trials are necessary to determine their efficacy in improving patient outcomes and achieving lasting structural changes in rotator cuff injuries.

Which is better? Early versus delayed rehabilitation after arthroscopic rotator cuff repair.

PURPOSE: This study aimed to compare the 5-year clinical and functional outcomes, including repaired tendon healing status, between early and delayed rehabilitation after arthroscopic rotator cuff repair METHODS: A total of 75 patients with rotator cuff tears (less than 5 cm) underwent arthroscopic repairs over a 60-month period. Participants were randomly assigned to early and delayed postoperative rehabilitation groups with distinct protocols. Clinical and functional outcome measures included Constant score, University of California at Los Angeles (UCLA) score, visual analogue scale for pain and isokinetic dynamometer test for muscle strength recovery. Clinical and functional scores were compared between baseline and 5 years postoperatively. Radiologic assessment via magnetic resonance imaging was performed at a minimum of 12 months postoperatively for evaluations of tendon integrity and recurrent tears. RESULTS: Baseline characteristics showed no statistically significant differences between groups. Both groups demonstrated equivalent improvement in range of motion and pain scores with no statistical differences. Clinical scores improved significantly in both groups by postoperative 12 months and plateaued. At the postoperative 5-year mark, the early group showed better improvement in the visual analogue scale and UCLA score, while the delayed group had superior Constant scores. Postoperative magnetic resonance imaging revealed six recurrent tears, two in the early group and four in the delayed group, with no statistical differences. Muscle strength recovery showed no differences between the two groups. CONCLUSION: Both the early and the delayed rehabilitation groups showed similar outcomes in postoperative range of motion, functional scores, muscle strength recovery and tendon healing in the short- and mid-term follow-ups. LEVEL OF EVIDENCE: Level III.