Supraspinatus Research Articles

Prospective Evaluation of Normal Supraspinatus Muscle Using Shear Wave Elastography: Comparison With Symptomatic Tendon Tears.

This study aimed to evaluate normal supraspinatus (SS) muscle elasticity using shear wave elastography (SWE) in an asymptomatic group, analyze its correlation with demographic factors and ultrasound (US) grayscale grade, and compare the elasticity between normal SS muscles and symptomatic SS muscles with tendon tears. A prospective study was conducted with 101 adult patients with normal SS muscle scheduled for surgery due to a contralateral shoulder with SS tendon tear. Both shoulders underwent US examinations, including SWE. The SWE values, including mean and median elasticity, as well as the elasticity ratio, were analyzed for their correlation with demographic characteristics and grayscale grades. A comparison of SWE values was performed between the normal and symptomatic SS muscle groups. The mean SWE modulus of the normal SS muscle was 27.87 kPa (±49.04), with an elasticity ratio of approximately 1.52 (±0.03). Males exhibited slightly higher elasticity ratios compared with females (1.61 vs 1.45, P = .016). The interobserver agreement for all SWE measurements was excellent (>0.8). Grayscale grade increased with age, showing a similar pattern in females (P < .001). However, no significant correlation was observed between SWE values and grayscale grade in the normal SS muscle group. SWE values in normal SS muscles were significantly lower than those with tendon tears (P < .001). SWE provides objective measurements of normal SS muscle elasticity. Gender-based variations were observed, with males exhibiting slightly higher elastography ratios. SWE values were significantly lower in asymptomatic SS muscles compared with those with tendon tears.

Fatigue-related changes in intermuscular electromyographic coherence across rotator cuff and deltoid muscles in individuals with and without subacromial pain.

Neuromuscular fatigue induces superior migration of the humeral head in individuals with subacromial pain. This has been attributed to weakness of rotator cuff muscles and overactive deltoid muscles. Investigation of common inputs to motoneuron pools of the rotator cuff and deltoid muscles offers valuable insight into the underlying mechanisms of neuromuscular control deficits associated with subacromial pain. This study aims to investigate intermuscular coherence across the rotator cuff and deltoid muscles during a sustained submaximal isometric fatiguing contraction in individuals with and without subacromial pain. Twenty symptomatic and 18 asymptomatic young adults participated in this study. Surface electromyogram (EMG) was recorded from the middle deltoid (MD) and infraspinatus (IS). Intramuscular EMG was recorded with fine-wire electrodes in the supraspinatus (SS). Participants performed an isometric fatiguing contraction of 30° scaption at 25% maximum voluntary contraction (MVC) until endurance limit. Pooled coherence of muscle pairs (SS-IS, SS-MD, IS-MD) in the 2-5 Hz (delta), 5-15 Hz (alpha), and 15-35 Hz (beta) frequency bands during the initial and final 30 s of the fatigue task were compared. SS-IS and SS-MD delta-band coherence increased with fatigue in the asymptomatic group but not the symptomatic group. In the alpha and beta bands, SS-IS and SS-MD coherence increased with fatigue in both groups. IS-MD beta-band coherence was greater in the symptomatic than the asymptomatic group. Individuals with subacromial pain failed to increase common drive across rotator cuff and deltoid muscles and have altered control strategies during neuromuscular fatigue. This may contribute to glenohumeral joint instability and subacromial pain experienced by these individuals.NEW & NOTEWORTHY Through the computation of shared neural drive across glenohumeral muscles, this study reveals that individuals with subacromial pain were unable to increase shared neural drive within the rotator cuff and across the supraspinatus and deltoid muscles during neuromuscular fatigue induced by sustained isometric contraction. These deficits in common drive across the shoulder muscles likely contribute to the joint instability and pain experienced by these individuals.

Proximal humeral fractures: association between displacement and fatty degeneration of the supraspinatus muscle.

To evaluate the relationship between initial displacement in proximal humeral fractures and fatty degeneration of the rotator cuff measured by CT according to the Goutallier classification. This cross-sectional observational study evaluated patients with proximal humeral fractures over a six-month period. The study included patients ≥ 18 years old with complete radiological views (anteroposterior, lateral, and Grashey) and a CT scan of the affected shoulder; previous fracture or ipsilateral shoulder surgery were excluded. Neer's classification system and Goutallier stages were used to evaluate the patients. Demographic data were collected and, two groups were analysed according to age (≤ 50 years and > 50 years). Sixty-two patients were included (m = 36, f = 26, ratio 1.3:1); seven patients were excluded. Male patients (36, 58.1%), patients older than 50 years (33, 53.2%) and a low-energy injury mechanism (36, 58.1%) were the most frequent cases. According to the Neer system, the most common proximal humerus fracture was fracture-dislocation in 17 (27.4%) cases. The most common stage in Goutallier's classification was I (some fatty streaks) in 22 (35.4%) cases. Younger patients (≤ 50 years) had more displaced fractures with low fatty degeneration (p = < 0.001) than older patients (> 50 years), who had minimally displaced fractures with greater fatty degeneration (p = 0.567). High-energy mechanisms are associated with younger patients and a more displaced fracture according to the Neer classification. Older patients had a more advanced Goutallier stage and lesser displaced fracture. We should consider a more aggressive approach in the treatment of non-displaced fractures in elderly patients, less conservative and more surgical management, to obtain a better clinical evolution after the treatment of these kinds of fractures. IV.

Spinal Accessory to Suprascapular Nerve Transfer in Traumatic Brachial Plexus Injury: A Comparative Study of Shoulder Recovery Outcomes in the Anterior versus Posterior Approach and Surgeons' Preference

Problem statementConventionally, neural transfer of SAN to SSN for shoulder abduction in traumatic brachial plexus injury is done via the anterior approach. But important advantages of the posterior approach like the proximity of neural coaptation to the muscle to be reinnervated and negating the effects of a second injury to the suprascapular nerve have made it an alternative option. MethodologyRetrospective data was collected for a total of 30 SAN to SSN transfer patients of brachial plexus injury in two groups of 15 patients each of anterior (Group A) and posterior approach (Group B) over four years. Functional outcome at the shoulder was measured as muscle power and active range of motion (ROM) at 18 months and data on patients’ satisfaction levels and surgeons’ perceptions were also collected. ResultsNo statistical difference was found in the muscle strength achieved in the two groups (p-value = 0.34) but significant recovery was found in the external rotation achieved by group B (p-value = 0.02). Statistical difference was insignificant in the two groups' active ROM during abduction and external rotation. The satisfaction index of patients was 86.7% in the posterior approach compared to 68% in group A. Surgeons’ perspective showed a faster speed of suprascapular nerve exploration as perceived in the posterior approach with better visibility of supraspinatus muscle contraction, and overall surgeons’ preference for a posterior approach. ConclusionExternal rotation at the shoulder is better with the posterior approach but no difference in abduction. Patients with the posterior approach were more satisfied with the recovery, and surgeons preferred the posterior approach.

The relationship between the duration and the retraction and atrophy grades in traumatic isolated full-thickness supraspinatus tears in young patients

BackgroundThe study aimed to determine the grade of retraction and atrophy according to the time elapsed in traumatic isolated full-thickness supraspinatus (SS) tears in young patients.MethodsOne thousand twenty-six patients, who underwent arthroscopic shoulder surgery, were retrospectively reviewed. Pre-operative magnetic resonance imaging (MRI) of 69 patients aged 18 to 40 years with isolated traumatic full-thickness SS lesions remaining after exclusion criteria were evaluated for tendon retraction and atrophy grades. SS retraction was determined from a T2-weighted oblique coronal MRI slice, and the atrophy grade was determined from the T1-weighted oblique sagittal MRI slice. The patients were divided into four groups 0–1 month, 1–3 months, 3–6 months, and 6–12 months according to the time between trauma and MRI. The relationship of tendon retraction and muscle atrophy with elapsed time was evaluated, in addition, comparisons between groups were made.ResultsThirty-one (45%) of the patients were female and their mean age was 30 ± 7.3 (18–40) years. The mean age of men was 30.5 ± 6.9 (18–39) years (p = 0.880). The time between rupture and MRI was moderately correlated with retraction and strongly correlated with atrophy grades (r = 0.599, 0.751, respectively). It was observed that there was a statistically significant difference between the 1st (0–1 month) and 2nd (1–3 months) groups (p = 0.003, 0.001, respectively), and between the 2nd and 3rd (3–6 months) groups (p = 0.032, 0.002, respectively), but there was no significant difference between the 3rd and 4th (6–12 months) groups (p = 0.118, 0.057, respectively). In addition, there was a moderate correlation between tendon retraction and atrophy grades (r = 0.668). Power (1- b) in post hoc analysis was calculated as 0.826.ConclusionsThe current study, supported by arthroscopy, showed that there is a moderate and strong positive correlation between the time elapsed after trauma and the level of retraction and degree of atrophy in traumatic full-thickness SS tears, and demonstrated the importance of early surgical intervention in young patients.

A visual marker for early atrophy of the supraspinatus muscle on conventional MRI: introduction of the blackbird sign.

The aim of this study was to introduce the blackbird sign as a fast, qualitative measure of early supraspinatus (SSP) muscle atrophy and to correlate the sign with quantitatively assessed muscle volume and intramuscular fat fraction (FF) in patients with full-thickness SSP tears. The blackbird sign describes the asymmetric pattern of early SSP atrophy: on sagittal MR images, the supero-posterior contour of the muscle becomes concave, resembling the shape of a blackbird. MRIs of patients with full-thickness SSP tears were retrospectively reviewed for the presence of the blackbird and tangent signs. Patients were then divided into group 1: negative tangent sign and negative blackbird sign (n = 67), group 2: negative tangent sign and positive blackbird sign (n = 31), and group 3: positive tangent sign (n = 32). A 2-point Dixon sequence was acquired in all patients from which quantitative FF and muscle volumes were calculated. In total 130 patients (mean age 67 ± 11 years) were included. Mean SSP volume was significantly smaller in group 3 (15.8 ± 8.1 cm3) compared to group 2 (23.9 ± 7.0 cm3, p = 0.01) and group 1 (29.7 ± 9.1 cm3, p < 0.01). Significantly lower muscle volumes were also found in group 2 compared to group 1 (p = 0.02), confirming that the blackbird sign is able to identify early SSP atrophy. Mean FF in the SSP was significantly higher in group 3 (18.5 ± 4.4%) compared to group 2 (10.9 ± 4.7%, p < 0.01) and group 1 (6.1 ± 2.6%, p < 0.01). Visual assessment of early muscle atrophy of the SSP is feasible and reproducible using the blackbird sign, allowing the diagnosis of early SSP atrophy. In routine clinical practice, the blackbird sign may be a useful tool for assessing early muscle degeneration before the risk of postoperative rotator cuff re-tears increases with progressive muscle atrophy and fatty infiltration. Quantitative measurements of rotator cuff injuries require time, limiting clinical practicality. The proposed blackbird sign is able to identify early SSP atrophy. Reader agreement for the blackbird sign was substantial, demonstrating reproducibility and ease of implementation in the clinical routine.

Transcriptional evidence for transient regulation of muscle regeneration by brown adipose transplant in the rotator cuff.

Chronic rotator cuff(RC) injuries can lead to a degenerative microenvironment that favors chronic inflammation, fibrosis, and fatty infiltration. Recovery of muscle structure and function will ultimately require a complex network of muscle resident cells, including satellite cells, fibro-adipogenic progenitors (FAPs), and immune cells. Recent work suggests that signaling from adipose tissue and progenitors could modulate regeneration and recovery of function, particularly promyogenic signaling from brown or beige adipose (BAT). In this study, we sought to identify cellular targets of BAT signaling during muscle regeneration using a RCBAT transplantation mouse model. Cardiotoxin injured supraspinatus muscle had improved mass at 7 days postsurgery (dps) when transplanted with exogeneous BAT. Transcriptional analysis revealed transplanted BAT modulates FAP signaling early in regeneration likely via crosstalk with immune cells. However, this conferred no long-term benefit as muscle mass and function were not improved at 28 dps. To eliminate the confounding effects of endogenous BAT, we transplanted BAT in the "BAT-free" uncoupling protein-1diphtheria toxin fragment A (UCP1-DTA) mouse and here found improved muscle contractile function, but not mass at 28 dps. Interestingly, the transplanted BAT increased fatty infiltration in all experimental groups, implying modulation of FAP adipogenesis during regeneration. Thus, we conclude that transplanted BAT modulates FAP signaling early in regeneration,but does not grant long-term benefits.

Overexpression of PRDM16 improves muscle function after rotator cuff tears

Muscle atrophy, fibrosis, and fatty infiltration are commonly seen in rotator cuff tears (RCTs), which are critical factors that directly determine the clinical outcomes for patients with this injury. Therefore, improving muscle quality after RCT is crucial in improving the clinical outcome of tendon repair. In recent years, it has been discovered that adults have functional beige/brown adipose tissue (BAT) that can secrete batokines to promote muscle growth. PRDM16, a PR-domain-containing protein, was discovered with the ability to determine the brown fat cell fate and stimulate its development. Thus, the goal of this study was to discover the role of PRDM16 in improving muscle function after massive tendon tears using a transgenic mouse model with an elevated level of PRDM16 expression. Transgenic aP2-driven PRDM16-overexpressing mice and C57BL/6J mice underwent unilateral supraspinatus (SS) tendon transection and suprascapular nerve transection (TTDN) as described previously (n=8 in each group). DigiGait was performed to evaluate forelimb function at 6 weeks post the TTDN injury. Bilateral SS muscles, interscapular brown fat, epididymal white fat, and inguinal beige fat were harvested for analysis. The expression of PRDM16 in adipose tissue was detected by Western blot. Masson Trichrome staining was conducted to evaluate the muscle fibrosis, and Oil Red O staining was used to determine the fat infiltration. Muscle fiber type was determined by major histocompatibility complex (MHC) expression via immunostaining. All data were presented in the form of mean±standard deviation. t test and 2-way analysis of variance was performed to determine a statistically significant difference between groups. Significance was considered when P<.05. Western blot data showed an increased expression of PRDM16 protein in both white and brown fat in PRDM16-overexpressing mice compared with wild-type (WT) mice. Even though PRDM16 overexpression had no effect on increasing muscle weight, it significantly improved the forelimbs function with longer brake, stance, and stride time and larger stride length and paw area in mice after RCT. Additionally, PRDM16-overexpressing mice showed no difference in the amount of fibrosis when compared to WT mice; however, they had a significantly reduced area of fatty infiltration. These mice also exhibited abundant MHC-IIx fiber percentage in the supraspinatus muscle after TTDN. Overexpression of PRDM16 significantly improved muscle function and reduced fatty infiltration after rotator cuff tears. Promoting BAT activity is beneficial in improving rotator cuff muscle quality and shoulder function after RCT.

Bridging Reconstruction With Interpositional Dermal Allograft Has Superior Healing Than Does Maximal Repair for Treatment of Large to Massive, Irreparable Rotator Cuff Tears—Secondary Analysis of a Randomized Control Trial

PurposeThe purpose of this study was to compare the radiographic results of bridging rotator cuff reconstruction (BRR) with dermal allograft and maximal repair for large or massive, irreparable rotator cuff tears. MethodsThis was a secondary analysis of data from a single-center, blinded-observer, randomized controlled trial that examined clinical outcomes of BRR compared to maximal repair. A sample size of 30 patients with MRI-proven large or massive (>3 cm), retracted rotator cuff tears and/or involvement of 2 or more tendons were randomly allocated to 1 of 2 groups: maximal repair or BRR using dermal allograft. MRIs were obtained preoperatively and 1 year postoperatively. The primary outcome of this study was the retear rate on MRI. Secondary outcomes included progression of muscle atrophy and fatty infiltration. ResultsThere was no difference in age or preoperative tear size between the two groups. Patients treated with BRR had decreased retear rate (21%) compared with patients who received maximal repair alone (87%). There was no difference in the number of patients who had progression of muscle atrophy (p=0.088 for supraspinatus and p=0.738 for infraspinatus) or fatty infiltration (p=0.879 for supraspinatus and p=0.693 for infraspinatus) between the two groups. A significant increase in mean postoperative supraspinatus muscle atrophy was identified in the maximal repair group (p=0.034). ConclusionThe results of this secondary analysis of a randomized controlled trial comparing radiographic results of maximal repair vs BRR using dermal allograft in the treatment of large or massive rotator cuff tears show that BRR results in a significantly reduced structural failure rate and a trend towards better preservation of supraspinatus muscle mass compared to maximal repair.

Does surgical intervention alter the natural history of degenerative rotator cuff tears? Comparative analysis from a prospective longitudinal study

The natural history of rotator cuff tears often involves progressive pain development, tear enlargement, and advancing muscle fatty degeneration. Both surgery and conservative management have proven to be effective treatments. Our study purpose was to compare the short to mid-term effects of rotator cuff repair on shoulder function, progression of tear size, and muscle degeneration compared to controls with asymptomatic tears that developed pain and were managed nonoperatively. This comparative study consists of two separate longitudinal study arms. The control group consisted of asymptomatic degenerative cuff tears followed until pain development and then managed nonoperatively with continued surveillance. The surgical group consisted of subjects with degenerative tears that failed nonoperative treatment and underwent surgical intervention with a minimum of 2 years follow-up. Outcomes included VAS pain, ASES, AROM, strength, and ultrasonography. There were 83 controls and 65 surgical shoulders. The surgical group was younger at enrollment (58.9±5.3 yr vs. 61.2±7.8 yr, p=0.04). The median follow-up for control subjects after pain development was 5.1 years (IQR 3.6) and the median postoperative follow-up for the surgical group was 3.0 years (IQR 0.2). Baseline tear widths (median 14 mm, IQR 9 vs. 13 mm, IQR 8; p=0.45) and tear lengths (median 14 mm, IQR 13 vs. median 11 mm, IQR 8; p=0.06) were similar between the surgical group and controls. There were no differences in the baseline prevalence of fatty degeneration of the supraspinatus or infraspinatus muscles between groups (p=0.43 and p=0.58, respectively). At final follow-up, the surgical group demonstrated significantly lower VAS pain (0 [IQR 2] vs. 3.5 [IQR 4], p=0.0002), higher composite ASES (95 [IQR 13] vs. 65.8 [IQR 32], p=0.0002) and ADL scores (29 [IQR 4] vs. 22 [IQR 8], p=0.0002), greater abduction strength (69.6 N [SD 29] vs. 35.9 N [SD 29], p=0.0002), greater active forward elevation (155˚ [SD 8] vs. 142˚ [SD 28], p=0.002), greater active external rotation in abduction (mean 98.5˚, SD 12 vs. mean 78.2˚, SD 20; p=0.0002) compared to controls. Additionally, the prevalence of fatty muscle degeneration was lower in the surgical group for the supraspinatus and infraspinatus (25% vs. 41%, p=0.05; 17% vs. 34%, p=0.03; respectively). This prospective longitudinal study comparing a surgical cohort undergoing rotator cuff repair with a control group treated nonoperatively supports the notion that surgical intervention has the potential to alter the early natural history of degenerative rotator cuff disease. Patients in the surgical group demonstrated clinically relevant differences in pain and functional outcomes. Surgical intervention was protective against progressive muscle degeneration compared to nonoperative treatment.

Utilizing Diagnostic Musculoskeletal Ultrasound for Assessment of the Infraspinatus Muscle and Tendon: Implications for Rehabilitation Professionals

The rotator cuff, comprising the subscapularis, supraspinatus, infraspinatus, and teres minor muscles, plays a crucial role in stabilizing the glenohumeral joint by securing the head of the humerus within the glenoid cavity of the scapula. The tendinous insertions of these muscles generate tension within the capsule, enhancing joint stability during muscular activity. The rotator cuff is susceptible to damage from disease, injury, or trauma, which can result in tears or ruptures of one or more tendons. The evaluation of the infraspinatus muscle and tendon is vital for diagnosing and managing various shoulder pathologies. Accurate imaging to determine the specific muscle involvement and injury severity significantly impacts treatment decisions. Diagnostic musculoskeletal ultrasound (MSK-US) has emerged as a valuable tool for assessing the infraspinatus muscle and tendon, offering real-time, dynamic assessment capabilities essential for precise diagnosis and effective rehabilitation planning. This article reviews the utility and advantages of MSK-US in evaluating the infraspinatus muscle and tendon, emphasizing technique specifics, diagnostic accuracy, and comparative efficacy against other imaging modalities. It details a systematic approach to the ultrasound examination technique for the infraspinatus, including patient positioning and identification of common pathologies such as tears, tendinopathy, and calcifications. With recent advancements in transducer strength, image resolution, and operator training, ultrasound serves as an excellent alternative imaging modality for diagnosing rotator cuff tears. This article aims to equip rehabilitation professionals with a comprehensive understanding of MSK-US as a diagnostic tool for the infraspinatus, promoting more precise diagnosis, treatment planning and improved patient outcomes.

Finite element analysis part 1 of 2: Influence of short stem implant polyethylene configuration on glenohumeral joint biomechanics

AbstractPurposeStress shielding in short‐stem arthroplasty can cause critical metaphyseal bone loss. If the size and shape of the humeral shaft are important factors, it is unknown whether the shape of the polyethylene component in reverse shoulder arthroplasty (RSA) affects bone stress around or within the stem. We explored the impact of polyethylene shape on humeral and scapular stress distribution using a finite element model.MethodsWe developed a shoulder‐specific finite element model. A defined set of muscle forces was applied to simulate movements. An intact rotator cuff state and a superior deficient rotator cuff state were modelled. We used the FX V135 short stem in three conditions: total shoulder arthroplasty (TSA), and RSA with symmetrical and asymmetrical polyethylene (145°/135°). We measured biomechanical markers related to bone stress for different implant sizes. Joint kinematics and the mechanical behaviour of the implant were compared.ResultsRupture of the supraspinatus muscle produced a functionally limited shoulder. The placement of an anatomic TSA with an intact rotator cuff restored function similar to that of a healthy shoulder. RSA in the rotator cuff‐deficient shoulder restored function regardless of stem size and polyethylene shape. While stem size had an impact on the stress distribution in the bone and implant, it did not show significant potential for increasing or decreasing overall stress. For the same stem, stress distribution at the humerus is different between TSA and RSA. Polyethylene shape did not alter the transmission of stress to the bone in RSA. Asymmetric polyethylene produced a greater abduction range of motion.ConclusionsIn terms of bone stress distribution, smaller stems seemed more appropriate for TSA, while larger stems may be more appropriate for RSA. Polyethylene shape resulted in different ranges of motion but did not influence bone stress.Level of EvidenceDiagnostic Tests or Criteria; Level IV.

Finite element analysis part 2 of 2: Glenohumeral bone stress distribution depends on implant configuration for anatomic and reverse stemless shoulder implants

AbstractPurposeOur purpose was to quantify stresses in the bone surrounding stemless implants in various configurations.MethodsA detailed finite element model of the glenohumeral joint was used to simulate abduction kinematics before and after arthroplasty and to measure bone stresses around the implants. Two digital patients were simulated: one healthy and one with supraspinatus muscle impairment (deficiency). Two anatomic total shoulder arthroplasty (TSA) configurations were placed in a 135° cutting plane. Two reverse shoulder arthroplasty (RSA) configurations with cutting angles of 135° and 145° were simulated with asymmetrical and symmetrical polyethylene cups, respectively, to obtain humeral neck‐shaft angles of 145°.ResultsCompared with preoperative models, TSA preserved and RSA restored abduction kinematics. The bone mechanical stresses were located mainly around the central stud of the TSA and were more peripheral to the RSA humeral components. The RSA configuration with the 145° cutting angle and symmetrical cup generated the lowest maximal bone stress and bone volume involvement. Stresses in the scapular cortical bone were highest in the supraspinatus fossa for TSA and the crest of the acromion for RSA.ConclusionEarly stability and glenohumeral bone stress change with implant configuration and should not be extrapolated from anatomic clinical data to reverse configurations.Level of EvidenceDiagnostic tests or criteria; Level IV.

Satellite myoblast and mesenchymal stem cell injections decrease fatty degeneration after rotator cuff tear in rats.

Rotator cuff (RC) tears cause fatty degeneration, aggravated by delayed treatment. Surgical repair alone cannot reverse fatty degeneration. It was aimed to test if local injections of satellite cell-derived myoblasts or satellite myoblasts (SM) from the deltoid region and mesenchymal stem cells (MSCs) from the subcutaneous abdominal fat pad would stimulate myogenesis and decrease adipogenesis in the rat model of fatty degenerated RC tear. A standardized RC tear surgery was performed on both shoulders of 24 Wistar albino rats at t = 0, and rats were followed for 8 weeks to create a chronic degeneration model. The animals were randomly divided into repair + SM and MSC (n = 12) or repair only (n = 12) groups. Transosseous repair with or without stem cell-based injection was performed on the right shoulder of all rats on week 8, with additional injections on weeks 9 and 10. The left shoulders were used as control. The animals were followed until week 14 for recovery. Histological and histomorphometric analyses were performed in week 14. The repair + SM and MSC group had a significantly greater supraspinatus muscle mass than the repair only and control groups. The adipose tissue ratio was significantly lower in the repair + SM and MSC groups versus the repair only and control groups. Histologically, the repair + SM and MSC group had improved muscle and tendon organization. In treating chronically degenerated RC tear in a rat model, surgical repair combined with injections of SM and MSC improved fatty degeneration, tendon healing and myogenesis. Level III.

Effects of Quality of Integrity on Clinical and Structural Outcomes of Rotator Cuff Repair: A Retrospective Cohort Study of 504 Cases

Background: The clinical implications of structural integrity have been a subject of long debate. The oversimplified binary categorization of structural integrity into either healing or retear, along with faulty preoperative baselines for comparison, may contribute to the controversy. Purpose: To determine how the quality of structural integrity in a repaired cuff tendon affects both clinical and structural outcomes by dividing the patients into groups based on integrity and using the immediate postoperative baseline (time zero). Study design: Cohort study; Level of evidence, 3. Methods: A total of 504 patients with a full-thickness rotator cuff tear who underwent arthroscopic rotator cuff repair and were followed up for at least a year with magnetic resonance imaging (MRI) were included. The quality of structural integrity was graded using the Sugaya classification. To evaluate clinical outcomes, pain, range of motion, strength, functional scores, and overall satisfaction and function were used for within- and between-group analyses at the last follow-up. For the assessment of structural outcomes, the Goutallier classification for fatty infiltration (FI) and the tangent sign, occupation ratio, and normalized cross-sectional area for muscle atrophy (MA) were used. The baselines for these structural measurements were both the preoperative and the time-zero MRI scans. Results: The mean clinical follow-up period was 31.8 ± 27.5 months, and the MRI follow-up period was 10.9 ± 5.3 months. There were 178 (35.3%), 228 (45.2%), 58 (11.5%), 14 (2.8%), and 26 (5.2%) shoulders with Sugaya grades 1, 2, 3, 4, and 5, respectively. Regardless of structural integrity, all clinical outcomes at a mean follow-up of 31.8 months after repair significantly improved compared with those before repair. Only in shoulders with Sugaya grade 1 did the FI of the supraspinatus muscle improve significantly from baseline. FI of the infraspinatus muscle did not change significantly in those with grades 1 and 2 but worsened in those with grades 3 and 5. MA measured using the occupation ratio improved significantly in shoulders with Sugaya grades 1 and 2 but declined in those with grade 5. Conclusion: This study established a correlation between improved structural integrity of the repaired cuff tendon and enhanced structural outcomes in rotator cuff muscles. Furthermore, the findings revealed that both FI and MA could be reversed in patients exhibiting high-quality structural integrity. However, these structural improvements were not mirrored in the clinical outcomes.

ЭФФЕКТИВНОСТЬ ВЫПОЛНЕНИЯ РЕЛИЗА НАДЛОПАТОЧНОГО НЕРВА ПРИ АРТРОСКОПИЧЕСКОМ ВЫПОЛНЕНИИ ШВА ПРИ РАЗРЫВЕ СУХОЖИЛИЯ НАДОСТНОЙ МЫШЦЫ

Supraspinatus injuries may be associated with traction injury to the suprascapular nerve, potentially responsible for rotator cuff pain or weakness and as a consequence have an impact on early recovery from tendon suture. Purpose: to study the results of release of the suprascapular nerve in the superior notch of the scapula during arthroscopic repair surgery of the supraspinatus tendon of the shoulder joint depending of the extent of damage. Materials and methods: The study included 121 patients. The patients were divided into 2 groups. Group A consisted of patients who underwent arthroscopic repair of the supraspinatus tendon. Group B included patients who underwent the same operation with additional release of the suprascapular nerve in the superior notch of the scapula. An assessment was made before surgery using the DASH (Disabilities of the Arm, Shoulder and Hand) and VAS (visual analogue scale) scales, and then at 1, 6, 12 months after surgery and the degree of dystrophy according to the Goutallier classification in T1-weighted MRI before surgery, and then 3, 6, 12 months after surgery. Results: The difference between the groups according to Goutalier classification in the third month after surgery was 0.04, according to the VAS assessment in the first month after surgery was p &lt; 0.01, and at the same period a statistically significant difference was found in the DASH assessment (p = 0.01). Discussion: There are conflicting results regarding the issue being studied. This is explained by the lack of knowledge of pathophysiological processes in this area, as well as the high level of evidence of published studies. Conclusion: Additional release of the supraspinatus nerve in the scapular notch during repair of the supraspinatus muscle is effective in the early stages of recovery, and is also of greatest importance in cases of massive tears.

Optimal immobilization position for conservative treatment of proximal humerus fractures by fracture type: a biomechanical cadaveric study

In conservative treatment for proximal humerus fractures (PHFs), the immobilization position of the affected arm should not be determined uniformly. The aim of this study is to investigate the optimal immobilization position for conservative treatment of different types of PHFs. We hypothesized that the optimal position minimizing the deforming force in PHFs depends on the fracture components involved. PHF models involving either the surgical neck (SN) or greater tuberosity (GT) were created using 12 fresh-frozen cadaveric shoulders. In the SN model, the deforming forces on the pectoralis major muscle were measured in full adduction by increasing external rotation. In the GT model, the deforming force of the supraspinatus muscle was measured in neutral rotation by decreasing abduction, and the deforming force of the infraspinatus muscle was measured in full adduction by increasing internal rotation, respectively. In the SN model, the deforming force of the pectoralis major muscle increased significantly with external rotation from full internal rotation to neutral rotation (P = 0.006), indicating that the arm should be placed in full internal rotation. In the GT model, the deforming force of the supraspinatus muscle increased significantly with adduction from 45° of abduction to full adduction (P = 0.006); the deforming force of the infraspinatus muscle increased significantly with internal rotation from neutral rotation to full internal rotation (P = 0.006). These findings should be considered when placing the arm in abduction and neutral rotation so as to minimize the deforming force by either the supra or infraspinatus muscle. In conservative treatment for PHFs, the affected arm should be placed in a position that minimizes the deforming force on the fracture components involved.

Supraspinatus Muscle and Tendon Characteristics 1 Year After Surgical Rotator Cuff Repair Compared With Contralateral Shoulder: Data From the CUT-N-MOVE Trial

Background: It is necessary to better understand the structural characteristics of the supraspinatus tendon and associated muscle after rotator cuff repair and in the event of retear. Purpose: To study structural differences between the repaired and contralateral shoulders 1 year after rotator cuff repair in patients who received either progressive exercise therapy (PR) or usual care (UC) in a randomized controlled trial and to investigate whether there was interaction with tendon retear and limb dominance. Study Design: Cohort study; Level of evidence, 2. Methods: Patients with surgically repaired traumatic full-thickness rotator cuff tears involving the supraspinatus tendon were included. After surgery, they were randomized to PR or UC (active from postoperative week 2 or 6, respectively). The subacromial structures (acromiohumeral distance, supraspinatus tendon thickness, and vascularity) and the supraspinatus muscle thickness were examined with ultrasound at the 1-year follow-up. Results: A total of 79 patients were included. The characteristics of the 2 intervention groups (PR and UC) were comparable, including the Western Ontario Rotator Cuff Index score and number of retears. The authors found significantly thinner supraspinatus tendon (PR, P < .001; UC, P = .003) and reduced acromiohumeral distance (PR, P = .023; UC, P = .025) in the repaired versus the contralateral shoulders in both intervention groups. For neovascularization, there was no interlimb difference in either of the groups or between groups (PR vs UC). In patients with intact tendons, there was no interlimb difference in the muscle thickness, but in patients with tendon retear the muscle was significantly thinner on the repaired side (P = .024 and P < .001, respectively). When the dominant supraspinatus tendon was repaired (both groups), it was significantly thinner than the nondominant healthy tendon, but this difference was not seen when the nondominant supraspinatus tendon was repaired (P = .006). Conclusion: One year after rotator cuff surgery, the repaired supraspinatus tendon was significantly thinner and the corresponding acromiohumeral distance was reduced. In patients with retear, the supraspinatus muscle was significantly thinner on the repaired side and early initiation of tendon-loading exercises did not affect these findings. Registration: NCT02969135 (ClinicalTrials.gov identifier).

Histological features of the structure of the long head of biceps brachii tendon in patients with concomitant injuries of the rotator cuff

Background. The long head of biceps brachii tendon plays an important role in shoulder pain. Surgical tactics remain controversial. There are two approaches: tenotomy of the long head of biceps brachii tendon and tenodesis. Both have positive and negative sides. There is also no consensus on the effective position for performing tenodesis.The aim. To assess the histological structure of various parts of the long head of biceps brachii tendon, which may be the causes for persistent pain syndrome.Materials and methods. In this study, we examined the histological structure of the long head of biceps brachii tendon in 12 patients aged 18–59 years having chronic anterior shoulder pain with concomitant damage to the supraspinatus and subscapularis tendons. In all cases, magnetic resonance imaging (MRI) revealed changes that made it impossible to perform intraarticular tenodesis. Patients were divided into two groups according to the World Health Organization classification: young (18–44 years) and middle-aged (45–59 years). All patients underwent arthroscopy with subpectoral tenodesis and correction of concomitant pathology. The obtained macropreparations are divided into three zones: the proximal zone, the intertubercular zone and the zone below the intertubercular groove. All macropreparations were sent for histological examination.It was revealed that the most common changes occur in the area of the intertubercular groove in all categories, however, in the middle-aged group, the signs of inflammation and degeneration are equally evident in this zone and in the proximal part of the tendon.Conclusions. Young and middle-aged patients with damage to the tendons of the supraspinatus and subscapularis muscles and signs of chronic tendinitis of the long head of biceps brachii tendon tendon and pronounced structural changes according to MRI should undergo a subpectoral tenodesis procedure; it is also necessary to take into account the anatomical features of the tendon and possible surgical risks.

Effects of TNF-α on Behaviour and Inflammation in Rats with Rotator Cuff Injury through NGF.

Rotator cuff injury is a common injury that includes inflammation, partial tearing, or complete tearing of the rotator cuff tendon. In cases of rotator cuff tears (RCTs), Tumor Necrosis Factor-alpha (TNF-α) can trigger the release of nerve growth factor (NGF). TNF-α is an important inflammatory mediator that affects rotator cuff activity and increased NGF expression is observed in RCTs. Therefore, this study aimed to investigate whether inhibition of TNF-α could reduce behavioural responses and inflammation levels in rats through NGF. A rat RCT model was established, and the CatWalk gait analysis system was used for behavioural assessment. Immunohistochemistry was used to detect NGF protein levels in tendon tissue. Hematoxylin eosin (HE) staining was used to observe histopathological changes. The expressions of Interleukin-1beta (IL-1β) and Cyclooxygenase-2 (COX2) were detected by western blotting (WB) and quantitative real-time polymerase chain reaction (qRT-PCR). The expression of apoptosis protein Bcl-2-associated X (Bax), B-cell lymphoma 2 (Bcl-2), and Cysteine-aspartic acid protease-3 (Caspase-3) were detected using WB. Oxidative stress markers, namely Reactive Oxygen Species (ROS), Malondialdehyde (MDA), and Superoxide Dismutase (SOD) were quantified in tissues using an ELISA kit. In the RCT model, elevated NGF protein expression, noticeable atrophy in the supraspinatus muscle tissue, and substantial fat infiltration were observed. The levels of IL-1β, COX2, apoptosis, and oxidative stress were all increased. TNF-α inhibition resulted in decreased NFG expression, decreased tissue fibrosis, and improved tendon atrophy. Moreover, when TNF-α was inhibited, the expressions of IL-1β and Cox2 were reduced and both apoptosis and oxidative stress were decreased. The results showed that inhibiting TNF-α had the potential to reduce inflammation levels and behavioural responses in rats. TNF-α can affect behaviour and inflammation in rats with RCTs through NGF, and TNF-α inhibition can improve rotator cuff injury.