Infraspinatus Research Articles

The Effect of Concavity Restoration on Glenohumeral Stability in a Glenoid Bone Loss Model: Comparing the Distal Tibial Allograft Reconstruction and the Latarjet Procedure

Objectives: Glenoid bone loss occurs in more than 80% of patients with recurrent glenohumeral instability. The Latarjet procedure has become the gold standard for restoration of bone loss despite a high (15-30%) complication rate.1–3 Distal tibial allograft (DTA) reconstruction has recently gained interest due to its ability to restore width and concavity to the glenoid while providing a cartilage surface.4 The purpose of this study is to evaluate the restoration of glenohumeral anterior stability and glenoid concavity after DTA reconstruction when compared to the Latarjet procedure in a glenoid bone loss model. Methods: Five human cadaveric specimens (mean age: 62.2, range 57-69; 80% male) underwent preoperative computed tomography (CT) scans to assess native glenoid concavity as determined by the glenoid depth and bony shoulder stability ratio (BSSR). Stability testing was performed using a cadaveric shoulder simulator that allows 6 DoF at the glenohumeral joint. The specimens were placed with the scapula at 30° upward rotation and humerus at 60° glenohumeral abduction with a constant compressive force created by loading the supraspinatus, infraspinatus, teres minor, and subscapularis muscles (2lbs, 3lbs, 1lb and 4lbs respectively). A Kuka robot applied a 40N anterior force through the pectoralis tendon with the humerus in neutral as well as 60 degrees of external rotation. A motion capture system recorded humeral head translations for each condition. To create the Latarjet and DTA conditions, the coracoid was first harvested and the thickness was measured. A distal tibial allograft was then contoured to an identical size. A glenoid defect was created to match the thickness of the graft since both Latarjet and DTA aimed for a 100% glenoid restoration.. The following conditions were tested: 1. intact, 2. Bankart lesion, 3. bone loss model with DTA reconstruction, 4. Latarjet procedure without the conjoint tendon loaded, and 5. Latarjet with conjoint tendon loading (‘sling effect’). All specimens underwent post-testing CT scan to measure the BSSR of the DTA and Latarjet reconstructions. A repeated measures ANOVA was performed to determine if there was a significant difference in maximum anterior translation or BSSR between the distal tibial allograft reconstruction and Latarjet procedure (with or without the sling effect). Results: The mean preoperative glenoid depth measured 2.61±1.03mm with a BSSR of 0.40±0.16. However, postoperative measurements showed that BSSR for the DTA was greater than the Latarjet (0.46±0.11 vs 0.35±0.5). The maximum anterior translation was significantly lower after the DTA reconstruction than the Latarjet procedure without the sling effect (5.5mm vs 9.6mm, p = 0.044). However, there was no difference in anterior translation between the DTA reconstruction and Latarjet procedure with the sling effect applied (5.5mm vs 4.7mm, p = 0.36). The DTA reconstructed the glenoid with a significantly greater concavity than the Latarjet procedure (BSSR: 0.46 vs 0.35, p = 0.036). Conclusions: When addressing bone loss in glenohumeral instability, additional factors besides the restoration of glenoid width contribute to stability. The concave reconstruction produced by the distal tibial allograft decreases anterior translation compared to the flat reconstruction produced by the Latarjet, but there is no difference in translation between the DTA and Latarjet procedure when the sling effect is applied. The DTA reconstruction provides an alternative to the Latarjet procedure with equivalent biomechanical properties and less morbidity or change to the native shoulder structure.

Lesions of the rotator cuff and biceps tendon

The rotator cuff is acomplex anatomical structure and the integrity is pivotal for the shoulder functionality. The pathologies are often multifactorial, resulting from degenerative, vascular, traumatic and mechanical factors. Radiography, ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) form the pillars of radiological diagnostics. Each modality has specific advantages and limitations in the visualization and assessment of pathologies of the rotator cuff and biceps tendon. The MR arthrography offers additional insights in unclear cases by enhancing the differentiation between complete and partial tears. The MRI provides detailed information on tendon quality and associated damages, such as muscle atrophy and fat infiltration, making it the preferred method. The use of MR arthrography can identify defects through increased intra-articular pressure or contrast medium leakage. Muscle damage, as induced by edema in acute injuries or fatty degeneration in chronic conditions, can be evaluated using imaging techniques. Special attention is warranted for the infraspinatus, subscapularis and teres minor muscles due to their unique injury patterns and prevalences.

Validation of a spring loaded probe for single and repeat pressure pain testing, including public domain specifications for design and manufacture.

Temporal summation of pressure pain is technically more challenging than simple pressure pain thresholds. The current study describes the design, manufacture and validation of a simple mechanical test apparatus to assess the temporal summation of deep pressure pain. We release design details into the public domain with the intention of providing free access for researchers especially in low income countries. Utility and validity of the probes were assessed by pressure application in three different experimental setups: A. Identifying potential issues which needed to be addressed to ensure a reliable test procedure (189 tests with 24 testers using four different probes). B. Selecting the most reliable target force curve (one tester conducted 20 tests). C. Estimating classic inter and intra-examiner reliability and comparing probe measures to other QST measures (repeated measures study with counterbalancing). We make recommendations on best use of the probes. Pressure pain thresholds assessed using probes were affected by anatomical test site and testing tool, but not by tester, day or session. Temporal summation of pressure pain was significantly greater than that of a single pressure application. We found no correlation between temporal summation using the probes on the Infra-Spinatus muscle and temporal summation using a pneumatic cuff on the lower leg. The probe was a useful tool for assessing pain intensity and temporal summation of pressure pain intensity, but not for pain thresholds. A number of caveats need to be considered when using the probe, including but not limited to audio cues and target ideal wave function.

Skeletal Muscle Deoxygenation in 11-13-year-old Children Swimmers During Arm and Leg Ergometry

Background: This study extends the current knowledge on muscle deoxygenation during arm and leg ergometry in preadolescent swimmers. We aimed to compare the deoxygenation of legs and arms muscles during maximal incremental legs and arms exercises on the cycle ergometer (CE) and arm crank ergometer (ACE) in preadolescent swimmers. Methods: Thirteen preadolescent swimmers (aged 12 ± 1 years) were enrolled in this study. They performed two maximal incremental legs and arms exercises to exhaustion on CE and on ACE. During both exercises, muscles oxygen saturation values (the changes of deoxygenated haemoglobin (Δ[HHb]) and [HHb] thresholds ([HHb] thresholds) of Biceps femoris, Vastus lateralis, Rectus femoris, Triceps brachii, Infraspinatus and Biceps brachii muscles were recorded using the near-infrared spectroscopy method (Moxy oxygen monitor). Results: During maximal incremental legs and arms exercises on CE and ACE Δ[HHb] and [HHb] thresholds did not differ significantly between legs and arms exercises (p>0.05) and between separate muscles (p>0.05) as well. Conclusion: Deoxygenation of legs and arms muscles was similar during incremental exercises on CE and ACE in preadolescent swimmers. Keywords: muscles oxygenation, NIRS, upper and lower body exercise, graded exercise test

Investigating the relationship between quantitative-based ultrasound and MRI estimations of rotator cuff fatty infiltration.

Fatty infiltration (FI) of the rotator cuff has important clinical implications. Quantitatively estimating FI using ultrasound (US) has considerable benefits for assessing FI in a non-invasive, accessible manner. This research investigated whether FI of the supraspinatus (SS) and infraspinatus (IS), estimated using US was related to intramuscular fat fractions measured from magnetic resonance images (MRI). Data from 12 healthy young adult participants were used for analysis. US images of the SS and IS were captured using multiple transducer placement techniques from which echogenicity of the muscle region was quantified. Shoulder MRI were captured from which SS and IS were manually segmented and intramuscular fat fractions calculated. Six upper limb strength exertions were performed, resisted by a hand dynamometer. IS and SS echogenicity explained a significant amount of variance in MRI fat fractions for certain body positions and transducer techniques. Echogenicity agreement was higher for IS than SS. Significant relationships were identified between strength exertions and both echogenicity and MRI muscle volume, but not MRI fat fraction. This research provides preliminary evidence showing that quantitative-based US methods can be used to estimate MRI calculated fat fractions for the rotator cuff.

Rehabilitation strategies and magnetic resonance imaging techniques for shoulder injuries in sports

ObjectiveShoulder sleeve injuries are high-risk in men's tennis, with rehabilitation focusing on activating shoulder muscle groups to regain strength. Specific plans use electromyography and isokinetic instruments to compare muscle activity and torque pre- and post-rehabilitation. The goal is to explore training effects on rotator cuff injuries and assess routine MRI and MRI shoulder arthrography for diagnostic value in shoulder injuries. This aims to provide a reference for restoring shoulder function in male tennis players. MethodsTwenty college students (n = 20) with rotator cuff injuries from a university tennis program were selected as experimental subjects, matched based on gender and injury severity, and divided into experimental (n = 10) and control (n = 10) groups. A paired sample T-test assessed the impact of rehabilitation training on muscle recruitment and strength around the shoulder joint in the experimental group before and after training. This evaluated the influence of rehabilitation plans on shoulder muscle mobilization and strength. Another paired sample T-test compared indicators before and after the experiment, examining mechanisms underlying the effects of functional rehabilitation training on shoulder sleeve injuries in male tennis players. Results(1) Surface electromyography (EMG) results for internal/external rotation showed a significant increase in anterior, middle, and posterior deltoid EMG values (P < 0.05). Supraspinatus and infraspinatus muscles exhibited substantial increases (P < 0.01), while no significant change occurred in the teres minor muscle. (2) Adduction/abduction EMG tests at 60°/s, 90°/s, and 120°/s revealed significant increases (P < 0.01) in deltoid bundles and supraspinatus/infraspinatus muscles for both experimental and control groups. Teres minor muscle showed no significant change. (3) Isokinetic muscle strength tests indicated a significant peak torque increase (P < 0.01) during inward/outward rotation at 60°/s, 90°/s, and 120°/s for the experimental group compared to the control group. ConclusionA 10-week functional shoulder rehabilitation training program can enhance the strength, endurance, and neuromuscular recruitment of shoulder-related muscles in male tennis players with rotator cuff injuries. This approach, combined with the diagnostic capabilities of routine MRI and MRI shoulder arthrography, enables modifications in the body's ongoing adaptation to injuries. This, in turn, contributes to improved shoulder joint stability and effectively facilitates the functional recovery of the rotator cuff muscle group.

Nerve Tracing in Juvenile Rats: A Feasible Model for the Study of Brachial Plexus Birth Palsy and Cocontractions?

Brachial plexus birth injuries cause diminished motor function in the upper extremity. The most common sequel is internal rotation contracture. A number of these patients also suffer from cocontractions, preventing the use of an otherwise good passive range of motion in the shoulder. One theory behind the co-contracture problem is that injured nerve fibers grow into distal support tissue not corresponding to the proximal support tissue, resulting in reinnervation of the wrong muscle groups. To further elucidate this hypothesis, we used rat neonates to investigate a possible model for the study of cocontractions in brachial plexus birth injuries. Five-day-old rats were subjected to a crush injury to the C5-C6 roots. After a healing period of 4 weeks, the infraspinatus muscle was injected with Fluoro-Gold. A week later, the animals were perfused and spinal cords harvested and sectioned. Differences in the uptake of Fluoro-Gold and NeuN positive cells of between sides of the spinal cord were recorded. We found a larger amount of Fluoro-Gold positive cells on the uninjured side, while the injured side had positive cells dispersed over a longer area in the craniocaudal direction. Our findings indicate that the method can be used to trace Fluoro-Gold from muscle through a neuroma. Our results also indicate that a neuroma in continuity somewhat prevents the correct connection from being established between the motor neuron pool in the spinal cord and target muscle and that some neurons succumb to a crushing injury. We also present future research ideas.

Fatty Degeneration of the Rotator Cuff Muscles Improves in Shoulders with Successful Arthroscopic Rotator Cuff Repair: A Prospective Study Using Quantitative T2 Mapping Techniques, with 2-Year Follow-up.

There remain arguments regarding whether fatty degeneration of the rotator cuff muscles improves following rotator cuff repair. The purpose of this study was to prospectively investigate changes in fatty degeneration of the rotator cuff muscles, quantitatively measured on magnetic resonance imaging (MRI) with use of transverse relaxation time (T2) mapping techniques, and to assess the relationship between these changes and clinical outcomes. Patients were included if they were scheduled for arthroscopic rotator cuff repair using the suture-bridge technique between June 2014 and December 2015, underwent preoperative MRI including the T2 mapping sequence, and consented to participate in the study. Exclusion criteria consisted of trauma within 2 months before preoperative MRI, isolated subscapularis tears, patch augmentation, neuromuscular disease, and a follow-up duration of <2 years. MRI scans were acquired preoperatively and at 2 years postoperatively, and T2 values of the supraspinatus and infraspinatus muscles were measured, with smaller T2 values indicating less fat content. Shoulders were evaluated on the basis of active range of motion (ROM), Constant and University of California Los Angeles Shoulder Rating Scale scores, shoulder external rotation strength with the arm at the side, and rotator cuff integrity on postoperative MRI. A total of 103 patients (103 shoulders) with a mean age of 65 ± 9 years (range, 42 to 83 years) were included, of whom 52 were male and 51 were female. There were 13 partial, 18 small, 35 medium, 33 large, and 4 massive tears. Concomitant subscapularis tears were observed in 35 shoulders. Overall, ROM, clinical scores, and external rotation strength significantly improved postoperatively. Retears were found in 27 shoulders (26%). External rotation strength significantly improved postoperatively only in shoulders without a retear. Among shoulders without a retear, the postoperative T2 values of the supraspinatus and infraspinatus were significantly smaller than the preoperative values (p < 0.001 for both); however, no improvement was seen in shoulders with a retear. Shoulders with successful repair demonstrated significantly smaller T2 values postoperatively as well as significantly improved external rotation strength. Fatty degeneration of the cuff muscles can be reversed, at least in part, and muscle strength improves in shoulders with successful repair. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Paralabral Cysts with Associated Infraspinatus and Teres Minor Denervation: A Case Report

Introduction: The shoulder is one of the most intricate articulation complexes in the human body. Any insult to its equilibrium can cause joint instability, pain, and dysfunction. The complex bony projections of the scapula, lengthy nature of the nerves, and extensive mobility of the joint places nerves at risk for impingement; this can, especially, be seen when examining the axillary and suprascapular nerves. Another rare cause of nerve impingement is a paralabral cyst secondary to labral tearing. If a paralabral cyst expands into the limited space occupied by the nerves, this can result in neuropraxia, muscle wasting, and loss of function. This phenomenon presents an interesting anatomic and clinical correlation. Case Report: A 41-year-old male with no past medical history presented with left shoulder pain for 3 months. Physical examination showed a great range of motion but diffusely decreased strength. Magnetic resonance imaging of the left shoulder demonstrated posterosuperior labral tearing with an associated paralabral cyst extending into the spinoglenoid notch. An additional anteroinferior labral tear with an associated paralabral cyst was also found. Extensive infraspinatus and teres minor muscle atrophy suggesting active denervation was present. The patient failed conservative management and underwent arthroscopic labral repair with posterosuperior and anteroinferior paralabral cysts excision. The patient had an unremarkable recovery and by 1 year had full motion and 5/5 strength in all planes. Conclusion: While paralabral cysts are well documented, there have been limited reports of cysts causing neural impingement of the axillary or the distal suprascapular nerve, let alone both occurring within the same individual. This case provides an interesting clinical scenario which very clearly depicts the neural innervation of the shoulder and pathologies that can impact function. This cystic impingement is a very interesting and rare finding that provides tremendous insight into both shoulder pathology and anatomy. This case is also useful to predict patient recovery after long-term nerve impingement and muscle denervation. This patient presented with significant loss of strength, motion, and shoulder dysfunction, but after surgical intervention, he regained complete motion and strength. This information can be used to help educate and guide patients in practice. Keywords: Arthroscopy, paralabral cyst, superior labral anterior to posterior tear, bankart tear, sports medicine, denervation, atrophy, orthopedics.

Infraspinatus function impairment after arthroscopic Bankart repair with Hill Sachs remplissage. Isokinetic, functional, and radiographic analysis

PurposeArthroscopic Bankart repair with Hill Sachs remplissage (BHSR) is an option for anterior shoulder instability with humeral defect. Our hypothesis was that infraspinatus capsulo-tenodesis is an effective solution, with good clinical results and no consequences on shoulder strength and ranges of motion. MethodsWe performed a retrospective case-control study involving 22 patients operated with arthroscopic BHSR. We compared isokinetic evaluation of both shoulders using a dynanometer in concentric, eccentric force and endurance. Ranges of motion were measured using a goniometer and compared to the contralateral unaffected side. Functional assessment included Constant, Rowe, Walch and Duplay and WOSI scores. Healing and fatty degeneration were analyzed with magnetic resonance imaging. ResultsAt mean 37.2 months follow-up, 21 patients (95.4%) were satisfied or very satisfied with the intervention. Range of motion in external rotation of the affected side decreased by 10.8° in adduction and 6° at 90° of abduction (p<0.05). Deficit in external rotation strength of the affected side greater than 15% was found in all isokinetic tests (p<0.05). Walch and Duplay, Rowe, WOSI and adjusted Constant average scores were respectively 71.05±14.1 (40–90), 67.63±19.7 (15–100), 34.6%±19.9 (8.43–76.23) and 69.8±13.57 (36.7–101). Postoperative MRI showed good capsulo-tenodesis healing without infraspinatus muscle fatty degeneration. ConclusionArthroscopic BHSR provides satisfactory functional outcomes but significant infraspinatus functional impairments in both strength and ranges of motion in external rotation. Level of evidenceIII; case-control study.

Association between myofascial trigger point therapy and conditioned pain modulation

IntroductionMyofascial trigger point therapy (MTrP) is a widely used therapeutic approach, although the underlying mechanisms remain unclear. Mechanisms discussed include peripheral involvement of muscles as well as central pain modulating processes such as the conditioned pain modulation (CPM). The aim of this study was to investigate whether the analgesic response of MTrP and the analgesic response of CPM correlate in asymptomatic participants in order to identify shared underlying mechanisms of MTrP and CPM. MethodBoth, CPM and MTrP protocols consisted of heat-based test stimuli (heat pain thresholds before and after the intervention) and pressure-based (conditioning) stimuli. Asymptomatic participants (n = 94) were randomly assigned to receive either mild, intense or no pressure stimuli (between-group design) to both the fingernail and the MTrP of the infraspinatus muscle (within-group design). Pressure stimuli at both locations (fingernail, MTrP) were applied with a pressure algometer for 120 s and continuously adjusted to maintain a constant pain intensity of mild or intense pain. All thermal stimuli were applied on the lower leg with a thermal stimulator. ResultsA significant correlation was shown between the analgesic effect of CPM and MTrP therapy for mild (r = 0.53, p = 0.002) and intensive stimuli (r = 0.73, p < 0.001). 17.3% of the variance of the MTrP effect were explained by CPM after mild stimulation, and 47.1% after intense stimulation. Pain-related characteristics did not explain the variance within the analgesic response using a regression analysis. ConclusionsBetween the analgesic responses following MTrP and CPM paradigms, a moderate to strong correlation was observed, suggesting shared underlying mechanisms.

Diagnosis and treatment of 11 patients with cevical spondylotic amyotrophy

To explore clinical features, treatment methods and clinical effects of cervical spondylosis with proximal muscular atrophy. Eleven patients with proximal-type cervical spondylotic amyotrophy were retrospectively studied from September 2016 to November 2020, including 7 males and 4 females, aged 38 to 68 years old. Clinical symptoms, MRI and neuroelectrophysiological manifestations were analyzed, and patients were treated with conservative treatment or anterior cervical decompression fusion surgery, respectively. The efficacy was evaluated by manual muscle test (MMT) before and after treatment, and patients' satisfaction was followed up at the same time. All patients were followed up for 6 to 19 months. All 11 patients were unilateral, mainly manifested by atrophy of deltoid muscle, supraspinatus muscle and infraspinatus muscle, and may be accompanied by ipsilateral neck and shoulder pain at early stage. MRI showed lesions at C4,5, C5,6 segments were more common. Electrophysiological examination showed the affected muscle was denervated, and amplitude of compound muscle action potential (CMAP) of innervated nerve on the affected side was lower than that on the healthy side. All patients were obtained bone fusion. One patient who were underwent anterior cervical corpectomy and fusion (ACCF) occurred developed contralateral C5 nerve root paralysis after operation, which recovered completely after 10 weeks of symptomatic treatment. At 12 months after operation, the efficacy was evaluated according to MMT, 3 patients were treated conservatively, 2 patients excellent and 1 good;in 8 patients treated by operation, 3 patients were excellent, 4 good, and 1 moderate. The incidence of cervical spondylosis with proximal muscular atrophy is low, which is manifested as unilateral proximal muscle atrophy and may be accompanied by ipsilateral neck and shoulder pain in the early stage. Combined with MRI and neuroelectrophysiological examination, misdiagnosis could be reduced. In the early stage of disease, especially in the case of nucleus pulposus protrusion leading to nerve compression, conservative treatment could be taken. When the conservative treatment is ineffective or the pain cannot be tolerated, anterior decompression surgery is recommended, and the overall effect is satisfactory.

Effect of isokinetic eccentric training on the human shoulder strength, flexibility, and muscle architecture in physically active men: A preliminary study.

Strengthening the rotator cuff muscles is important for injury prevention and rehabilitation. Since muscle fascicle length improves motor performance and is suggested to reduce the risk of injury for the hamstring, it may be an important variable to promote multidirectional changes in the function and macroscopic structure for the shoulder. Recent literature reviews overwhelmingly suggest that eccentric exercises improve fascicle length and functional measures for the lower limb. However, there is a research gap for the shoulder. Since ultrasound imaging is the most commonly used imaging technique to quantify muscle structure, but has yielded heterogeneous results in different studies, there is another issue and a research gap for the imaging method. Based on the research gaps, the purpose of this study was to evaluate the effects of standardized eccentric strength training on the function and structure of the external rotator cuff muscles using an isokinetic dynamometer and MRI. Therefore, a preliminary pre-post intervention study was conducted and 16 physically active men were recruited in October 2021. For the right shoulder, an eccentric isokinetic training was performed twice a week for almost six weeks. The primary outcome measures (external rotators) were active and passive range of motion, eccentric and concentric torque at 30, 60, and 180°/s isokinetic speed, and fascicle length and fascicle volume for the supraspinatus and infraspinatus muscles. The findings show a training effect for the absolute mean values of eccentric strength (+24%, p = .008). The torque-angle relationship increased, especially in the final phase of range of motion, although a 4% (p = .002) decrease in passive range of motion was found in the stretch test. Positive changes in muscle structure were shown for the supraspinatus muscle fascicle length (+16%, p = .003) and fascicle volume (+19%, p = .002). Based on the study results, we can conclude that eccentric isokinetic training has a significant positive effect on the shoulder. To our knowledge, this is the first eccentric training study using both isokinetic dynamometer and muscle diffusion tensor imaging to access functional and structural changes in the human shoulder rotator cuff muscles. The methods were shown to be applicable for interventional studies. Based on these results, populations such as high-performance handball players with highly trained shoulders should be included in future studies.

Role of Magnetic Resonance Imaging (MRI) in the Diagnosis of Rotator Cuff Injuries and Correlation With Arthroscopy Findings.

The prevalent cause of shoulder pain is rotator cuff tears (RCT), which induce profound discomfort and morbidity. Hence, their detection and appropriate management become important to alleviate morbidity and enhance quality of life. Imaging has an important role in the diagnosis of such patients to guide for further management. A wide array of radiological approaches has been explored for the detection of RCT. The study aimed to assess the sensitivity (SN) and specificity (SP) of regular magnetic resonance imaging (MRI) in the diagnosis and characterization of RCT and furthermore to link the results of MRI with the arthroscopy findings. The limitations and pitfalls if any with MRI patients presenting were also addressed. The study was a diagnostic evaluation study conducted at the Department of Radiodiagnosis, Muslim Educational Society (MES) Medical College,Perinthalmanna, India, among individuals with RCT between December 1, 2015, and May 31, 2017. Patients who were referred for MRI and then taken up for arthroscopy were included. The findings for each tendon of rotator cuff on MRI were contrasted with that of arthroscopy, and the percentage of agreement was calculated. Additional findings relevant to the study were also noted. SN, SP, positive predictive value (PPV), and negative predictive value (NPV) of MRI were determined by taking arthroscopic findings as the gold standard. The study was comprised of 36 patients assessed using MRI and arthroscopy for RCT. The study participants ranged in age from 31 to 70 years, with a mean of 52.69±8.86 years. The majority of the patients (69.4%) were between the ages of 41 and 60 years. MRI had 100% SN and SP for full-thickness supraspinatus (SS) tear, 50% SN and 100% SP for partial-thickness SS tear, 100% SN and 80% SP for full-thickness infraspinatus (IS) tear, 75% SN and 80% SP for partial-thickness IS tear, and 95% SN and 86.6% SP for subscapularis (SC) tear. The MRI RCT investigation had a high SN, SP, and PPV compared to arthroscopy. The most frequently involved tendon reported in the present study was SS (n=35; 97.22%) followed by IS (n=32; 88.88%) and SC (n=22; 61.11%). The teres minor tendon was least commonly affected (n=0).Moreover, 61.11% (n=22) of the patients had joint effusion, 41.66% (n=15) had subacromial-subdeltoid bursal effusion, and 27.77% (n=10) had subcoracoid effusion, suggesting that RCT include joint effusion or bursal fluid. Acromioclavicular (AC) joint hypertrophy was found in 53% (n=19) of the patients, and 90% (n=17) were over 45 years old, indicating an association between age, AC joint hypertrophy, and RCT. Therefore, MRI has a good SN and SP for detecting various RCT. Therefore, it could be used to investigate a suspected RCT and should be considered a near-reference standard to arthroscopy for RCT diagnosis.

Outcomes After Rotator Cuff Repair With Transverse Scapular Ligament Release in Patients With Severe Fatty Degeneration of the Infraspinatus

Background: In some large to massive rotator cuff tears (RCTs), fatty degeneration (FD) is more severe in the infraspinatus than the supraspinatus muscle, and in such cases, suprascapular neuropathy is highly suspected. Nerve release at the suprascapular notch might alleviate this problem. Purpose: To evaluate the effects of the transverse scapular ligament (TSL) release in patients with large to massive RCTs with more severe FD of the infraspinatus than the supraspinatus. Study Design: Cohort study; Level of evidence, 3. Methods: Between September 2017 and January 2022, arthroscopic TSL release with rotator cuff repair was performed in patients with large to massive RCTs and more severe FD of the infraspinatus muscle than the supraspinatus muscle (TSL group). Cuff integrity, FD, and atrophy of cuff muscles were evaluated using preoperative and 1-year postoperative magnetic resonance imaging. In addition, results were compared with those of patients who did not undergo TSL release during arthroscopic large to massive rotator cuff repair (NTSL group). Results: A total of 103 patients—20 in the TSL group and 83 in the NTSL group—were included. Group preoperative characteristics, including tear size and supraspinatus FD, were not significantly different, but infraspinatus FD (TSL vs NTSL; grade, 0-4, 0/0/5/10/5 vs 1/33/42/4/3) and atrophy (grade, 1-3. 3/9/8 vs 56/20/7) differed significantly (P < .001). Healing failure occurred in 13 of 20 (65%) patients in the TSL group and 30 of 83 (36%) patients in the NTSL group, which was a statistically significant difference (P = .019). Postoperatively, infraspinatus FD and atrophy were more severe in the TSL group than in the NTSL group (P < .001), and supraspinatus FD was more severe in the TSL group (P = .029). Seven patients in the TSL group achieved healing, but FD and atrophy of the supraspinatus and the infraspinatus showed no improvement in this group (all, P > .05). Conclusion: In patients with more FD in the infraspinatus than the supraspinatus muscle, TSL release appeared to have no benefit for cuff healing or FD reversal in cuff muscles. The possibility of suprascapular nerve entrapment remains in patients with more FD in the infraspinatus than the supraspinatus, and this potential nerve problem is not properly addressed by TSL release alone.

The Posterosuperior Tetralogy Scoring System as a Practical Tool to Predict Shoulder Function After Posterosuperior Large-to-Massive Rotator Cuff Repairs.

Fatty infiltration (FI) or atrophy alone has been found to be inaccurate in predicting shoulder function after repair of large-to-massive rotator cuff tears (L/MRCTs), especially when a diverse extent of FI and atrophy presents in multiple rotator cuff muscles. The Posterosuperior Tetralogy Scoring System (PS-Tetra Score), which integrates FI and atrophy, was proposed to predict shoulder function after surgery. It was hypothesized was that a PS-Tetra Score ≥3 would be a risk factor for poor shoulder function after repair of posterosuperior L/MRCTs and would possess greater diagnostic value than using isolated FI or atrophy of the supraspinatus (SSP) or infraspinatus (ISP). Case-control study; Level of evidence, 3. A total of 187 arthroscopic repairs of posterosuperior L/MRCTs were reviewed. Magnetic resonance imaging evaluations were performed of FI and atrophy of the SSP and ISP, teres minor hypertrophy, tendon retraction, and acromiohumeral distance. A postoperative American Shoulder and Elbow Surgeons (ASES) score of 70 was used to subgroup patients according to shoulder function. Univariate and multivariate analyses were performed to determine the risk factors of poor shoulder function (ASES ≤70). The diagnostic values of different indicators for predicting shoulder function were evaluated. In univariate analysis, female sex, higher Goutallier grade of the SSP and ISP, positive SSP tangent sign, and PS-Tetra Score ≥3 was significantly associated with ASES score ≤70, whereas in binary logistic regression analysis, a PS-Tetra Score ≥3 was the only significant risk factor for poor shoulder function. The occurrence rate of poor function in shoulders with a PS-Tetra Score of 0, 1, 2, 3, and 4 was 0% (0/52), 0% (0/52), 19.57% (9/46), 58.06% (18/31), and 83.33% (5/6), respectively. PS-Tetra Score ≥3 possessed higher crude agreement (87.70%), specificity (90.97%), positive predictive value (62.16%), and area under the receiver operating characteristic curve (0.814) than the other 3 indicators, with relatively high negative predictive value (94.00%) and moderate sensitivity (71.88%). PS-Tetra Score ≥3 was a risk factor of poor shoulder function after repair of posterosuperior L/MRCTs and possessed greater diagnostic value than using isolated FI or atrophy of SSP or ISP alone for predicting shoulder function.

No Evidence of Short-Term Changes in Muscle Activity Elicited by Dry Needling in Chronic Unilateral Shoulder Pain Patients.

The aim of the study was to assess short-term changes in shoulder muscle activity elicited by dry needling in chronic unilateral shoulder pain patients. A double-blind, placebo-controlled clinical trial was conducted, in which 30 volunteers with unilateral shoulder pain (USP) were recruited and randomly assigned to either real or sham dry needling conditions. Pain intensity scores, pressure pain threshold (PPT), glenohumeral internal rotation angles, and electromyographic activity during isotonic shoulder tasks (shoulder flexion and extension) were assessed before, immediately and 72 h after the intervention in the infraspinatus and deltoid muscles. A single application of real dry needling resulted in lower pain intensity scores and a larger range in glenohumeral internal rotation 72 h after the intervention in comparison with sham dry needling. No differences in PPT or muscle activity were observed due to the intervention. A single application of real dry needling resulted in clinically significant changes in the short-term. No differences were detected in muscle activation in the infraspinatus or deltoid muscles. Complementary interventions and longer follow-up times may be required to observe changes in muscle activity.

Decreased rotator cuff muscle cross-sectional areas in subjects with adhesive capsulitis: a study comparing male and female subjects.

To compare rotator cuff (RC) muscle cross-sectional areas (CSA) in subjects with adhesive capsulitis (AC) to age- and sex-matched controls. We retrospectively analyzed 97 shoulder MRIs or MR arthrography studies, of which 42 were clinically diagnosed with AC (27 female, 15 male) and 55 were age- and sex-matched controls (38 female, 17 male). All AC subjects underwent imaging ≥ 6 months after symptom onset. All imaging was examined to exclude RC full-thickness tears and prior surgery. A standardized T1 sagittal MR image was segmented in each subject to obtain the CSA of subscapularis (SSC), supraspinatus (SSP), and infraspinatus (ISP) muscles. Differences in CSAs between AC and control subjects were analyzed by sex (females and males separately) and all subjects combined. AC females had significantly decreased SSC (P = 0.002) and total (P = 0.006) CSAs compared to controls. Male AC subjects showed decreased SSC (P = 0.044), SSP (P = 0.001), and total (P = 0.005) CSAs. Across all subjects, male and female, the AC cohort had significantly decreased SSC (P = 0.019) and total (P = 0.029) CSAs compared to controls. Decreased RC muscle CSAs were present in AC subjects with ≥ 6 months of symptom duration, with decreased SSC and total CSAs in male and female subjects, and decreased SSP CSA in males.

Infraspinatus muscle atrophy in a 23-year-old hockey player.

Infraspinatus muscle atrophy in a 23-year-old hockey player.

Rotator cuff muscle fibrosis can be assessed using ultrashort echo time magnetization transfer MRI with fat suppression.

Muscle degeneration following rotator cuff tendon tearing is characterized by fatty infiltration and fibrosis. While tools exist for the characterization of fat, the ability to noninvasively assess muscle fibrosis is limited. The purpose of this study was to evaluate the capability of quantitative ultrashort echo time T1 (UTE-T1) and UTE magnetization transfer (UTE-MT) mapping with and without fat suppression (FS) for the differentiation of injured and control rotator cuff muscles and for the detection of fibrosis. A rat model of chronic massive rotator cuff tearing (n = 12) was used with tenotomy of the right supraspinatus and infraspinatus tendons and silicone implants to prevent healing. Imaging was performed on a 3-T scanner, and UTE-T1 mapping with and without FS and UTE-MT with and without FS for macromolecular fraction (MMF) mapping was performed. At 20 weeks postinjury, T1 and MMF were measured in the supraspinatus and infraspinatus muscles of the injured and contralateral, internal control sides. Histology was performed and connective tissue fraction (CTF) was measured, defined as the area of collagen-rich extracellular matrix divided by the total muscle area. Paired t-tests and correlation analyses were performed. Significant differences between injured and control sides were found for CTF in the supraspinatus (mean ± SD, 14.5% ± 3.9% vs. 11.3% ± 3.7%, p = 0.01) and infraspinatus (17.0% ± 5.4% vs. 12.5% ± 4.6%, p < 0.01) muscles, as well as for MMF using UTE-MT FS in the supraspinatus (9.7% ± 0.3% vs. 9.5% ± 0.2%, p = 0.04) and infraspinatus (10.9% ± 0.8% vs. 10.1% ± 0.5%, p < 0.01) muscles. No significant differences between sides were evident for T1 without or with FS or for MMF using UTE-MT. Only MMF using UTE-MT FS was significantly correlated with CTF for both supraspinatus (r = 0.46, p = 0.03) and infraspinatus (r = 0.51, p = 0.01) muscles. Fibrosis occurs in rotator cuff muscle degeneration, and the UTE-MT FS technique may be helpful to evaluate the fibrosis component, independent from the fatty infiltration process.