Immediate effects of kinesiotaping on acromiohumeral distance and shoulder proprioception in individuals with symptomatic rotator cuff tendinopathy

BackgroundKinesiotaping is widely used for the rehabilitation of rotator cuff tendinopathy. It has been argued to reduce symptoms and functional limitations through improvement of proprioceptive feedback. In addition, kinesiotaping has been reported to increase the subacromial space in healthy subjects. However, its effects on the acromiohumeral distance and shoulder proprioception of individuals with rotator cuff tendinopathy have not been ascertained. This study investigated the immediate effects of kinesiotaping on the acromiohumeral distance and shoulder proprioception in individuals with rotator cuff tendinopathy.MethodsTwenty-two individuals with chronic rotator cuff tendinopathy were included. The acromiohumeral distance was measured using an ultrasound scanner at rest and 60° shoulder abduction. Proprioception was measured through active joint repositioning in low- (45°–65°) and mid-amplitude (80°–100°) of shoulder flexion and abduction. A wireless inertial measurement unit system was used to quantify shoulder angles. First, measurements were taken without kinesiotaping. Thereafter, kinesiotaping was applied on the symptomatic shoulder, and the same measurements were retaken. Repeated measures ANOVAs were used for statistical analyses.FindingsKinesiotaping induced a significant increase in acromiohumeral distance at 60° abduction (∆AHD = 0.94 mm; 95%CI: 0.50–1.38, p < 0.001), exceeding the minimal detectable change (0.70 mm). No significant difference was observed in acromiohumeral distance at rest or in proprioception during active joint repositioning in both low- and mid-amplitude (p > 0.05).InterpretationKinesiotaping led to an immediate increase in acromiohumeral distance at 60° of abduction that, although it seems a minor change (↑10.5%), it may be significant for symptomatic patients, whereas it had no immediate effect on active joint repositioning.     

Comparison of acromiohumeral distance in symptomatic and asymptomatic patient shoulders and those of healthy controls

BackgroundThe reduction of the subacromial space has traditionally been linked to rotator cuff pathology. The contribution of this narrowing, both in the development and maintenance of rotator cuff tendinopathy, is still under debate. The objective of the present study was compare the acromiohumeral distance at 0 and 60 degrees of active shoulder abduction in scapular plane, static position, in both symptomatic and contralateral shoulders, between participants with unilateral rotator cuff related shoulder pain, and in asymptomatic participants.MethodThis was a cross-sectional observational study. Seventy-six participants with chronic shoulder pain were assessed. Forty participants without shoulder pain were also recruited to compare the acromiohumeral distance with symptomatic participants. The acromiohumeral distance was measured at 0 and 60 degrees of active shoulder abduction in all the groups by ultrasound imaging. Mean differences between symptomatic versus contralateral shoulders, and versus healthy controls, were calculated.FindingsThere were no statistical significant differences (p > .05) in the acromiohumeral distance at 0 degrees of shoulder elevation between the groups. However, significant differences were found at 60° between symptomatic and contralateral shoulder groups (0,51 mm; 95% CI: −0.90 to −0.12).InterpretationsDifferences in shoulder pain perception at 0° are not attributable to acromiohumeral distance differences. However, treatments focused on increasing AHD at 60° could be prescribed, as a significantly reduced AHD was found in symptomatic shoulders when compared with contralateral shoulders. Further research is needed to determine, not only static differences in AHD, but also dynamic differences.     

In vivo dynamic acromiohumeral distance in shoulders with rotator cuff tears

BackgroundThere are no previous studies on the acromiohumeral distance in shoulders with large-to-massive full-thickness rotator cuff tears. In this study, the acromiohumeral distance in rotator cuff tear and healthy shoulders was measured using 3D-to-2D model-to-image registration techniques.MethodsThe dynamic glenohumeral kinematics during scapular plane abduction and axial rotation were analyzed in 11 rotator cuff tear patients and 10 healthy control subjects. Periodic radiographic images of scapular plane abduction and axial rotation were taken using a flat-panel radiograph image detector. Movements of the shoulder joint were assessed using radiographic images and computed tomography-derived digitally reconstructed radiographs. The acromiohumeral distance was defined as the shortest 3D distance between the acromion and the proximal humerus.FindingsFor scapular plane abduction, the rotator cuff tear group had significantly smaller acromiohumeral distance than the control group at 15°, 30°, 45°, 60°, 75°, 135°, and 150° of humeral abduction (P < 0.05 at each measured angle). For axial rotation in the adducted position, the rotator cuff tear group had significantly smaller acromiohumeral distance than the control group at each point between −20° and 40° of glenohumeral external rotation (P < 0.05 at each measured angle).InterpretationThe minimum measured acromiohumeral distance was 0.9 mm in the rotator cuff tear shoulders and 2.1 mm in the healthy shoulders at 90° of scapular plane abduction. The findings are of clinical relevance because quantitative evaluation of the dynamic acromiohumeral distances in rotator cuff tear and healthy shoulders might provide important insight into subacromial impingement.     

Comparative Analysis of Acromiohumeral Distances According to the Locations of the Arms and Humeral Rotation

[Purpose] The purpose of this study was to compare the potential effects of resistance exercise according to the positions of the arms and the rotation of the humerus on the subhumeral acromial space. [Subjects] The study subjects were 34 subjects without shoulder pain. [Methods] Ultrasonographic measurements of the acromiohumeral distance of the subjects were made at three shoulder positions: 90° flexion, scaption at 90° abduction, and 90° abduction in an upright sitting position. The subjects were instructed to vertically push against a table to the maximum level with the humerus in internal, neutral, and external rotation. The measurements were made three times in each position. [Results] There was a significant difference in acromiohuneral distance between neutral and internal rotation of the humerus, and between external rotation and internal rotation of the humerus. In the scaption position, there was a significant difference between neutral and internal rotation of the humerus, and between external rotation and internal rotation of the humerus. In the 90° flexion position, there was a significant difference between neutral and internal rotation, and between neutral and external rotation. There was a significant difference between the flexion position and the abduction position, and between the flexion position and the scaption position. In terms of the internal rotation of the humerus, there was a significant difference between 90° flexion and 90° abduction. [Conclusion] These findings can be applied in exercises prescribed to increase the acromiohumeral distance and to aid the treatment and evaluation of shoulder dysfunctions.Key words: Ultrasonographic, Acromiohumeral distance, Humeral rotation     

Quantifying acromiohumeral distance in elite male field hockey players compared to a non-athletic population

BackgroundShoulders of elite field hockey players are loaded continuously during play. Frequent high shoulder loading is known to influence certain shoulder variables, such as acromiohumeral distance. However, the influence of elite field hockey play on acromiohumeral distance is not examined yet.ObjectiveTo examine the acromiohumeral distance in elite male field hockey players compared to a non-athletic control group.DesignCross-sectional study.MethodsFifty male participants were included; 25 elite field hockey players (age: 24.0 ± 2.72 years; weight: 77.2 ± 5.29 kg; height; 180.5 ± 5.37 cm) and 25 age- and gender matched non-athletes (23.0 ± 2.29 years; weight: 75.7 ± 9.53 kg; height: 181.8 ± 5.52 cm). A Telemed-Colormaster-128 EXT-IZ device was used to bilaterally obtain ultrasound acromiohumeral distance images at 3 different angles of shoulder abduction in the frontal plane.ResultsField hockey players showed a bilateral larger acromiohumeral distance at 45° (mean difference: 1.46 mm [95% CI 0.46; 2.46]; p = 0.005) and 60° (mean difference: 1.07 mm [95% CI 0.21; 1.93]; p = 0.016) compared to controls. In both groups, a significant but clinically less relevant, side difference was established for the acromiohumeral distance at 60° (mean difference: 0.79 mm [95% CI 0.21; 1.34]; p = 0.009).ConclusionWith active shoulder abduction, elite field hockey players show a larger acromiohumeral distance in comparison to non-athletic participants. This may be a protective sport-specific adaptation, to better guard the shoulder from injury. Thus, acromiohumeral distance measurement may help physical therapists/coaches decide which athletes could benefit from specific, additional exercises aimed at enlarging the subacromial space.     

Validation of Ultrasound Measurement of the Subacromial Space Using a Novel Shoulder Phantom Model

Ultrasound has a high degree of diagnostic accuracy in the assessment of rotator cuff tendons. Increasingly, ultrasound is being used to measure other parameters of rotator cuff pathology, including the size of the subacromial space, or acromiohumeral distance (AHD). Although this measure has been found to be clinically reliable, no assessment of its validity has been carried out. This technical study reports on the development of a novel ultrasound phantom of the shoulder and its use in validation of ultrasound measurement of AHD. There was a close agreement between AHD measures using ultrasound and the true subacromial space of the phantom model, providing support for the construct validity of this measurement. The phantom model has good potential for further development as a training tool for shoulder ultrasound and guided injections.     

Poster 7: Shoulder impingement syndrome: clinical indicators and short-term predictors of disability

Objective: To identify the best indicators of the current disability of patients with shoulder impingement syndrome (SIS) and the strongest predictors of 3-month SIS-related disability. Design: Prospective cohort study. Setting: Movement analysis laboratory. Participants: 41 subjects with SIS. Interventions: Evaluations at baseline and at 3 months. Main Outcome Measures: Personal, occupational, and impairment variables and the Shoulder Pain and Disability Index (SPADI). Cross-sectional explicative and 3-month predictive regression models of the level of disability (SPADI score) were developed using multivariate analyses. Results: Strength deficits in shoulder abduction-lateral rotation, pain during muscle strength testing, painful arc in abduction, scapular anterior tilting asymmetry, gender, and age explained 91% of the variance of the SPADI at baseline. The SPADI score at baseline, perceived work capacity, acromiohumeral distance at 90° of abduction, acromiohumeral distance difference between shoulders at 110° of flexion, difference between active and passive range of motion in abduction, and the presence of SIS on the dominant side predicted 86% of the variance of the SPADI at 3 months. Conclusions: Variables that best explain the current disability level and predictors of short-term level of disability should be considered in SIS treatment planning as well as for establishing prognosis.     

Cranial humerus translation,deltoid activation,adductor co-activation and rotator cuff disease — Different patterns in rotator cuff tears,subacromial impingement and controls

Background

Arm adductor co-activation during abduction has been reported as a potential compensation mechanism for a narrow subacromial space in patients with rotator cuff dysfunction. We assessed differences in acromiohumeral distance at rest and the amount of humerus translation during active abduction and adduction in patients with rotator cuff tears (n = 20) and impingement (n = 30) and controls (n = 10), controlled for deltoid, pectoralis major, latissimus dorsi and teres major activation (electromyography).

Methods

During the acquirement of shoulder radiographs, subjects performed standardized isometric arm abduction and adduction tasks. EMG's were normalized between − 1 and 1 using the “Activation Ratio”, where low values express (pathologic) co-activation, e.g. adductor activation during abduction.

Findings

In patients with cuff tears mean rest acromiohumeral distance was 7.6 mm (SD = 1.6): 3.5 mm narrower compared to patients with impingement (95%-CI: 2.4–4.5) and 1.3 mm narrower compared to controls (95%-CI: − 0.1–2.7). Both during abduction and adduction tasks, cranial translation was observed with equal magnitudes for patients and controls, with average values of 2.3 and 1.7 mm, respectively. Where patients with cuff tears had lower adductor Activation Ratios (i.e. more adductor co-activation during abduction), no association between abductor/adductor muscle activation and acromiohumeral distance was found.

Interpretation

The subacromial space is narrower in patients with rotator cuff tears compared to patients with impingement and controls. We found additional subacromial narrowing during isometric abduction and, to a lesser amount, during adduction in all subjects and more adductor co-activation in patients with cuff tears. We found no association between subacromial space and activation of the deltoid and main adductors.     

A finite element model of the shoulder: application to the comparison of normal and osteoarthritic joints

Objective. The objective of the present study was to develop a numerical model of the shoulder able to quantify the influence of the shape of the humeral head on the stress distribution in the scapula. The subsequent objective was to apply the model to the comparison of the biomechanics of a normal shoulder (free of pathologies) and an osteoarthritic shoulder presenting primary degenerative disease that changes its bone shape.

Design. Since the stability of the glenohumeral joint is mainly provided by soft tissues, the model includes the major rotator cuff muscles in addition to the bones.

Background. No existing numerical model of the shoulder is able to determine the modification of the stress distribution in the scapula due to a change of the shape of the humeral head or to a modification of the glenoid contact shape and orientation.

Methods. The finite element method was used. The model includes the three-dimensional computed tomography-reconstructed bone geometry and three-dimensional rotator cuff muscles. Large sliding contacts between the reconstructed muscles and the bone surfaces, which provide the joint stability, were considered. A non-homogenous constitutive law was used for the bone as well as non-linear hyperelastic laws for the muscles and for the cartilage. Muscles were considered as passive structures. Internal and external rotations of the shoulders were achieved by a displacement of the muscle active during the specific rotation (subscapularis for internal and infrapinatus for external rotation).

Results. The numerical model proposed is able to describe the biomechanics of the shoulder during rotations. The comparison of normal vs. osteoarthritic joints showed a posterior subluxation of the humeral head during external rotation for the osteoarthritic shoulder but no subluxation for the normal shoulder. This leads to important von Mises stress in the posterior part of the glenoid region of the pathologic shoulder while the stress distribution in the normal shoulder is fairly homogeneous.

Conclusion. This study shows that the posterior subluxation observed in clinical situations for osteoarthritic shoulders may also be cause by the altered geometry of the pathological shoulder and not only by a rigidification of the subscapularis muscle as often postulated. This result is only possible with a model including the soft tissues provided stability of the shoulder.

Relevance One possible cause of the glenoid loosening is the eccentric loading of the glenoid component due to the translation of the humeral head. The proposed model would be a useful tool for designing new shapes for a humeral head prosthesis that optimizes the glenoid loading, the bone stress around the implant, and the bone/implant micromotions in a way that limits the risks of loosening.     

68例成年人肩宽测量及适宜枕头相应数据研究

目的：通过对68例成年人肩颧距及肩宽的调查、测量和分析,为适宜枕头设计提供依据。方法：68例成年志愿者,用两副平行滑动角尺测量其左右肩颧距（肩峰至同侧颧弓垂直距离）和肩宽（两肩峰间的距离）。结果：男性,肩颧距两侧最大值13.75cm,最小值10.50cm,平均（12.36±0.92）cm;肩宽最大值48.00cm,最小值38.00cm,平均（42.69±2.16）cm。女性,肩颧距两侧最大值13.70cm,最小值9.00cm,平均（10.82±1.01）cm;肩宽最大值44.00cm,最小值34.00cm,平均（39.14±2.81）cm。结论：肩颧距及肩宽数据测量为颈曲康复枕设计和改进提供出重要的参考依据。     

Reliability and minimal detectable change of inclinometric shoulder mobility measurements

The shoulder complex is one of the most commonly affected regions for which individuals present to physical therapy. Numerous shoulder disorders result in altered mobility with posterior shoulder tightness (PST), impaired internal rotation (IR), and either decreased or increased external rotation (ER) often reported in research investigations. The accurate assessment of shoulder mobility is an integral component of both the physical therapy examination and intervention. Therefore, the reliability and sensitivity to change of instruments used to measure mobility must be established. The purpose of this study was to investigate the intrarater reliability and minimal detectable change (MDC₉₀) of inclinometric measurements designed to quantify shoulder mobility. Active shoulder IR, ER, and passive PST were measured on the nondominant side of 30 asymptomatic volunteers in an intersession design. Intraclass correlation coefficients (ICCs) using model 3, k were excellent using the protocols described in this investigation with IR?=?0.987, ER?=?0.970, and PST?=?0.964. The MDC₉₀ indicates that a change of greater than or equal to 4° (IR), 5° (ER), and 8° (PST) would be required to be 90% certain that the change is not due to intertrial variability or measurement error.     

Ultrasonography of the shoulder.

Musculoskeletal ultrasound (MSUS) is an important modality in evaluating shoulder disease. Following a baseline shoulder conventional radiographic examination, MSUS can be used to screen the painful shoulder. It is accurate in diagnosing full- and partial-thickness tears of the rotator cuff. Both types of tears can be further characterized by size, location, and extension. Postoperatively, the rotator cuff can also be evaluated for recurrent full-thickness tears. MSUS is the only modality that can visualize and characterize synovial disease, without radiographic contrast, and when necessary, US-guided aspiration and biopsy can be performed. Real-time scanning shows the actual motion of the shoulder and its parts. Multiple attempts can be made to achieve optimal images for accurate documentation. Accessibility to MSUS facilitates the rapid turnaround of patients. US imagers and bone radiologists would do well to use MSUS to help their referring physicians establish a quick and accurate diagnosis of shoulder disorders. This article presents a comprehensive, pictorial review of the technical aspects of shoulder sonography as well as major types of pathology that can be diagnosed with US.     

Evaluation of three methods for determining EMG-muscle force parameter estimates for the shoulder muscles

BACKGROUND: Accurate prediction of in vivo muscle forces is essential for relevant analyses of musculoskeletal biomechanics. The purpose of this study was to evaluate three methods for predicting muscle forces of the shoulder by comparing calculated muscle parameters, which relate electromyographic activity to muscle forces. METHODS: Thirteen subjects performed sub-maximal, isometric contractions consisting of six actions about the shoulder and two actions about the elbow. Electromyography from 12 shoulder muscles and internal shoulder moments were used to determine muscle parameters using traditional multiple linear regression, principal-components regression, and a sequential muscle parameter determination process using principal-components regression. Muscle parameters were evaluated based on their sign (positive or negative), standard deviations, and error between the measured and predicted internal shoulder moments. FINDINGS: It was found that no method was superior with respect to all evaluation criteria. The sequential principal-components regression method most frequently produced muscle parameters that could be used to estimate muscle forces, multiple regression best predicted the measured internal shoulder moments, and the results of principal-components regression fell between those of sequential principal-components regression and multiple regression. INTERPRETATION: The selection of a muscle parameter estimation method should be based on the importance of the evaluation criteria. Sequential principal-components regression should be used if a greater number of physiologically accurate muscle forces are desired, while multiple regression should be used for a more accurate prediction of measured internal shoulder moments. However, all methods produced muscle parameters which can be used to predict in vivo muscle forces of the shoulder.     

Return to Sports After Shoulder Stabilization Surgery for Anterior Shoulder Instability

Purpose of Review

Young athletes continue to experience traumatic shoulder instability and are often plagued by recurrent instability, limiting their return to sport. The purpose of this paper was to review return to sport in athletes after shoulder stabilization surgery for anterior shoulder instability.

Recent Findings

Athletes managed nonoperatively demonstrate unacceptably high rates of recurrent instability and are less likely to successfully return to sport. Operative management includes capsuloligamentous repair (arthroscopic versus open) and bone augmentation techniques. While modern arthroscopic techniques have provided favorable outcomes, open techniques have demonstrated lower recurrence rates among young collision athletes. A subset of athletes continue to experience recurrent instability, leading to further investigation of concomitant pathologies, which may put patients at risk of failure following Bankart repair. Bony augmentation procedures remain favorable for patients with glenoid bone loss; however, what constitutes critical bone loss in the decision between anterior labral repair versus bone augmentation has recently been questioned.

Summary

Operative management of anterior shoulder instability provides superior results, including lower recurrent instability and return to sport. Future research on patient-specific risk factors may aid surgical decision-making and optimization of outcomes.

     

Mesenchymal stromal cells improve the osteogenic capabilities of mineralized agarose gels in a rat full‐thickness cranial defect model

The authors previously created HAp or CaCO₃ formed on or in agarose gels (HAp and CaCO₃ gels, respectively) as biocompatible and biodegradable bone graft materials. However, these gels have limitations for bone regeneration. Mesenchymal stromal cells (MSCs) have osteogenic potential and are considered useful for bone tissue engineering. The purpose of this study was to clarify the osteogenic abilities of MSCs loaded in HAp or CaCO₃ gels (MSC/HAp and MSC/CaCO₃ gels, respectively) using a rat cranial defect model compared to HAp and CaCO₃ gels alone. HAp, CaCO₃, MSC/Hap, and MSC/CaCO₃ gels were prepared for in vivo analyses and implanted into full‐thickness bone defects created in the rat cranium. All samples were assessed radiologically and histologically at 4 and 8 weeks after implantation. Using microfocus‐computed tomography, an increase in bone formation was observed in the MSC‐loaded gels compared to the gels alone. In addition, peripheral quantitative computed tomography revealed higher bone mineral contents in the MSC‐loaded gels compared to the gels alone. After transmission X‐ray diffraction analyses, the degree of apatite c‐axis orientation as a bone quality index of newly formed bone in the MSC‐loaded gels was close to that of living cranial bone. Histologically, more extensive bone formation was detected in the MSC‐loaded gels compared to gels alone. Overall, MSC/HAp and MSC/CaCO₃ gels showed equivalent efficacy for bone regeneration. These findings demonstrate that loading of MSCs into the gels strengthened their osteogenic ability and improved the quality of the newly formed bone. As a result, MSC‐loaded gels could represent viable therapeutic biomaterials for bone tissue engineering. Copyright © 2012 John Wiley & Sons, Ltd.     

Ultrasound‐Guided Proximal Suprascapular Nerve Block With Radiofrequency Lesioning for Patients With Malignancy‐Associated Recalcitrant Shoulder Pain

The classic suprascapular nerve block has limitations, such as postural requirements and lack of direct nerve visualization. This series investigated the analgesic effect of ultrasound‐guided supraclavicular suprascapular nerve blocks in patients with malignancy‐associated shoulder pain. Ablative radiofrequency lesioning of the suprascapular nerve in 6 patients provided substantial pain relief. The mean distance from the suprascapular nerve to the brachial plexus was 8.05 mm, and the mean angle of needle entry was 20.6°. This approach appears to be effective in relieving malignancy‐associated shoulder pain and is tolerated by patients unable to sit or lie prone.     

Arthroscopic Bankart Repair for the Management of Anterior Shoulder Instability: Indications and Outcomes

Purpose of Review

Arthroscopic Bankart repair is commonly utilized for shoulder stabilization in patients with anterior shoulder instability with minimum glenoid bone loss. The purpose of this review is to provide the indications, surgical technique, complications, and recent outcomes in arthroscopic Bankart repair for shoulder instability.

Recent Findings

Improvements in arthroscopic techniques have led to better patient outcomes, as well as an improved understanding of the pathoanatomy of instability. More recent studies have shown that one of the potential failures of primary arthroscopic repair may be due to unaddressed bone loss. This underscores the importance of evaluating glenoid bone loss and proper patient selection for this procedure to ensure successful outcome.

Summary

When indicated, arthroscopic stabilization is the treatment of choice for many surgeons due to its lower morbidity and low overall complication rate. Future work must focus on longer-term outcomes in patients undergoing arthroscopic Bankart repair, as well as the clinical outcomes of new fixation techniques, augmentation techniques, and the effect of glenoid bone loss in outcome.

     

Bone remodelling of the humerus after a resurfacing and a stemless shoulder arthroplasty

BackgroundNew implant designs, such as resurfacing and stemless implants, have been developed to improve the long-term outcomes of the shoulder arthroplasty. However, it is not yet fully understood if their influence on the bone load distribution can compromise the long-term stability of the implant due to bone mass changes. Using three-dimensional finite element models, the aim of the present study was to analyse the bone remodelling process of the humerus after the introduction of resurfacing and stemless implants based on the Global C.A.P. and Sidus Stem-Free designs, respectively.MethodsThe 3D geometric model of the humerus was generated from the CT data of the Visible Human Project and the resurfacing and stemless implants were modelled in Solidworks. Considering a native humerus model, a humerus model with the resurfacing implant, and a humerus model with the stemless implant, three finite element models were developed in Abaqus. Bone remodelling simulations were performed considering healthy and poor bone quality conditions. The loading condition considered comprised 6 load cases of standard shoulder movements, including muscle and joint reaction forces estimated by a multibody model of the upper limb.FindingsThe results showed similar levels of bone resorption for the resurfacing and stemless implants for common humeral regions. The regions underneath the head of the resurfacing implant, unique to this design, showed the largest bone loss. For both implants, bone resorption was more pronounced for the poor bone quality condition than for the healthy bone quality condition.InterpretationThe stemless implant lost less density at the fixation site, which might suggest that these implants may be better supported in the long-term than the resurfacing implants. However, further investigation is necessary to allow definite recommendations.     

Anterior shoulder instability: correlation between magnetic resonance arthrography, ultrasound arthrography and intraoperative findings

The purpose of the present study was to determine ultrasound (US) arthrography diagnostic accuracy in patients with recurrent shoulder dislocation by comparing US arthrography and magnetic resonance arthrography (MRA) with intraoperative findings. Fifty-six consecutive patients with diagnosis of chronic anterior instability of the shoulder were evaluated for assessment of bone and soft tissue lesions by three radiologists. Twenty-five cases were confirmed by surgery. Sensitivity, specificity, inter- and intraobserver agreement were calculated. Ultrasound sensitivity ranged from 20% to 100% and specificity from 25% to 90%. MRA sensitivity ranged from 80% to 100% and specificity from 50% to 100%. Interobserver agreement was good for MRA (0.54-0.70) and fair for US arthrography (0.19-0.40). Despite a higher interobserver variability for US arthrography than for MRA, our results indicate that US is capable of demonstrating bone and soft tissue lesions related to chronic instability of the shoulder in the presence of intra-articular fluid.