Shoulder impingement syndrome: MR findings in 53 shoulders

The shoulder impingement syndrome refers to a condition in which the supraspinatus tendon and subacromial bursa are chronically entrapped between the humeral head inferiorly and either the anterior acromion itself, spurs of the anterior acromion or acromioclavicular joint, or the coracoacromial ligament superiorly. As a result, the space for the bursa and tendon is reduced, and repeated trauma to these structures leads to bursitis and rotator cuff injury. Although pain and limitation of motion are common early findings, the diagnosis is often delayed until a complete tear of the rotator cuff has occurred. In an attempt to determine if MR can be used to depict the abnormalities associated with impingement syndrome (subacromial bursitis, supraspinatus tendinitis, and rotator cuff tear), we reviewed 107 MR scans of painful shoulders. Changes consistent with impingement syndrome were found in 53 patients (50%), 32 of whom underwent subsequent arthrography or surgery. MR was found capable of depicting several soft-tissue and bony abnormalities that have been clinically described in impingement syndrome. In regions of inflammation, we found that the supraspinatus tendon and/or the subacromial bursa were compressed by spurs (25 shoulders), capsular hypertrophy of the acromioclavicular joint (six shoulders), and/or low-lying acromion (14 shoulders). While T1-weighted MR imaging was highly sensitive to abnormalities of the supraspinatus tendon, tendinitis could be differentiated from a small tear of the supraspinatus tendon only with T2-weighted imaging. Large, full-thickness tears, especially if chronic, produced characteristic MR findings on both T1- and T2-weighted images. We conclude that MR can be used to detect several abnormalities associated with the shoulder impingement syndrome.     

直接数字X线摄影对肩峰下撞击综合征的诊断价值

目的探讨肩关节正位、轴位、肩峰出口位直接数字X线摄影(DR)在肩峰下撞击综合征诊断中的意义。方法选取以肩部疼痛及活动受限为主诉的患者20例进行分析,其中男性13例,女性7例,右肩15例,左肩5例,分别摄取肩关节正位、轴位、肩峰出口位DR片,20例患者均行患肩关节磁共振成像(MRI)检查。结果 DR检查9例阳性患者,磁共振成像(MRI)检查均可见肩袖表面毛糙、部分或全层撕裂,而DR检查阴性患者仅1例可见肩袖损伤。结论肩关节正位、轴位、肩峰出口位DR对诊断肩峰下撞击综合征具有病因学意义。     

Ultrasound measurement of rotator cuff thickness and acromio-humeral distance in the diagnosis of subacromial impingement syndrome of the shoulder

The usefulness of ultrasound measurements in the diagnosis of the subacromial impingement syndrome of the shoulder was evaluated. Fifty-seven patients with unilateral symptoms of the impingement syndrome underwent ultrasound examination of both shoulder joints, which included assessment of rotator cuff integrity, measurement of rotator cuff thickness and the distance between the infero-lateral edge of acromion and the apex of the greater tuberosity of humerus (AGT distance) in the standard ultrasonographic positions. As a control group, 36 volunteers (72 shoulders) with no history of shoulder pain were examined sonographically. Ultrasonographic assessment of humeral head elevation, measured as the AGT distance, proved to be useful in establishing the diagnosis of the subacromial impingement syndrome of the shoulder. A difference in rotator cuff thickness of more than 1.1 mm and a difference in the AGT distance of more than 2.1 mm between both shoulder joints may reflect dysfunction of rotator cuff muscles.     

The coracoacromial arch: MR evaluation and correlation with rotator cuff pathology

The relative prevalence of various acromial shapes, appearance of the coracoacromial ligament and enthesophytes along the inferior aspect of the acromioclavicular joint in patients with and without rotator cuff tears were evaluated. Of 76 patients with clinical instability and impingement, 31 had a normal rotator cuff and 45 demonstrated a partial or full tear of the supraspinatus tendon at surgery. Results were compared with those from magnetic resonance (MR) scans of 57 asymptomatic volunteers. Of the 45 patients with a supraspinatus tear, 38% (17) had a flat acromial undersurface (type I), 40% (18) had a concave acromial undersurface (type II), 18% (8) had an anteriorly hooked acromion (type III), and 4% (2) had an inferiorly convex acromion (type IV). Among the 31 patients with a normal rotator cuff at surgery and the 57 asymptomatic volunteers, the respective prevalences of the type I acromion were 39% (12) and 44% (25), of type II 48% (15) and 35% (20), type III 3% (1) and 12% (7), and type IV 10% (3) and 9% (5). Shoulders with surgically proven rotator cuff tears showed a tendential association with a type III acromion (8/45) and statistically significant associations with a thickened coracoacromial ligament (17/45) and acromioclavicular enthesophytes (18/45). For the association between inferiorly directed acromioclavicular joint enthesophytes and rotator cuff tears, age appears to be a confounding factor. The type IV acromion, newly classified by this study, does not have a recognizable association with rotator cuff tears. Assessment of the osseous-ligamentous coracoacromial outlet by may prove helpful to the orthopedic surgeon in patients for whom surgical decompression is contemplated.     

Lateral down-sloping of the acromion: A useful MR sign?

Objective:

The anterior acromion may appear to slope downward in a lateral direction on coronal-oblique magnetic resonance (MR) images of the shoulder. We sought to determine the significance of this finding as a marker of rotator cuff impingement.

Patients and methods:

MR studies of 58 subjects (26 with impingement, 32 with glenohumeral instability) were retrospectively analysed. Subjective down-sloping of the acromion was compared to standardized acromial measurements made on MR (acromial axis, width of the anterior acromion, and distance of the acromioclavicular joint from the superior glenoid) and clinical diagnosis.

Results:

Interobserver variance for lateral down-sloping was fair (κ = 0.5). One reader's assessment of lateral down-sloping of the acromion correlated with standardized MR measurements. Subjective lateral down-sloping of the acromion did not, however, correlate with impingement.

Conclusion:

The subjective finding of a laterally down-sloping acromion on coronal-oblique MR images, while partially validated by standardized measurements, is not predictive of impingement syndrome.     

The shoulder impingement syndrome: prevalence of radiographic findings and correlation with response to therapy

The shoulder impingement syndrome is believed to be caused by compression of the rotator cuff tendons and subacromial bursa between the humeral head and structures that make up the coracoacromial arch. Plain film findings were tabulated for 36 patients, 22-81 years old, who had signs and symptoms of an acute impingement syndrome. The most common radiographic abnormalities were subacromial bony proliferation in 68%, degenerative changes in the greater tuberosity of the humerus in 66%, and degenerative joint disease in the acromioclavicular joint in 66%. There was evidence of calcium deposition in the rotator cuff in 37%, inferiorly oriented acromioclavicular osteophytes in 32%, and degenerative changes of the lesser humeral tuberosity in 29%. The acromiohumeral space was narrowed in only 21%. The radiographic findings were scored blindly and compared to the treatment outcome of 6 weeks of medical therapy. There was no statistically significant correlation between any of the radiographic findings and the response to medical therapy. The results suggest that radiographic findings are extremely common in patients with the acute impingement syndrome, but that they are not useful as prognostic indicators of the short-term response to medical treatment.     

The importance of imaging technics in the diagnosis of sports related periarticular shoulder lesions

Numerous kinds of sports lead to lesions of the periarticular tissue of the shoulder, which can result in the supraspinatus syndrome or incomplete and complete rupture of the rotator cuff. Standard radiography is of limited use in the diagnosis of periarticular diseases of the shoulder. Osseous alterations in the greater tubercle and undersurface of the acromion can be explained as a supraspinatus syndrome or a long-standing rupture of the rotator cuff in connection with high positioning of the head of the humerus. A rupture of the rotator cuff is demonstrated by arthrography of the shoulder joint, a diagnostic method that we think is necessary despite regular examinations with ultrasonography.     

Measurement of subacromial impingement of the rotator cuff

Objective: Recent evidence suggests that shoulder impingement syndrome arises from primary rotator cuff pathology and may be related to the inability of the rotator cuff to prevent superior humeral head migration in shoulder elevation. Impingement involves compression of subacromial structures, including the rotator cuff. Previously, clinical tests have been shown to be inaccurate in diagnosing rotator cuff impingement. A lack of anatomical validity might explain the inaccuracy of these tests. This study aimed to clarify the anatomical basis of subacromial compression of the rotator cuff by analysing the compression forces generated and observing the structures impinged in a variety of shoulder positions. Design: This observational case series involved the dissection of nine embalmed cadaveric shoulders. Method: Pressure transducers were placed deep to the coracoid process, coracoacromial ligament, the anterior acromion and the posterior acromion. Shoulders were moved into internal and external rotation from the positions of flexion, abduction and extension. At each position, pressure readings were recorded and structures being compressed observed visually. Results: Highest pressures were recorded in flexion/internal rotation at the coracoacromial ligament, in abduction/internal rotation at the coracoid process (both involving the rotator interval) and in abduction/internal rotation at the coracoacromial ligament (involving supraspinatus). Supraspinatus was also observed to be compressed in extension/external rotation (against the anterior acromion). Infraspinatus was compressed in extension/external rotation (against the posterior acromion), while subscapularis was compressed in flexion/internal rotation and flexion/external rotation (both against the coracoid process). Conclusion: This study identifies shoulder positions likely to impinge particular rotator cuff tendons.     

肩关节冈上肌出口位X线摄影在肩峰下撞击综合征中的应用价值

目的:探讨肩关节冈上肌出口位X线摄影所示肩峰形态、肩峰下间隙与肩峰下撞击综合征(shoulder impingement syndrome,SIS)的相关性,总结其临床应用价值。方法:回顾性分析60例经临床证实的SIS患者的临床及影像资料,对X线摄影所示的肩峰形态及肩峰下间隙进行分型、测量,并与MRI所见进行对照,分析肩峰形态及肩峰下间隙与SIS的相关性。结果:60例患者中,肩峰平坦形(Ⅰ型)8例、弧形(Ⅱ型)10例、钩状(Ⅲ型)42例。冈上肌出口位X线摄影所示肩峰下间隙为(1.21±0.36)cm,MRI所示肩峰下间隙值为(1.10±0.18)cm,两者差异无统计学意义(P0.05)。肩袖损伤MRI分级Ⅰ级27例,Ⅱ级20例,Ⅲ级13例。肩峰下间隙值与肩袖损伤MRI分级呈正相关(P0.05)。结论:肩关节冈上肌出口位X线摄影所示肩峰形态、肩峰下间隙与SIS发生密切相关;当肩峰形态为钩状及肩峰下间隙值1cm,强烈提示SIS可能,对于无MRI的基层医院诊断SIS临床意义明显,值得临床应用。     

Os acromiale: evaluation of markers for identification on sagittal and coronal oblique MR images

 An os acromiale is a developmental abnormality of ossification involving the anterior acromion which may contribute to impingement and rotator cuff disease. When axial MR sections do not include the acromioclavicular joint, the diagnosis of this often subtle abnormality will rest on its recognition on oblique coronal and sagittal images where it mimics the acromioclavicular joint. The identification of this anomaly is important as it frequently alters the type of surgical procedure utilized in symptomatic patients. We evaluate several imaging features which may be used to diagnose an os acromiale in these cases.     

MR evaluation of factors predicting the development of rotator cuff tears

PURPOSE: The purpose of this work was to assess the incidence of various factors predicting impingement in the shoulder. METHOD: MR examination was used to assess various anatomic parameters in 46 patients with clinical abnormalities of the shoulder and 40 asymptomatic volunteers. All patients had undergone surgery, showing no rotator cuff tear. RESULTS: A few of the parameters evaluated were significantly different in the two groups: The acromion was more frequently curved or hook-shaped in patients than in volunteers. The acromiohumeral distances differed (4.87 mm in patients and 6.05 mm in volunteers); so did the coracohumeral distances (7.9 mm in patients and 8.9 mm in volunteers). The shape of the acromioclavicular joint and the anterior covering of the humerus, defined on the coronal view, also differed (1.07 mm in patients and 1.49 mm in volunteers). Only the shapes of the acromioclavicular joint and of the acromion were linked with age. CONCLUSION: All these factors reflected a decrease in the acromiohumeral space, except for the anterior covering of the acromial arch, which could be due to anterior instability.     

Shoulder impingement: objective 3D shape analysis of acromial morphologic features

PURPOSE: To retrospectively and quantitatively analyze the acromial undersurface in three dimensions and to determine its association with impingement syndrome and rotator cuff tears. MATERIALS AND METHODS: Institutional review board approval was received with exemption of informed consent for this retrospective HIPAA-compliant study. Magnetic resonance images were evaluated in 84 patients (63 males, 21 females; mean age, 42.6 years; age range, 15-74 years). On the basis of surgical results, patients were separated into three groups: those without shoulder impingement or rotator cuff tears (31 patients), those with shoulder impingement (22 patients), and those with rotator cuff tears (31 patients). To quantitate the acromial undersurface, the structure was manually plotted, and a mathematic model was created by using splines. The undersurface was divided into a 20 x 20 grid. For each patient, a shape index (SI) data set and local undersurface angulation (LUA) data set were determined. Regression analyses were used to identify differences between groups, and prediction models were constructed on the basis of correspondent areas. RESULTS: Analysis of both data sets yielded no apparent progression between groups and demonstrated a lack of similarity between the impingement and rotator cuff tear groups. Discrimination between groups could be demonstrated by dividing the lateral portion of the acromial undersurface into contiguous blocks. The highest overall diagnostic accuracy of our prediction models was 58.3% (49 of 84) by using 10 blocks of the SI data set and 73.8% (62 of 84) by using five blocks of the LUA data set. Conclusion: Three-dimensional modeling yields objective data about the acromial undersurface. On the basis of this method, osseous impingement by the acromion is not a primary cause of shoulder impingement syndrome or rotator cuff tears.     

The prevention and treatment of injuries to the shoulder in swimming

The biomechanics of swimming cause considerable stress on the shoulder joint which may be accentuated by improper stretching or training techniques. The rotator cuff, and particularly the supraspinatus tendon, is at risk in repetitive overhead stroke activity. Arthritis in the shoulder is primarily centered at the acromioclavicular joint; degeneration may occur as a result of overuse or leverage of the scapuloclavicular mechanism, or from motion related to upward pressure at the undersurface of the acromion due to subluxation or instability of the glenohumeral joint. Instability of the glenohumeral joint is a major problem which may occur in itself or in combination with rotator cuff tendinitis. The glenohumeral joint is stabilised superiorly by a posterior superior sling consisting of the long biceps tendon, the superior joint capsule, and the coracoacromial and coracohumeral ligaments. An anterior inferior sling mechanism consisting of the inferior glenohumeral ligament and subscapularis musculotendinous unit provides significant stability if uninjured. Fragments of labral tissue may mechanically wedge into the joint also leading to symptoms of subluxation. If the humeral head is wedged or allowed to slip out of joint due to capsular incompetency, secondary rotator cuff 'impingement' may occur; this is particularly difficult to manage. Prevention of injury is best accomplished through a programme of flexibility and strengthening avoiding overuse.     

The relationship of acromial architecture to rotator cuff disease

Variations in the architecture of the coracoacromial arch can lead to a clinically symptomatic rotator cuff lesion. Differences in the development and morphology of the acromion, and the presence of anterior acromial spurs and inferior acromioclavicular osteophytes decrease the volume of the subacromial space, leading to impingement. Recent anatomic, radiographic, biomechanical, and SPG studies have confirmed these architectural variations and their effects on the contents of the subacromial space. Abnormal contact between the acromion and these soft tissues can lead to pathologic lesions. Surgical procedures should be directed at increasing the space beneath the coracoacromial arch to reduce wear on the rotator cuff.     

Arthroscopic acromioclavicular resection

Injury to the acromioclavicular joint is common and represents the source of many shoulder-related symptoms.Frequently, nonoperative treatment regimens such as physical therapy, oral antiinflamatory medication, and corticosteroid injections resolve symptoms. However, certain patients with cases refractory to conservative therapy require an operative intervention. The traditional open resection of the distal clavicle, as described independently by Mumford and Gurd has been a reproducible and reliable surgical method of treatment in patients with posttraumatic, degenerative disease of the acromioclavicluar joint associated with osteoarthritis, distal clavicle osteolisis, fractures and separations, and shoulder impingement syndrome. Advances in arthroscopic shoulder surgery and subacromial decompression have made debridement of the acromioclavicular joint and resection of the distal clavicle a viable alternative to the open approach, avoiding complication such as AC joint instability and residual postoperative shoulder weakness, and with distinct advantages like 1) evaluation of glenohumeral joint, 2) evaluation and treatment of coexistent impingement and rotator cuff pathology, 3) generally, performed on an outpatient basis, which decreases hospital cost and increases patient convenience.     

Shoulder impingement syndrome: impingement view and arthrography study based on 100 cases

A prospective evaluation combining the shoulder impingement view and arthrography was made in patients presenting with chronic shoulder pain. Five hundred and twenty-three patients with chronic shoulder pain were X-rayed using conventional views and impingement views. One hundred of these patients (mean age 62 years) had subacromial bony spurs on the impingement view; these underwent arthrography. They were divided into two groups according to the degree of spur formation — whether or not the size of the spur exceeded one half of the acromial width as measured from the outer margin to the acromioclavicular joint. Of the 100 subacromial spurs demonstrated on the impingement view, only 18 were visible on the conventional view as assessed by an independent radiologist. Arthrography showed 35 cases of rotator cuff tear. The size of the bony spur was strongly associated with the incidence of rotator cuff tear (P < 0.02).     

Impingement of the rotator cuff in athletes caused by instability of the shoulder joint

An impingement of the rotator cuff can be caused by chronic anterior instability of the shoulder joint. This particular disease is often found in athletes engaged in overhead motion in abduction/external rotation of the arm, such as in ball sports like volleyball or European handball, racket sports like tennis or badminton, or swimming. For those patients that cannot be cured by conservative treatment such as muscular stabilization, surgical treatment is indicated: anterior reconstruction of the capsule and/or the glenoid labrum, and in addition — if necessary — subacromial decompression and revision of the rotator cuff. Between October 1988 and April 1992, we operated on 66 shoulders in 64 top athletes suffering from chronic anterior or multidirectional instability of the shoulder joint that had caused an impingement syndrome of the rotator cuff. In all cases, the athlete was unaware of the instability. Conservative treatment had been unsuccessful. Surgical treatment was successful in close to 90% of the athletes.     

Imaging techniques of the shoulder: present perspectives

Through its ability to evaluate the individual components of the rotator cuff, the labral-capsular complex, the subacromial and subdeltoid spaces, and the glenoid, humerus, clavicle, and acromion, MRI provides a means of comprehensively evaluating the shoulder. Further advances in the use of intra-articular MRI contrast agents will undoubtedly enhance the role of MRI in the evaluation of subtle labralcapsular pathology. Although they are experimental, kinematic studies of the shoulder may provide valuable insight into the pathogenesis of disorders such as impingement syndrome. The ability of MRI to provide detailed pathologic information about individual components of the shoulder, particularly the rotator cuff, presents a challenge to shoulder surgeons. Patient symptomatology should be correlated with MRI findings and the clinical significance attached to different pathologies reevaluated. Through rigorous confirmation of MRI findings, dedicated therapeutic algorithms can be established based on detailed clinicopathologic data. Present and future surgical and nonsurgical management of the shoulder will undoubtedly be shaped by MRI.     

Imaging shoulder impingement

Appropriate imaging and clinical examinations may lead to early diagnosis and treatment of the shoulder impingement syndrome, thus preventing progression to a complete tear of the rotator cuff. In this article, we discuss the anatomic and pathophysiologic bases of the syndrome, and the rationale for certain imaging tests to evaluate it. Special radiographic projections to show the supraspinatus outlet and inferior surface of the anterior third of the acromion, combined with magnetic resonance images, usually provide the most useful information regarding the causes of impingement.