MDCT arthrography of the shoulder with datasets of isotropic resolution: indications, technique, and applications

OBJECTIVE: The purposes of this review are to summarize the indications for MDCT arthrography of the shoulder, highlight the features of MDCT acquisition, and describe the normal and abnormal MDCT arthrographic appearances of the shoulder. CONCLUSION: MDCT arthrography is a valid alternative for shoulder imaging of patients with contraindications to MRI or after failed MRI. MDCT arthrography is accurate for assessment of a variety of shoulder abnormalities and, with further validation, may become the imaging test of choice for evaluation of the postoperative shoulder.     

Quadrilateral space syndrome: incidence of imaging findings in a population referred for MRI of the shoulder

OBJECTIVE: The purpose of this study was to determine the incidence of MRI findings suggesting quadrilateral space syndrome in a population referred for shoulder MRI. CONCLUSION: Focal teres minor atrophy or abnormal signal suggesting quadrilateral space syndrome is an uncommon, although not rare, finding on MRI of the shoulder in our referral population and is rarely an isolated abnormality.     

CT空气—碘水双对比造影对肩关节不稳定诊断的意义

目的：探讨ＣＴ空气－碘水双对比造影对诊断肩关节不稳定的临床意义。材料与方法：８例患者做肩前穿刺，分别注入７６％泛影葡胺４ｍｌ和过滤空气１０ｍｌ，在全身ＣＴ机上行肩关节扫描。结果：所有患者气－碘双对比造影ＣＴ表现均与术中所见一致。主要特征为：（１）盂唇前部变钝、撕脱、游离；（２）关节囊前部撕脱或者关节囊破裂；（３）关节囊松弛、囊腔扩大。结论：ＣＴ气－碘双对比造影可以明确诊断肩关节不稳定，并为肩关节不稳定的解剖修复提供重要的影像学信息。     

Association of biceps tendon tears with rotator cuff abnormalities: degree of correlation with tears of the anterior and superior portions of the rotator cuff

OBJECTIVE: This study was performed to examine the relationship and association of abnormalities seen in the long head of the biceps brachii tendon to abnormal findings in the rotator cuff. MATERIALS AND METHODS: One hundred eleven patients underwent MR imaging for shoulder pain followed by arthroscopic or open shoulder surgery from January 1997 to December 2000. Patients were identified by a retrospective search, and all consecutive patients having undergone both MR imaging and surgery were included in the patient cohort. Official MR imaging interpretations were compared with operative reports, and all findings were recorded. RESULTS: Twenty-three patients were identified with partial- or full-thickness tears of the long head of the biceps tendon. The sensitivity, specificity, and accuracy of unenhanced MR imaging of the shoulder for detecting these bicipital tears were 52%, 86%, and 79%, respectively. When a tear was present in the biceps tendon, the prevalence of supraspinatous, infraspinatus, and subscapularis tendon tears was 96.2%, 34.6%, and 47.1%, respectively. Patients with biceps tendon tears were significantly more likely to also have subscapularis tendon tears (p < 0.0001) and supraspinatous tendon tears (p < 0.008) than those patients who did not have biceps tendon tears. No significant relationship was found between the presence or absence of a biceps tendon tear and the presence or absence of a infraspinatus or teres minor tendon tear (p = 0.17). CONCLUSION: Tears of the long head of the biceps tendon have a statistically significant association with tears of the anterior and superior rotator cuff and are highly correlated with tears of the supraspinatous and subscapularis tendons. When tears of these tendons are detected, specific attention directed toward the long biceps tendon is warranted to characterize the status of this structure that provides additional stability to the shoulder joint.     

Anterior oblique projection in radiography of the traumatized shoulder

A series of 132 consecutive shoulder radiographs of traumatized patients was analyzed prospectively. Each shoulder examination included anteroposterior projections with external and internal rotation of the humerus and an anterior oblique projection. Each view was evaluated for the abnormalities that were identifiable on it. There were 84 normal examinations and 48 abnormal examinations. There were 29 fractures, dislocations, or acromioclavicular separations identified. Two fractures of the greater tuberosity were seen only on the anteroposterior projection with external rotation. One humeral head fracture and three scapular fractures were visualized only on the anterior oblique projection.     

Shoulder activity level varies by diagnosis

Patient activity level may be an important prognostic variable relating to outcome in patients with shoulder disorders. The purpose of this cross-sectional study was to test the hypothesis that a shoulder activity scale will detect differences in shoulder activity based on the patient diagnosis and age. A total of 157 patients of four academic orthopedic surgeons with a diagnosis of rotator cuff disease (86), glenohumeral instability (31) or osteoarthritis (40) were asked to fill out a previously validated shoulder activity scale and the ASES shoulder questionnaire. The patient’s diagnosis, gender and age were recorded. The activity level was significantly higher in patients with instability than in patients with rotator cuff disease or osteoarthritis. Patients with rotator cuff disease were significantly more active than patients with osteoarthritis. Linear regression of activity level on patient age and diagnosis demonstrated a statistically significant relationship between activity level and both independent variables. Diagnosis influenced activity level independent of age. This is the first study to document diagnosis-based differences in the shoulder activity level of patients with different shoulder disorders. Shoulder activity level should be evaluated as a prognostic variable in studies of patients with shoulder disorders that may predict outcome and guide treatment in these patients.     

Sonography of the postoperative shoulder

Fifty-three patients with 60 symptomatic shoulders underwent shoulder sonography for recurrent postoperative symptoms after either acromioplasty (10 shoulders) or repair of a full-thickness rotator cuff tear in addition to acromioplasty (50 shoulders). Because surgery distorts landmarks, an understanding of the surgical procedures and their characteristic sonographic appearances is essential. After acromioplasty, the characteristic sharp margination or the acromion was replaced by a less distinct, irregular surface. After repair of a cuff tear, characteristic sonographic appearances included visualization of a reimplantation trough and loss of the echogenic subdeltoid bursa. When the cuff was intact after surgery, echogenicity was abnormal in all cases (17 shoulders). Sonography accurately diagnosed recurrent cuff tears in all 26 shoulders in which surgical proof was available and confirmed an intact cuff in 10 of 11 cases. In one shoulder, a cuff hematoma was incorrectly interpreted as a full-thickness tear. These findings suggest that sonography is an effective procedure for evaluating a postoperative patient with recurrent shoulder symptoms.     

Evaluation of 67Ga accumulation around the shoulder joint--comparison with 99mTc-MDP

67Ga scintigraphy was performed in 865 patients, and in 1078 examinations. 67Ga accumulation was evaluated retrospectively for asymmetric accumulation in the shoulders. Approximately 50% of patients showed no asymmetric distribution of 67Ga in the shoulders. About 40% of patients showed increased accumulation in the right side and about 10% of patients showed increased accumulation in the left side. A change of 67Ga distribution in the shoulder joints was recognized in about 30% of patients during the follow-up study. Reasons for asymmetric distribution of 67Ga in the shoulders were considered to be due to bone metastasis, changes of local blood flow, edema, irradiation, muscle atrophy after cerebral paralysis, and operation. 67Ga scintigraphy showed a broader range and more prominent accumulation in the soft tissues around the shoulder joint than 99mTc-MDP scintigraphy. The accumulation of 99mTc-MDP was recognized to be in the center of the region of 67Ga accumulation. 99mTc-MDP scintigraphy showed more prominently increased accumulation than 67Ga scintigraphy in patients with osseous lesions. Similar factors appeared to have had an influence on the abnormal accumulation of 67Ga and 99mTc-MDP around the shoulder joint.     

Improved imaging of bone with scan equalization radiography.

Use of scan equalization radiography (SER) for imaging bone in the head, face, neck, and shoulder was evaluated in a clinical comparison study with conventional radiographs of randomly selected patients. Two hundred nine pairs of normal and abnormal SER images and conventional radiographs were compared by four radiologists in a side-by-side viewing situation. The radiologists compared the visibility of specific anatomic features and rated the SER images as better than, equal to, or worse than the conventional radiographs. In the evaluation of the images of the cervical spine, the radiologists much preferred the SER images 63% of the time because of slight improvement in bone detail and marked improvement in detail of the soft tissues. In the evaluation of the images of the shoulder, the radiologists preferred the SER image 58% of the time and preferred the conventional radiograph only 5% of the time (p less than .05). In the evaluation of the images of the skull, face, and mandible, the radiologists preferred the SER images 62% of the time and the conventional images 4% of the time (p less than .05). The superior image quality with the SER technique was recognized by all radiologists in the study and was the overwhelmingly preferred way of imaging the shoulder, neck, head, and face.     

卒中患者偏瘫侧肩关节病变的高频超声诊断

目的 探讨高频超声诊断卒中患者偏瘫侧肩关节病变,分析偏瘫侧肩痛的可能病因,为进一步治疗提供依据.方法 选择首次发病的卒中偏瘫患者93例,进行肩关节高频超声检查,分为肩痛组和无肩痛组,比较两组肩关节病变情况.同时应用改良Ashwonh评分及Brunnstrom评分分别评定上肢肌张力及其运动功能.结果 93例中,超声发现异常75例,占80.7％,主要病变包括肩袖损伤(25例),滑囊炎、滑囊积液(31例),肩关节半脱位(28例),肱二头肌长头腱及腱鞘病变(50例).两组比较,在肩袖损伤,肩关节半脱位,滑囊炎、滑囊积液,肱二头肌长头腱及腱鞘积液的发病率上有统计学差异(x2=8.67,P＜0.01;x2=6.99,P＜0.01;x2 =13.44,P＜0.01;x2 =3.87,P＜0.05),两组在年龄、性别、偏瘫侧、中风类型、病程、上肢肌张力和上肢运动功能评分等均无统计学差异.结论 高频超声可用于诊断卒中患者偏瘫侧肩关节的病变,为指导康复治疗提供依据.     

Examination under anesthesia for evaluation of anterior shoulder instability.

Thirty patients with unilateral, traumatic recurrent anterior instability were assessed by examination under anesthesia of both shoulders in the anterior, anteroinferior, inferior, posterior, and posteroinferior directions while the examiner controlled the patients' arm rotation. There were significant side-to-side differences in humeral head translation, depending on arm rotation. Humeral head translation was significantly greater in the abnormal shoulder only in the anteroinferior direction with 40 degrees and 80 degrees of external rotation of the arm. Defining an "abnormal" examination as grade 3 translation (translation of the humeral head up onto the glenoid rim) or grade 4 translation (translation of the humeral head over the glenoid rim, that is, dislocated) and translation two grades greater than the contralateral uninjured side, the test sensitivity was 83%, and the test specificity was 100%. Assessing humeral head translation by examination under anesthesia is a useful adjunct to the diagnostic tools for shoulder instability, but the number of tests should be expanded to include the anteroinferior and posteroinferior directions, and the tests should be done with the arm in varying degrees of rotation.     

The value of ultrasonography in the preoperative diagnostic evaluation of patients with recurrent anterior shoulder dislocation: a prospective study of 44 patients

The purpose of this study was to investigate the value of ultrasonography in the pre-operative assessment of patients with recurrent post-traumatic, anterior shoulder instability. Forty-four consecutive patients, 44 men and 12 women, with unilateral, post-traumatic, recurrent instability of the shoulder were included in the study. One experienced radiologist examined all patients, using a 5.0 or 7.5 MHz linear-array transducer, with the arm in different positions, one of which was used to provoke apprehension of the shoulder. Special attention was paid to the evaluation of the joint capsule, the anterior labrum, especially in terms of the presence of a Bankart lesion. All patients were subsequently treated surgically. After a diagnostic arthroscopy either an open or arthroscopic stabilisation of the shoulder was performed. Ultrasonography disclosed an unstable anterior labrum (equivalent to a Bankart lesion) in 36 shoulders; the lesion was verified in all 36 shoulders during arthroscopy. In three shoulders, arthroscopy disclosed an injured labrum, which had healed in an anterio-medial position on the scapular neck. In these three shoulders, ultrasonography failed to show any lesion. In five shoulders no Bankart lesion was found at arthroscopy. All these patients had increased shoulder laxity, and ultrasonography did not show any Bankart lesion. Furthermore a judgement of the joint capsule was not possible either. A bony Bankart lesion was found in four shoulders, using both arthroscopy and ultrasonography. The sensitivity of the ultrasonographic evaluation was 92%, and the specificity 100%. The positive predictive value was 100%, and the negative predictive value 63%. Ultrasonography showed a high correlation with the arthroscopic findings, with a high sensitivity and specificity. Therefore, we conclude that US can give important pre-operative information in patients with recurrent, unilateral, post-traumatic, anterior shoulder instability.     

The surgical outcome of immediate arthroscopic Bankart repair for first time anterior shoulder dislocation in young active patients

This study evaluated the surgical outcomes of young active patients with arthroscopic Bankart repair within 1 month after first-time anterior shoulder dislocation. From July 2002–October 2004, patients presented with first-time traumatic anterior shoulder dislocation and treated with arthroscopic stabilization within 1 month of injury were retrospectively reviewed. Magnetic resonance imaging and computed tomography were performed before the operation in all cases. Cases with contralateral shoulder multidirectional instability or glenoid bone loss of more than 30% on preoperative computed tomography on the injury side were excluded. All patients were treated with arthroscopic Bankart repair, using metallic suture anchors or soft tissue bio-absorbable anchors by a same group of surgeons and followed the same rehabilitation protocol. Recurrence, instability signs, range of motion, WOSI score, Rowe score and complications were assessed. Thirty-eight patients were recruited: the average age was 21 (16–30). All patients had definite trauma history. Radiologically, all patients had Bankart/Hill-Sachs lesion. All the operations were done within 1 month after injury (6–25 days). The average hospital stay was 1.2 days (1–5 days). The average follow-up was 28 months (24–48 months). There were two cases of posttraumatic re-dislocation (5.2%). The average external rotation lag was 5° (0–15) in 90° shoulder abduction when compared with contralateral side. 95% of patients had excellent or good Rowe score. The average WOSI score was 83%. There was one case of transient ulnar nerve palsy and one case of superficial wound infection. This study concluded that immediate arthroscopic Bankart repair with an accelerated rehabilitation program is an effective and safe technique for treating young active patients with first-time traumatic anterior shoulder dislocation. This study complies with the current laws of the Hong Kong Special Administration Region Government.     

Posterior glenoid rim deficiency in recurrent (atraumatic) posterior shoulder instability

Objective. To assess the shape of the posterior glenoid rim in patients with recurrent (atraumatic) posterior instability. Design and patients.CT examinations of 15 shoulders with recurrent (atraumatic) posterior instability were reviewed in masked fashion with regard to abnormalities of the glenoid shape, specifically of its posterior rim. The glenoid version was also assessed. The findings were compared with the findings in 15 shoulders with recurrent anterior shoulder instability and 15 shoulders without instability. For all patients, surgical correlation was available. Results.Fourteen of the 15 (93%) shoulders with recurrent (atraumatic) posterior shoulder instability had a deficiency of the posteroinferior glenoid rim. In patients with recurrent anterior instability or stable shoulders such deficiencies were less common (60% and 73%, respectively). The craniocaudal length of the deficiencies was largest in patients with posterior instability. When a posteroinferior deficiency with a craniocaudal length of 12 mm or more was defined as abnormal, sensitivity and specificity for diagnosing recurrent (atraumatic) posterior instability were 86.7% and 83.3%, respectively. There was a statistically significant difference in glenoid version between shoulders with posterior instability and stable shoulders (P=0.01). Conclusion.Recurrent (atraumatic) posterior shoulder instability should be considered in patients with a bony deficiency of the posteroinferior glenoid rim with a craniocaudal length of more than 12 mm. Received: 13 September 1999 Revision requested: 9 November 1999 Revision received: 13 December 1999 Accepted: 4 January 2000     

MRI findings of 26 patients with Parsonage-Turner syndrome

OBJECTIVE: The objective of our study was to describe the MRI features of patients with Parsonage-Turner syndrome. Familiarity with the MRI features associated with this entity is important because radiologists may be the first to suggest the diagnosis. Twenty-six patients with Parsonage-Turner syndrome were treated at our institution between 1997 and 2005. We retrospectively reviewed the MR images of patients with clinical or electromyographic evidence (or both) of acute brachial neuritis without a definable cause. CONCLUSION: MRI of the brachial plexus and shoulder in patients with Parsonage-Turner syndrome showed intramuscular denervation changes involving one or more muscle groups of the shoulder girdle. The supraspinatus and infraspinatus muscles were the most commonly involved. MRI is sensitive for detecting signal abnormalities in the muscles of the shoulder girdle of patients with Parsonage-Turner syndrome. MRI may be instrumental in accurately diagnosing the syndrome.     

Shoulder adhesive capsulitis in cancer patients undergoing positron emission tomography - computed tomography and the association with shoulder pain

BACKGROUNDAdhesive capsulitis is a relatively common condition that can develop in cancer patients during treatment. Positron emission tomography - computed tomography (PET-CT) is routinely performed as a follow-up study in cancer patients after therapy. Being aware of PET-CT findings to suggest shoulder adhesive capsulitis may help to alert clinicians for the diagnosis of unsuspected shoulder capsulitis.AIMTo assess the association of shoulder adhesive capsulitis with cancer/therapy type and symptoms in cancer patients undergoing PET-CT.METHODSOur prospective study received Institutional Review Board approval. Written informed consent was obtained from all patients, who answered a questionnaire regarding shoulder pain/stiffness at the time of PET-CT study, between March 2015 and April 2019. Patients with advanced glenohumeral arthrosis, metastatic disease or other mass in the shoulder, or shoulder arthroplasty were excluded. Patterns of shoulder capsule 18F-fluorodeoxyglucose (FDG) uptake were noted. Standard Uptake Value (SUV)max and SUVmean values were measured at rotator interval (RI) and deltoid muscle in bilateral shoulders. Normalized SUV (SUV of RI/SUV of deltoid muscle) was also calculated. We assessed if SUV values are different between symptomatic and asymptomatic patients in both shoulders. Covariates were age, gender, and therapy type (surgery, chemotherapy, radiation). Wilcoxon rank sum tests were used to compare unadjusted marginal differences for age, SUV measurements between symptomatic and asymptomatic patients. Multiple linear regression models were used to examine the relationship between right or left shoulder SUV measurements and symptom status, after adjusting for covariates. Statistical significance level was set at P < 0.05.RESULTSOf 252 patients initially enrolled for the study (mean age 66 years, 67 symptomatic), shoulder PET-CT data were obtained in 200 patients (52 were excluded due to exclusion criteria above). The most common cancer types were lymphoma (n = 61), lung (n = 54) and breast (n = 53). No significant difference was noted between symptomatic and asymptomatic patients in terms of age, gender, proportion of patients who had surgical therapy and radiation therapy. A proportion of patients who received chemotherapy was higher in patients who were asymptomatic in the right shoulder compared to those symptomatic in the right shoulder (65% vs 48%, P = 0.012). No such difference was seen for the left shoulder. In both shoulders, SUVmax and SUVmean were higher in symptomatic shoulders than asymptomatic shoulders (Left SUVmax 2.0 vs 1.6, SUVmean 1.6 vs 1.3, both P < 0.002; Right SUVmax 2.2 vs 1.8, SUVmean 1.8 vs 1.5, both P < 0.01). For lung cancer patients, bilateral RI SUVmax and SUVmean values were higher in symptomatic shoulders than asymptomatic shoulders. For other cancer patients, symptomatic patients had higher left RI SUVmax/mean than asymptomatic patients after adjustment.CONCLUSIONIn symptomatic patients metabolic activities in RI were higher than asymptomatic patients. Adhesive capsulitis should be considered in cancer patients with shoulder symptoms and positive FDG uptake in RI.     

Diffuse FDG shoulder uptake on PET is associated with clinical findings of osteoarthritis

OBJECTIVE: Our objective was to examine the degree and pattern of (18)F-FDG uptake within the shoulder as a potential marker of joint inflammation or injury. SUBJECTS AND METHODS: Twenty-four patients undergoing (18)F-FDG PET for clinical oncologic assessment completed questionnaires regarding history of shoulder disease, trauma, pain, and/or functional impairment. Thorough physical examination of the shoulder was performed. A clinical diagnosis of specific shoulder derangement or normal was established for each patient. PET scans were evaluated blindly by a nuclear medicine physician and a musculoskeletal radiologist qualitatively for location, distribution, and intensity of shoulder uptake. Standardized uptake values (SUV) were measured. RESULTS: Twenty-one patients had shoulder PET findings. Fourteen had clinical findings consistent with a specific diagnosis in the PET-positive shoulder. The remaining seven PET-positive patients were clinically normal. Three recognizable patterns of uptake were appreciable. Eight of 10 patients with diffuse uptake had findings of osteoarthritis (n = 7) or bursitis (n = 1). Two of four patients with focal greater tuberosity uptake had findings of rotator cuff injury. Two of four patients with focal glenoid uptake had findings of frozen shoulder. SUV showed a positive correlation with subject age (p < 0.01), but no association with clinical findings was identified. CONCLUSION: The pattern of FDG uptake within the shoulder may point to specific clinical entities. While focal uptake is less reliably related to clinical findings, diffuse uptake is associated with signs and symptoms of osteoarthritis or bursitis.     

Hypoplasia of the glenoid neck of the scapula: imaging findings and report of 16 patients

OBJECTIVE: Our purpose was to describe the primary and associated imaging findings in patients with glenoid hypoplasia required for an accurate diagnostic appraisal of this uncommon abnormality. METHODS: The medical records and imaging studies of 16 patients with glenoid hypoplasia were retrospectively reviewed. Plain films were available in all patients, arthrography in 2, computed tomography (CT) in 5, CT arthrotomography in 3, magnetic resonance (MR) imaging in 9, and MR arthrography in 3 patients. The imaging studies were reviewed with special attention to the primary and secondary findings associated with glenoid hypoplasia. RESULTS: On radiographs, the 21 abnormal shoulders documented in the 16 patients with glenoid hypoplasia had an irregular (n=15) or shallow and smooth (n=6) articular surface of the glenoid. Computed tomography findings showed subluxation of the humeral head in 5 cases. On MR images, the hypoplastic bony glenoid and scapular neck were replaced by abnormal tissue of inhomogeneous signal intensity, showing the signal intensity characteristics of fibrocartilage (n=6) or fat (n=5). Widening of the inferior glenohumeral joint space was seen in all cases. Magnetic resonance imaging or MR arthrography revealed variable abnormalities of the labrum, including enlargement (10 shoulders), detachment of labrum from the bony glenoid (6 shoulders), intrasubstance tear (4 shoulders), and perilabral cyst (2 shoulders). The posterior labrum was absent (n=1) or torn (n=1) in one patient with bilateral deformity. Other findings included partial tear of the subscapularis tendon (n=1) and rotator cuff atrophy (n=1) and tear (n=2). CONCLUSION: Glenoid hypoplasia is a developmental skeletal anomaly comprising a spectrum of associated osseous and cartilaginous changes of the articular cartilage and glenoid labrum. Cross-sectional imaging studies, with or without arthrography, may help further characterize associated derangements of the shoulder, some of which are indicative of shoulder instability.     

MRI of adhesive capsulitis of the shoulder: Distension of the bursa in the superior subscapularis recess is a suggestive sign of the pathology

Objective

To evaluate the diagnostic values of the superior subscapularis recess sign in patients with shoulder adhesive capsulitis. The sign consists in evaluating in MRI of the shoulder the presence of fluid distension of the bursa in the superior subscapularis recess.

Materials and methods

We evaluated MRI of 165 shoulders in 48 consecutive patients with a diagnosis of shoulder adhesive capsulitis in the freezing phase (group I), in 49 short-wide superior cuff tear (group II) and in 65 controls (group III) between 2010 and 2013. On the T2 weighted images, we evaluated the presence of an high intensity signal within the superior subscapularis recess, consistent with fluid distension of the bursa.

Results

The sign was found in 43/48 patients (89.58%) with shoulder adhesive capsulitis in 3/49 (6.12%) patients with superior cuff tear and in 1/65 controls (1.53%) (p < 0.001). The mean diagnostic values were: sensibility 0.91; specificity 0.96–0.98; positive predictive value 0.93–0.97; negative predictive value 0.92–0.94; likelihood ratios for an abnormal test result 15.16–60.6; likelihood ratios for a normal test result 0.086–0.095.

Conclusion

For the orthopedic surgeon or the clinician, the sign is useful to confirm in MRI the clinical diagnosis of shoulder adhesive capsulitis; accordingly, the radiologist should describe and relate this sign to the pathology in the report, looking eventually for further typical sign of shoulder adhesive capsulitis.     

Histologic evaluation of the shoulder capsule in normal shoulders,unstable shoulders,and after failed thermal capsulorrhaphy

BACKGROUND: Attenuation of the shoulder capsule has been noted during revision surgery for failed thermal capsulorrhaphy. HYPOTHESIS: The attenuated capsule seen in patients who have undergone failed thermal capsulorrhaphy will show histologic characteristics distinguishing it from the capsule of normal shoulders and dislocating shoulders. STUDY DESIGN: Case control study. METHODS: The shoulder capsules were studied in 12 patients with traumatic anterior instability and in 7 patients who experienced recurrent instability after a thermal capsulorrhaphy. The capsules of six fresh-frozen cadavers with no shoulder lesions were used as controls. RESULTS: Among patients who had a history of traumatic instability, a denuded synovial layer was present in 58%, subsynovial edema in 58%, increased cellularity in 25%, and increased vascularity in 83%. At the time of surgery, five of seven shoulders in the failed thermal capsulorrhaphy group (71%) were subjectively felt to be thin and attenuated. Denuded synovium was found in 100% of these patients, subsynovial edema in 43%, and changes in the collagen layer in 100%. Changes in the collagen layer in these patients included a "hyalinization" appearance in five cases (71%), increased collagen fibrosis in two cases (29%), and increased cellularity in two cases (29%). CONCLUSIONS: There was no one characteristic observable on histologic evaluation that would explain the attenuation of the capsule in cases of failed thermal treatment. Morphologic collagen structure can be histologically abnormal for up to 16 months after thermal capsulorrhaphy.