Radiographic evaluation of the acromioclavicular and sternoclavicular joints

Plain radiography is useful for the initial assessment of suspected disorders of the sternoclavicular and acromioclavicular joints. Other modalities are often required to further assess more complex pathologies involving these joints, however. Ultrasound has been described as a screening tool to assess possible sternoclavicular joint dislocation; however, it is usually used only if CT and MRI are not readily available. It has also been used to confirm intraoperative relocation. Ultrasound has a limited role in the evaluation of the AC joint, where it is most useful to exclude the presence of joint inflammation. If joint fluid is detected sonographically, it is considered a nonspecific finding, which could represent active inflammation or simply joint effusion due to degenerative arthrosis. CT allows for excellent visualization of the articular surfaces, osseous changes, subtle or complex fractures, and joint malalignment, with a rapid scan time, making it particularly helpful in the work up of trauma patients. With its multiplanar capabilities and superior soft-tissue resolution, MRI is a very effective modality for characterizing soft-tissue injuries, inclusive of ligamentous tears and cartilaginous injuries. In the specific case of posterior sternoclavicular dislocations, both CT and MR angiography can be very helpful in elucidating occult associated vascular injury.

The relationship between clinical outcomes and the amount of arthroscopic acromial resection

PURPOSE

In 47 consecutive patients who had a shoulder impingement syndrome treated by arthroscopic subacromial decompression, we compared the functional outcome with the amount of the acromion resection.

TYPE OF STUDY

Prospective study.

METHODS

The inclusion criteria for patient selection was a chronic impingement syndrome unresolved by conservative treatment with an intact rotator cuff or with an irreparable rupture of the rotator cuff. The assessment was performed with the scoring system of Constant preoperatively and postoperatively. Quantitative measurements of the acromion resection were made by comparing preoperative and postoperative anteroposterior radiographic views, standardized under fluoroscopic control in order to become reproducible and comparable. There were 39 patients (41 shoulders) available for follow-up at 37 months.

RESULTS

The condition of the shoulder, concerning pain, motion and activities, was improved at the time of follow-up, the mean gain of the total functional score was 29 points/100. Age, side, activity, duration of pain before procedure and cuff statement had no influence on preoperative and postoperative Constant's score. The difference between preoperative and postoperative measurements of anterior acromion protuberance was significant. There was no correlation between the amount of the acromion resection and the improvement of Constant's score (P =.84).

CONCLUSIONS

The origin of impingement syndrome is multi-factorial, and efficiency of arthroscopic decompression may not be only due to the amount of acromion resection. From these results and a literature review, this study analyzes several morphologic factors, which could explain the good results of arthroscopic subacromial decompression in impingement syndrome.

The use of a hook-plate in the management of acromioclavicular injuries. Report of ten cases

A hook-plate is a clavicular small fragment AO plate with a hook engaging below the acromion. It is primarily used to secure the ligament repair in the treatment of displaced acromioclavicular joint dislocations. We have used the hook-plate in conjunction with a Weaver-Dunn procedure to secure the repair in seven patients. In another three we used this plate to reduce and stabilize distal clavicular fractures. Satisfactory results were obtained in all patients; the deformity disappeared, full pain-free shoulder movement was regained with no motor weakness, with a mean follow-up of 11 months (6-25 months). Our patients returned early to work and sports activities (mean period of three months). The three clavicular fractures healed. One patient developed a superficial would infection, which responded to antibiotics and would dressing. None of our patients required removal of the implant. The hook-plate appears to be a useful device for acromioclavicular trauma.

Detection of acromioclavicular joint pathology in asymptomatic shoulders with magnetic resonance imaging

The purpose of this study was to determine the prevalence of acromioclavicular joint (ACJ) arthritis with magnetic resonance imaging (MRI) evaluation in asymptomatic patients. Fifty shoulders in 42 patients were evaluated with the use of standard MRI techniques. There were 18 men and 24 women with an average age of 35 years (range, 19 to 72). ACJ arthritic changes were graded on a scale from 1 to 4 (none, mild, moderate, and severe), based on the amount of subacromial fat effacement, joint space narrowing, irregularity, capsular distension, and osteophyte formation. Forty-one (82%) of 50 shoulders had abnormalities consistent with arthritis on MRI. Patients were divided into two groups according to age: those older than 30 years and those 30 years old or younger. In the 30-and-under age group, 68% of the shoulders had arthritic changes, whereas in the over-30 age group, 93% had arthritic changes. Furthermore, in a comparison of the two groups, more advanced arthritic changes were found in the over-30 age group (P <.05). Clinical decisions to resect the ACJ should correlate the physical examination with the MRI findings because many patients may be clinically asymptomatic.

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.

Increased T2 signal intensity in the distal clavicle: incidence and clinical implications

OBJECTIVE

The objectives of the current study were (1) to quantify the incidence of increased T2 signal in the distal clavicle and (2) to assess the clinical significance of this finding in patients with chronic acromioclavicular (AC) joint pain.

DESIGN AND PATIENTS

Eight patients (five male and three female, 15-41 years of age) with disabling shoulder pain localized to the AC joint and marked increased T2 signal in the distal clavicle are presented. These eight patients underwent MR examination over a 25 month period (August 1996 to September 1998). The dictated reports of all shoulder MR examinations conducted over this same time period were reviewed retrospectively for the presence of signal abnormality in the distal clavicle. Clinical data and, in five patients, findings at shoulder arthroscopy or open surgery, were correlated with the results of MR imaging. One patient underwent arthroscopy on both shoulders.

RESULTS

The selected eight patients each presented clinically with disabling shoulder pain localized to the AC joint. One patient is presented twice, as both shoulders were symptomatic (n=9). Plain film examination (9/9) failed to indicate a structural cause of shoulder pain in any of the patients. MR examination demonstrated abnormally increased T2 signal in the distal clavicle in all nine cases and no other cause for AC joint pain. Three patients responded to a course of conservative therapy. Six experienced refractory pain despite conservative therapy. Resection of the distal clavicle was performed in five of the six cases. All patients who underwent resection of the distal clavicle experienced complete resolution of AC joint pain. A retrospective review of the dictated reports for all shoulder MR imaging examinations performed at out institution over a 25 month period (August 1996 to September 1998; n=761) demonstrated a 12.5% incidence of abnormally increased T2 signal in the distal clavicle.

CONCLUSIONS

Increased T2 signal in the distal clavicle is a relatively common finding (12.5%) on MR imaging examinations of the shoulder and in most cases is of no clinical significance. However, in patients with chronic AC joint pain and no other abnormality on plain film or MR imaging, increased T2 signal may represent an early manifestation of, or a process similar to, osteolysis of the distal clavicle. Patients with this presentation who continue to suffer from disabling pain following conservative therapy may benefit from surgical resection of the distal clavicle.

Vanishing distal clavicle after arthroscopic acromioplasty

Arthroscopic subacromial decompression is gaining wide acceptance. There are several reports on its technique, its limitations, and its efficacy. However, papers describing complications are rare. We describe a case of osteolysis of the distal clavicle after overenthusiastic arthroscopic subacromial decompression.

Detached deltoid during arthroscopic subacromial decompression

SUMMARY

Arthroscopic subacromial decompression has become increasingly popular as an operative treatment for shoulder impingement syndrome. It is generally a safe procedure with low morbidity and very few complications. A case where the deltoid became detached during arthroscopic subacromial decompression is presented as an example of the perils of overaggressive subacromial decompression. This is the first reported case of such a complication related to arthroscopic subacromial decompression.

[The acromioclavicular joint]

The anatomy and biomechanics of the acromioclavicular (AC) joint have been understood for a long time; however, the importance of this joint in the clinical setting is often underestimated. During clinical examination various sensitive functional tests can document any AC pathology. For X-ray documentation special techniques are necessary. Other imaging techniques are rarely indicated. The Rockwood classification for AC joint separation has increased our understanding of the pathology, which, in turn, leads to a better understanding of conservative and surgical therapy. Within the last few decades surgical treatment has shifted from AC to coracoclavicular stabilization. In patients with clinically relevant degenerative joint disease, resection of the lateral clavicle has proved to be a reproducible procedure. This operation can be performed using the conventional, open technique or with a minimally invasive procedure (arthroscopic resection of the AC joint; ARAC). In unstable joints, resection should be combined with a stabilization procedure.

Monoarticular acromioclavicular joint gout: a case report

Acromioclavicular joint gout is extremely rare. The case presented represents the first case of monoarticular acromioclavicular joint gout reported. It is also the first reported case of acromioclavicular joint gout in an immunosuppressed patient. The diagnostic pitfalls inherent in the evaluation of acute monoarticular arthritis in an immunosuppressed patient are illustrated. Furthermore, the case demonstrates one of the atypical presentations of gout that may occur in renal transplant patients taking cyclosporin A.

Shoulder pathology associated with symptomatic acromioclavicular joint degeneration

We report the incidence and nature of shoulder disease found in association with symptomatic degenerative change in the acromioclavicular joint in 218 shoulders. Coexisting pathologic conditions were present in 213 shoulders: rotator cuff degeneration in 176 shoulders (79 with complete thickness tears), labral tears in 72, glenohumeral degeneration in 31, and biceps tendon disease in 49. In 59 shoulders findings were unexpected. We looked specifically at 2 age groups: <50 years and > or =50 years. In the <50 years group labral tears were seen in 42% (30 of 71) and rotator cuff disease in 65% (46 of 71). Cuff tears tended to be incomplete. In the older age group only 14% (21 of 147) had an intact cuff, with 72 shoulders having a full-thickness tear. Labral tears were seen in 29% (42 of 147). We recommend that all patients undergo shoulder arthroscopy at the time of acromioclavicular surgery.

MRI of the shoulder

Shoulder imaging is one of the major applications in musculoskeletal MRI. In order to analyze the images it is important to keep informed about anatomical and pathological findings and publications. In this article MRI technique, anatomy and pathology is reviewed. Technical considerations about MR sequences and examination strategy are only shortly discussed with emphasis on turbo spin echo and short T1 inversion recovery imaging. Basic anatomy as well as recent findings, including macroscopic aspects of the supraspinatus fat pad, composition of the supraspinatus muscle belly, and variability of the glenohumeral ligaments or coracoid ligament, are presented. Basic pathological conditions are described in detail, e. g. instability particularly problems in differentiating the various subtypes of labral pathology. Rotator cuff diseases are elucidated with emphasis on some rarer entities such as subscapularis calcifying tendinitis, coracoid impingement, chronic bursitis producing the double-line sign, prominent coraco-acromial ligament and the impingement due to an inflamed os acromiale.

Which stabilization technique corrects anatomy best in patients with AC-separation? An experimental study

In ten human cadaveric shoulder specimens four different parameters were documented prior to, and after, dissecting all passive stabilizers. These included the vertical, horizontal and mediolateral acromioclavicular distance, as well as the clavicular rotation. In addition, the same parameters were documented after acromioclavicular (AC) reconstruction using eight different techniques. The results showed a good reconstruction of the vertical ac-distance. Most of the techniques, especially the coracoid-sling procedure, led to a significant anterior displacement of the clavicle in relation to the scapula. To a lesser degree, most of the conventional procedures also resulted in a lateralization of the acromion and/or clavicular rotation. A bone anchor system for distal fixation in the base of the coracoid process and a medialized hole in the clavicle restored anatomy best. This new technique therefore is recommended for anatomical AC-reconstruction.

MR observations of postraumatic osteolysis of the distal clavicle after traumatic separation of the acromioclavicular joint

PURPOSE

The purpose of this work was to characterize the MR features of post-traumatic osteolysis of the distal clavicle in patients who have sustained a previous separation of the ipsilateral acromioclavicular (AC) joint.

METHOD

We studied eight male patients (mean age 25 years) with intractable pain in the AC joint after sustaining a traumatic joint separation. With use of the Rockwood classification, the separations were classified as Type 1 in one patient, Type 2 in two patients, and Type 3 in five patients. The MR studies were evaluated for periarticular soft tissue swelling, cortical irregularity defined as thinning or absence of portions of the cortex in the acromial and clavicular articular surfaces, hypertrophic osseous changes, periostitis, bone marrow edema, periarticular cyst-like changes, and joint space widening exceeding 6 mm. Radiographs were evaluated independently of the MR studies. Osteolysis of the distal clavicle was confirmed pathologically in seven patients and with surgery in one patient.

RESULTS

The incidence of osteolysis in patients who have had a previous AC joint separation was estimated to be approximately 6%. Observations on MRI included soft tissue swelling, bone marrow edema in the distal clavicle, and cortical irregularity associated with periarticular cyst-like erosions in eight patients, joint space widening in six patients, clavicular periostitis in three patients, and marrow edema in the cromion in five patients. Only one patient had osteophyte formation. Radiographic observations of periarticular soft tissue swelling, osteopenia of the distal clavicle, articular erosions, and joint space widening allowed diagnosis in only four patients prospectively.

CONCLUSION

The MR features of posttraumatic osteolysis are characteristic of this process. We advocate the use of MRI in patients with chronic AC joint pain who have had a prior AC joint dislocation, particularly if follow-up radiographs are nonspecific, equivocal, or do not indicate the presence of secondary osteoarthritis.

Radiographic joint space in rheumatoid acromioclavicular joints: a 15 year prospective follow-up study in 74 patients

OBJECTIVE

To evaluate radiographically the acromioclavicular joint space in patients with long-term rheumatoid arthritis (RA).

METHODS

A cohort of 74 patients with RA was followed prospectively for 15 yr. At the end point, 148 shoulders were radiographed with a standard method. The acromioclavicular (AC) joint space was examined from the radiographs with a method developed previously for population studies; the joint space was measured at its superior and inferior border, and the average of the two measurements, the integral space, calculated.

RESULTS

Mean AC joint space in RA patients was 4.9 (S.D. 3.7), range 0-20.5 mm; 6.2 mm (S.D. 5.1) in men and 4.5 mm (S.D. 3. 0) in women. An AC joint space wider than 7 mm in men was found in 11 (31%) out of 36 joints and wider than 6 mm in women in 17 (15%) out of 112 joints. Joint space widening was associated (r=0.87, 95% CI 0.82-0.90) with increasing destruction (Larsen grading) of the joint and it seems to be an inevitable consequence of AC joint affection in RA. Joint space widening is more progressive on the caudal side because of the nature of the erosive destruction. Degeneration with joint space narrowing was observed in 8 (11%) patients (11 joints, 7%; three bilateral).

CONCLUSIONS

The largest value of the joint space may be used when evaluating rheumatoid AC joint space. In RA patients, a joint space of >7 mm in men and >5 mm in women is a sign of destructive AC joint affection.

Painful conditions of the acromioclavicular joint

The acromioclavicular (AC) joint may be affected by a number of pathologic processes, most commonly osteoarthritis, posttraumatic arthritis, and distal clavicle osteolysis. The correct diagnosis of a problem can usually be deduced from a thorough history, physical examination, and radiologic evaluation. Asymptomatic AC joint degeneration is frequent and does not always correlate with the presence of symptoms. Selective lidocaine injection enhances diagnostic accuracy and may correlate with surgical outcome. Nonoperative treatment is helpful for most patients, although those with osteolysis may have to modify their activities. In appropriately selected patients, open or arthroscopic distal clavicle resection is necessary to relieve symptoms. Recent biomechanical and clinical data emphasize the importance of capsular preservation and minimization of bone resection; however, the optimal amount of distal clavicle resection remains elusive. Patients with AC joint instability have poor results after distal clavicle resection.

Incidence of acromioclavicular joint complications after arthroscopic subacromial decompression

We performed a chart and radiograph review of 173 patients (183 shoulders) who underwent arthroscopic subacromial decompression between 1991 and 1994 and had preoperative and postoperative radiographs. The study focused on the presence of preoperative acromioclavicular joint pathology, intraoperative violation of the acromioclavicular joint, extent of distal clavicle excision, and subsequent development of acromioclavicular joint symptoms. The 183 surgical procedures were divided into three groups: shoulders with subacromial decompression without acromioclavicular joint violation (103 of 183; 56%; group A); shoulders with subacromial decompression with acromioclavicular joint violation and partial distal clavicle resection (36 of 183; 20%; group B); and shoulders with subacromial decompression with complete distal clavicle resection (44 of 183; 24%; group C). Groups A and C had no postoperative sequelae in reference to the acromioclavicular joint. In contrast, 14 of the 36 shoulders (39%) in group B with a documented acromioclavicular joint violation and a partial distal clavicle resection developed acromioclavicular joint symptoms at an average of 8.4 months (range, 1.8 to 19 months) after surgery. This finding was statistically significant (P=.0001). The results of this study suggest that any violation of the acromioclavicular joint in the course of an arthroscopic subacromial decompression may jeopardize the result. The degree of violation is not helpful in predicting outcome. As a result of this study, we suggest an all-or-none surgical approach to the acromioclavicular joint and distal clavicle resection.

Post-traumatic and stress-induced osteolysis of the distal clavicle: MR imaging findings in 17 patients

OBJECTIVE

To describe the MR imaging findings in patients with osteolysis of the distal clavicle and to compare the MR imaging appearance of clavicular osteolysis following acute injury with that related to chronic stress.

DESIGN AND PATIENTS

MR imaging examinations were reviewed in 17 patients (14 men, 3 women; ages 16-55 years) with the diagnosis of post-traumatic or stress-induced osteolysis of the clavicle. A history of a single direct injury was present in seven patients and a history of weight-lifting, participation in sports, or repetitive microtrauma was present in 10 patients.

RESULTS

MR imaging showed edema in the distal clavicle in 17 patients and, of these, eight also had edema in the acromion. The edema was most evident in STIR and fat-suppressed T2-weighted pulse sequences. Other findings about the acromioclavicular (AC) joint were prominence of the joint capsule in 14, joint fluid in eight, cortical irregularity in 12, and bone fragmentation in six patients. No differences in the MR imaging features of post-traumatic and stress-induced osteolysis of the distal clavicle were observed.

CONCLUSION

Post-traumatic and stress-induced osteolysis of the distal clavicle have similar appearances on MR imaging, the most common and conspicuous MR imaging feature being increased T2 signal intensity in the distal clavicle.

The influence of acromioclavicular joint morphology on rotator cuff tears

A detailed anatomic study of 123 shoulders was performed to define the location of the acromioclavicular (AC) joint within the supraspinatus outlet and to determine the correlation of AC joint morphologic characteristics with the presence of full-thickness rotator cuff tears (RCTs). The presence, location, and extent of RCTs were first documented for each shoulder, and 2 anatomic landmarks consisting of the anterolateral acromial corner and the inferior midpoint of the AC joint were identified and their positions digitized in 3 dimensions to calculate outlet space and clearance and AC joint locations. High resolution x-ray films were then obtained to determine the extent of degenerative changes including the location and size of inferior osteophytes and joint space. These specimens were cleaned of all soft tissues, and additional measurements were made. All data were entered into a computerized database and analyzed with respect to age, sex, and the presence of RCT. Comparison of age-matched RCT versus non-RCT groups revealed no significant differences in the position of the AC joint within the supraspinatus outlet. When AC joint morphologic characteristics were compared with those of a nontear, age-matched group, no significant differences with regard to joint space narrowing were found, but significantly larger and greater number of osteophytes were identified on both sides of the joint in the RCT group. In conclusion, the position of the AC joint is fairly constant within the supraspinatus outlet and does not appear to predispose to RCTs. The morphology of the AC joint contribution of the tears seems to be acquired in nature rather than inherent in its location within the outlet.

[Histopathological findings in the proprioception of the shoulder joint]

Purpose of this study was the evaluation of distribution and morphology of mechanoreceptors in the glenohumeral joint capsule and rotator cuff in comparison to the coracoacromial ligament by means of specific immunfluorescence microscopy. The complemente joint capsules, rotator cuffs and coracoacromial ligaments of three fresh cadaver shoulder were harvesed. Serial cryostate sections were taken and alternately incubated with antiserum against neurofilament, lamin or myelin of peripheral nerves. The antibody-reaction was visualized with fluorescin lg-G. The nerve endings were photographed and computer-aided 3-dimensional reconstructions were performed. Three types of corpuscular and free nerve endings of different morphology were found in different distributions: whereas the Ruffini corpuscles were much more frequent in the coracoacromial ligament and rotator cuff, Pacini endings were predominantly found in the joint capsule. Generally corpuscular nerve endings were more frequent in the coracoacromial ligament and the rotator cuff than in the antero-inferior capsule and the number of corpuscles increased from medial to lateral within the anterior and inferior parts of the capsule. The dense ligamentous tissue was almost aneural whereas the periarticular fatty or loose connective tissue contained nerve fibres and nerve endings. In view of the results of other experimental and clinical studies the high frequency of Ruffini and Pacini endings in the rotator cuff and coracoacromial ligament suggest, that both are involved in the neurosensory control of glenohumeral stability and subacromial impingement. In contrast our findings in the joint capsule do not clearly prove, that those joint receptors predominantly maintain joint stability.