Relationship between MRI and clinical findings in the acromioclavicular joint

Morphology of the acromioclavicular-joint score (MAC)

INTRODUCTION

To date there is no generally accepted specific definition or classification of acromioclavicular (AC) joint osteoarthritis. The aim of this study is to analyze morphological parameters using magnetic resonance imaging (MRI) and to develop a scoring system as a basis for decision making to perform an AC-joint resection.

MATERIALS AND METHODS

In a retrospective-monocentric matched pair study, healthy and affected subjects were investigated using T2 MRI scans in the transverse plane. There were two groups, group 1 (n = 151) included healthy asymptomatic adults with no history of trauma. In group 2, we included n = 99 patients with symptomatic AC joints, who underwent arthroscopic AC-joint resection. The central and posterior joint space width and the AC angle were measured. Morphological changes such as cartilage degeneration, cysts and bone edema were noted. Malalignment of the joint was defined as: posterior joint space width < 2 mm in conjunction with an AC angle > 12°. A scoring system consisting of the measured morphologic factors was developed.

RESULTS

Symptomatic and asymptomatic patients showed significant differences in all measured items. We observed a significant difference in the MAC score for symptomatic and asymptomatic patients (mean 10.4 vs. 20.6, p = 0.0001). The ROC (receiver operator characteristic) analysis showed an excellent AUC of 0.899 (p = 0.001). The sensitivity of the MAC score was 0.81 and the specificity 0.86. The MAC score shows a significant moderate correlation with age (r = 0.358; p = 0.001). The correlation of age and the development of symptoms was only weak (r = 0.22, p = 0.001). Symptomatic patients showed significantly more frequent malalignment compared to asymptomatic patients (p = 0.001), but the positive predictive value that a patient with malalignment is also symptomatic is only 55%.

CONCLUSION

Patients with symptomatic AC joints showed a typical pattern of morphological changes on axial MRI scans with early posterior contact of the joint surfaces, reduction of joint space and malalignment as the basis for the development of a scoring system. The MAC score shows excellent test characteristics, and therefore, proved to be both an appropriate guidance for clinical practice as well as an excellent tool for comparative studies and is superior to the assessment of malalignment alone.

LEVEL OF EVIDENCE

Level IV, retrospective diagnostic study.

Bony Edema and Clinical Examination Findings Predict the Need for Distal Clavicle Excision at the Time of Shoulder Arthroscopy

Background: Deciding to perform a distal clavicle excision for acromioclavicular joint arthritis, especially in conjunction with other arthroscopic shoulder procedures, is challenging for surgeons. Studies have reported mixed results on the value of magnetic resonance imaging (MRI) in decision making. Purpose: We sought to correlate MRI findings with clinical symptoms and the surgeon's decision to perform a distal clavicle excision. Methods: We compared MRI, clinical examination, and MRI findings of 200 patients who underwent distal clavicle excision for symptomatic acromioclavicular joint arthritis with 200 patients who underwent arthroscopic shoulder procedures for other reasons. Univariate statistics were used to determine correlations between physical examination findings, MRI findings, and the decision to perform distal clavicle excision. A binary logistic regression model was used to determine independent predictors of need for distal clavicle excision. Results: There was no difference in mean age, sex, and race between groups. Advanced acromioclavicular joint osteoarthritis was strongly correlated with positive physical examination findings. Bony edema correlated strongly with tenderness at the acromioclavicular joint but not pain with cross-body adduction testing. There was no association between higher MRI grade of osteoarthritis and the need for distal clavicle excision. Regression analysis identified both physical examination findings and bony edema on MRI as independent predictors of the need for distal clavicle excision. Conclusion: In the setting of positive clinical examination findings and bony edema of the distal clavicle, surgeons should feel reassured that distal clavicle excision is likely indicated.

Imaging of the Acromioclavicular Joint: Anatomy, Function, Pathologic Features, and Treatment

The acromioclavicular joint is an important component of the shoulder girdle; it links the axial skeleton with the upper limb. This joint, a planar diarthrodial articulation between the clavicle and the acromion, contains a meniscus-like fibrous disk that is prone to degeneration. The acromioclavicular capsule and ligaments stabilize the joint in the horizontal direction, while the coracoclavicular ligament complex provides vertical stability. Dynamic stability is afforded by the deltoid and trapezius muscles during clavicular and scapular motion. The acromioclavicular joint is susceptible to a broad spectrum of pathologic entities, traumatic and degenerative disorders being the most common. Acromioclavicular joint injury typically affects young adult males and can be categorized by using the Rockwood classification system as one of six types on the basis of the direction and degree of osseous displacement seen on conventional radiographs. MRI enables the radiologist to more accurately assess the regional soft-tissue structures in the setting of high-grade acromioclavicular separation, helping to guide the surgeon's selection of the appropriate management. Involvement of the acromioclavicular joint and its stabilizing ligaments is also important for understanding and classifying distal clavicle fractures. Other pathologic processes encountered at this joint include degenerative disorders; overuse syndromes; and, less commonly, inflammatory arthritides, infection, metabolic disorders, and developmental malformations. Treatment options for acromioclavicular dysfunction include conservative measures, resection arthroplasty for recalcitrant symptoms, and surgical reconstruction techniques for stabilization after major trauma.

Acromioclavicular osteoarthritis and shoulder pain: a review of the role of ultrasonography

Acromioclavicular joint osteoarthritis is often a cause of shoulder pain. On the other hand, imaging frequently leads to such a diagnosis, especially in elderly patients, and some authors believe it to have a poor correlation with the clinical picture. It is, however, widely accepted that such a condition can be the cause of rotator cuff impingement. In the case of shoulder pain, it is important to distinguish between symptomatic acromioclavicular osteoarthritis and other causes, especially rotator cuff pathology, which is more common. Sometimes, the clinical picture does not allow for differential diagnosis; in these cases, the injection of a local anesthetic into the acromioclavicular joint or into the subacromial bursa can be of great help. Ultrasonography can easily detect acromioclavicular osteoarthritis and rotator cuff pathology, and it is highly effective in guiding the articular or bursal injection of a local anesthetic to assess the origin of the pain. In addition, in conservative therapy, ultrasonography can guide the articular or bursal injection of corticosteroids and hyaluronic acid.

Seven-year course of asymptomatic acromioclavicular osteoarthritis diagnosed by MRI

BACKGROUND

Asymptomatic acromioclavicular osteoarthritis (AC-OA) is a frequent finding in shoulder magnetic resonance imaging (MRI). Its natural course is unknown. Therefore, the question arises whether a resection should be performed simultaneously with shoulder surgery for another reason to prevent future pain and reoperation. The purpose of this study was to investigate the mid-term course of asymptomatic AC-OA.

METHODS

Overall, 114 asymptomatic AC-OA diagnosed on MRI were followed for 7 years between 2011 and 2018. At baseline, MRI signal enhancement in the clavicle and acromion, OA grade, physical demand as well as the parameters (1) Constant Score Visual Analogue Scale, (2) pain on AC-joint compression, and (3) cross-body adduction test were measured. All patients were followed up after 7 years by interview, and in case of symptoms by clinical examination. The endpoint "deterioration" was reached if 2 of the 3 parameters turned worse.

RESULTS

Asymptomatic AC-OA remained asymptomatic in 83% of cases, 7% turned better, 10% turned worse. Physical demand and osteoarthritis grade increased the risk of deterioration, whereas MRI signal enhancement in the clavicle or acromion had no influence on outcome. During follow-up, the frequency of pain on AC-joint compression increased from 11% to 16% (P = .24), the frequency of a positive cross-body adduction test increased from 6% to 20% (P = .017), and the mean Constant Score Visual Analogue Scale increased from 10 to 13 points (P < .001) indicating less pain.

CONCLUSIONS

Asymptomatic AC-OA remained asymptomatic in 90% over 7 years. A simultaneous resection of an asymptomatic AC-OA during shoulder surgery for another reason is not indicated in every patient.

Magnetic resonance imaging scans are not a reliable tool for predicting symptomatic acromioclavicular arthritis

BACKGROUND

We investigated whether magnetic resonance imaging (MRI) scans can accurately diagnose arthritis of the acromioclavicular joint (ACJ) because it has recently been suggested that bone marrow oedema on MRI scans is a predictive sign of symptomatic ACJ arthritis.

METHODS

The MRI scans of 43 patients (50 shoulders) who underwent ACJ excision for clinically symptomatic ACJ arthritis were compared to a control group of 43 age- and sex-matched patients (48 shoulders) who underwent an MRI scan for investigation of shoulder pain but did not have clinical symptoms or signs of ACJ arthritis. The scans were evaluated by an experienced musculoskeletal radiologist, who was blinded to the examination findings.

RESULTS

Bone marrow oedema was present in only 15 (30%) shoulders in the ACJ excision group, although this was higher than the six shoulders in the asymptomatic group (p = 0.03). Forty-one (82%) shoulders in the symptomatic group had grade III/IV ACJ arthritis compared to 31 (65%) in the asymptomatic group (p = 0.05). However, 44 out of 48 (92%) shoulders in the asymptomatic group had signs of osteoarthritis on MRI scans.

CONCLUSIONS

In contrast to recent reports, the present study shows that MRI is not helpful in making the diagnosis of ACJ arthritis. A focused history and clinical examination should remain the mainstay for surgical decision making.

LEVEL OF EVIDENCE

Level 3.

Predictive findings on magnetic resonance imaging in patients with symptomatic acromioclavicular osteoarthritis

BACKGROUND

A magnetic resonance imaging (MRI) scan of the shoulder can have added value in diagnosing symptomatic osteoarthritis of the acromioclavicular (AC) joint. Specific MRI signs have been recognized but not analyzed extensively before. This study aims to identify predictive MRI signs in patients with symptomatic AC osteoarthritis.

METHODS

The MRI scans of 70 patients with symptomatic AC osteoarthritis were compared with those of 70 patients with subacromial pain syndrome and no clinical signs of symptomatic AC osteoarthritis. Seven variables were evaluated on the MRI scans of the AC joint: joint space narrowing, inferior osteophytes, joint effusion, osteolysis, bone marrow edema, impression on the supraspinatus, and inferior joint distension. Logistic regression analysis of these variables was performed.

RESULTS

The presence of inferior osteophytes, bone marrow edema, impression on the supraspinatus, and inferior joint distension was individually associated with symptomatic AC osteoarthritis. Bone marrow edema was observed only in patients with symptomatic AC osteoarthritis. Multivariate analysis showed a significant association between inferior joint distension, as well as impression on the supraspinatus muscle, and symptomatic AC osteoarthritis. The area under the receiver operating characteristic curve in the multivariate logistic model was 0.839 (95% confidence interval, 0.771 to 0.907). Interobserver and intraobserver variability showed good to excellent κ values (range, 0.68 to 0.88).

CONCLUSION

We identified predictive MRI signs in patients with symptomatic AC osteoarthritis. These findings, including bone marrow edema, inferior joint distension, and impression on the supraspinatus muscle, showed good discriminative ability. They are practical and easy to use and can assist the physician in diagnosing symptomatic AC osteoarthritis.

MRI versus radiography of acromioclavicular joint dislocation

OBJECTIVE

Acromioclavicular joint injuries are usually diagnosed by clinical and radiographic assessment with the Rockwood classification, which is crucial for treatment planning. In view of the implementation of MRI for visualization of the acromioclavicular joint, the purpose of this study was to describe the MRI findings of acromioclavicular joint dislocation in comparison with the radiographic findings.

SUBJECTS AND METHODS

Forty-four patients with suspected unilateral acromioclavicular joint dislocation after acute trauma were enrolled in this prospective study. All patients underwent digital radiography and 1-T MRI with a surface phased-array coil. MRI included coronal proton density-weighted turbo spin-echo and coronal 3D T1-weighted fast field-echo water-selective sequences. The Rockwood classification was used to assess acromioclavicular joint injuries at radiography and MRI. An adapted Rockwood classification was used for MRI evaluation of the acromioclavicular joint ligaments. The classifications of acromioclavicular joint dislocations diagnosed with radiography and MRI were compared.

RESULTS

Among 44 patients with Rockwood type I-IV injuries on radiographs, classification on radiographs and MR images was concordant in 23 (52.2%) patients. At MRI, the injury was reclassified to a less severe type in 16 (36.4%) patients and to a more severe type in five (11.4%) patients. Compared with the findings according to the original Rockwood system, with the adapted system that included MRI findings, additional ligamentous lesions were found in 11 (25%) patients.

CONCLUSION

In a considerable number of patients, the MRI findings change the Rockwood type determined with radiography. In addition to clinical assessment and radiography, MRI may yield important findings on ligaments that may influence management.

Ironman triathletes: MRI assessment of the shoulder

OBJECTIVE

The objective of this paper was to demonstrate the prevalence of shoulder magnetic resonance imaging (MRI) abnormalities, including abnormal bone marrow signal at the acromioclavicular (AC) joint in symptomatic and asymptomatic Ironman Triathletes.

MATERIALS AND METHODS

The shoulders of 23 Ironman Triathletes, seven asymptomatic (group I) and 16 symptomatic (group II), were studied by MRI. A separate, non-triathlete group was evaluated specifically for AC joint marrow signal abnormalities to compare with the Ironman Triathletes.

RESULTS

Partial thickness tears of the rotator cuff, rotator cuff tendinopathy, and AC joint arthrosis were common findings in both groups of triathletes. Tendinopathy was the only finding that was more prevalent in the symptomatic group, but this was not a statistically significant difference (p = 0.35). There were no tears of the glenoid labrum seen in group I or II subjects. Of note is that 71% (5/7) of group I subjects and 62% (10/16) of group II subjects had increased signal changes in the marrow of the AC joint (p = 0.68). The comparison group showed a lower prevalence (35%, p = 0.06) of this finding.

CONCLUSIONS

No statistically significant difference was found among the findings for group 1, group 2, or the comparison group, although the difference between the comparison group and Ironman Triathletes approached statistical significance when evaluating for AC joint abnormal signal. Shoulder MRI of Ironman Triathletes should be interpreted with an appreciation of the commonly seen findings in asymptomatic subjects.

MR imaging of the intraarticular disk of the acromioclavicular joint: a comparison with anatomical, histological and in-vivo findings

OBJECTIVE

To characterize MRI features of the intraarticular disk of the acromioclavicular joint.

DESIGN

We studied the appearance of 11 acromioclavicular joints of six cadavers (subjects aged 57-89 years at the time of death) and six healthy shoulders on T1-weighted, T2 (TSE)-weighted, STIR and PD (fat saturated) magnetic resonance imaging (MRI) and compared the findings with observations during dissection and histological examination.

RESULTS

Macroscopic examinations showed two wedge-shaped disks underneath the superior and above the inferior joint capsule in nine specimens. In two specimens the acromioclavicular joints were degenerated. Histologically, the disk tissue consisted of fibrocartilage whereas the joint cartilage was partly degenerated, containing zones of fibrocartilage amidst degenerated hyaline cartilage, which may explain the similar signal intensity of both structures in all sequences used. MR appearance of the intraarticular structures of the acromioclavicular joint was similar in cadaveric and healthy shoulders.

CONCLUSIONS

The difficulties related to imaging the acromioclavicular joint may be explained by the anatomy. Similar signal intensity of cartilage and disk may be explained by their similar histological structure (fibrocartilage). MRI findings should be interpreted with respect to the variable anatomy. These results may serve as a basis for further radiological studies of the acromioclavicular joint.

Visualization of Intraarticular Structures of the Acromioclavicular Joint in an Ex Vivo Model Using a Dedicated MRI Protocol

OBJECTIVE

The purpose of this study was to develop an MRI protocol that could visualize the intraarticular structures of the acromioclavicular (AC) joint.

MATERIALS AND METHODS

Using six fresh specimens from cadaveric shoulders, several MRI sequences were performed on 1.0-T scanners with a superficial coil (the temporomandibular joint coil). After the radiologic examination, the specimens were prepared for histology and 300-microm-thick, toluidine blue-stained sections were prepared that corresponded to the MR images. In each series of sections, immunohistochemistry using a type II collagen antibody was performed to further characterize the intraarticular structures.

RESULTS

The coronal 3D T1-weighted fast-field echo water-selective sequence allowed the identification of the intraarticular disk in all cases. Determination on MRI of other intraarticular structures--adipose tissue, synovial fluid, and the borders between neighboring tissues of different types--that corresponded to the histologic sections was possible. The use of a second plane in the 1.0-T sequences did not reveal additional information.

CONCLUSION

The described MRI protocol allows the visualization of the intraarticular fibrocartilaginous disk and the border between articular cartilage and the disk. Future clinical studies will indicate the diagnostic value of this protocol. We assume that this MRI protocol could help us to better understand AC joint disorders, in particular those located intraarticularly, and dislocations.

The causes of pain in benign solitary enchondromas of the proximal humerus

Patients with benign solitary enchondromas of the proximal humerus frequently present to the diagnosing physician with shoulder pain. Once the lesion is considered benign, emphasis can be placed on identifying the etiology for the pain. We reviewed our experience with these patients to identify the cause of the presenting pain. A retrospective review of clinical records and radiographic studies (radiographs, magnetic resonance images, and bone scans) was done for all patients presenting to an orthopaedic oncology unit with solitary enchondroma of the proximal humerus. Attention was focused on diagnostic evidence of additional disease in the shoulder. Fifty-seven patients (mean age, 53.6 years) met the criteria of the study and were included for evaluation. Of patients presenting with pain, 82% (47 of 57 patients) had findings seen on magnetic resonance imaging scans that correlated with the initial clinical diagnostic impression, suggesting that other disease was present that could explain the pain. Solitary enchondromas of the proximal humerus often are found incidentally during the initial evaluation of patients with shoulder pain. This study showed that additional treatable disease usually is present in patients with enchondromas of the proximal humerus.

MRI features of the acromioclavicular joint that predict pain relief from intraarticular injection

OBJECTIVE

Our objective was to evaluate the predictive value of various MRI findings in the acromioclavicular joint for pain relief after intraarticular injection.

MATERIALS AND METHODS

The acromioclavicular joint of 50 patients (20 women, 30 men; mean age, 51 years; range, 25-75 years) was evaluated on MRIs of the shoulder. Osteophytes, subchondral cysts and irregularities, bone marrow edema, joint effusion, and joint capsule hypertrophy were assessed by two musculoskeletal radiologists in consensus. Local anesthetics were injected into the acromioclavicular joint with fluoroscopic guidance. Patients graded pain relief on a visual analogue scale (0-100%) after 15 min. The relationship between pain relief and MRI findings was assessed with the Mann-Whitney U test. Pain relief equal to or greater than 70% was rated as a positive response to the injection. This cutoff value was used to calculate sensitivity, specificity, accuracy, and predictive values of the various MRI findings in determining which acromioclavicular joints were responsive to joint injections.

RESULTS

Mean pain relief after injection was 38%. Pain relief was significantly related to capsular hypertrophy (p = 0.007) and was equal to or greater than 70% in 11 patients. The sensitivity in diagnosing a successful injection (range, 9-82%) was highest for caudal osteophytes (82%) and capsular hypertrophy (73%). The specificity (range, 51-97%) was highest for subchondral cysts (97%), subchondral bone marrow edema (95%), and joint effusion (92%).

CONCLUSION

Pain relief after intraarticular injection is significantly related to capsular hypertrophy diagnosed on MRI. MRI findings have a reasonable sensitivity and a high specificity in predicting relevant short-term pain relief after intraarticular injection.