Coracoclavicular joints. Reflections upon incidence, pathophysiology and etiology of the different forms

Coracoclavicular Joint Arthrosis - An Uncommon Cause of Shoulder Pain

The coracoclavicular joint is a diarthrodial synovial joint that is eventually located between the upper surface of the horizontal part of the coracoid process and the conoid tubercle of the clavicle, and is considered an unusual anatomical alteration. The coracoclavicular joint has a low prevalence and can be diagnosed by imaging tests - radiography and computed tomography. Treatment can be performed both conservatively and surgically. We report a case of an 81-year-old female patient presenting of pain in her left shoulder due to coracoclavicular joint arthrosis. A radiograph of the left shoulder was performed, which detected a deformity in the lower portion of the middle third of the clavicle and the upper portion of the coracoid process, corresponding to the coracoclavicular joint, a finding confirmed by computed tomography. The patient was treated conservatively with analgesics (Dipyrone) and anti-inflammatories (Ibuprofen) with improvement in symptoms.

A review of the coracoclavicular joint: Description, etiology, and clinical significance

The coracoclavicular joint (CCJ) is a synovial joint that forms between the conoid tubercle of the clavicle and the coracoid process of the scapula in approximately 2.5% of the population. The number of bilateral to unilateral cases is almost equal. The number of right-sided and left-sided cases is also almost equal. It is found in both males and females but most often in male adults. Very few cases have been identified in juveniles. Found in populations all over the world, the highest frequencies of CCJ are in Asia. The etiology is unknown but it is most likely caused by metaplastic change of the trapezoid and surrounding tissue due to compression and friction of the coracoacromial ligament between the clavicle and coracoid process. Typically asymptomatic, but if so, the most common complaint is anterior should pain exacerbated by extreme abduction. Successful treatment includes steroid injection and surgical excision.

Coracoclavicular bursal changes on MRI: a diagnostic consideration in patients with shoulder pain and reduced coracoclavicular distance

OBJECTIVE

To describe MRI changes of the coracoclavicular bursa in patients presenting with shoulder pain and examine whether there is an association with coracoclavicular distance measurements.

METHODS

Retrospective analysis of 198 shoulder 3T MRI scans for patients with shoulder pain was performed. Two musculoskeletal trained radiologists read all MRI scans. Inter-reader and intra-reader agreements for the bursal changes were assessed using the Kappa coefficient. The coracoclavicular distance was stratified into three intervals: < 5 mm, 5-10 mm, and > 10 mm. Statistical analysis for the coracoclavicular bursal changes and coracoclavicular distance was conducted using Fisher's exact test.

RESULTS

Coracoclavicular bursal changes were detected in 9% (n = 18/198) of patients. There was a statistically significant association between coracoclavicular distance (< 5 mm) and the presence of coracoclavicular bursal changes (p-value = 0.011). All patients (100%, n = 18/18) with coracoclavicular bursal fluid presented with shoulder pain with 44.5% of the patients (n = 8/18) describing anterior shoulder pain. A statistically significant association was detected between coracoclavicular bursal changes and anterior shoulder pain (p-value = 0.0011). Kappa coefficient for the bursal changes inter-reader agreement was moderate (0.67) and the intra-reader agreement was almost perfect (0.91).

CONCLUSION

Coracoclavicular bursal changes were detected in 9% of shoulder MRI scans and were associated with reduced coracoclavicular distance (< 5 mm) suggesting an underlying mechanical disorder such as a friction or an impingement process. Documenting coracoclavicular bursal changes in the MRI report could help address patients' concerns and guide further management particularly in the context of shoulder pain and coracoclavicular distance of less than 5 mm.

Prevalence and Morphology of the Coracoclavicular Joint: An Osteological Study of 2,724 Subjects Using Univariable and Multivariable Logistic Regression Analyses

Background: The coracoclavicular joint (CCJ) is an anomalous articulation between the surfaces of the inferior clavicle and superior coracoid and its etiology is controversial. Reportedly, symptomatic patients demonstrate significant functional limitations including shoulder abduction loss and potential for brachial plexus compression and impingement. Purpose: To determine the prevalence of CCJ across age, gender and ethnicity, and to identify clinically useful morphological characteristics. Methods: 2,724 subjects with intact clavicles and scapulae from the Hamann-Todd Osteological Collection were evaluated for the presence of CCJ. Logistic regression was used to determine the effect of age, height, gender, and race on prevalence of CCJ. 354 clavicles with CCJ were measured for size and location of the CCJ facet. Results: CCJ was observed in 9% of subjects. CCJ was more prevalent in African-Americans (12%) than Caucasian-Americans (6%) (p < 0.001) and more prevalent in females (11%) than males (8%) (p = 0.055). Facet location along clavicle length was consistent (average 25%, range 15-35%). But, facet location along clavicle width varied (average 60%, range 10-90%), with males having a more posterior location. For every 10-year increase in age, facet elevation (p = 0.001) and surface area (p < 0.001) increased. Conclusions: CCJ prevalence was 9% in our large osseous population, found more commonly in African-Americans and females. Facet location is predictable with respect to clavicle length, but less so along clavicle width. The clavicular facet may develop at some point in life and continue to grow in size after its appearance. Clinical Relevance: Presence of a CCJ represents a potential overlooked source of anterior shoulder pain and supracoracoid impingement. Epidemiologic and morphological characteristics presented in our study can aid in the identification, clinical understanding, and surgical excision of a symptomatic CCJ. Level of Evidence: Level IV.

Acromioclavicular Joint: What to Look for

Acromioclavicular joint (ACJ) pathology is a common source of shoulder girdle pain, frequently coexisting with and sharing overlapping clinical features of rotator cuff and glenohumeral articular lesions. ACJ trauma and osteoarthritis dominate clinical presentation; however, an array of pathologies can affect the joint. MR imaging of the ACJ is a powerful secondary diagnostic tool in early diagnosis of ACJ pathology and in accurate assessment of ACJ injuries, helping to resolve clinically challenging cases and allowing for individualized treatment planning. Knowledge of ACJ anatomy, biomechanics, and pathology is fundamental to interpreting and providing a clinically relevant ACJ MR imaging report.

Radiographic/MR Imaging Correlation of the Shoulder

This article discusses the typical findings seen on conventional radiography in 3 common shoulder pathologies, namely glenohumeral instability, rotator cuff pathology, and acromioclavicular joint dislocation. Correlative MR images are used to explain and illustrate the significance of radiographic findings that suggest the presence of underlying shoulder pathology.

Coracoid Process: The Lighthouse of the Shoulder

The coracoid process is a hook-shaped bone structure projecting anterolaterally from the superior aspect of the scapular neck. Surgeons often refer to the coracoid process as the "lighthouse of the shoulder" given its proximity to major neurovascular structures such as the brachial plexus and the axillary artery and vein, its role in guiding surgical approaches, and its utility as a landmark for other important structures in the shoulder. The coracoid also serves as a critical anchor for many tendinous and ligamentous attachments. These include the tendons of the pectoralis minor, coracobrachialis, and short head of the biceps brachii muscles, and the coracoclavicular, coracohumeral, coracoacromial, and transverse scapular ligaments. Consequently, the coracoid and its associated structures are linked to numerous shoulder pathologic conditions. This article will detail the anatomy of the coracoid and its associated structures and review the clinical and radiologic findings of corresponding pathologic conditions in this region with original illustrations and multimodality imaging examples. Highlighted in this article are the coracoclavicular joint, the classification and management of coracoid fractures, subcoracoid impingement, the coracoacromial arch and subacromial impingement, the coracohumeral ligament and the biceps pulley, the coracoclavicular ligament and its surgical reconstruction, adhesive capsulitis, the suprascapular notch and suprascapular notch impingement, subcoracoid bursitis, coracoid transfer procedures, and coracoid tumors. A brief summary of the pathophysiology, potential causes, and management options for each of the pathologic entities will also be discussed. ^©RSNA, 2016.

Morphometric Study of Clavicular Facet of Coracoclavicular Joint in Adult Indian Population

INTRODUCTION

Anthropologists have used Coracoclavicular Joint (CCJ), a non-metric anatomical variant in population, as a marker for population migration from prehistoric times to present.

AIM

The aim of this osteological study was to determine the incidence and morphometry of articular facet of CCJ on conoid tubercle of clavicle in Indian population, as Indian studies are scanty and incomplete.

MATERIALS AND METHODS

The study was done on 144 adult human clavicles (76 right and 68 left; 93 males and 51 females) collected from osteology museum in Department of Anatomy, Maulana Azad Medical College, New Delhi, India. The presence of articular facet on the conoid tubercle was determined and Maximum Antero-Posterior (MAPD) and maximum transverse diameter (MTD) was measured by digital vernier calliper. The incidence was compared on the basis of sex, side and with other osteological studies in the world. Statistical analysis was done using the Chi-Square test for nominal categorical data and student's t-test for normally distributed continuous variables in Microsoft Excel 2007 to assess the relationship between the examined variables.

RESULTS

Articular facet on conoid tubercle was found in 8 cases (5.6%). Seven (9.2%) were present on the right side and one (1.5%) on the left side. Seven cases (7.5%) were present in males and one case (2%) was found in females. The facets were generally oval, with MAPD and MTD of 12.28 and 17.17 mm respectively. A significant side variation was present with right sided facet being more common. The left sided facet was more transversely elongated than right. In males, the facets were more elongated antero-posteriorly than in females.

CONCLUSION

The Indian population showed an incidence of 5.6%, which was comparable to other ethnic groups in world population. The morphometric and side differences could be attributed to the occupational factors and range of movements associated with the CCJ. The CCJ should be borne in mind as a differential diagnosis for thoracic outlet syndrome and in general for shoulder pain.

The coracoclavicular joint. A systematic review and meta-analysis

The coracoclavicular joint (CCJ) is considered as a rare articulation in humans. Though rarely it could be symptomatic, its presence should be acknowledged by physicians. The aim of this systematic review is to conduct an evidence synthesis on the prevalence of this condition in different ethnic populations. Thirty nine studies including 51 sub-studies met the inclusion criteria. The meta-analytical results showed true prevalence values of ≃5%, ≃7% and ≃2.7% from skeletal, cadaveric and radiological studies, respectively. The bilateral occurrence of CCJ was found to be approximately the half of the crude prevalence and that in all study types. European populations showed the least frequency whereas the Eastern Asian and Native American populations showed the highest values in skeletal/cadaveric studies. European, modern American, Native American and modern South American populations showed the least CCJ occurrence rates in radiological studies. The Chinese population stood out from all other ancestries with a prevalence of 21%, followed by the Southeast Asians with a frequency of 6%. No association was found with variables such as sex or side. This evidence-based anatomical and anthropological review shed the light on the rare and poorly investigated CCJ. It yielded more accurate overall and ancestry-based frequencies from skeletal, cadaveric and radiological studies.

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.

Functional aspects of the coracoclavicular space

BACKGROUND

The coracoclavicular joint has been described as an articulation found inconstantly between the coracoid process and clavicle. We often observe a small space bordered by the fascia which covers the anterior surface of the subclavius muscle and the coracoclavicular ligament. The aim of this study was to observe the space in detail and to discuss the functional role of the coracoclavicular joint.

MATERIALS AND METHODS

Sixteen shoulder girdles from eight Japanese cadavers were used in this study. The scapula, clavicle, and anterior half of the first rib were extracted en bloc together with the subclavius muscle and the surrounding fascia. After observing the motion of the scapula and clavicle, we investigated macroscopically the attachments of the coracoclavicular ligaments and the subclavius muscle, and the extension of the fascia.

RESULTS

The fascia divided laterally into two sheets: the anterior sheet attached to the trapezoid ligament and the posterior to the conoid ligament. Among the two sheets, the coracoclavicular ligaments, coracoid process, and clavicle, a small space was observed. This small space can be recognized as a part of the coracoclavicular joint. When manually moving the inferior angle of the scapula with the sternal end of the clavicle fixed, we observed that the clavicle collided with the trapezoid ligament on the superior surface of the coracoid process within the space and that the scapular motion was restricted by this collision.

CONCLUSION

The coracoclavicular joint could be much more recognizable than in previous papers and play an important role in the normal function of the shoulder joint.

LEVEL OF EVIDENCE

Basic science study.

Symptomatic coracoclavicular joint: incidence, clinical significance and available management options

PURPOSE

Coracoclavicular joint (CCJ) is a rare anomalous joint occasionally found between the coracoid process of scapula and the conoid tubercle of clavicle. The articulation has been extensively studied by means of anatomical, osteological and radiological investigations. Most cases are discovered incidentally, with the symptomatic variety remaining an exceptional rarity. Our aim was to review all reported symptomatic CCJ to increase the level of evidence and formulate a treatment algorithm to aid clinicians in management planning.

METHODS

A thorough literature search was performed, and data from 17 (n = 17) symptomatic cases of CCJ were analysed.

RESULTS

CCJ is a rare finding and mostly an incidental discovery, which is rarely symptomatic. However, when symptomatic, the most common symptom is shoulder pain. The mean age at presentation is 42 years, with a male:female ratio of 1.4:1. Brachial plexus involvement was the most common pathophysiological explanation provided. First-line treatment was conservative, with a very low success rate of 5.9%. Surgical intervention in the form of excision of anomalous joint by osteotomy had success rate of 100%.

CONCLUSIONS

Symptomatic CCJ is rare, and its rarity leads to lack of awareness in the general orthopaedic community. When symptomatic, CCJ may lead to delayed diagnosis or inappropriate management due to lack of evidence and poor description in most orthopaedic textbooks. Despite its low success rate, conservative treatment is advocated before embarking upon surgical intervention.

A symptomatic coracoclavicular joint

Bilateral coracoclavicular joints were found in a 44-year-old male patient following a fall. He had an Indonesian mother and a Dutch father. Prior to the injury he was asymptomatic and had full range of movement in both shoulders but the trauma resulted in pain and limitation of movement in the left shoulder which required resection of the anomalous joint, after which full pain-free movement was restored.