October 06, 2017
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A 14-year-old athlete with left shoulder pain and decreased range of motion

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A 14-year-old right hand dominant female patient presented with the chief complaint of left non-dominant shoulder pain associated with a decreased range of motion. She described her pain as being diffusely throughout the shoulder joint anteriorly, posteriorly and laterally. She rated her pain at 5 out of 10 and took naproxen occasionally as needed. She initially noted this pain about 3 months prior to consultation after she sustained a minor trauma during tae kwon do lessons which was not sufficient to remove her from participation in the sport. A few weeks prior to her presentation, she was evaluated by a physical therapist, however, no formal recommendations were made and she received formal treatment for her symptoms. In addition to tae kwon do, the patient participated in soccer and softball. Upon systems review, she refuted any numbness, tingling or paresthesia distal to her shoulder joint on both her left and right side.

Physical examination showed a markedly asymmetric scapulothroacic rhythm with left shoulder hiking and asymmetric retraction with lowering in the frontal and sagittal planes. She endorsed general tenderness to palpation around the acromioclavicular joint, the belly of the supraspinatus and the trapezius. Abduction of the left shoulder and internal rotation at 90° were moderately reduced on left shoulder exam compared to the right shoulder. Motor strength was slightly diminished in the supraspinatus and subscapularis and both the Hawkins and Neer tests were positive on the left. Radiographs of the left shoulder were obtained for further evaluation and were noted to be negative (Figure 1). She was placed on a trial of physical therapy to improve scapulothoracic mechanics and rotator cuff strengthening. Despite excellent engagement, her symptoms slightly worsened.

Eight weeks later, an MRI of the patient’s left shoulder was obtained, which demonstrated distention of the glenohumeral joint capsule by fluid, which was associated with a diffuse proliferative synovial response. There were multiple small loose bodies seen, notably within the axillary pouch and adjacent anterior joint recess. Loose bodies extended to the rotator interval and subscapularis recess, and to the long head of biceps tendon sheath (Figure 2).

Radiograph and MRI of glenohumeral joint
Figure 1. A radiograph of the glenohumeral joint without any abnormalities noted.
Figure 2. Multiple hyperintense bodies within the glenohumeral joint were identified on MRI.

Source: Peter D. Fabricant MD, MPH

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Synovial chondromatosis

From the presentation and imaging, there was a high suspicion for primary synovial chondromatosis (SC), however the radiographic differential diagnosis also included tuberculosis, inflammatory vs. infectious arthropathy and diffuse pigmented villonodular synovitis. The patient underwent arthroscopic synovectomy with loose body removal, intraoperative culture and biopsy.

Surgical approach

We performed arthroscopy via the standard posterior viewing portal and found multiple loose bodies throughout the shoulder joint. The synovium showed signs of inflammation and pedunculation throughout the joint. There were no changes of the humeral head and glenoid. The rotator cuff was intact at its insertion site. Biopsies of the pedunculated synovium were sent to pathology. The loose bodies were meticulously removed through a large bore screw-in cannula in the anterior working portal until none could be visualized. The pedunculated synovium was lightly debrided and radiofrequency ablation was used to perform subtotal synovectomy. Intraoperative arthroscopic images showed loose bodies (Figure 3).

After the synovectomy, a final diagnostic arthroscopy was performed to ensure complete removal of visible loose bodies. The subacromial space was avoided during the procedure as imaging did not indicate pathology on MRI and the rotator cuff was completely intact. After surgery, the patient’s left arm was immobilized in a shoulder sling and she was discharged the same day.

When the intraoperative pathology was reviewed it showed cartilage metaplasia within the synovial villi-forming hyaline cartilage bodies which were moderately cellular and demonstrated foci of micronodular clustering of the chondrocytes. There were also interstitial calcifications in the larger cartilage formations. The remaining synovium was thickened and fibrotic. The histopathologic appearance confirmed the diagnosis of synovial chondromatosis.

intra-articular loose bodies
Figure 3. These intraoperative arthroscopic images revealed loose bodies. A yellow star denotes the site of the intra-articular loose bodies.

Clinical outcome

The patient underwent biweekly physical therapy for 3 months after surgery and she was followed closely during this time. She successfully regained active flexion and abduction of her left arm to 160° and denied any pain in left shoulder joint 1 month after her arm was removed from the sling. Twelve weeks after surgery she was asymptomatic, had full motion and strength, had drastically improved scapulothoracic symmetry, and was able to return to competitive participation in tae kwan do, soccer and softball. She remained asymptomatic at 6 months and 12 months postoperatively, and will be followed yearly for recurrence with clinical examination. Follow-up with MRI will be reserved should any shoulder pain or mechanical symptoms occur.

Discussion

SC is a rare monoarticular disorder of poorly understood etiology. It is characterized by the presence of synovial metaplasia and proliferation resulting in the formation of numerous intra-articular cartilaginous loose bodies at various stages of ossification. Milgram and colleagues initially described SC as occurring in three stages: active intrasynovial process prior to the development of loose bodies; transitional phase with active intrasynovial proliferation and intra-articular loose bodies; and multiple chondral or osteochondral loose bodies without active intrasynovial disease. The most widely accepted etiology hypothesis involves metaplasia of the synovial tissue. The rare yet reported malignant transformation of SC to chondrosarcoma supports the possibility that SC may be neoplastic. On histology, the chondrocytes in SC demonstrate atypical cytology and architecture.

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Epidemiologically, SC most commonly involves the knee joint and has a decreasing incidence in the hip, elbow, wrist and shoulder. Bloom and Patterson performed a meta-analysis of SC, in which 10 patients of 191 patients had shoulder involvement. SC is most prevalent in the fourth to fifth decades of life. It is widely accepted that men are more frequently affected by SC than women at a ratio between 2:1 and 4:1. Few cases of SC have been described in the pediatric and young adolescent population, which puts this patient outside of the typical demographic.

SC has the potential to involve any joint and patients present with symptoms that vary based on the site of disease. Pain, swelling, and reduced range of motion, are the most common presenting symptoms associated with SC, although crepitus, mechanical clicking and catching, and muscle atrophy have also been associated with the condition. When the symptoms of SC present at the shoulder joint, as in this case, the diagnosis is commonly confused with adhesive capsulitis, necessitating an image-guided diagnosis. Plain radiographs and ultrasonography can be used for visualization of calcified loose bodies and CT helps to demonstrate the precise location of calcified nodules. MRI has the greatest sensitivity for the detection of SC and the capability of ruling out malignant lesions and helping assess any further intra-articular pathology. Definitive diagnosis of SC is made via histologic confirmation of cartilage metaplasia of the synovial membrane of the affected joint.

Treatments for extra-articular SC include removal of loose bodies with or without synovectomy. Optimal management of SC at the shoulder is debated, but arthroscopy is commonly performed for intra-articular loose body removal given the low rate of postoperative comorbidity and the short subsequent rehabilitation. Synovectomy is recommended because of an increased rate of recurrence when it is not performed. In this case, we removed the loose bodies and performed subtotal synovectomy in accordance with recommendations in the literature, which indicate the dual treatment modality for active synovitis. Total shoulder synovectomy is reserved for advanced arthritis secondary to SC.

Disclosures: Adjei, Fabricant and Nwachukwu report no relevant financial disclosures.