Primary synovial chondromatosis of the shoulder followed for 11 years after arthroscopic surgery: A case report

Abstract

We report a case of primary synovial chondromatosis of the shoulder (Milgram classification, stage III) in a 25-year-old woman. She underwent arthroscopic removal of multiple loose bodies and partial synovectomy. Histological findings revealed primary synovial chondromatosis. Eleven years after surgery, the clinical results have been excellent with no recurrence, although X-ray showed slight degenerative changes of the glenohumeral joint. This is the first report of primary synovial chondromatosis of the shoulder observed over a 10-year follow-up period after arthroscopic surgery.

Introduction

Primary synovial chondromatosis (SCM) is less common than secondary SCM. Since primary SCM has a high risk of recurrence and malignancy, long-term follow-up is required even after the surgery, which consist of resection of both loose bodies and synovium. However, there has been no report of follow-up over 10 years in these patients. This report describes a case of primary SCM in a young woman who underwent arthroscopic removal of the loose bodies and partial synovectomy, and has been followed for 11 years after surgery with no evidence of recurrence. The patient was informed that data concerning the case would be submitted for publication, and she provided consent.

Case report

A 25-year-old right-handed woman presented with pain on motion and loss of range of motion (ROM) at the right shoulder. The symptoms had started when she was 20-year-old and progressed gradually. She had no history of trauma. She worked as a waitress. She complained of pain on motion in the right shoulder without spontaneous pain or night pain. The ROM was limited to 110 degrees in forward elevation, 0 degrees in external rotation, and the level of L4 in internal rotation. Her Japanese Orthopaedic Association (JOA) score was 68 points (pain: 20/30, function: 18/20, ROM: 12/30, X-ray findings: 3/5, instability: 15/15) and her University of California, Los Angeles (UCLA) score was 16 points (pain: 4/10, function: 4/10, active forward flexion: 3/5, strength of forward flexion: 5/5, satisfaction of patient: 0/5). Plain X-ray showed multiple calcified nodules in the glenohumeral joint (Fig. 1). Subsequent computed tomography and magnetic resonance imaging demonstrated multiple loose bodies filling the glenohumeral joint and extending into the proximal biceps tendon sheath and the subscapularis bursa (Fig. 2). Based on these findings, she was suspected to have stage III SCM according to the Milgram classification and underwent arthroscopic removal of the loose bodies and partial synovectomy. Arthroscopic findings demonstrated a large number of cartilaginous loose bodies and slightly synovial proliferation in the glenohumeral joint, with mild erosion of the surface of humeral head (Fig. 3). Loose bodies were partly adhered to the capsular synovium. When those bodies were removed from the capsule, bleeding was observed from the synovium and coagulation was performed with a radiofrequency device. Some loose bodies in the proximal biceps tendon sheath and in the axillary pouch could not be completely removed. Pathological examination revealed that chondrocytes in the loose body were clustered together in nests and were not uniformly distributed. A characteristic nodular pattern with a number of plump chondrocytes and synovial hypertrophy with slight inflammation and monocyte infiltration were also observed (Fig. 4). Those findings indicated primary SCM. She was started on passive ROM exercise 3 days after surgery. Two weeks after surgery, active ROM exercise and Cuff Y exercise were allowed. At the most recent follow-up, 11 years after surgery (she was 36-year-old), ROM was improved to 155 degrees in elevation, 50 degrees in external rotation, and the level of Th8 in internal rotation. She reported complete relief of pain on motion. Her JOA score was 95 points (pain: 30/30, function: 20/20, ROM: 27/30, X-ray: 3/5, instability: 15/15) and her UCLA score was 35 points (full mark). Although X-ray showed mild degenerative osteoarthritis and some loose bodies remained in the axillary pouch, there was no clinical or radiographic evidence of recurrence (Fig. 5).

Fig. 1.

Plain radiographs of the right shoulder demonstrated well-defined multiple calcified nodules filling the glenohumeral joint (A: anteroposterior view; B: scapular Y view).

Fig. 2.

Computed tomography (A: coronal view; B: axial view), 3-dimensional computed tomography (C: anteroposterior view, D: scapular Y view) and T2-weighted magnetic resonance imaging (E: coronal view; F: axial view) demonstrated multiple loose bodies in the glenohumeral joint, proximal biceps tendon sheath, axillary pouch, and subscapularis bursa.

Fig. 3.

(A-C) Arthroscopic views from the standard posterior portal showed a large number of cartilaginous loose bodies (A: *), mild erosion of the surface of humeral head (B: white arrow), and slightly synovial proliferation (C: black arrow) in the glenohumeral joint. (D) Photograph of the variously sized loose bodies removed from the glenohumeral joint.

Fig. 4.

(A) Histological examination of the loose bodies showed chondrocytes clustered together in nests and not uniformly distributed. A characteristic nodular pattern with many plump chondrocytes was also observed (white arrow) (hematoxylin and eosin stain, original magnification × 50). (B) Histological examination of bursal synovium showed synovial hypertrophy with slight inflammation and monocyte infiltration (hematoxylin and eosin stain, original magnification × 100).

Fig. 5.

Plain radiographs of the right shoulder at the 11-year follow-up show no evidence of recurrence. Mild degenerative changes in the glenohumeral joint and some loose bodies in the axillary pouch are seen (A: anteroposterior view; B: scapular Y view).

Discussion

SCM is a rare metaplastic condition characterized by the presence of multiple cartilaginous loose bodies in articular joints, bursae, or tendon sheaths. It is typically monoarticular and most commonly affects the knee joint, followed by the hip, elbow, wrist, and ankle joints [1]. The prevalence of SCM in the shoulder has been reported as approximately 5% of all SCM cases [2]. The prevalence of SCM in males is 2-3 times that in females, with diagnosis usually in the 20s to 40s [3,4]. Villacin et al [5] reported 2 different patterns of SCM according to its histopathological characteristic: primary and secondary. In primary SCM, the foci of chondrometaplasia in the loose bodies and synovium are characterized by a markedly disorganized pattern with plump chondrocytes and patchy diffuse calcification. In secondary SCM, on the other hand, the loose bodies and synovium include fragments of articular cartilage or subchondral bone as a nidus, and the pattern of calcification is ring-like with uniformly distributed chondrocytes. The etiology of secondary SCM is suspected to arise from a central nidus, such as an osteochondral fragment in trauma, avascular necrosis, or degenerative disease such as osteoarthritis. However, the etiology of primary SCM is still unknown, and it is less common than secondary SCM [6]. Milgram [7] described 3 stages of SCM: (I) active intrasynovial disease with no loose bodies, (II) transitional lesions with both active intrasynovial proliferation and free loose bodies, and (III) multiple osteochondral loose bodies with no active intrasynovial disease. The present case is rare because it was a stage III primary SCM that developed in the shoulder of a relatively young woman.

Primary SCM has been reported to be more aggressive than secondary SCM, with malignant transformation to chondrosarcoma [5,8]. Moreover, the incidence of recurrence of primary SCM is reported to be as high as 15%-25%, even after surgical treatment [5,8]. Recently, arthroscopic surgery has been reported to be as effective as conventional open surgery [9,10]. However, some reports have pointed out disadvantages of arthroscopic surgery, including insufficient removal of loose bodies from the biceps tendon sheath and subscapular recess [11]. There is no doubt that removal of loose bodies is effective for the treatment of SCM, but controversy remains as to whether additional extensive synovectomy is necessary. Kamineni et al [12] and Shpitzer et al [13] reported that there was no difference in recurrence rate between patients treated by loose body removal alone and those treated by loose body removal with additional synovectomy. On the other hand, Lee et al [14] proposed that synovectomy to the extent possible should be performed regardless of histopathological characteristic and/or Milgram classification. To date, however, there has been no report on the long-term results of SCM of the shoulder. In our present case, stage III disease was suspected at the preoperative evaluation, arthroscopic removal of the loose bodies and partial synovectomy was performed. As of 11 years postoperatively, although X-ray has shown gradual progression of degenerative changes in the shoulder joint, the clinical results have been excellent, with no evidence of recurrence or malignant transformation. Arthroscopic removal of loose bodies and partial synovectomy can be useful for stage III primary SCM.

Patient consent

The patient was informed that data concerning the case would be submitted for publication, and she provided consent.