Synovial chondromatosis is a synovial disease where synovium has foci of cartilage tissue. These could be found in the synovial lining of joint, tendon sheath and bursae. These ectopic foci of cartilage can result in painful joint effusions and, on the generation of loose bodies, mechanical symptoms.
It is also known as Reichel’s syndrome or Reichel-Jones-Henderson syndrome, synovial osteochondromatosis, and synovial chondrometaplasia.
The disease typically affects a single joint, knee being the most common joint to be involved [60-70%] followed the shoulder, elbow, and hip. Rarely, it also involves temporomandibular joint.
The disorder is rare though actual prevalence is not known. Males have been reported to be affected twice as commonly than females.
Synovial chondromatosis is said to be of two types – primary and secondary. In primary synovial chondromatosis, there is ectopic cartilage in synovial tissue and loose bodies but there is no identifiable joint pathology. It is thought to be due to metaplasia.
Secondary synovial chondromatosis is more common. It occurs in the setting of preexistent osteoarthritis, rheumatoid arthritis, osteonecrosis, osteochondritis dissecans, neuropathic osteoarthropathy, tuberculosis, or osteochondral fractures. It leads to the formation of larger free bodies than the primary one.
Synovial chondromatosis is considered a benign process associated with an extremely low risk of malignancy, though the coexistence of chondrosarcoma and synovial chondromatosis has been reported. Synovial chondromatosis may lead to articular damage and subsequent development of osteoarthritis.
Pathophysiology of Synovial Chondromatosis
Cause of the condition is not clear but growth factors BMP-2 and BMP-4 have been thought to promote cartilaginous and osteogenic metaplasia.
Primary synovial chondromatosis appears to occur in the following 3 phases
- Phase 1 – Active intrasynovial disease without loose bodies
- Phase 2 – Transitional lesions with osteochondral nodules in the synovial membrane and osteochondral bodies lying free in the joint cavity
- Phase 3 – Multiple free osteochondral bodies with quiescent intrasynovial disease
Presentation of Synovial Chondromatosis
Long-standing pain in the joint, usually for months or years is the main complaint. Pain is not relieved with drugs or steroid injections.
Swelling and stiffness may be present. On examination, the joint may be enlarged and effusion may be present. Loose bodies may or may not be palpable. Stiffness is a common finding.
TLC, ESR, and CRP may be raised in cases with systemic inflammation like rheumatoid arthritis. Otherwise, these findings would be quite within normal limits. Patient’s individual profile may guide on the kind of lab tests required
Xrays are frequently normal in 5-30% of patients with no visible calcifications.
The visibility of the loose body depends on calcification. Type of calcification may differ with the size of a loose body.
MRI catches the disease earlier, especially with gadolinium enhancement. Cartilage loose bodies which are not visible on x-ray show intermediate signal intensity on T1-weighted images and high signal intensity on T2-weighted images.
This is useful only for identifying calcified loose bodies.
Treatment of Synovial Chondromatosis
Nonsteroidal anti-inflammatory drugs, ultrasonic therapy, thermal therapy may lessen pain and inflammation. Mechanical symptoms are not benefited by nonoperative therapy.
Patients with recurrent painful effusions, mechanical symptoms, or both due to synovial chondromatosis refractory to conservative intervention are candidates for surgical intervention.
Open total synovectomy along with the removal of loose bodies was the standard procedure in the past but total synovectomy can lead to significant stiffness after surgery.
Arthroscopic removal of loose bodies and partial synovectomy for mechanical symptoms is the best surgical strategy.
When large loose bodies are abundant, some authors have favored open excision.
Studies have suggested that arthroscopic treatment is appropriate for disease knee, shoulder, and hip joints but is not successful for ankle, elbow, and minor joints.
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