Synovial chondromatosis is a rare benign [the one which is noncancerous] condition in which foci of cartilage develop in the synovial membrane of joints, bursae, or tendon sheaths. The foci of cartilage often develop as a result of metaplasia. Metaplasia refers to the replacement of one type of cell with another mature cell that is not normally present in that tissue].
Synovial condromatosis often presents as painful joint effusions. Later in the course of the disease, they may lead to the formation of loose bodies and mechanical symptoms.
It is associated with an extremely low risk of malignancy. Some reports suggest the coexistence of chondrosarcoma and synovial chondromatosis.
Synovial chondromatosis may lead to articular damage and subsequent development of osteoarthritis.
It is also known by other names such as
- Reichel’s syndrome
- Reichel-Jones-Henderson syndrome
- Synovial osteochondromatosis
- Synovial chondrometaplasia.
The disease typically affects a single joint. The knee is the most common joint to be involved. It is followed by the shoulder, elbow, and hip. Rarely, it also involves the temporomandibular joint. Other less commonly involved joints are
- Facet joints of the spine
- Acromioclavicular joint
- Joints of wrist
- Hand/foot joints
- Ankle joint
- Extra-articular locations [Those occurring outside the joints]
Relevant Anatomy
Synovium is the lining membrane of diarthrodial joints. It also lines the tendon sheaths and bursae.
The cells of the synovium are called synoviocytes. Synovium is quite rich in blood supply, nerves and lymphatics.
The synovial chondromatosis results due to metaplasia in synovial cells that results in the formation of cartilage cells.
The disorder is rare though the actual prevalence is not known. Males have been reported to be affected twice as commonly as females.
Milgram described three phases of the disease
- Active intrasynovial disease without loose bodies
- Transitional lesions with osteochondral nodules in the synovial membrane and osteochondral bodies lying free in the joint cavity
- Multiple free osteochondral bodies with quiescent intrasynovial disease
Types of Synovial Chondromatosis
Synovial chondromatosis is said to be of two types – primary and secondary.
Primary
In this type, 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
This is the commoner of the two. It may occur in associated joint pathologies. These joint pathologies could be due to
- Osteoarthritis
- Rheumatoid arthritis
- Osteonecrosis
- Osteochondritis dissecans
- Charcot’s joints
- Tuberculous pathology
- Osteochondral fractures.
The loose bodies in the secondary type are larger than the primary.
Presentation of Synovial Chondromatosis
There is the complaint of pain in a joint, most often the knee joint. Often, there would be associated swelling and there could be a limitation of the joint motion as well.
There are no symptoms and signs suggestive of infection.
There may be occasional complaints of locking or catching in the joint.
Pain is present at rest but increases with weight-bearing.
There is no history of trauma.
In the secondary form, there may be a history of joint pathologies like osteoarthritis, post-traumatic arthritis, or rheumatoid arthritis.
The joint is swollen as compared to the uninvolved side. Overlying skin appears normal. A large effusion can be palpated. The effusion increases with activity. Increased swelling may result in greater pain.
Other signs are
- Tenderness along the joint line
- Reduced decreased patellar mobility.
- Loss of terminal 10-15 degrees of flexion and extension.
Lab Investigations
Following may be raised due to inflammation
- Total leucocyte count
- Erythrocyte sedimentation rate
- C-reactive proteins
- Arthrocentesis and joint fluid studies
- Image-guided synovial biopsy
- Can establish definitive diagnosis
Other lab tests may be done as needed on an individual basis.
Imaging
Xrays
Xrays are frequently normal in up to one-third of patients. This happens because there is no visible calcification.
The type of calcification may differ with the size of a loose body.
Calcified loose bodies may be visible in the joint space. The pattern of mineralization varies with size of the loose bodies.
Large nodules show large, stippled, or ringlike calcified areas whereas small nodules have flecks of calcium.
In the secondary type, the changes consistent with the underlying disease process are often seen.
MRI/CT
MRI can identify the disease earlier. The imaging is better with gadolinium enhancement of MRI. Cartilage loose bodies which are not visible on x-ray often can be seen on MRI.
CT is useful for identifying calcified loose bodies.
Treatment of Synovial Chondromatosis
Nonoperative or conservative treatment options are considered first and consist of-
- Nonsteroidal anti-inflammatory drugs
- Ultrasonic therapy and/ or thermal therapy for lessening the pain and inflammation.
Nonoperative treatment does not benefit the mechanical symptoms.
Surgery is considered in following patients
- Recurrent effusions that are painful
- Presence of mechanical symptoms
- Patients who do not respond to nonoperative treatment
Open total synovectomy along with the removal of loose bodies was the standard procedure in the past. But it has been found that total synovectomy can lead to significant stiffness after surgery.
Arthroscopic removal of loose bodies and partial synovectomy for mechanical symptoms is the best surgical option especially in knee, hip and shoulder.
In presence of abundant large bodies, few authors recommend open excision.
The outcome is less predictable in severe cases and those with secondary synovial chondromatosis.
References
- Bynum CK, Tasto J. Arthroscopic treatment of synovial disorders in the shoulder, elbow, and ankle. J Knee Surg. 2002 Winter. 15 (1):57-9.
- McCarthy C, Anderson WJ, Vlychou M, Inagaki Y, Whitwell D, Gibbons CL, et al. Primary synovial chondromatosis: a reassessment of malignant potential in 155 cases. Skeletal Radiol. 2016 Jun. 45 (6):755-62.
- Samson L, Mazurkiewicz S, Treder M, Wisniewski P. Outcome in the arthroscopic treatment of synovial chondromatosis of the knee. Ortop Traumatol Rehabil. 2005 Aug 30. 7 (4):391-6.
- Boyer T, Dorfmann H. Arthroscopy in primary synovial chondromatosis of the hip: description and outcome of treatment. J Bone Joint Surg Br. 2008 Mar. 90 (3):314-8.
