Synovial Osteochondromatosis - An Overview

Introduction

The joints (the area where two or more bones meet) are covered by a slippery substance that helps in the smooth, gliding movement of the bones called the articular cartilage. Thick bands of connective tissues surround these joints, forming a capsule, and a thin membrane that lines the undersurface of the joint capsule is called the synovium. It produces a fluid called synovial fluid, which helps in the lubrication of the joint.

What Is Synovial Osteochondromatosis?

Synovial osteochondromatosis is also called synovial chondromatosis; it is a rare non-cancerous (benign) condition that involves the synovium. It can affect any joint in the body but commonly occurs in the knee joint, followed by the hip, elbow, and shoulder joints. It may also affect the temporomandibular joint or the ankle. Due to the abnormal growth of the synovium during the disease, it produces nodules, which break off from the synovium, become loose bodies, and roll in the joint space. These loose bodies get calcified or ossified, and the condition is called synovial osteochondromatosis. It causes severe pain, may damage the cartilage, and also lead to osteoarthritis (a condition in which the joints become inflamed due to damage to the cartilage). It affects people between 30 and 50 years, and males are affected up to four times more than females. In some rare cases, the loose chondral bodies may appear as extra-articular lesions (outside the joint capsule), which usually occurs in synovial lined bursal tissue or tenosynovium and is called tenosynovial chondromatosis or bursal chondromatosis. It is usually seen in the fifth decade of life and rarely affects children and individuals below the age of 20 years.

What Are the Types of Synovial Osteochondromatosis?

Synovial osteochondromatosis is of two types; primary and secondary.

1. Primary Synovial Osteochondromatosis: It is a monoarticular disorder, and the cause of the same is unknown. It is also called Reichel syndrome, as it was first described by German surgeon Friedrich Reichel in the year 1900. It is the formation of new chondrocytes and their proliferation. Primary synovial osteochondromatosis can be distinguished into three stages:

• Phase I: Inflammation of the synovium (synovitis) without the loose bodies.

• Phase II: Nodular synovitis, along with the loose bodies.

• Phase III: The presence of loose bodies with the resolution of synovitis.

1. Secondary Synovial Osteochondromatosis: It results from mechanical changes in the joint due to arthropathy (joint disease) or denotes loose chondral bodies that occur secondary to joint pathology like trauma, infections, osteoarthritis, etc. The articular nodules ossify frequently and are large and vary in size, compared to the primary form in which the nodules are small and uniform in size.

What Are the Causes of Synovial Osteochondromatosis?

The cause of synovial osteochondromatosis is unknown; it is not inherited (not genetic) but may occur spontaneously. However, bone morphogenic protein, vascular endothelial growth factor, and interleukin - 6 are found to be elevated in the loose fragments and joints of the affected people. The loose bodies vary in number and may even combine to form large bodies. These loose bodies result in pathological and mechanical wear of the joint, leading to the erosion of the joint surface, and the condition is hence classified as a benign neoplastic lesion.

What Are the Signs and Symptoms of Synovial Osteochondromatosis?

Some of the signs and symptoms of synovial osteochondromatosis include:

• Pain and swelling of the affected joint.

• Locking or catching sensation in the joint.

• Pain increases on weight bearing and is also present during rest.

• Tenderness and stiffness of the joint.

• Increase in joint effusion (accumulation of fluid in the joint) with increased activity.

• Difficulty in the movement of the joint.

• Nodules are felt at the joints that are close to the skin.

How Is Synovial Osteochondromatosis Diagnosed?

It is required to diagnose and treat synovial osteochondromatosis as early as possible to relieve pain and prevent the progression of the condition. Synovial osteochondromatosis can be diagnosed with a medical history and physical examination followed by a radiological evaluation. The patient usually presents with pain in the joint; swelling may also be present in some cases, and the joint is tender and swollen on palpation. Radiological evaluation helps differentiate primary and secondary types and synovial osteochondromatosis from osteoarthritis.

• X-ray: It reveals the presence of loose bodies in the joint space; the number and size can also be determined. Small bodies may not be visible in an X-ray and require an MRI (magnetic resonance imaging) scan. If no pathology is present, it may be diagnosed as primary synovial osteochondromatosis.

• Other Tests: Magnetic resonance imaging (MRI), an MRI arthrography (use of contrast material during the MRI scan), or computed tomography (CT Scan) is recommended for an accurate diagnosis, as small loose bodies may not be visible under an X-ray. It also helps to diagnose the signs of osteoarthritis and the presence of tissue fluid in the joint space.

How Is Synovial Osteochondromatosis Managed?

• The management of synovial osteochondromatosis depends on the symptoms of the condition; sometimes, the doctor may consider observation with periodic monitoring of the disease progression as an option. Non-steroidal anti-inflammatory drugs (NSAIDs) are prescribed to relieve pain and inflammation. Administration of corticosteroid injections into the joint space may be sometimes preferred.

• In advanced cases with nodular synovitis, the presence of large loose bodies, or those developing neurological symptoms, and restricted joint movements due to degenerative changes, surgical intervention may be necessary. The two surgical methods include open surgery and arthroscopic surgery. The surgical technique depends on the number and size of the loose bodies, along with the condition of the synovium. However, arthroscopic surgery has been favored recently, as the incisions are smaller and it causes less pain and scarring than open surgery. The main objective is to remove the loose bodies, along with partial or complete removal of the synovium (synovectomy).

• Arthroscopic surgery involves the induction of general anesthesia and the application of tourniquets. Small incisions are made at the site; a tiny camera is inserted through one opening, and surgical instruments are inserted through the other. The camera displays the condition of the disease on the monitor, following which the loose bodies are removed with the help of arthroscopic graspers, and the excision is performed with shavers and graspers. The area is irrigated and cleaned, and the loose bodies are sent for histopathological examination. The instruments are withdrawn, and the surgical site is then sutured with non-absorbable sutures. A sterile dressing is done, followed by immobilization of the joint, and pain relief medications are prescribed.

• Post-surgical instructions include the application of ice for three to seven days, following which sutures are removed, and sterile bandages are placed. Physiotherapy is advised to achieve a full range of motion in around four to eight weeks.

Conclusion

Synovial osteochondromatosis is a rare, benign condition affecting the synovium of the joints, especially the knee joint, and is characterized by severe pain, swelling, and difficulty in movement. It occurs due to abnormal growth of the synovium, forming nodules, which break off and result in the formation of loose bodies that harden by calcification. Treatment depends on the symptoms and severity of the disease, and initial phases are managed by nonsurgical treatment, and severe cases are managed by arthroscopic surgery followed by physiotherapy.