What Is Synovial Osteochondromatosis

  • Natalia Ewa Grzesik Bachelor of Science – BSc Pharmacology and Innovative Therapeutics, Queen Mary University of London
  • Jialu Li Master of Science in Language Sciences (Neuroscience) UCL

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Introduction to synovial osteochondromatosis

Definition and overview

Synovial osteochondromatosis is a rare benign condition characterized by the formation of multiple cartilage nodules, and it primarily impacts the synovial lining, which produces the lubricating fluid in joints, leading to the formation of these abnormal nodules.1 This condition, also known as primary synovial chondromatosis, leads to the growth of small, cartilage-like bodies called osteochondromas within the synovial fluid, and these nodules gradually calcify.1,2 This can cause pain, inflammation, and restricted movement within the affected joint.1 It typically occurs around the age of 50, and the initial symptoms mirror traditional arthropathies, such as osteoarthritis.1 

Affected areas

Synovial osteochondromatosis predominantly affects the larger weight-bearing joints, including the knee, hip, and shoulder.1,2 However, it is not limited to these areas and can also manifest in smaller joints like the elbow or ankle.1 In these joints, the synovial lining experiences abnormal growth of cartilage-like nodules leading to joint pain, swelling, stiffness, and potential joint dysfunction.1 While it primarily impacts the synovial membrane, its effects can extend to the joint's entire structure, impacting mobility and causing discomfort.2

Causes and risk factors

Underlying causes

The precise cause of synovial osteochondromatosis remains uncertain, often categorized as an idiopathic condition without a clear origin.1 However, it's believed to stem from an abnormal response of the synovial tissue within the joint to irritation, inflammation or trauma.3 Genetic factors might also play a role, as some cases have shown familial tendencies, suggesting a potential genetic predisposition.3 Additionally, alterations in certain chromosomes and genes related to cartilage formation or regulation could contribute to the development of this condition.3

Factors contributing to its development

Several factors can contribute to the development or exacerbation of osteochondromatosis. Joint trauma or injury, repetitive microtrauma, or chronic irritation to the synovial lining may trigger the abnormal growth of cartilaginous nodules.3 Furthermore, chronic inflammatory conditions within the joint, such as osteoarthritis or rheumatoid arthritis, could create an environment conducive to the formation of these nodules.3 While the exact interplay of these factors remains under investigation, they collectively contribute to the pathogenesis and progression of synovial osteochondromatosis, influencing its onset and severity in affected individuals.3


Explanation of the condition's process

Synovial osteochondromatosis begins with an abnormal proliferation of cells within the synovial membrane.3 This abnormal growth results in the formation of small, cartilage-like nodules called osteochondromas.3 The nodules detach from the synovium and enter the synovial fluid within the joint.3 Over time, these loose bodies undergo a process of calcification, hardening into solid structures.3 As they accumulate, they can cause irritation, inflammation, and mechanical interference within the joint, leading to pain, swelling, and reduced mobility.3 The condition progresses as these calcified nodules can cause damage to the joint surfaces and surrounding tissues, further progressing the condition and worsening symptoms.3

How synovial osteochondromatosis affects joints

Synovial osteochondromatosis primarily impacts joint health by disrupting normal joint function.2 The presence of multiple calcified nodules within the synovial fluid leads to friction and mechanical interference within the joint.2 These nodules can irritate the synovial lining, causing inflammation and the release of inflammatory mediators, resulting in pain, swelling, and stiffness.2 As the nodules grow and accumulate, they can impede joint movement, causing limitations in range of motion and, in severe cases, joint locking.2 Moreover, the mechanical pressure exerted by these nodules can damage the cartilage and adjacent structures, potentially leading to joint degeneration and long-term joint dysfunction if not managed appropriately.2

Signs and symptoms

Common symptoms experienced by individuals

Individuals with synovial osteochondromatosis commonly experience symptoms such as joint pain, swelling, and stiffness.2 The pain often worsens with movement or weight-bearing activities and may be accompanied by a sensation of grinding or clicking within the affected joint.2 Some individuals might notice a reduced range of motion in the joint, along with episodes of joint locking or catching.2 As the condition progresses, these symptoms can intensify, leading to chronic discomfort and functional limitations.2

How symptoms manifest in affected joints

Symptoms of synovial osteochondromatosis manifest differently depending on the affected joint.2 In weight-bearing joints like the knee or hip, individuals may notice difficulty walking, stiffness when rising from a seated position, and pain during physical activities.2 Swelling and tenderness might also be present around the joint.2 In other joints, such as the shoulder or elbow, symptoms can include pain during movements like reaching overhead or lifting objects.2 Joint swelling and a sensation of instability or clicking may also occur.2 Overall, the symptoms in affected joints result from the presence of calcified nodules disrupting normal joint mechanics, leading to pain, swelling, and functional limitations specific to each joint's movement patterns.2


Methods and tests used for diagnosis

Diagnosing synovial osteochondromatosis involves a combination of clinical assessment and various imaging studies. The process typically begins with a detailed medical history and physical examination, focusing on joint movement, tenderness, and any characteristic symptoms.2 Imaging studies, such as X-rays or MRI (magnetic resonance imaging), also play a crucial role in confirming the diagnosis.2 In certain cases, CT (computerized tomography) may also be performed to supplement diagnosis, as it offers a better visualization of the mineralised areas compared to MRI.3 Furthermore, biopsies and pathological analysis of the tissue can be performed to characterize the condition.4

Imaging techniques employed

Various imaging techniques are utilized to diagnose and evaluate synovial osteochondromatosis. X-rays serve as an initial imaging modality, highlighting calcified nodules within the joint space.1 However, MRI scans are the preferred imaging tool for a comprehensive assessment.1 MRI provides detailed images of soft tissues, allowing visualization of the synovial membrane, cartilage, and loose bodies within the joint.1 It offers superior sensitivity in detecting early-stage lesions and assessing the extent of joint involvement.1 Additionally, ultrasound might be used, especially for joints accessible to this modality, providing real-time images that can help identify joint abnormalities, though it's less commonly employed compared to X-rays and MRI in diagnosing the condition.3

Treatment options

Medical interventions

The management of synovial osteochondromatosis often involves a combination of medical interventions aimed at alleviating symptoms and controlling inflammation.1 Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly prescribed to reduce pain and inflammation associated with the condition.1 In some cases, intra-articular corticosteroid injections might be recommended to provide localized relief from swelling and discomfort.1 Physical therapy plays a vital role in improving joint mobility, strengthening surrounding muscles, and enhancing overall joint function.3 Therapeutic exercises and modalities are tailored to the affected joint, aiming to restore flexibility and stability while minimizing pain and preventing further joint damage.3

Surgical approaches 

Surgical intervention becomes necessary in cases where conservative treatments fail to provide adequate relief or if there's joint dysfunction due to extensive involvement. The primary surgical approach involves the removal of loose bodies or nodules from the affected joint through open surgery or arthroscopic techniques.1 Arthroscopic surgery, a minimally invasive procedure, involves small incisions through which a camera and surgical tools are inserted to remove the nodules while minimizing tissue damage.1 Without surgical excision of the calcified bodies, the disease can lead to joint degeneration.1 At this point, where the condition has led to significant joint damage, joint reconstruction or replacement might be considered to restore function and alleviate pain.1 The choice of surgical approach depends on the extent of joint involvement and the individual's overall health status.

Prognosis and complications

Outlook for individuals with synovial osteochondromatosis

The outlook for individuals with synovial osteochondromatosis varies depending on the extent of joint involvement, the effectiveness of treatment, and individual factors. Generally, with proper management and timely intervention, many individuals experience relief from symptoms and improved joint function.3 Early diagnosis and appropriate treatment can help mitigate pain, reduce inflammation, and preserve joint mobility.3 However, in some cases where the condition progresses extensively or remains undiagnosed for an extended period, joint damage can lead to persistent pain and impaired joint function, impacting daily activities.2,3 Regular monitoring and adherence to treatment plans significantly contribute to a better prognosis for those affected.3

Potential complications associated with the condition

Synovial osteochondromatosis, if left untreated or inadequately managed, can lead to several complications. One significant complication is joint degeneration, whereby the continuous presence of calcified nodules causes progressive damage to the joint surfaces and surrounding structures, leading to osteoarthritis.1 Persistent joint inflammation and pain can significantly impact an individual's quality of life, limiting mobility and causing chronic discomfort.1 In severe cases, the development of joint stiffness or contractures might occur, resulting in further functional limitations.1 Additionally, although rare, there have been instances of synovial osteochondromatosis transforming into malignant tumours, highlighting the importance of regular monitoring and appropriate management of this condition.1,4

Management and lifestyle modifications

Lifestyle changes to alleviate discomfort or prevent progression

Lifestyle modifications play a pivotal role in alleviating discomfort and slowing the progression of synovial osteochondromatosis as with other conditions affecting the joints.5 Maintaining a healthy weight is essential as excess weight can put additional stress on weight-bearing joints, exacerbating symptoms.5 Engaging in low-impact exercises such as swimming or cycling can help maintain joint flexibility and strengthen muscles without placing excessive strain on the affected joints.5 Using proper joint protection techniques, such as using assistive devices or ergonomic modifications, can prevent joint injury and reduce discomfort during daily activities.5 Regular monitoring and communication with healthcare providers are also vital to ensure proper management and timely intervention if symptoms worsen.3


Synovial osteochondromatosis is a rare benign condition characterized by the formation of cartilage nodules within the synovial lining of joints. Its exact cause remains unclear, but it's often associated with joint trauma or irritation. This condition affects various joints, leading to symptoms like joint pain, swelling, stiffness, and restricted movement. Diagnosis typically involves imaging studies like X-rays and MRI scans. Treatment involves a combination of medical interventions such as NSAIDs, corticosteroid injections, and physical therapy. Surgical removal of nodules through open or arthroscopic surgery might be necessary in severe cases. Lifestyle changes, exercise modifications, and weight management are essential for symptom management and slowing disease progression.

The future outlook for managing synovial osteochondromatosis shows promise with ongoing research and advancements in treatment modalities. Advancements in imaging technologies may lead to more precise and early diagnoses, enabling timely interventions to prevent joint damage. Additionally, targeted drug therapies aimed at interrupting the pathological process responsible for nodule formation may emerge, providing more effective and less invasive treatment options. Further understanding of the underlying genetic and molecular mechanisms contributing to the condition could pave the way for innovative therapies or targeted interventions, offering improved outcomes for individuals affected by synovial osteochondromatosis. Continued research endeavours focusing on personalized medicine and novel therapeutic approaches hold the potential for enhancing patient care and overall outcomes in the management of this condition.


  1. Bhagat SS, Hammond J, Fuller-Sincock DM, Zehra SB. Incidental finding of synovial osteochondromatosis: A case report. Cureus 2022;14:e28051. https://doi.org/10.7759/cureus.28051.
  2. Giannetti S, Santucci A, Patricola A, Stancati A, Di Sanzo V. Neglected synovial osteochondromatosis of the elbow: a rare case. World J Surg Oncol 2013;11:233. https://doi.org/10.1186/1477-7819-11-233.
  3. Habusta SF, Tuck JA. Synovial Chondromatosis. StatPearls, Treasure Island (FL): StatPearls Publishing; 2019.
  4. Dheer S, Sullivan PE, Schick F, Karanjia H, Taweel N, Abraham J, et al. Extra-articular synovial chondromatosis of the ankle: Unusual case with radiologic-pathologic correlation. Radiol Case Rep 2020;15:445–9. https://doi.org/10.1016/j.radcr.2020.01.031.
  5. O’Reilly S, Doherty M. Lifestyle changes in the management of osteoarthritis. Best Pract Res Clin Rheumatol 2001;15:559–68. https://doi.org/10.1053/berh.2001.0173

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Natalia Ewa Grzesik

Bachelor of Science – BSc Pharmacology and Innovative Therapeutics, Queen Mary University of London

Natalia boasts a solid background in pharmacology and neuroimmunology research, honing her skills through hands-on laboratory work and active involvement in scientific endeavors. With extensive experience in scientific writing, medical communication, and teaching various subjects, she brings a well-rounded expertise to the table.

In addition to her academic prowess, Natalia is a certified first aider and instructor, providing her with valuable insights into the practical aspects of healthcare. Her teaching extends beyond theoretical knowledge, encompassing vital medical and academic skills.

Driven by a genuine passion for healthcare and a desire to push the boundaries of research, Natalia advocates for the broader dissemination of scientific knowledge. She believes in fostering inclusive scientific communication, inviting everyone to participate in this expansive and crucial field.

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