Synovial Chondromatosis

                             

                                    Dr. KS Dhillon

Introduction

Synovial chondromatosis (SC) is an uncommon benign condition that affects the synovial membrane of joints, tendon sheaths, and bursae. It can produce severe disability and dysfunction of the synovial joint that is involved. Synovial chondromatosis rarely undergoes malignant transformation but transformation to chondrosarcoma is a possible complication [1]. Synovial chondromatosis of the knee was first described by Ambrose Pare in 1958 [2]. In 1813, Laennec described intra-articular loose bodies originating from subsynovial tissues [1,3]. 

Diagnosis is made through a good history, physical examination, and radiological evaluation of the affected joint. There is swelling of the joint due to an effusion and or synovial hypertrophy. The joints are painful at rest and there is more pain with joint motion. The range of motion of the joints is reduced. X-rays of the joint show multiple loose radio-opaque chondroid bodies of different sizes. MRI studies may be required in early disease to show cartilage nodules throughout the joint space. 

Synovial chondromatosis usually involves one joint. In rare cases, multiple joint involvements can occur. The process may occur in two forms: primary synovial chondromatosis [4] or synovial chondrometaplasia [5]) and secondary synovial chondromatosis. The primary and secondary forms have different presentations. They are treated differently. In rare cases, an extra-articular form of the disease can be identified.

Etiology

The etiology of the primary form of the disease has not been determined. In patients with synovial chondrmatosis, elevated levels of bone morphogenic protein in the loose body lesions and the affected synovial joints have been found. The etiological importance of this finding, however, has not been determined. Elevated levels of interleukin-6 and vascular endothelial growth factor-A have also been found in these joints. The importance of these findings is also not certain.

Secondary synovial chondromatosis is believed to occur as a result of mechanical changes in the joint due to arthropathy. The formation of loose bodies is believed to be part of the degenerative process in the joints. The disease process whether primary or secondary results in the formation of multiple chondroid nodules, and osteochondral or osseous loose bodies [5-8]. Monoarticular involvement is the usual presentation. There are, however, over 33 different locations where the disease has been found [9]. Intraarticular pathology is typical but extraarticular cases have also been reported [10,11].

Epidemiology

Synovial chondromatosis is more common in men. It is up to four times more common in men as compared to women. It most commonly involves the knee joint. It typically affects diarthrodial, weight-bearing joints of individuals between the ages of 30-60 years. The descending frequency of involvement of the various joints is [3,5,7,10,12,13,14]:  

• Knee (70%)

• Hip (20%)

• Shoulder 

• Elbow 

• Ankle 

• Wrist.

Larger joints through which more weight passes have a greater potential for developing synovial chondromatosis. Synovial chondromatosis has also been reported to affect the temporomandibular joint, the intervertebral facet joints, and a variety of other tenosynovial locations [11,15,16].

Extra-articular presentation of synovial-chondral lesions is a rare occurrence. This occurs in synovial lined bursal tissue or tenosynovium. Here loose bodies can form. These are called tenosynovial chondromatosis or bursal chondromatosis. Synovial chondromatosis most commonly occurs in the fifth decade of life. It is rare before the age of 20, and it is very rare in children.

The primary form occurs in joints where there is no evidence of concurrent joint pathology. The secondary form occurs in joints undergoing degeneration. The secondary form occurs more commonly in older individuals. Both the primary and secondary forms are uncommon [5,7,12,16]. The exact incidence of the disease is unknown. It has been reported as 1.8 per million individuals per year in England [1]. It is bilateral in 10% of the individuals.

Pathophysiology

Synovial chondromatosis develops as foci of cartilage in synovial tissue [7,8,12]. There is metaplasia but no atypia and invasion. It is considered neoplastic due to its association with clonal chromosomal changes. The cartilaginous foci originate as sessile synovial attachments. As they grow, they become pedunculated and then they break loose and become free intraarticular or periarticular loose bodies [8,16]. Once they are loose in the joint, they continue to grow. They get their nutrition from the synovial fluid. Ultimately they end up getting reattached to the synovium or they get reabsorbed. The major proportion of these loose bodies are in a transitional zone between synovium and hyaline cartilage. There is abundance of pluripotent stem cells in this area [7,17]. The hyaline cartilage is hypercellular, and the cells are usually atypical. These atypical changes include myxoid degeneration of matrix, crowding of cell nuclei, large nuclei and the cells are multinucleated. 

About two-thirds of these loose bodies will ossify through endochondral ossification. The rest will remain unossified [18]. The number of loose bodies varies from two or three loose bodies to several dozen loose bodies. The size of these loose bodies varies. Several loose bodies can combine to form larger bodies. The number of intraarticular lesions is higher in the primary type as compared to the secondary type. In primary SC, loose bodies are small, rounded, and uniform in size. In secondary SC, loose bodies size is more variable. The loose bodies can cause mechanical wear of the joint surfaces and cause erosion of articular surfaces. 

It presents between the ages of 30 to 40 years. It is relatively rare. In secondary synovial chondromatosis, there is an underlying joint pathology, such as trauma, osteochondritis dissecans, advanced osteonecrosis, or Charcot neuropathic joint, resulting in synovitis and/or articular destruction. Secondary SC is seen in patients who are between the age of 50 and 60 years.

There has been no consensus on whether synovial chondromatosis is metaplastic or neoplastic. There is, however, a small risk of malignant transformation to chondrosarcoma. It is associated with recurrence after initial treatment [13,19]. The rate of malignant transformation is unknown. In a large orthopedic oncology database 5 out of seventy-eight patients with primary synovial chondromatosis developed malignant chondrosarcomas[1].

History and Physical Examination

The clinical presentation of SC is nonspecific. Some patients are asymptomatic and others can be symptomatic. The symptomatic patients will present with joint pain. There will be swelling of the joint with reduced range of motion. Sometimes there will be crepitus and mechanical locking of the joint [1,5,7,20,21]. The pain is usually worse with activity but can also be present at rest. Sometimes patients may complain of joint instability and joint effusions. The joint involvement is usually monoarticular in the primary form and may be multi-articular in the secondary form. Rarely primary chondromatosis can recur. In patients with the secondary form, a history of osteoarthritis, post-traumatic arthritis, or rheumatoid arthritis may be present. The diagnosis is usually an incidental finding and is very often delayed. The average time from onset of symptoms to diagnosis is about five years [1].

Evaluation

Radiographs can help differentiate primary from secondary types of SC. In primary SC radiographs will show no underlying joint pathology. In secondary SC there will be joint pathology such as osteoarthritis. MRI and MRI arthrography are also useful in the diagnosis of SC. MRI can help diagnose the bursal extension of the disease process. In the hip, bursal extension into the obturator externus and iliopsoas have been identified in up to 71% of the cases. 

X rays (fig 1) will show rounded, multifocal, articular, or periarticular calcific bodies [16]. In 20% of cases, calcification and mineralization will be delayed as they are time-dependent. Nonminerazlied nodules can fill the joint or bursa and resemble an effusion. Patients can be symptomatic months to years before the development of calcifications. X-rays may need to be repeated to detect recurrence.

Fig 1

Computed tomography (CT) and magnetic resonance imaging (MRI) can help make a diagnosis in the early pre-mineralization stage of the disease [5,7,8]. 

Treatment 

The disease can be self-limiting. Hence, conservative management can work for some patients. Nonsteroidal anti-inflammatory drugs, modification of activities, and cryotherapy can be useful in the conservative treatment of SC [10]. The loose bodies can reduce the range of joint motion and produce mechanical symptoms of locking and catching which can lead to joint damage. Hence, the definitive treatment of synovial chondromatosis is the surgical removal of loose bodies with or without synovectomy.  

Surgical Management

The Necessity of Synovectomy in the treatment of SC is controversial [16,22]. Synovectomy is suitable for a synovium-based pathology.  However, there is no strong evidence that favors this option along with surgical removal of the loose bodies. 

There are multiple studies that support isolated removal of loose bodies with no additional synovectomy [23-26]. There are some studies that recommend synovectomy to prevent recurence [27-29]. 

Whether to perform synovectomy arthroscopically or through an open approach is controversial. Open synovectomy provides better visualization of the joint. Arthroscopic treatment, on the other hand, has lower morbidity, quicker return to normal function, shorter hospital stay, reduced postoperative pain, and faster rehabilitation [29,30].

Secondary synovial chondromatosis is treated with anti-inflammatory drugs if there are no mechanical symptoms. When there are mechanical symptoms surgical management is indicated. Joint arthroplasty may be required in addition to the removal of loose bodies.

Differential Diagnosis

The differential diagnosis includes all pathologies that result in the formation of intra-articular loose bodies or synovial proliferation such as [5,7,10,12]:

• Osteochondritis dissecans.

• Neurotrophic arthritis

• Tuberculous arthritis.

• Osteochondral fractures.

• Crystal deposition disease (tendinosis Calcarea).

• Osteocartilaginous loose bodies.

• Rheumatoid arthritis.

• Degenerative arthritis.

• Soft tissue tumors.

• Synovial hemangioma.

• Lipoma arborescent

• Pigmented villonodular synovitis (PVNS).

Staging

In 1977, Milgram reported that SC is a self-limiting disease. Microscopically and macroscopically, it was classified into 3 stages [31]:

Stage I: There is presence of an active inflammatory intrasynovial process without loose bodies. It can be asymptomatic or present with localized joint pain and swelling. 

Stage II:  There is active synovial proliferation with transitional loose bodies. Patients usually present with mechanical symptoms and decreased range of motion of the joint.

Stage III: This is a quiescent stage of the disease with no ongoing metaplasia. There are several loose bodies with minimal synovial disease and inflammation. Patients tend to be asymptomatic in this stage. 

Prognosis

Synovial chondromatosis can cause intraarticular or periarticular destruction. Hence, prompt diagnosis and treatment is essential to prevent secondary pathology [5]. The most important prognostic factor is the condition of the articular cartilage of the involved joint [25].

There is rarely a recurrence of primary synovial chondromatosis after surgical treatment with the removal of the loose bodies and partial synovectomy. Recurrence has been reported in a case involving the temporal mandibular joint.

Spontaneous regression has been reported in the literature but is uncommon. It often takes several years from the onset to the resolution of symptoms [6,8,2132].

References

1. Evans S, Boffano M, Chaudhry S, Jeys L, Grimer R. Synovial chondrosarcoma arising in synovial chondromatosis. Sarcoma. 2014;2014:647939.

2. Barwell R. Clinical Lectures on Movable Bodies in Joints. Br Med J. 1876 Apr 01;1(796):403-5.

3. Halstead AE. IV. Floating Bodies in Joints. Ann Surg. 1895 Sep;22(3):327-42.

4. Wagner S, Bennek J, Gräfe G, Schmidt F, Thiele J, Wittekind C, Meier T. Chondromatosis of the ankle joint (Reichel syndrome). Pediatr Surg Int. 1999 Jul;15(5-6):437-9. 

5. Adelani MA, Wupperman RM, Holt GE. Benign synovial disorders. J Am Acad Orthop Surg. 2008 May;16(5):268-75.

6. Ranalletta M, Bongiovanni S, Calvo JM, Gallucci G, Maignon G. Arthroscopic treatment of synovial chondromatosis of the shoulder: report of three patients. J Shoulder Elbow Surg. 2009 May-Jun; 18(3):e4-8. 12.

7. Tokis AV, Andrikoula SI, Chouliaras VT, Vasiliadis HS, Georgoulis AD. Diagnosis and arthroscopic treatment of primary synovial chondromatosis of the shoulder. Arthroscopy. 2007 Sep;23(9):1023.e1-5. 

8. Jung KA, Kim SJ, Jeong JH. Arthroscopic treatment of synovial chondromatosis that possibly developed after open capsular shift for shoulder instability. Knee Surg Sports Traumatol Arthrosc. 2007 Dec;15(12):1499-503.

9. Bojanić I, Vuletić LB, Troha I, Smoljanović T, Borić I, Seiwerth S. [Synovial chondromatosis]. Lijec Vjesn. 2010 Mar-Apr;132(3-4):102-10.

10. Aydogan NH, Kocadal O, Ozmeric A, Aktekin CN. Arthroscopic treatment of a case with concomitant subacromial and subdeltoid synovial chondromatosis and labrum tear. Case Rep Orthop. 2013;2013:636747. 

11. Mata BA, Eward WC, Brigman BE. Pancarpal synovial and tenosynovial chondromatosis in a 65-year-old man: a highly unusual presentation of a common condition. Am J Orthop (Belle Mead NJ). 2013 Aug;42(8):E60-3.

12. Chillemi C, Marinelli M, de Cupis V. Primary synovial chondromatosis of the shoulder: clinical, arthroscopic and histopathological aspects. Knee Surg Sports Traumatol Arthrosc. 2005 Sep;13(6):483-8.

13. Davis RI, Hamilton A, Biggart JD. Primary synovial chondromatosis: a clinicopathologic review and assessment of malignant potential. Hum Pathol. 1998 Jul;29(7):683-8. 

14. Huang TF, Wu JJ, Chen TS. Bilateral shoulder bursal osteochondromatosis associated with complete rotator cuff tear. J Shoulder Elbow Surg. 2004 Jan-Feb;13(1):108-11.

15. Chen MJ, Yang C, Qiu YT, Jiang Q, Shi HM, Wei WB. Synovial chondromatosis of the tempromandibular joint: relationship between MRI information and potential aggressive behavior. J Craniomaxillofac Surg. 2015 Apr;43(3):349-54. 

16. Alexander JE, Holder JC, McConnell JR, Fontenot E. Synovial osteochondromatosis. Am Fam Physician. 1987 Feb;35(2):157-61.

17. Small R, Jaffe WL. Tenosynovial chondromatosis of the shoulder. Bull Hosp Jt Dis Orthop Inst. 1981;41:37-47.

18. Marchie A, Panuncialman I, McCarthy JC. Efficacy of hip arthroscopy in the management of synovial chondromatosis. Am J Sports Med. 2011 Jul;39 Suppl:126S-31S.

19. Sachinis NP, Sinopidis C, Baliaka A, Givissis P. Odyssey of an elbow synovial chondromatosis. Orthopedics. 2015 Jan;38(1):e62-7.

20. Ogawa K, Takahashi M, Inokuchi W. Bilateral osteochondromatosis of the subacromial bursae with incomplete rotator cuff tears. J Shoulder Elbow Surg. 1999 Jan-Feb;8(1):78-81. 

21. Horii M, Tamai M, Kido K, Kusuzaki K, Kubo T, Hirasawa Y. Two cases of synovial chondromatosis of the subacromial bursa. J Shoulder Elbow Surg. 2001 Mar-Apr;10(2):186-9.

22. Lim SJ, Chung HW, Choi YL, Moon YW, Seo JG, Park YS. Operative treatment of primary synovial osteochondromatosis of the hip. J Bone Joint Surg Am. 2006 Nov;88(11):2456-64.

23. Jeffreys TE. Synovial chondromatosis. J Bone Joint Surg Br. 1967 Aug;49(3):530-4. 

24. Paul GR, Leach RE. Synovial chondromatosis of the shoulder. Clin Orthop Relat Res. 1970 Jan-Feb;68:130-5. 

25. Dorfmann H, De Bie B, Bonvarlet JP, Boyer T. Arthroscopic treatment of synovial chondromatosis of the knee. Arthroscopy. 1989;5(1):48-51. .

26. Shpitzer T, Ganel A, Engelberg S. Surgery for synovial chondromatosis. 26 cases followed up for 6 years. Acta Orthop Scand. 1990 Dec;61(6):567-9.

27. Ogilvie-Harris DJ, Saleh K. Generalized synovial chondromatosis of the knee: a comparison of removal of the loose bodies alone with arthroscopic synovectomy. Arthroscopy. 1994 Apr;10(2):166-70. 

28. Schoeniger R, Naudie DD, Siebenrock KA, Trousdale RT, Ganz R. Modified complete synovectomy prevents recurrence in synovial chondromatosis of the hip. Clin Orthop Relat Res. 2006 Oct;451:195-200. 

29. Maurice H, Crone M, Watt I. Synovial chondromatosis. J Bone Joint Surg Br. 1988 Nov;70(5):807-11.

30. Ozmeric A, Aydogan NH, Kocadal O, Kara T, Pepe M, Gozel S. Arthroscopic treatment of synovial chondromatosis in the ankle joint. Int J Surg Case Rep. 2014;5(12):1010-3.

31. Milgram JW. Synovial osteochondromatosis: a histopathological study of thirty cases. J Bone Joint Surg Am. 1977 Sep;59(6):792-801.

32. Ko JY, Wang JW, Chen WJ, Yamamoto R. Synovial chondromatosis of the subacromial bursa with rotator cuff tearing. J Shoulder Elbow Surg. 1995 Jul-Aug;4(4):312-6.