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Knee chondromatosis

Synovial chondromatosis is a rare, benign, predominantly monoarticular lesion of the synovial membrane. It affects one in every 100,000 inhabitants. It is 3 times more frequent in men, its main location is in large joints: knee (70%), hip (20%) and shoulder (19%). Imaging studies are essential to be able to make a diagnosis, and biopsy as a definitive diagnosis.


We present the case of a 50-year-old patient, who began with an increase in volume and limitation of movements at the level of the right knee at one year of evolution; He goes to a consultation where arthrocentesis is performed obtaining clear inflammatory fluid and medical treatment is indicated, as he does not improve, complementary studies are carried out. The case is presented because it is a rare entity, in which imaging studies play an important role for diagnosis and subsequent arthroscopic treatment.

Key words: synovial chondromatosis, diagnostic imaging, treatment, adult, man, knee arthroscopy.


Synovial chondromatosis is a benign idiopathic metaplasia of the synovium. It affects one in every 100,000 inhabitants. It is 3 times more common in men, arises between 30-50 years and mainly affects large joints: knee (70%), hip (20%) and shoulder (19%). Its etiology is unknown, although it has been associated with chromosomal mutations (p21.3 and 12q13) that affect proteins.

Synovial chondromatosis, name given by Reichel in 1900, whose synonyms are Osteochondromatosis (Henderson 1917) and osteochondrosis (Pontvill 1966), is a rare benign pathology characterized by the metaplastic formation of multiple cartilaginous nodules within the connective tissue of the membrane. synovium of the joints, tendon sheaths and bursae.

Chondromatosis can be primary or secondary.

Primary chondromatosis: presence of multiple rounded bodies of the same shape and size, with a variable degree of calcification.

Secondary chondromatosis: it is generally associated with the presence of osteoarthritis, but also with other pathologies that condition injuries to the cartilage (arthritis, trauma, osteochondritis dissecting). The cartilaginous bodies generally have different sizes and are less numerous, have a reactive appearance, with concentric growth rings and ring-shaped calcifications.

Milgram described 3 stages: (1) active intra-articular disease without loose bodies; (2) transitional lesions with synovial proliferation and loose bodies; and (3) loose bodies without synovial disease.

It begins with small, very numerous villi that take a form at first sessile, then pedunculous, these become cartilaginous and can detach and float within the joint. In some cases the bodies released to the joint may present amorphous and irregular calcifications, sometimes followed by endochondral ossification, which may be visible on common radiographic studies.

Radiographic signs are very characteristic if the loose bodies are calcified (osteochondromatosis), their interpretation being difficult if they are radiolucent (chondromatosis).

An MRI was performed which revealed joint effusion, soft tissue swelling and absence of signal in cartilaginous lesions. A pap-stained arthrocentesis specimen showing no pyogens, with characteristic normal synovial fluid.


The diagnosis of synovial osteochondromatosis is made on the basis of clinical radiological examination, the imaging findings depend on the degree of ossification that has occurred. In the case of patients with suspected soft tissue injury, ultrasound is considered the initial diagnostic modality.

In ultrasound studies, a heterogeneous mass can be seen that contains hyperechoic foci that represent the chondral bodies, which may present a posterior shadow, depending on the degree of calcification.

Plain radiography is useful, although it should be considered that in 30% of cases the nodules are not seen when they are not calcified.

Calcifications can follow a trabecular or heterogeneous pattern and reach a variable size, up to several centimeters. Direct radiographic signs consist of the presence of calcified intra-articular foreign bodies of variable size, frequently numerous. Indirect signs are less evident: bone erosions due to synovial hypertrophy, increased joint interline due to the interposition of foreign bodies, or osteoarthritis.

The best way to see intra-articular loose bodies is with computed tomography (CT) since they even detect non-calcified nodules, which are not visible on plain radiography.

CT is used to visualize the precise location of the osteocartilaginous bodies, and thus carry out operative planning. CT can show small masses in the synovium, whose density is similar to that of skeletal muscle and allows erosions to be evident before they are apparent in simple plaques.

Magnetic resonance imaging (MRI) confirms the diagnosis in most cases and allows

evaluate the degree of joint deterioration, detect the presence of nodules, increased synovial fluid, inflamed membrane and the presence of bone erosions.

MRI shows heterogeneous intra-articular masses with hypo-signal in T1 and hypersignal in T2.

Magnetic resonance imaging allows differential diagnosis with synovitis and locates the presence

foreign bodies eventually developed in the adjoining serous pockets.

On MRI, hyaline cartilage nodules have low signal intensity on T1-weighted sequences and high signal intensity on T2-weighted sequences, due to their high water content, but areas of calcification or ossification provide a low signal in both sequences. In advanced stages of the disease, the joints may show osteopenia and also secondary degenerative changes. Extra-articular synovial chondromatosis presents calcifications of the nodules more frequently (39%), which can have a certain linear arrangement along the tendon sheath and cause cortical erosions in a quarter of cases.

Treatment of synovial chondromatosis in the shoulder consists of removal of loose bodies (either by open or arthroscopic surgery) and synovectomy in recurrences. Arthrography is indicated when there is a clinical suspicion without calcified bodies, it allows a complete evaluation of the joint and the complete evacuation of the nodules with minimal morbidity and early functional recovery.

Imaging studies are of vital importance in the precise diagnosis of synovial osteochondromatosis, its interpretation, as well as the clinical examination in terms of anamnesis and physical examination of the patient, leading to the taking of surgical conduct for the resolution of the present picture.

[1] J.W. Milgram

Synovial osteochondromatosis: A histological study of thirty cases

J Bone Joint Surg Am, 59 (1977), pp. 792-801

[2] A.V. Tokis, S.I. Andrikoula, V.T. Chouliaras, H.S. Vasiliadis, A.D. Georgoulis

Diagnosis and arthroscopic treatment of primary synovial chondromatosis of the shoulder

Arthroscopy., 23 (2007), pp. 1023

[3] R.A. Sachs, B. Williams, M.L. Stone

Open bankart repair correlation of results with postoperative subscapularis function

Am J Sport Med, 33 (2005), pp. 1458-1462

[4] J.V. Lunn, J. Castellanos-Rosas, G. Walch

Arthroscopic synovectomy, removal of loose bodies and selective biceps tenodesis for synovial chondromatosis of the shoulder

J Bone Joint Surg Br, 89 (2007), pp. 1329-1335

[5] M. Ranalletta, S. Bongiovanni, J.M. Calvo, G. Gallucci, G. Maignon

Arthroscopic treatment of synovial chondromatosis of the shoulder: Report of three patients

J Shoulder Elbow Surg, 18 (2009), pp. e4-e8

[6] D. Urbach, F.X. McGuigan, M. John, W. Neumann, S.A. Ender

Long-term results after arthroscopic treatment of synovial chondromatosis of the shoulder

Arthroscopy, 24 (2008), pp. 318-323

4. Stroe A, Martínez S, Castaño LM, Aldea J, Bayona I, Laffite OD.

Condromatosis sinovialespectro de hallazgos por imagen. SERAM

[Internet]. Burgos: Sociedad Europea de Cardiología; 2012 [citado 27 Ene 2017].

11. Pazos AE, Ruiz A, Pecharromán I, Casares S, A l l o z a M , V a l b u e n a E , e t a l . M a s a s

intraarticulares en imagen. SERAM [Internet].

Granada: Sociedad Europea de Cardiología; 2014 [citado 27 Ene 2017].

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