Synovial chondromatosis of the temporomandibular joint: A clinical, radiological 
and histological study
Condromatosis sinovial de la articulación temporomandibular: Estudio clínico, radiológico e histológico

(1) Médico Adjunto. Servicio de Cirugía Oral y Maxilofacial
(2) Médico Adjunto. Servicio de Radiodiagnóstico
(3) Médico Adjunto. Servicio de Anatomía Patológica. Hospital Clínico San Carlos. Madrid

Address:
Rafael Martín-Granizo López
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28015, Madrid
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E-mail: rmartinlo@wanadoo.es

Received: 25-04-2004 Accepted: 27-06-2004

Synovial condromatosis (SC) is a cartilaginous metaplasy of the mesenchymal remnants of the synovial tissue of the joints. It is characterized by the formation of cartilaginous nodules in the synovium and inside the articular space (loose bodies). According to Ginaldi (1), it was originally described by Ambroise Paré in the year 1558, although the first in publishing the involvement of the temporomandibular joint (TMJ) was Georg Axhausen in 1933 (2). This disease is also known by names such as: synovial osteochondromatosis, synovial chondrometaplasy, synovial chondrosis, synovial metaplasy, synovialoma and periarticular tenosynovial chondrometaplasy (3).

SC mainly affects to big synovial joints such as the knee and the elbow, being uncommon the onset within the TMJ, where 75 cases have been published (4), with just one case of a bilateral involvement (5). Although the involvement of other joints is double in males, in the TMJ the frequency is four times higher in females (6). Due to the chronic and slow progression of this disease, the medium age for the diagnosis is around 55 year-old.

The main symptoms are pain (69%), inflammation (68%), limitation of the movements of the jaw (46%) and crepitation (40%). Different methods of diagnosis include panoramic radiograph, CT, MR and arthroscopy of the TMJ (4).

Therefore, we describe a new case of unilateral SC of the TMJ, including diagnostic images, treatment performed and histological analysis.

CLINICAL CASE

A 49 year-old female was referred to the Department of Oral and Maxillofacial Surgery by her dentist, referring pain over her left TMJ from 6 months ago along with a swelling of the left preauricular area. The patient described hearing strange noises in that joint from long time ago, without episodes of mandible locking. She did not have any relevant medical antecedents although she assumed to have night clenching.

On exploration an oral opening of 40 mm without lateral deviation was checked, along with an evident swelling over the left TMJ area. Also, manifest crepitates were palpated.

Imaging test included a panorex where only a slight increase of the articular space in the left TMJ along with moderate degenerative changes of the osseous components of the joint. CT and MR showed the presence of multiple nodules of different sizes inside the articular cavity of the left TMJ, which was extremely expanded (Fig. I). TC clearly showed the presence of calcified nodules of different sizes (Fig. 1 a). In addition, the MR revealed a normal position of the articular disk (Fig. 1 b).

With the suspect diagnosis of synovial chondromatosis of the left TMJ the patient underwent surgery under general anaesthesia and nasotracheal intubation and a previous antibiotic prophylaxis was administered, initially performing an articular arthroscopy with a 1.9 mm diameter Dyonics^® arthroscope, which confirmed the initial diagnosis (Fig. 2 a). Due to the size of the free bodies, too wide to be retrieved through an arthroscopic way, and to the huge number of them, an open arthrotomy approach was carried out through a preauricular incision with an Al-Kayat design. After exposing the articular capsule the articular space was entered through a "T" incision proceeding to the meticulous retrieve of a great number of articular nodules (Fig. 2 b). Due to the important expansion of the articular space and with the aim of approaching all the areas within, a Wilkes articular retractor was placed fixed to both the cigomatic arc and the neck of the condyle. After the complete retrieve of all nodules a synovectomy with a diamond burr was performed ending the operation with the exploration of the inferior compartment of the joint where no nodules were found. An aspirative drainage was placed and a closure in planes was achieved. The patient started to carry out articular physiotherapy 48 hours later with hospital discharge with anti-inflammatory drugs and a soft diet for 3 months. In further follow-ups the pain disappeared without recurrence of the SC and with no disc pathology one year later.

The macroscopic histopathologic analysis revealed the presence of over 200 free bodies of variable sizes that varied from 1 to 7 mm, all of them with a brilliant surface (Fig. 3 a). The microscopic study showed nodules of hyaline cartilage some of them with an osseous core, covered by a normal synovial surface (Fig. 3 b).

DISCUSSION

In 1977, Milgram described three phases in the evolution of the SC (7). Later, Blankenstijn et al. (8), review this concept: the first stage or initial phase includes a metaplasy of the synovial membrane with a proliferation of undifferentiated cells but without free bodies; in the second stage or transitional phase a progressive metaplasy onsets that slowly manage to the formation of loose bodies which take-off from the synovium though a phenomenon similar to gemation, and these bodies contain active chondrocytes partially covered by synovial membrane; in the third stage or advanced phase there is no intrasynovial metaplasy activity and degeneration with calcification of the loose bodies may appear and then it is called Henderson-Jones syndrome (9). Some authors have described two forms (10): primary form represents an active cartilaginous metaplasy originated in the synovial membrane; secondary form should be a more passive process with intra-articular loose fragments produced by traumatism, arthritis and other arthropaties and in these cases less cellular atypia than in the primary forma are found. Surprisingly, and without knowing the cause, all the SC described exclusively involved the superior compartment of the joint and few cases where loose bodies were found inside the inferior compartment was due to a perforation of the articular disk and the subsequent migration of these bodies from the superior compartment (4, 11).

Pathogenesis of the SC is still unknown. Previous traumatisms, parafunctions and infections have been suggested to be implicated in a small percentage of the cases reported and they do not seem to be the main cause of the SC (4, 10, 11). Some studies as the one by Sato et al. (12) suggest that the fibroblast growing factor 2 (FGF-2) is produced by the chondrocytes and joins to the receptor 1 of the fibroblast growing factor (FGFR-1), contributing to the cellular growth through an autocryne or paracryne pathway. Furthermore, the increase of the FGFR-1 in the chondrocytes of the SC contributes to raise the growth capacity in the SC and, thus, it seems that the FGF-2/FGFR-1 could play an important role in the pathogenesis of the SC.

Diagnosis of the SC is based on the clinical, radiographic, arthroscopic and histological findings (12, 13), as we did in the present case. Noyek et al. (14), pointed out some radiological features of the SC: 1) widening of the articular space, 2) restriction of movements, 3) irregularity of the articular surfaces, 4) presence of calcified loose bodies (cartilaginous) and, 5) sclerosis or hyperostosis (overgrowth) of the glenoid fossae and mandibular condyle. Nevertheless, plain radiographs are not capable to reveal the loose bodies up to 40% of the cases as many of them are not ossified (3, 12, 15, 16), as occurred in the present case. Nowadays with the modern imaging techniques, CT, 3D-CT and MR, is easy to make an appropriate suspect diagnosis, that may be confirmed with a biopsy (14) or an arthroscopy of the joint (16).

Differential diagnosis must be made with entities such as condilar tumours, osteochondrytis, avascular necrosis, arthritis or intracapsular condylar fractures. There have been reported some cases coexisting with disorders such as villonodular synovitis and condilar hyperplasia (10, 17).

Treatment should always be surgical and, although the arthroscopy of the TMJ is a non invasive technique, it is extremely difficult to retrieve the intra-articular loose bodies through this way (16, 19). Therefore, the majority of the cases require an arthrotomy of the joint in order to performed an adequate articular synovectomy or even an associated diskectomy (6), destroying the tissue with recurrence potential (19). In addition, and as in some cases the expansion of the articular capsule can involve the periarticular masticator spaces and even intracranial (20), this surgical way is the only one that guaranties an adequate approach to all the spaces within the joint. A recent review of the literature showed that in the majority of the cases that recurred an associated synovectomy have not been performed (4).

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