Prevalence of morphological changes in the surfaces of the temporomandibular joint disc associated with internal derangement

PURPOSE: The purpose of this study was to determine the prevalence of morphological changes in the superior and inferior surfaces in the temporomandibular joint (TMJ) disc and relate them to disc displacement. MATERIALS AND METHODS: Thirty TMJs obtained from fresh cadavers were studied. The TMJs were dissected, and the superior and inferior surfaces of the disc were inspected and classified as intact, irregular, or perforated. These findings were corrolated to the position of the disc. RESULTS: There was a greater prevalence of morphologic changes in the inferior (57%) than in the superior surface (17%) of the disc (P < .001). This was found for joints both with normal disc position and those with disc displacement. There was no relationship between surface irregularities of the inferior surface and the position of the disc. Perforation was seen more frequently in joints with disc displacement than in those with normal disc position. CONCLUSION: Morphologic changes in the inferior surface of the TMJ disc are more prevalent than those in the superior surface, but this is not related to disc position. However, this needs to be considered when doing arthroscopy of only the superior joint compartment.     

Neural structures within the sheep temporomandibular joint

To better understand pathologic processes associated with arthritis of the temporomandibular joint (TMJ), detailed information on the innervation of TMJ tissues in normal as well as arthritic joints is needed. The aim of this study was to describe the normal innervation of the sheep TMJ in preparation for using this animal as a model for the study of the effects of arthritis on joint innervation. The macroscopic and microscopic appearance plus the distribution of neural structures within the TMJ were examined using fluorescence histochemistry (glyoxylic acid), immunohistochemistry (calcitonin gene-related peptide), silver, and gold chloride techniques. Joints from 10 mature merino sheep were studied. Calcitonin gene-related peptide-immunoreactive nerve fibers were found in the capsule and the synovial membrane, but not in the disc. Nerve bundles and single nerve fibers in the capsule, synovial membrane, and the peripheral 2 to 3 mm of the disc were stained by glyoxylic acid. Ruffini, paciniform-type, and Golgi organ nerve endings plus free nerve endings were located in the capsule, with the highest density of nerve endings occurring at the site of attachment of the disc to the capsule. The highest density of neural structures (using gold chloride) was in the posterior part of the joint. The highest density of autonomic fibers (using glyoxylic acid) was in the anterior capsule. The highest density of sensory fibers (using calcitonin gene-related peptide) was in the synovial and subsynovial tissues of the anterior capsule. These results confirm the existence of autonomic and sensory nerves in the capsule, synovial membrane, and peripheral disc in healthy adult sheep.     

The natural course of anterior disc displacement without reduction in the temporomandibular joint: follow-up at 6, 12, and 18 months

PURPOSE: The purpose of this study was to examine the natural course of anterior disc displacement without reduction in the temporomandibular joint (TMJ). PATIENTS AND METHODS: The subjects were patients who had been diagnosed as having anterior disc displacement without reduction in the TMJ, but who had not undergone any treatment. Forty-four patients were followed for 6 months, 38 for 12 months, and 22 for 18 months. Clinical signs and symptoms were evaluated at each follow-up, and the incidence of successful resolution was determined using the criteria established in 1984 by the American Association of Oral and Maxillofacial Surgeons. RESULTS: The range of motion increased at each time during the follow-up period. Tenderness in the TMJ and the masticatory muscles was alleviated, but the noise in the TMJ remained unchanged at each follow-up time. The incidence of successful resolution was 34.1% at 6 months, 50.0% at 12 months, and 68.2% at 18 months. CONCLUSIONS: The clinical signs and symptoms of anterior disc displacement without reduction tend to be alleviated during the natural course of the condition. This should be taken into consideration when anterior disc displacement without reduction is treated.     

Arthroscopic management of temporomandibular joint disc perforations and associated advanced chondromalacia by discoplasty and abrasion arthroplasty: a supplemental report

PURPOSE: This article describes the results of treating temporomandibular joint (TMJ) articular disc perforation and advanced chondromalacia arthroscopically by the use of discoplasty and abrasion arthroplasty. PATIENTS AND METHODS: Forty-four joints were treated in 25 patients (23 females and 2 males). Twenty-nine disc perforations were present, 24 joints had grade III chondromalacia (fibrillated cartilage), and 14 joints had grade IV chondromalacia (exposed bone). Surgical procedures included 14 abrasion arthroplasties and 24 motorized shavings or holmium laser vaporizations. Holmium laser discoplasty with mobilization was used in 29 joints. Patients were followed-up for an average of 40.8 months (11 to 74 months). RESULTS: Preoperative pain on the visual analog scale (VAS) (1 to 10 cm) ranged from 5 to 10 cm, with an average of 7.4 cm. Postoperatively, nine patients had no pain and 16 patients had an average VAS of 2.7 cm (range, 1 to 5 cm). Preoperatively, 30 joints had clicking, and 14 joints had crepitation. Postoperatively, 25 joints had no noise, 12 joints had slight intermittent clicking, and seven joints had crepitation. The preoperative range of motion averaged 29.7 mm. Postoperatively, the range of motion averaged 37.7 mm (range, 33 to 42 mm). All patients could masticate a regular diet except hard food after an average of 40.8 months (11 to 74 months). CONCLUSIONS: These findings seem to justify the arthroscopic surgical procedures of discoplasty for disc perforations, motorized shaving, or holmium laser vaporization of grade III chondromalacia, and abrasion arthroplasty for bone exposure. The results also question the need for discectomy in the treatment of disc perforation.     

Morphologic changes in the elastic fibers of the temporomandibular joint after experimental disc perforation in the rabbit

PURPOSE: Elastic fibers in the attachment regions of the temporomandibular joint (TMJ) are considered important in the movements of the disc during jaw motion. This study was designed to determine whether there are change in the elastic fibers of the TMJ when the disc is perforated for a long period. MATERIALS AND METHODS: Each TMJ of five rabbits was surgically exposed, and a mediolateral perforation was made in the center of the articulating region of the disc with a scalpel. Five untreated and three sham-operated rabbits were used as controls. The TMJs were removed after 10 months and processed for histochemical demonstration of elastic fibers. RESULTS: Osteoarthritic changes and a significant decrease in number of the elastic fibers in the anterior-inferior attachment and posterior-inferior attachment of the TMJ disc were observed after disc perforation. Conversely, elastic fibers appeared in the fibrous tissue on the resorbed bone of the articular eminence. CONCLUSIONS: Experimental disc perforation changes the distribution and density of the elastic fiber in the TMJ as well as causes osteoarthritis. A knowledge of these facts may improve our understanding of perforation of the disc.     

Surgical management of temporomandibular joint ankylosis type III by retaining the displaced condyle and disc

PURPOSE: This article proposes a hypothesis regarding the value of saving the fractured condyle and disc in their displaced position in ankylosis type III for optimal temporomandibular joint (TMJ) function and growth, and describes four cases treated in this manner. PATIENTS AND METHODS: Four patients (three females and one male, 9 to 48 years old) with TMJ ankylosis type III of 3 to 8 years' duration, a maximal mouth opening of 15 to 19 mm, and severely limited lateral and protrusive movements were treated. The ankylosed sites were resected, leaving the displaced condyle and disc in their medial position. RESULTS: Fifteen to 60 months after surgery, the patients had a maximal mouth opening of 44 to 50 mm, as well as better contralateral and protrusive movements. In addition, two young patients (9 and 11 years old) showed an improved facial symmetry. CONCLUSIONS: Treatment of patients with type III TMJ ankylosis should involve retention rather than removal of the displaced condyle and disc. The condyle and disc are left untouched in their precarious medial position so as to provide normal function and growth.     

Biologic attachment of an allograft bone and tendon transplant to a titanium prosthesis

An Achilles tendon allograft with its bony insertion was used to bridge a Titanium implant, containing an endoprosthetic tendon anchor, and the sheep biceps muscle. Twelve sheep were operated on unilaterally and followed up clinically and histologically for 2, 4 (n = 2), 8, and 12 months (n = 4). Full function of the front limb was regained after 8 to 12 weeks. There were no signs of mechanical loosening at all times. The morphologic changes at the bone block and implant fixation site were an initial revascularization of the allograft bone, which was observed at 2 months and enhanced at 4 months but occurred without any evidence of bone remodeling. This was changed in all specimens taken at 8 and 12 months where intensive new bone development, remodeling, and bone ingrowth in the titanium implant was found. Bone mass was shifted significantly to the tendon insertion half of the bone block because of a creeping substitution of the cancellous allograft bone and bone ingrowth to the implant. Overall bone mass slightly decreased with time but resorption of allograft bone outweighed new bone development only at lesser loaded areas. Transplantation of a bone and tendon allograft to an implant resulted in a revitalized, mechanically stable, and biologically anchored compound.     

A balloon pumping technique for treatment of internal derangement of the temporomandibular joint

PURPOSE: This article reports on the use of a silicone or latex balloon to ablate adhesions associated with internal derangement of the temporomandibular joint (TMJ). MATERIALS AND METHODS: Wedge pressure catheters or Swan-Ganz catheters were used. The balloon was inflated with air and also moved forward and backward. RESULTS: TMJ arthroscopic balloon pumping therapy was performed on 11 joints in 11 cases of persistent closed locking. Ablation could be completed with only a balloon in seven joints. Maximal interincisal distances were increased in all cases. The increases ranged from a minimum of 3 mm to a maximum of 23 mm. TMJ pain was not recognized in any case in which 5 months or more had passed since surgery. TMJ noise (clicking) after surgery were recognized in six cases and was dependent on time after surgery. CONCLUSIONS: We are convinced that TMJ balloon pumping therapy is a useful and easy noninvasive method of ablation.     

The distinction between coronary and myocardial reperfusion after thrombolytic therapy by clinical markers of reperfusion

BACKGROUND: On the basis of a previous experience in a chronic sheep model in which partial mitral allografts remained viable and properly functioning 12 months after operation, we assessed the results obtained by replacing the tricuspid valve with fresh antibiotic-preserved mitral allografts. METHODS: Twenty 3-month-old sheep with a mean weight of 23.7 +/- 2.3 kg underwent cardiopulmonary bypass and had a fresh antibiotic-preserved mitral allograft implanted in the tricuspid position with the heart beating under normothermic conditions. The tricuspid valve apparatus was not excised. After a mean follow-up of 13.2 months, the allograft was evaluated by gross inspection and light and electron microscopy. RESULTS: Nine sheep died of technical causes within the first week after operation and 2 at 4 and 6 months of infective endocarditis of the allograft. The hemodynamic study before heart explantation revealed residual tricuspid incompetence in 3 of the 9 survivors. Macroscopic examination showed flexible valves with no signs of structural deterioration, calcification, or thrombosis. Under light and scanning electron microscopic examination, allografts were almost completely denuded of endothelial cells and showed loosely arranged connective tissue with scarce signs of inflammatory reaction. Despite these findings, allografts were free from major structural damage. CONCLUSIONS: The mitral homograft could be an alternative to replacement of the tricuspid valve with a bioprosthesis or a mechanical prosthesis.     

Uses of magnetic resonance imaging (MRI) in presurgical evaluation of internal derangement of temporomandibular joint (TMJ)

Nine cases of unilateral internal derangement of TMJ indicated for surgical intervention, were selected for this study. The affected joints were imaged by MRI presurgically. The non-affected joints were also imaged as controls. MRI findings were correlated with intraoperative surgical findings. The results were absolutely accurate as regards degenerative joint pathosis and capsular rupture, and with high degree of accuracy (85.7%) in detection of disc displacement. Two cases of disc perforation were not detected by MRI. The results were promising and encouraging the use of this noninvasive imaging technique as presurgical aid in TMJ disorders.     

A 2.5-Mb transcript map of a tumor-suppressing subchromosomal transferable fragment from 11p15.5, and isolation and sequence analysis of three novel genes

The purpose of this prospective study was to determine whether or not abrasion arthroplasty promotes cartilage regeneration in osteoarthritic (OA) knees with eburnation. Patients with OA knees were divided into a group of 51 knees treated by osteotomy with abrasion arthroplasty (Group A) and another group of 37 knees treated by osteotomy alone (Group B). Regeneration of cartilage was compared between the groups both arthroscopically and histologically. The Outerbridge classification was used for arthroscopic grading with Grade 0 being normal and Grade IV representing eburnation. On arthroscopic examination, around 12 months after surgery, Group A showed a significantly higher incidence of Grade II repair (a smooth articular surface and small fissures) and a lower incidence of Grade IV repair than Group B on both the femoral (P < .001) and tibial (P < .01) joint surfaces. Age was the only factor influencing the grade of tibial cartilage in Group A. Histological examination showed that 64% of the regenerated tissue studied consisted of fibro-cartilage at around 12 months after surgery. There was no difference in the clinical outcome at 2 to 9 years postoperatively between Groups A and B.     

Primary rhabdomyosarcoma of the brain: observations on a case with clinical and radiological evidence of cure

BACKGROUND: After heart transplantation, accelerated coronary vasculopathy is a major factor that limits long-term survival and is usually detected by serial coronary angiography. The aim of this study was to determine whether dobutamine stress echocardiography could accurately identify the progression of cardiac allograft vasculopathy. METHODS: Two sequential controls by dobutamine stress echocardiography were performed at an 18-month interval in 37 heart transplant recipients at the time of their routine coronary angiography. The first control (control 1) occurred 37+/-20 months after transplantation, and the second control (control 2) occurred after 56+/-21 months. Standard echocardiographic views were acquired at baseline and at incremental dobutamine infusion levels. Regional wall motion score was calculated in a 16-segment model, and each segment was graded from 1 (normal) to 4 (dyskinesia). Visual and quantitative coronary angiographic analysis were used to assess the severity of the coronary vasculopathy. RESULTS: The incidence of coronary vasculopathy increased from 46% (17/37 patients, four of whom had stenoses > 50%) at control 1 fo 70% (26/37 patients, six of whom had stenoses > 50%) at control 2. Progression of coronary vasculopathy was diagnosed by coronary angiography in 25 patients (new abnormalities in 19 and worsening of previous abnormalities in 6). Dobutamine stress echocardiography correctly identified the progression of vasculopathy in 21 of these 25 patients (84%) with new abnormalities in 17 and worsening in four. In the four remaining patients with evidence of progression of vasculopathy on coronary angiography, the result of dobutamine stress echocardiography was abnormal in three patients and normal in only one. Therefore dobutamine stress echocardiography results were abnormal in 12 patients at control 1 (sensitivity: 65%, specificity: 95%) and in 27 at control 2 (92% sensitivity, 73% specificity). CONCLUSION: Dobutamine stress echocardiography is a sensitive, noninvasive method to diagnose the progression of allograft vasculopathy, and a negative test result is a strong predictor of absence of allograft coronary vasculopathy. Therefore serial routine coronary angiography may be deferred when dobutamine stress echocardiography results are normal.     

Effects of sex hormones on protein and collagen content of the temporomandibular joint disc of the rat

PURPOSE: The effect of sex hormones on the protein and collagen content of the temporomandibular joint (TMJ) disc of adult male and female rats. MATERIALS AND METHODS: One hundred forty-four Wistar rats were assigned to 14 groups of 12 each. Two groups, one female and one male, served as a control and received no treatment, and two other groups (one female and one male) received a sham gonadectomy and placebo hormone. The remaining 10 groups (five males and five females) received either orchiectomy or ovariectomy, followed by administration of estrogen, progesterone, combined estrogen and progesterone, or testosterone. The total protein and collagen content of the TMJ disc were determined using the calorimetric hydroxyproline method. RESULTS: The collagen content of TMJ discs of control males was statistically greater than the collagen content of the control female rats. This difference disappeared after ovariectomy of females and orchiectomy of males. Also, there was a general trend for a decrease in collagen and protein content to be produced by estrogen, progesterone, and by estrogen combined with progesterone in castrated male and female rats, and by orchiectomy of male rats. There was also a trend toward an increase in collagen and protein content after ovariectomy in female rats and administration of testosterone to castrated male and female rats. However, the only statistically significant effect of the drugs tested was that of estrogen combined with progesterone in ovariectomized female rats (a lowering effect on the total protein) and of estrogen alone in orchiectomized male rats (a lowering effect on the collagen content). CONCLUSION: Steroid sex hormones have an effect on the collagen and protein content of the TMJ disc of the rat as indicated by the difference in the values between control males and females and by the disappearance of this difference on castration of both male and female animals. This was also manifested by the significant effect of estradiol on collagen content of castrated males, by the effect of estrogen combined with progesterone on the protein content of castrated females.     

Ultrastructural study on adhesions in internal derangement of the temporomandibular joint

PURPOSE: This study examined the ultrastructural characteristics of adhesions in the upper joint compartment of temporomandibular joint (TMJ). MATERIALS AND METHODS: Tissue biopsy specimens of adhesions were obtained during arthroscopic operation on 36 joints in 22 patients with internal derangement (ID). The biopsy specimens were examined by light and transmission electron microscopy. RESULTS: Adhesions were grossly divided into two types based on arthroscopic observation: 1) a band-like type, which connected the articular fossa and TMJ disc, and 2) a pseudowall-like type, which faced the synovial fluid and was lined by articular tissue. Two types of collagen arrangement were observed at the electron microscopic level: orderly arranged collagen bundles and randomly arranged collagen bundles. Orderly arranged collagen bundles were prominent in the band-like adhesions. In pseudowall-like adhesions, mainly the randomly arranged collagen bundles were seen. However, in some dense fiber parts, orderly arranged collagen bundles also were observed. In other pseudowall-like adhesions, only orderly arranged collagen bundles were seen. Elastic fibers were abundant in some pseudowall-like adhesions with randomly arranged collagen bundles. There were no elastic fibers in the band-like adhesions, some dense fiber parts of the pseudowall-like adhesion, pseudowall-like adhesions consisting of only orderly arranged collagen bundles, and in the synovial membrane. CONCLUSION: The different arrangement of collagen fibers and presence or absence of elastic fibers were observed in the two types of adhesions. These findings served to show that extracellular components correspond to a dysfunction involving an ID of TMJ.     

Disk displacement of the temporomandibular joint: correlation of magnetic resonance tomography and clinical findings

PURPOSE: To evaluate the value of magnetic resonance imaging (MRI) in symptomatic patients with different degrees of internal derangement. MATERIAL AND METHODS: We prospectively investigated 117 temporomandibular joints (TMJ) of 59 symptomatic patients and 31 asymptomatic volunteers and correlated this with clinical parameters. RESULTS: There was a positive correlation between the degree of internal derangement and deformity of the disc, maximal mouth opening, signal intensity of the posterior band, thickness of the bilaminar zone, proliferative bony changes, size of the condyle and reduced translation movement of the condyle, which in addition moved upward and backward. Patients most often complained of pain which was dependent on the degree of disc displacement and condylar changes. Clinical parameters were found to be inaccurate in predicting disc displacement. CONCLUSION: Patients with internal derangement of the temporomandibular joint may be asymptomatic. Patients history may give the only pointer to the disorder.     

Histomorphological and immunohistochemical evaluation of joint changes in a model of osteoarthritis induced by lateral meniscectomy in sheep

OBJECTIVE: To evaluate the histomorphological and immunohistochemical changes induced in cartilages of ovine stifle (knee) joints 6 months after unilateral lateral meniscectomy. METHODS: Osteochondral sections were obtained from 8 distinct regions of knee joints of 6 adult Merino wethers that 6 months earlier had undergone lateral meniscectomy. Joint regions of 6 age matched sheep housed under identical conditions were used for controls. Serial sections were stained with toluidine blue or immunolocalized with monoclonal antibodies (Mab) 3B3(-), 7D4, and 5B10, which recognize epitopes on proteoglycans. RESULTS: In control joints the cartilage from the region of the tibial plateau not protected by the meniscus had significantly (p < 0.005) more structural abnormalities than other joint regions. After meniscectomy, only cartilages in the lateral femorotibial compartment showed histomorphological changes consistent with osteoarthritis (OA). The nature and severity of the lesions differed between the topographical regions within the joint. The most severe were found on the lateral femoral condyles and tibial plateaus. Reactivity with Mab 3B3(-), 7D4, and 5B10 was increased only in the lateral compartment cartilages, and was stronger in mild rather than moderate OA. CONCLUSION: Six month lateral meniscectomy in sheep produces histomorphological and immunohistochemical cartilage changes analogous to those described for early human OA and in other animal models. The severity and type of lesions obtained were dependent on the topographical joint location, but were most evident in cartilages from the lateral compartment.     

Observations on the miraxonal attraction exercised by sexually immature or adult Biomphalaria glabrata infected or not by Schistosoma mansoni

With CT imaging, the lumbar facet joints are well visualised and enlargement secondary to degeneration may be noted. We measured the cross-sectional area of the superior articular process of the L5 facet joint in 100 consecutive CT scans and in 71 patients, the L4 process was also measured. We found that the mean cross-sectional area was significantly larger at L5 than at L4. Patient age and sex had no significant effect on the size at either L4 or L5. A review of the radiological reports revealed that the 13 patients with degenerative facet joints and radiologically normal discs did not have significantly larger facet joints than the 35 patients with disc disease and radiologically normal facet joints. In conclusion, the term "facet joint hypertrophy" should not be used when osteoarthritic changes are noted on CT scan, because these joints are not significantly larger than normal facet joints.     

Histological integration of allogeneic cancellous bone tissue treated by supercritical CO2 implanted in sheep bones

Different chemical or physical methods of bone processing have been developed to decrease the antigenicity of allogeneic bone which may delay or prevent graft integration. We have developed a method based on delipidation and deproteination of the bone with a supercritical fluid and hydrogen peroxide. Cylinders of cancellous allogeneic bone treated in this way were implanted for four weeks, four months or eight months in holes drilled in sheep condyles or tibial plateau. Histological sections were then processed and analysed qualitatively and quantitatively using an image analysis software coupled to a light microscope. Measurements were made of the trabecular bone surface (BS/TS), the relative osteoid surface (OS/BS), the active osteoid surface (OS/BS), active resorption surface (Oc.S/BS) and the relative surface of newly formed bone. After four weeks, the control cylinders (non-treated allogeneic bone) had been invaded by cellular tissue composed of lymphocytes and plasmocytes surrounding remnants of the donor bone marrow tissue. The processed cylinders showed osteoid apposition at the surface of their external trabeculae. The trabecular bone and osteoid surfaces were significantly higher in the processed bone sections than in the control bone sections. After four months, most of the control material had been osteolysed and replaced by connective tissue containing lymphocyte islets, while the processed materials showed a large amount of bone synthesized at the surface of implant trabeculae which appeared fragmented and disseminated within the newly formed bone. All the histomorphometric parameters measured were significantly different from those of the control. By eight months, most of the control material had been totally osteolysed with very little bone ingrown in the implantation site. Only one control implant had been integrated. The processed cylinders were difficult to discern from the bone in which they were implanted. The parameters measured on the processed cylinders were significantly higher than those measured on the control sections. IN CONCLUSION: the treatment applied to the bone enhanced allogeneic bone integration and could provide a new kind of tissue treatment for bone banking.     

Development and histologic characterizations of an animal model of antigen-induced arthritis of the juvenile rabbit temporomandibular joint

Children with juvenile rheumatoid arthritis or juvenile chronic arthritis often exhibit temporomandibular joint (TMJ) involvement accompanied by pain, dysfunction, and growth abnormalities. Despite the severe functional and developmental consequences of this disease, its pathogenesis remains poorly understood, but important insights may be provided by a suitable animal model of this disease. The purpose of this study was to develop and histologically characterize a juvenile animal model of antigen-induced arthritis of the TMJ. Arthritis was induced with an intra-articular administration of ovalbumin in previously sensitized 10-week-old male New Zealand white rabbits. Sham-treated and untreated rabbits were used as controls. The TMJs were retrieved en bloc at 5, 10, 15, 35, and 55 days post-challenge for histology and matrix histochemistry. Antigen-treated joints demonstrated severe arthritis, including mononuclear cell infiltration, synovial lining and villous hyperplasia, and pannus formation, as early as 5 days after challenge; the arthritis was maintained up to 55 days post-challenge. A decrease in the area of the TMJ disc that stained positively for glycosaminoglycans was observed throughout the experimental period. Loss of collagen staining was primarily localized to sites at the junction of the synovium with bone and fibrocartilage. The histopathologic features of this model of antigen-induced arthritis of the juvenile rabbit TMJ are similar to those observed previously in adult animal models of experimental arthritis and in human rheumatoid arthritis. This animal model will be useful for understanding the pathogenesis of juvenile rheumatoid arthritis of the TMJ, and for exploring the mechanisms for aberrant craniofacial growth.     

Matrix metalloproteinase activity in equine synovial fluid: influence of age, osteoarthritis, and osteochondrosis

OBJECTIVE: To investigate the influence of age, osteoarthritis (OA), and osteochondrosis (OC) on the matrix metalloproteinase (MMP) activity in the synovial fluid (SF) of equine joints. METHODS: SF was collected from normal and osteoarthritic metacarpophalangeal joints (normal: 14 adult, 28 juvenile; OA: 22 adult). And from normal and osteochondrotic tarsocrural joints (5 months: 11 normal, 8 OC; 11 months: 7 normal, 6 OC). Subsequently, overall MMP activity was measured. RESULTS: The level of active MMPs was almost twofold higher in SF from juvenile horses (age up to 11 months) than in SF from mature animals (4-30 years; p < 0.001). In juvenile horses MMP activity was higher in 5 month old foals than in 11 month old foals (p < 0.01). In adult horses MMP activity was independent of age. In OA joints the activity was nearly twice as high as in normal joints (p < 0.001). In OC joints MMP activity was not significantly different from normal, age matched, control joints. CONCLUSIONS: MMP activity in SF from normal adult joints is not related to age. In juvenile joints MMP activity is significantly higher than activity in joints from adult animals. It is hypothesised that the gradual decrease in MMP activity with increasing age reflects the declining metabolic activity resulting from ceasing growth and the accompanying decrease in cartilage remodelling. The increased MMP activity in osteoarthritis joints most likely reflects matrix destruction. In osteochondrosis MMP mediated matrix degradation appears not to be different from normal joints.