Role of interstitial fluid pressurization in TMJ lubrication.
In temporomandibular joints (TMJs), the disc and condylar cartilage function as load-bearing, shock-absorbing, and friction-reducing materials. The ultrastructure of the TMJ disc and cartilage is different from that of hyaline cartilage in other diarthrodial joints, and little is known about their lubrication mechanisms. In this study, we performed micro-tribometry testing on the TMJ disc and condylar cartilage to obtain their region- and direction-dependent friction properties. Frictional tests with a migrating contact area were performed on 8 adult porcine TMJs at 5 different regions (anterior, posterior, central, medial, and lateral) in 2 orthogonal directions (anterior-posterior and medial-lateral). Some significant regional differences were detected, and the lateral-medial direction showed higher friction than the anterior-posterior direction on both tissues. The mean friction coefficient of condylar cartilage against steel was 0.027, but the disc, at 0.074, displayed a significantly higher friction coefficient. The 2 tissues also exhibited different frictional dependencies on sliding speed and normal loading force. Whereas the friction of condylar cartilage decreased with increased sliding speed and was independent of the magnitude of normal force, friction of the disc showed no dependence on sliding speed but decreased as normal force increased. Further analysis of the Péclet number and frictional coefficients suggested that condylar cartilage relies on interstitial fluid pressurization to a greater extent than the corresponding contact area of the TMJ disc.
['Zimmerman|B K|BK|', 'Bonnevie|E D|ED|', 'Park|M|M|', 'Zhou|Y|Y|', 'Wang|L|L|', 'Burris|D L|DL|', 'Lu|X L|XL|']
D000818:Animals D001696:Biomechanical Phenomena D002358:Cartilage, Articular D003094:Collagen D005260:Female D017276:Friction D007368:Interferometry D017746:Joint Capsule D008153:Lubrication D008297:Male D008335:Mandibular Condyle D009068:Movement D011312:Pressure D013232:Steel D013314:Stress, Mechanical D013552:Swine D013582:Synovial Fluid D013704:Temporomandibular Joint D019224:Temporomandibular Joint Disc
TMJ disc friction articular cartilage fibrocartilage mandibular condyle permeability