Gene expression of fibrinolytic factors urokinase plasminogen activator and plasminogen activator inhibitor-1 in rabbit temporo-mandibular joint cartilage with disc displacement

Background The urokinase plasminogen activator system is believed to play an important role in degradation of the extracellular matrix associated with cartilage and bone destruction; however its precise roles in temporomandibular disorders have not yet been clarified. The aims of this study were to investigate the gene expression of fibrinolytic factors urokinase plasminogen activator (uPA) and plasminogen activator inhibitor-1 (PAI-1) in the articular cartilage of rabbit temporomandibular joint (TMJ) with disc displacement (DD) and to probe the relationship between fibrinolytic activity and cartilage remodeling. Methods Disc displacement of right joints was performed in 36 of 78 rabbits under investigation. The animals were sacrificed at 4 days and 1, 2, 4, 8 and 12 weeks after surgery, respectively. The right joints of these animals were harvested and processed for the examination of mRNA expression of uPA and PAI-1 in articular cartilage using in situ hybridization techniques. Results The expression of uPA and PAI-1 was co-expressed weakly in the chondrocytes from transitive zone to hypertrophic zone and mineralized zone, while no hybridizing signals were shown in proliferative zone and superficial zone in control rabbits. The most striking was the up-regulation of uPA and PAI-1 mRNA in 4-day rabbits postoperatively at the onset of cartilage degeneration. The strongest hybridizing signals for uPA and PAI-1 were seen in 2-week rabbits postoperatively. After 2 weeks, the expression of uPA and PAI-1 began to decrease and reached nearly normal level at 12 weeks. Conclusions The expression of the uPA/PAI-1 system coincides with the pathological changes in condylar cartilage after DD. The uPA/PAI-1 system may be one of the essential mediators in articular cartilage remodeling.

Mini suture anchor: An effective device for reduction and fixation of displaced temporomandibular joint disc with intracapsular condylar fracture

Purpose::The main aim is to provide clinical reference for the application of mini suture anchor in the reduction and fixation of displaced temporomandibular joint(TMJ)disc with intracapsular condylar fracture.Methods::From October 2018 to October 2019,21 patients(31 sides)with intracapsular condylar fractures and articular disc displacement from West China Hospital of Stomatology,Sichuan University were included.The selection criteria were:(1)mandibular condylar fractures accompanied by displacement of the TMJ disc,confirmed by clinical examination,CT scan and other auxiliary examinations;(2)indication for surgical treatment;(3)no surgical contraindications;(4)no previous history of surgery in the operative area;(5)no facial nerve injury before the surgery;(6)informed consent to participate in the research program and(7)complete data.Patients without surgical treatment were excluded.The employed patients were followed up at 1,3,6 and 12 months after operation.Outcomes were assessed by success rate of operation,TMJ function and radiological examination results at 3 months after operation.Data were expressed as number and percent and analyzed using SPSS 19.0.Results::All the surgical procedures were completed successfully and all the articular discs were firmly attached to the condyles.The articular disc sufficiently covered the condylar head after the fixation.The fixation remained stable when the mandible was moved in each direction by the surgeons.No complications occurred.The functions of the TMJ were well-recovered postoperatively in most cases.CT scan revealed that the screws were completely embedded in the bone without loosening or displacement.Conclusion::Mini suture anchor can provide satisfactory stabilization for the reduced articular disc and also promote the recovery of TMJ functions.