Alloplastic Total Temporomandibular Joint Replacement in Degenerative Joint Diseases: A Systematic Review and Meta-Analysis.

BACKGROUND: Degenerative temporomandibular joint (TMJ) disorders are a major cause of chronic pain and functional limitation. Evidence specific to alloplastic total temporomandibular joint replacement (TJR) in degenerative pathology remains heterogeneous and incompletely synthesized. PURPOSE: To evaluate the therapeutic effectiveness of alloplastic TJR in subjects with degenerative TMJ disease who failed conservative and joint-preserving treatments. DATA SOURCES: This systematic review was prospectively registered in PROSPERO (CRD420261280616). Electronic searches were conducted in PubMed, Embase, Scopus, and ScienceDirect, along with ClinicalTrials.gov and the Clinical Trials Registry of India, from inception through December 31, 2025. Manual journal searches were also performed. Only English-language human studies were included. STUDY SELECTION: Randomized and observational clinical studies reporting outcomes of unilateral or bilateral alloplastic TJR performed exclusively for degenerative TMJ disease were included. Degenerative TMJ disease was operationally defined a priori using a Population, Intervention, Comparator, Outcomes, Time and Study Design-based framework as structural joint degeneration due to osteoarthritis, idiopathic condylar resorption, or inflammatory arthropathies (eg, rheumatoid arthritis, juvenile idiopathic arthritis). Study selection was performed independently by 2 reviewers. DATA EXTRACTION AND SYNTHESIS: Data extraction and quality assessment followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines. Risk of bias was assessed using Risk Of Bias In Non-randomized Studies of Interventions. Random-effects meta-analysis with inverse-variance weighting was performed. MAIN OUTCOMES AND MEASURES: Primary outcomes were postoperative TMJ pain reduction and improvement in maximum mouth opening. Secondary outcomes included dietary function and postoperative complications. RESULTS: Eleven observational studies (n = 366 subjects) were included. Meta-analysis demonstrated statistically significant reductions in TMJ pain (standardized mean change = -3.67; 95% CI: -5.69 to -1.65; P < .001), improvement in maximum mouth opening (mean difference = 7.81 mm; 95% CI: 3.99 to 11.64 mm; P < .001), and dietary function (standardized mean change = -3.05; 95% CI: -3.61 to -2.49; P < .001). Subgroup analysis showed greater improvements among subjects with osteoarthritis. Despite substantial heterogeneity, sensitivity analyses confirmed the robustness of findings. CONCLUSIONS AND RELEVANCE: Alloplastic TJR is associated with statistically significant improvements in TMJ pain, mandibular function, and dietary capacity in subjects with degenerative TMJ disease refractory to conservative therapy. These findings support TJR as a definitive reconstructive option in appropriately selected subjects.