Influence of preoperative anatomy and functional status on outcomes after total temporomandibular joint replacement with patient-specific endoprostheses: A retrospective cohort study.

Abstract

BACKGROUND Temporomandibular joint (TMJ) replacement may be indicated for various pathological conditions, and the type of condition can affect the surgical procedure and outcomes. The causes of limited range of motion after alloplastic TMJ replacement have not been extensively studied. OBJECTIVES The present study aimed to evaluate the impact of preoperative jaw anatomy and functional status on the immediate and long-term outcomes of total TMJ replacement using a two-component patient-specific TMJ endoprosthesis. MATERIAL AND METHODS This retrospective study included 31 patients who underwent total TMJ replacement surgery between 2016 and 2020. The main outcome variable was the maximal incisal opening (MIO) after treatment. Secondary outcome variables included MIO improvement and the presence and type of postoperative complications. The primary predictive variable was the preoperative initial MIO. Secondary predictive variables included sex, age, indications for TMJ replacement, preoperative occlusion, condition of the glenoid fossa and/or condyle, shortening of the mandibular ramus, sagittal mandible position, lateral chin deviation, shape of the coronoid process, and type of surgery. RESULTS The mean preoperative MIO was 13.0 ±8.0 mm, while the mean MIO 1 month after surgery was 20.6 ±5.5 mm, which was not statistically significant. However, at a later follow-up, functional parameters showed a significant improvement (p = 0.003), with a mean MIO of 32.5 ±5.0 mm 3 years after surgery. Statistical analysis indicated that the initial mouth opening is the strongest predictor of long-term functional recovery after TMJ replacement. Postoperative complications occurred in 4 cases (12.9%) following patient-specific endoprosthesis (PSE) placement. CONCLUSIONS The use of PSEs for TMJ replacement has enabled the restoration of anatomical relationships in complex clinical cases and an improvement in mouth opening. The preoperative MIO was the only factor that significantly influenced long-term functional outcomes.