Does the Amount of Screw Fixation Utilized for the Condylar Component of the TMJ Concepts Total Temporomandibular Joint Reconstruction Predispose to Hardware Loss or Postoperative Complications?

PURPOSE: To determine whether the number of screws used to fixate a TMJ Concepts total joint prosthesis correlates with loss of hardware fixation or postoperative complications. MATERIALS AND METHODS: A retrospective cohort study of patients undergoing total temporomandibular joint (TMJ) reconstruction with the TMJ Concepts custom prosthesis at the Mayo Clinic from 2005 to 2015 was undertaken. The primary predictor variable was the percentage of screw fixation used in the condylar component. The primary outcome variable was loss of hardware fixation. Secondary outcome variables included postoperative wound infection, removal of hardware, and return to the operating room. Covariates abstracted included patient demographics, comorbidity indices, preoperative occlusion, contralateral TMJ reconstruction, performing surgeon, duration of procedure and anesthesia, intraoperative fluid administration, concomitant surgical procedures, perioperative antibiotics, prior TMJ surgeries, prior Proplast Teflon implantation, prior head and neck radiation, use of heterotopic ossification radiation protocol, and use of the 2 most superior screw holes in the condylar component. RESULTS: The study sample was composed of 45 patients representing 64 TMJ Concepts reconstructions. Mean age was 49.1 years (standard deviation, 13.4 yr; range, 19 to 85 yr). The female distribution was 86%. There were 15 simultaneous bilateral reconstructions, 26 unilateral reconstructions, and 4 staged bilateral reconstructions. Eighteen reconstructions (28%) were placed using 100% of the available screw holes in the condylar component. Forty-six reconstructions (72%) were placed using fewer than 100% of the available screw holes in the condylar component (range of screw fixation, 56 to 89%). The minimum number of screws used to fixate the condylar component was 5, which was observed in 9 reconstructions (14%). There was no postoperative loss of hardware fixation in any reconstruction under study. Six reconstructions showed a postoperative complication defined by the secondary outcomes. Univariable or multivariable modeling was precluded for the primary and secondary outcomes owing to the low frequency of observed complications. CONCLUSION: Fixating the condylar component of the TMJ Concepts total joint prosthesis using fewer than 100% of the available screw holes does not predispose the reconstruction to hardware loss, particularly if greater than 50% screw fixation can be achieved or a minimum of 5 screws are used.