Abstract: PURPOSE: We design and fabricate a digital guide to help retaining the residual condyle in the lateral gap arthroplasty (LAP) of temporomandibular joint ankylosis (TMJA) and evaluate the effect. METHODS: All TMJA patients treated in our department from January 2012 to January 2014 were included for the study with the inclusion criteria as follows there was a residual condyle on the coronal CT and digital guides were designed to help retaining the residual condyle in LAP; ProPlan CMF 1.4 software (Materialise Medical, Leuven, Belgium) was used to complete preoperative design. Range and relation between bone fusion and residual condyle was determined. The guides were designed and made by stereolithography, and then applied in surgeries. The effect of the digital guides including the intraoperative fitness and protection of important structures was evaluated. The fusion results of the postoperative CT and preoperative design were analyzed. RESULTS: Among the total 5 surgeries with 7 joints, the digital guides fit well and accurately guide the osteotomy. The residual condyle, skull base and external auditory canal were well protected. Postoperative CT showed the average difference between the surgical results and the preoperational designs was 1.044 mm. CONCLUSIONS: Digital guides can accurately guide the osteotomy of the lateral bone fusion and protect residual condyle, skull base and external auditory canal.

Key words: Residual condyle, Digital guide, Temporomandibular joint ankylosis, Lateral gap arthroplasty