计算机导航辅助下口内入路髁突切除术精确性分析

目的:在计算机导航辅助下,通过口内入路进行下颌骨髁突切除术,评估其术前设计方案在术中实现的精确性,并分析误差产生的部位和原因,为术式改良提供参考和思路。方法:收集2012年12月至2016年12月,在北京大学口腔医学院口腔颌面外科接受计算机导航辅助下口内入路髁突切除术的患者资料共23例。术前将患者螺旋CT数据导入ProPlan软件,将患侧下颌升支进行三维重建并根据病变范围设计髁突截骨线,生成术前设计模型,导入BrainLab导航系统,术中在计算机导航辅助下,采用口内入路,按术前设计截骨线完成髁突切除术。术后1周内拍摄颅颌面部螺旋CT,将术后患侧下颌升支进行三维重建,生成术后即刻模型,应用Geomagic软件将术前设计模型与术后即刻模型进行对齐,并在术后即刻模型的实际截骨面划分6个区域并定义相应区域测量点P1~P6,比较术前设计截骨面与术后实际截骨面在三维空间位置上的偏差,分析导航辅助手术实施的精确性。结果: 23例患者均顺利完成手术,获得满意疗效,术后CT复查病变完整切除,髁突截骨线与手术设计基本吻合。术后随访期内未见肿物复发及关节粘连。术后对髁突切除术实施精确性的验证分析显示,P1~P6共6组测量点所测得的偏差可信区间分别为(-2.26 mm,-1.89 mm),(-2.30 mm,-1.45 mm),(-3.37 mm,-2.91 mm),(-2.83 mm,-1.75 mm),(-1.13 mm, 0.99 mm),(-1.17 mm, 0.17 mm), 其中P3组与其他5组比较差异均有统计学意义,P5、P6组间差异无统计学意义而与其他4组差异有统计学意义。结论: 在计算机导航辅助下可以较精确地完成口内入路髁突切除术;截骨面各部位的手术偏差以过多切除为主,其中前内侧测量点所代表的髁突前内侧区域实际过多切除现象最明显,后侧、后外侧测量点所代表的髁突后外侧区域平均偏差不大,但偏差值的波动较其他4组大;计算机导航辅助下髁突切除术的精确性还有待提高。

Accuracy analysis of computer assisted navigation for condylectomy via intraoral approach

Objective: To explore the application accuracy of virtual preoperative plan after the condylectomy via intraoral approach under computer assisted surgical navigation, and to analyze the location and cause of the surgical deviation to provide reference for the surgical procedure improvement in the future. Methods: In the study, 23 cases with condylar hypertrophy (11 with condylar osteochondroma and 12 with condylar benign hypertrophy) in Department of Oral and Maxilloficial Surgery, Peking University School and Hospital of Atomatology from December 2012 to December 2016 were treated by condylectomy via intraoral approach under computer assisted surgical navigation. The patient’s spiral CT data were imported into ProPlan software before operation, and the affected mandibular ramus was reconstructed three-dimensionally. The condylar osteotomy line was designed according to the lesion range, and the preoperative design model was generated and introduced into the BrainLab navigation system. Under the guidance of computer navigation, the intraoral approach was used to complete the condylar resection according to the preoperative design of the osteotomy line. Cranial spiral CT of the craniofacial region was taken within one week after operation. Three-dimensional reconstruction of the mandibular ramus at the condylectomy side was performed, and the condylar section was divided into six segments (anterolateral, anterior, anteromedial, posteromedial, posterior, and posterolateral) and the corresponding regional measurement points P1 to P6 were defined. Then the preoperative virtual model and the postoperative actual model were matched by Geomagic studio 12.0 to compare the differences and to analyze the accuracy of the operation. Results: All the patients had successfully accomplished the operation and obtained satisfactory results. Postoperative CT showed that the condyle lesion was completely resected, and the condylar osteotomy line was basically consistent with the surgical design. No tumor recurrence or temporomandibular joint ankylosis during the follow-up period. The postoperative accuracy analysis of the condylar resection showed that the confidence intervals measured by the six groups of P1 to P6 were(-2.26 mm, -1.89 mm), (-2.30 mm, -1.45 mm),(-3.37 mm, -2.91 mm),(-2.83 mm, -1.75 mm),(-1.13 mm, 0.99 mm), and(-1.17 mm, 0.17 mm), where P3 group was different from the other 5 groups. There was no significant difference between the P5 and P6 groups and the difference between the other four groups was statistically significant. Conclusion: Under the guidance of computer navigation, the intraoral approach can be performed more accurately. The surgical deviation of each part of the osteo-tomy surface is mainly due to excessive resection. The anterior medial area of the anterior medial condyle represents the most excessive resection. The posterior and posterior lateral measurement points represent the posterior condylar area. The average deviation is not large, but the fluctuation of the deviation value is larger than that of the other four groups. The accuracy of computer-assisted subtotal resection has yet to be improved.