USE OF A CT-BASED NAVIGATION SYSTEM TO INSERT CUSTOM-MADE STEMS INTO DYSPLASTIC HIPS AFTER INTERTROCHANTERIC OSTEOTOMY IN JAPANESE PATIENTS

Introduction Deformity after femoral osteotomy varies between patients. Some researchers reported good results when using cemented stems for the hips after femoral osteotomy, but there are many disadvantages that obstruct ideal fixation using cemented stems. Therefore, we developed cementless custom-made stems and inserted those using a computed tomography (CT) –based navigation system Methods Eighteen dysplastic hips of 15 patients after intertrochanteric osteotomy were investigated in the present study. Individual computed tomography data were used to manufacture cementless custom-made femoral stems out of Ti-6Al-4V. The proximal 1/3 of each stem was coated using porous coating covered with hydroxyapatite coating. The stems were inserted using a CT-based fluoro navigation system for accuracy of insertion. The average patient age at time of surgery was 66 years, and the average follow-up period was 3.5 years. Results No fracture was observed during any surgery or follow-up period. The average preoperative Harris Hip Score was 44 points, and the average postoperative score was 85 points. No patient complained of postoperative thigh pain. The average difference between preoperatively planned anteversion and postoperative anteversion was 2° (range 0–5°). According to Engh9s radiological classification system, there was bone ingrowth fixation in all hips. Conclusions The technique of inserting the custom-made stems using a computed tomography-based navigation system was useful; however, there was an associated increase in manufacture time and cost.