A new modification of the Trapdoor Procedure without surgical hip dislocation in the management of patients with osteonecrosis of the femoral head: A retrospective case series

Objective: The aim of this paper was to investigate the mid-term results of a modified Trapdoor procedure that can allow grafting of the femoral head without surgical hip dislocation in the management of patients with osteonecrosis of the femoral head. Methods: 16 hips of 12 patients (7 female, 5 male; mean age = 38.5 +/- 10.7) surgically treated by the new modification of Trapdoor procedure were retrospectively reviewed and included in the study. Based on the Association Research Circulation Osseous (ARCO) classification system, seven hips (43.7%) were stage 2, and nine hips (56.3%) were stage 3. The mean follow-up was 48.4 +/- 25.7 months (range = 12-107). All the patients were evaluated postoperatively at the 6th week, 3rd month, 6th month, 1st year, and annually thereafter until their final follow-up. Clinical assessment was performed using the Harris Hip scoring (HHS) system, Non-Arthritic Hip score (NAHS) and Visual analogue pain scale (VAS). At the final follow-up, degenerative changes were examined according to the Kellgren-Lawrence scale. Results: The mean HHS increased from 53.43 +/- 9.0 (range = 36-67) preoperatively to 83.81 +/- 6.1 (range = 72-95) at the final follow-up (P < 0,001). The mean NAHS increased from 51.5 +/- 8.2 (range = 36.25-61.25) preoperatively to 86 +/- 3.2 (range = 81.5-90) (P < 0,001) at the final follow-up. The mean preoperative VAS decreased from 7.85 +/- 0.9 (range = 6.45-9.5) to 3.05 +/- 0.9 (range = 1.6-5.2) (P < 0,001) at the final follow-up. 13 hips demonstrated 80 and higher scores according to HHS. In the remaining three hips (ARCO stage 3), the mean postoperative HHS, NAHS, and VAS scores were 76, 82, and 3,2 respectively. According to Kellgren-Lawrence scale, three hips (18,75%) were determined as grade 0, 10 hips (62.5%) as grade 1, and 3 hips (18.75%) as grade 2. Conclusion: The Modified Trapdoor procedure without surgical hip dislocation seems to be a suitable technique with favorable clinical outcomes for the treatment of ARCO stage 2 and stage 3 osteonecrosis of the femoral head.