En Bloc Resection and Pelvic Ring Reconstruction for Primary Malignant Bone Tumors Involving Sacroiliac Joint.

OBJECTIVE: To observe the process of sacroiliac joint invasion by primary malignant tumors of sacrum and iliac bone, and to explore the methods of surgical resection and reconstruction. METHODS: From January 2009 to November 2017, there were nine patients with primary malignant bone tumors involving sacroiliac joints, five males and four females, aged from 16 to 63 years, with an average age of 35 years. Of these there were three cases of primitive neuroectodermal tumors, three cases of chondrosarcoma, and three cases of osteosarcoma. Pelvic ring reconstruction was performed with longitudinal half sacrum, sacroiliac joint and partial iliac bone block excision and screw-rod system combined with bone grafting. RESULTS: The operation time was 155-310 min, with an average of 245 ± 55 min, and the bleeding volume was 1400-8500 ml, with an average of 3111 ± 2189 ml. Follow-up ranged from 5 to 108 months, with a median follow-up of 24 months. Three patients (33.3%) had local recurrence, three patients (33.3%) survived without tumors, and one patient had lung metastasis 2 years after operation, and survived with tumors. Five patients (55.6%) died, of which four died of lung metastasis and one died of brain metastasis. Survival analysis showed that the 3-year overall survival rate was 57%. Bone grafts did not heal in four patients, and bone grafts healed in five patients. The healing time ranged from 5 to 7 months, with an average of 6.2 months. COMPLICATIONS: one patient developed deep infection 2 months after operation; one patient had skin edge necrosis; titanium rod loosening and displacement were found in two patients with nonunion of bone graft, and no fracture of nail rod was found. The MSTS 93 functional score of nine patients ranged from 20% to 50%, with an average of 34%. CONCLUSION: The tumors around the sacroiliac joint often invade the contralateral bone by ligament, and the en bloc resection and pelvic ring reconstruction for primary malignant bone tumors involving sacroiliac joint was feasible.