[Effectiveness analysis of resection and reconstruction of primary bone tumor in pelvic zone Ⅱ]

To investigate the effectiveness of complete resection of bone tumor in pelvic zone Ⅱ and reconstruction with allogeneic pelvis, modular prosthesis, and three-dimensional (3D) printing prosthesis.

The clinical data of 13 patients with primary bone tumor in pelvic zone Ⅱ who underwent tumor resection and acetabular reconstruction between March 2011 and March 2022 were retrospectively analyzed. There were 4 males and 9 females with an average age of 39.0 years ranging from 16 to 59 years. There were 4 cases of giant cell tumor, 5 cases of chondrosarcoma, 2 cases of osteosarcoma, and 2 cases of Ewing sarcoma. The Enneking classification of pelvic tumors showed that 4 cases involved zone Ⅱ, 4 cases involved zone Ⅰ and zone Ⅱ, and 5 cases involved zone Ⅱ and zone Ⅲ. The disease duration ranged from 1 to 24 months, with an average of 9.5 months. The patients were followed up to observe the recurrence and metastasis of the tumor, and the imaging examination was performed to observe the status of implant in place, fracture, bone resorption, bone nonunion, and so on. The improvement of hip pain was evaluated by visual analogue scale (VAS) score before operation and at 1 week after operation, and the recovery of hip function was evaluated according to the Musculoskeletal Tumor Society (MSTS) scoring system after operation.

The operation time was 4-7 hours, with an average of 4.6 hours; the intraoperative blood loss ranged from 800 to 1 600 mL, with an average of 1 200.0 mL. There was no reoperation or death after operation. All patients were followed up 9-60 months (mean, 33.5 months). No tumor metastasis was found in 4 patients receiving chemotherapy during follow-up. Postoperative wound infection occurred in 1 case, and prosthesis dislocation occurred in 1 case at 1 month after prosthesis replacement. One case of giant cell tumor recurred at 12 months after operation, and the puncture biopsy showed malignant transformation of giant cell tumor, and hemipelvic amputation was performed. The postoperative hip pain significantly relieved, and the VAS score was 6.1±0.9 at 1 week after operation, which was significantly different from the preoperative score (8.2±1.3) ( t=9.699, P<0.001). At 12 months after operation, the MSTS score was 23.0±2.1, including 22.8±2.1 for patients with allogenic pelvis reconstruction and 23.3±2.3 for patients with prosthsis reconstruction. There was no significant difference in the MSTS score between the two reconstruction methods ( t=0.450, P=0.516). At last follow-up, 5 patients could walk with cane assistance and 7 patients could walk without cane assistance.

The resection and reconstruction of primary bone tumor in pelvic zone Ⅱ can obtain satisfactory hip function, and the interface of allogeneic pelvis and 3D printing prosthesis have better bone ingrowth, which is more in line with the requirements of biomechanics and biological reconstruction. However, pelvis reconstruction is difficult, the patient's condition should be evaluated comprehensively before operation, and the long-term effectiveness needs further follow-up.