Participants
From January 2016 to June 2020, a total of 33 patients with pelvic ischium and inferior pubic branch involving acetabular tumors were reviewed from the department of bone oncology of Shanghai General Hospital Affiliated to Shanghai Jiaotong University. 20 patients were included in this study. There were 12 males and 8 females; The age ranged from 19 to 76 years, with an average of 45.8 years; It included 6 cases of chondrosarcoma, 6 cases of osteosarcoma, 2 cases of epithelioid sarcoma, 1 case of renal cancer metastasis, 1 case of lung cancer metastasis, 1 case of liver cancer metastasis and 3 cases of giant cell tumor of bone; All 20 patients involved the hip joint, which was divided into zone II + III according to Enneking pelvic tumor division.
Preoperative Management
20 patients in this group underwent biopsy before operation to confirm pathology. The main symptoms before operation were local pain. there were 10 cases of osteolytic destruction, osteogenic destruction in 6 cases and mixed bone destruction in 4 cases. All patients underwent X-ray, CT scan and MRI before operation, and PET-CT scan to determine the general condition and metastatic status. This study has been approved by the ethics committee of our hospital, and all patients signed informed consent.
All patients underwent preoperative internal iliac angiography to determine the tumor blood supply and tumor vascular embolization within 1–2 days before operation. According to the blood supply of internal iliac artery branches, gelatin sponge embolization was routinely used during operation. Patients with giant cell tumor of bone should use desudumab (120 Mg, 3–4 times) before operation, the patients with abundant blood supply can be blocked by abdominal aortic balloon or ligated by internal iliac artery during operation. The pelvic bone and soft tissue involvement was evaluated by enhanced CT and magnetic resonance images, and the osteotomy during operation was determined. The acetabular defect was often repaired with appropriate tantalum metal patch or autologous femoral head patch combined with cannulated screw fixation.
Tumor Resection And Reconstruction
In brief, general anesthesia was applied to all patients, patients were then placed with lateral position, slightly pading up the affected lower limb, and maintain the neutral position of the lower limb. During the operation, the affected limb can bend the hip and knee, adduct and rotate the lower limb, and the pelvis is perpendicular to the operating table. The affected lower limbs were routinely disinfected, and the proximal end was disinfected to a 15cm area near the proximal end of the iliac spine. The skin incision is shown in Fig. 1. The incision passes through the posterior lower corner of greater trochanter to the area between sciatic nodules, with a length of about 20–25 cm. The osteotomy plan was determined through intraoperative fluoroscopy combined with preoperative CT and MRI reconstruction. For patients with difficulty in osteotomy, the tumor was completely removed through intraoperative o-arm combined with intraoperative navigation and positioning.
For patients involving acetabulum, the acetabular bone defect was reconstructed individually according to the acetabular bone defect. Our previous clinical research summarized our experience in acetabular defect reconstruction [4]. According to the classification of acetabular defect, it can be classified as three types: type A: the tumor involves the anterior acetabular edge, after tumor resection, the posterior acetabular column has complete continuity and good structural bone graft stability; Type B: the tumor of sciatic branch involved the posterior lower part of acetabulum. After tumor resection, the continuity of acetabular anterior column was complete and the stability of structural bone graft was poor; Type C: iliac bone tumor involves the upper edge of acetabulum. After tumor resection, pelvic continuity is interrupted. There are many bone defects above acetabulum, which require autologous bone grafting and large bone volume. This group of cases belong to pelvic continuity, and some acetabular defects. The classification is type B defect after acetabular resection [5]. The key points of acetabular reconstruction are mainly the defect at the posterior edge of acetabulum after tumor resection, which is difficult to do structural bone grafting and fixation. Therefore, after tumor resection and osteotomy, the acetabular repair method can be determined according to the defect size, tumor type and expected survival. For example, acetabular reinforcing ring and tantalum metal reconstruction are often used for metastatic tumors with short expected survival time; In case of low-grade malignancy or young age, autologous femoral head bone block is preferred, and the autologous bone is fixed above the acetabulum by cannulated screw. The specific operations are as follows: firstly, grind the acetabulum, choose proper method according to the size of the defect, fix and install the acetabular reinforcing ring with the front residual bone, then fix the bone graft block on the front residual bone and acetabular reinforcing ring, trim the excess bone into granules after installation, implant into the structural bone graft, and then install the acetabulum; If it is an autologous femoral head, first fix the femoral head with acetabular screws, and then grind and file the acetabulum. After installing the acetabular prosthesis, decide whether to use tantalum block for fixation according to its stability, as shown in Fig. 2 (partial acetabular osteotomy, reconstruction of femoral head and tantalum block). The position and rotation center of the prosthesis are determined according to the residual acetabulum. At the same time, the femoral anteversion angle is adjusted to increase the joint stability. During the operation, the polyethylene padded acetabular prosthesis with high edge is used to reduce the risk of posterior dislocation, and the large femoral head is used as much as possible to increase the joint stability. The stability of the hip joint was tested by completely suturing the external rotator muscle, repairing the gluteus medius and gluteus maximus, and repairing the joint capsule.
Postoperative Management And Follow-up
Negative pressure drainage is routinely placed after operation. The second-generation cephalosporin is used for 2–3 days after operation. The drainage tube is removed according to the postoperative drainage flow. If the drainage flow is less than 50 ml within 24 hours after operation, the drainage tube is removed for no more than 3 days in principle, so as to prevent retrograde infection of the drainage tube. One week after operation, the patient was instructed to sit up at the bedside, the wound healed well after operation, and early ground activities were encouraged. The patients who underwent partial acetabular resection and reconstruction were helped to stand with partial weight-bearing of double crutches, accompanied with progressive lower limb muscle function exercise, and fixed with lower limb anti rotation shoes for 4 weeks during bed rest.
Pelvic X-ray examination was performed after drainage tube was removed. The patients were followed up at 6 weeks, 3 months and 6 months after operation. The pelvic CT, X-ray film and lung CT were rechecked. Bone scan was performed once every half a year to evaluate the local control of the tumor; The affected limb function was evaluated by msts-93 score of Musculoskeletal Tumor Society [6].