Resection and reconstruction of bone tumors were determined by the location and range of tumors, which commonly according to splitting criterion of pelvis tumors, that is, the pelvis could be assigned into 4 regions based on anatomic sites: region Ⅰ: ilium; region Ⅱ: acetabulum; region Ⅲ: ischium and pubis (surrounding of obturator foramen ring); region Ⅳ: ala sacralis. Based on the variation of tumors, the reconstruction methods had significant differences. Resection and reconstruction of bone tumors around the Ⅱ section of pelvis challenged ultimately, bone graft reconstruction and prosthesis reconstruction were commonly used in treating pelvis tumors, including cases with pubis, ischium tumor invading acetabulum or iliac bone tumor invading acetabulum. Allograft or pelvic prosthesis can be used to reconstruct the acetabulum after resection of tumors.
Regardless of which method is selected, the basic principle for the treatment of bone tumor is removal the tumor completely, and then, functional reconstruction could be considered. If radical excision of tumor can be achieved, the reconstruction is possible for low potential malignancy, even highly malignancy if only sensitive to chemotherapy. However, this operation is not suitable for cases with stage Ⅱb tumor or other organ metastasis.
Traditional way for bone excision and construction was based on MRI and determined by surgeons’ experience in the operation. Recently, many scholars utilized semi-pelvic prosthesis replacement to reconstruct bone defects after tumor excision[13]. There were three junction points among prosthesis and residual pelvis, namely, proximal end of the iliac bone or sacral bone, horizontal branch of the pubic bone, and ramus of ischium, which should be fixed effectively to ensure the pelvic ring stability and maintain hip functions. In addition, the hip prosthesis should be symmetric with opposite side, and the lunate surface should be kept for 45° abduction 15° anteversion. Due to the operative complexity and difficulties, the implantation of prosthesis was hard or inaccessible.
With the development of computer-aided technology, researchers applied computer-aided technique in preparing individualized joints[14], or treating complicated pelvis fractures[15]. Here, computer-aided technique was utilized in bone tumors therapy around the Ⅱ section of pelvis. Constructing three-dimensional models, simulating bone excision, and labeling of resected surface with body surface symbol or bony landmarks can guarantee the accuracy of osteotomy. By simulating prosthesis construction, the potential problems could be avoided and the prosthesis accuracy could be assured, therefore, it is guaranteed the operation successful, shorted the operative duration and reduced bleeding, in addition, it is reduced the occurrence of complication and increased life quality of patients.
In these 8 cases, 7 cases scored more than 70, and the functional recovery was satisfactory. Whether the dynamic structure of muscle or tendon was maintained may affect the hip functions. Thus, on the basis of non tumor performances, the iliopsoas, gluteus maximus, medius and minimus should be mostly maintained and sutured in situ. By doing this, not only the pars iliaca of prosthesis could be covered, but also the tension of the hip muscle could be maintained, which guaranteed the good therapeutic effect.
The nature and malignancy of tumor are the important factors effecting therapeutic effect. Besides non tumor performances and extensive excision, the combined therapy should be ensured. The therapeutic regimen should be personalized according to tumor kinds to reduce the possibility of relapse and metastasis. The operation has positive significances if there was potential to remove the tumor completely and bring high life quality for patients with malignant tumor though the survival period can not be prolonged.
The cases were followed for 3-7 years. All cases could partially weight bearing walk with double crutches at 4-6 weeks after operation, and gradually walked without crutch at 4 months after operation. Due to individual differences, the recovery of limb functions was differential in cases. According to Harris scoring criteria after total hip replacement[14], 2 cases scored 80-89, 5 cases scored 70-79, and 1 case scored 60-69 in limb function.
During follow-up, 1 case had bolt loosened at 2 years after operation, complicated with injury of femoral artery. By asking the disease history and intraoperative examination, we found that the pubic rami had fractured and the bone flap shifted into medial to the femoral artery due to long term postoperative sports, thus, results in a vertical cleft. Partial of prosthesis and bone flap were removed and the patient could walk with one crutch after the artery repair.
In conclusion, the simulated resection and reconstruction of bone tumors around the Ⅱ section of pelvis based on
computer-aided technique makes the operation easy and reconstruction precise, which produces good clinic results and offers a good promise for the application by combining with effective comprehensive treatment prior to and after operation.
