Pelvic reconstruction with different rod-screw systems following Enneking type I/I + IV resection: a clinical study

Abstract

The mechanical outcomes of patients with pelvic bone tumors involving zone I or zone I + IV who received resection and different reconstructions are not clear. Therefore, the purpose of this study was to compare the outcomes of different rod-screw systems in reconstruction for these patients, and evaluate the relative risk of mechanical failure for them. We reviewed 30 patients for a mean duration of 40.4 months of follow-up (range, 13.1-162.2 months), five patients had mechanical complications. The mechanical survival rate of two-rod and four-screw (TRFS) group was significantly higher than one-rod and two-screw (ORTS) group (p = 0.000). The implant survival rate was correlated with ages (p = 0.010), younger people are more likely to fail. Thus, TRFS fixation for pelvic reconstruction after Enneking type I/I + IV resection can provide better short to long-term mechanical stability compared with ORTS fixation, the strength of ORTS fixation is not enough. In addition, biological reconstruction such as autologous bone graft is recommended for the patients who are younger or suffered from benign tumor. As for the patients who are older, with malignant tumors, underwent adjuvant radiotherapy or chemotherapy, functional reconstruction with bone cement is a good choice.

Keywords: Enneking type I/I + IV; limb salvage surgery; mechanical failure; pelvic girdle reconstruction; pelvic tumor.

Figure 1. A 16-year-old female (case 4) with diagnosis of pelvis osteosarcoma affecting zone I + IV

(A) AP radiograph at one week post-operatively. (B) AP radiograph at 61.9 months post-operatively, showing failure of the implant, and the implant was stabbed to the skin when she stooped, (C) AP radiograph after the construction was revised and augmented with an autologous fibular graft 80 months post-operatively.

Figure 2. A 20-year-old male (case 25) with diagnosis of pelvis osteosarcoma affecting zone I

(A) AP radiograph at two weeks post-operatively. (B) AP radiograph at 30.5 months post-operatively, showing failure of the implant and with functional impairment. (C) AP radiograph at one week after removal of the implant.

Figure 3. A 37-year-old female (case 26) with diagnosis of pelvis chondrosarcoma affecting zone I

(A) AP radiograph of the pelvis after bone tumor resection and reconstruction with an autograft bone and screw-rod system. (B) AP radiograph showing the implant loosening 3 months post-operatively without functional impairment. (C) at 51.3 months post-operatively, AP radiograph showing failure of the implant, pseudoarthrosis formation was found in the resection site, and degeneration was developed in the symphysis pubis.

Figure 4. A 15-year-old female (case 28) with diagnosis of pelvis osteosarcoma affecting zone I

(A) AP radiograph of the pelvis after bone tumor resection and reconstruction with screw-rod system and bone cement. (B) AP radiograph showing the implant loosening 14 months post-operatively without functional impairment.

Figure 5. Overall implant survival analysis through Kaplan-Meier for different reconstruction method

Number of patients: 30 patients. A statistically significant difference was noted between the one-rod two-screw group and the two-rod four-screw group (p = 0.000).

Figure 6. A 32-year-old woman (case 27) with diagnosis of pelvis chondrosarcoma affecting zone I

(A) AP radiograph of the pelvis after internal hemipelvectomy and subsequent pelvic ring reconstruction with screw-rod system and autograft bone. (B) AP radiograph showing the bone union 12.3 months post-operatively.

Figure 7. A 26-year-old female (case 1) with diagnosis of pelvis osteoclastoma affecting zone I

(A) AP radiograph of the pelvis shows internal hemipelvectomy and subsequent pelvic ring reconstruction with screw-rod system and bone cement. (B, C) CT images show no evidence of tumor recurrence or implant loosening 144.1 months post-operatively.

Figure 8. A 44-year-old woman (case 6) with diagnosis of pelvis osteoclastoma affecting zone I

(A) AP radiograph of the pelvis after bone tumor resection and reconstruction with an autograft bone in the pelvis stabilized with the implantation of screw-rod system. (B) Coronal CT image showing the bone union 17.5 months post-operatively. (C) AP radiograph of the pelvis shows no evidence of tumor recurrence or implant loosening 36 months post-operatively.