A retrospective study of 3D-printed custom titanium prostheses for reconstruction of bone defects after resection of pelvic tumors: technical points and early results.
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BACKGROUND: With the development of limb salvage technology for pelvic malignant tumor, 3D-printed custom prosthesis has become a main way to reconstruct pelvis after resection of pelvic malignant tumor. the purpose of this study is to explore the technical points of using 3D-printed custom titanium alloy prosthesis to reconstruct bone defect after resection of pelvic tumor, and to analyze the early curative effect, complications and prognosis, in order to provide clinical reference for the resection and reconstruction of pelvic malignant tumor. METHODS: We reviewed 7 patients (4 males, 3 females; mean age 42 years, range 16–54) receiving 3D-printed titanium alloy prostheses for pelvic reconstruction following malignant tumor resection (June 2022-December 2023). Cases included 4 primary bone malignancies (2 chondrosarcomas, 2 osteosarcomas) and 3 secondary malignant tumors (endometrial, rectal, hepatocellular carcinomas). Enneking zones involved I + II/I + II + III/II + III (n = 4) and I + II + IV/I + II + III + IV (n = 3), with resections including wide (n = 3), marginal (n = 3), and intracapsular (n = 1). VAS and KPS assessed pain and physical strength preoperatively and at 1/3/6 months postoperatively. MSTS 93 evaluated limb function pre-/postoperatively. Pelvic stability was assessed via pre- and 6-month postoperative sacroiliac joint space measurements. Complications were documented during follow-up (mean 10.6 months, range 6-18.2), while overall survival, progression-free survival, and prognostic factors were analyzed using Kaplan-Meier/COX methods. RESULTS: All 7 patients underwent successful procedures, comprising 5 standard semi-pelvic/iliac prosthesis implantations and 2 screw-connected semi-pelvic reconstructions. Significant improvements were observed in both pain and functional outcomes. The median preoperative VAS score was 7.0 (IQR 6.0-8.5), which decreased to 4.0 (3.5-5.0) at 1 month, 3.0 (2.0-4.5) at 3 months, and 2.5 (2.0-3.5) at 6 months (χ² = 9.46, P = 0.024), with all pairwise comparisons remaining significant after Bonferroni correction (P < 0.001). Simultaneously, median KPS scores improved from 60.0 (40.0–60.0) preoperatively to 60.0 (50.0–70.0) at 1 month, 70.0 (60.0–80.0) at 3 months, and 80.0 (70.0–80.0) at 6 months (χ² = 13.36, P = 0.004), with all inter-timepoint comparisons also statistically significant (P < 0.001). The mean MSTS 93 score was 11.00 ± 4.20 preoperatively and significantly improved to 23.86 ± 4.06 at 3 months postoperatively (P < 0.001). A significant difference in the contralateral sacroiliac joint space was observed between preoperative and 6-month postoperative measurements in patients with Zone IV involvement (IV group) (P = 0.048). Complications included heterotopic ossification (4/7, 57.1%), pubic screw fracture (1/7, 14.3%), femoral neck dislocation (1/7, 14.3%), delayed wound healing (1/7, 14.3%), local recurrence (2/7, 42.8%), and distal metastasis (2/7, 42.8%). No deep infection, periprosthetic osteolysis, or implant loosening occurred. With a mean follow-up of 10.6 months (range: 6–18.2 months), one patient died due to tumor recurrence and metastasis. Kaplan–Meier analysis and Cox multivariate regression showed that gender, tumor type, extent of resection, and Zone IV involvement were not significant variables affecting progression-free survival. CONCLUSION: 3D-printed custom titanium alloy prostheses exhibit favourable early efficacy, safety, and prognostic outcomes in the reconstruction of pelvic defects following tumor resection. Nevertheless, observed alterations in the contralateral unaffected sacroiliac joint space following Zone IV reconstruction have led to a hypothesis regarding potential instability risk.