Clinical effects of 3D printed porous titanium-alloy prosthesis in reconstruction of long bone defects of lower extremities / 中华骨科杂志

ABSTRACT

Objective:To analyze and summarize the clinical effects of 3D printed porous titanium-alloy prosthesis implantation in the treatment of long bone defects of lower extremities.Methods:We retrospectively studied the clinical cases with lower extremity bone defect treated by 3D printed porous titanium prostheses from December 2017 to November 2021. 18 patients who were followed up for more than 12 months were included in this study. The enrolled patients included 12 males and 6 females, with an average of 48.9±22.5 years (range, 13-79 years), and an average body mass index of 23.1±4.3 kg/m 2 (range, 17.2-27.1 kg/m 2). There were 14 osteomyelitis-derived bone defects and 4 nonunion-derived bone defects. The bone defect locations included 10 cases of femur and 8 cases of tibia. The average bone defect distance was 13.9±9.7 cm (range, 5.8-31.2 cm), and the proportion of the defect length to the long bone (femur of tibia) was average 33.7%±16.8% (range, 15.0%-63.0%). The clinical efficacy was comprehensively evaluated through gross observation, imaging evaluation, changes in the total length of lower extremities and long bones, femorotibial angle (FTA) measurement, lower extremity functional scale (LEFS), satisfaction, complications and other indicators, focusing on the stabilization mechanism of the prosthesis and the regeneration of new bone. Results:All 18 patients were followed up for 12-35 months, with an average of 16.3 months. Postoperative X-rays at 1, 3, 12 and 24 months showed that new bone could gradually creep along the prosthesis surface. The preoperative bone defect length of long bone and total length of lower limb were respectively 39.4±4.0 cm and 80.5±5.7 cm, which were different from those of the healthy side by 1.6±1.0 cm and 1.5±1.1 cm. One week after implantation, the length of long bone and lower limb was 39.9±3.5 cm and 80.9±6.2 cm, respectively, and the average difference was 1.0±0.6 cm and 0.9±1.1 cm compared with the healthy side. At the last follow-up, the length of long bone and lower limb was 39.7±3.6 cm and 80.9±7.8 cm, with an average difference of 1.8±1.1 cm and 1.0±0.7 cm from the healthy side. There were no significant differences in the length of long bone and lower limbs at the three time points before surgery, one week after surgery and the last follow-up ( F=0.12, 0.04; P>0.05). The average FTA of the affected limb was 174.7° (173.9°, 175.5°), 175.2°(173.5°, 176.4°), and 175.0°(173.5°, 176.3°) at three time nodes, before surgery, one week after surgery and the last follow-up, respectively, and there was no significant statistical difference in pairwise comparison ( Z=0.01, P>0.05). Patients had a mean LEFS score of 50 (46, 51) at the last follow-up, significantly higher than the preoperative score of 20 (17, 21) ( Z=-5.56, P<0.001). The mean satisfaction score of the 18 patients at the last follow-up was 9.7. Two patients (11.1%) had screw fractures but all 3D printed porous titanium alloy prostheses remained stable without significant loosening or displacement. Two patients (11.1%) had nail channel infection of external fixator, all patients with channel infection were cured by intravenous antibiotics combined with local disinfection and dressing change. Conclusion:The implantation of 3D printed porous titanium-alloy prosthesis could efficiently and safely repair the long bone defects of the lower extremities. The prosthesis could maintain stable in the early and middle postoperative period. The length of the long bones and lower limbs did not change significantly with the weight-bearing and functional exercise of the limbs. The new bone could gradually crawl and grow from both ends of the defect, and the patient's limb function recovered significantly, and the patient's satisfaction was high.