Percutaneous reinforced osteoplasty for long bone metastases: a feasibility study

Objective While percutaneous osteoplasty is common for the treatment of vertebral fractures, low strength of fixation remains a major challenge for use in metastatic weight-bearing bones. With stent, wire, and cement augmentation, this study explores the feasibility of percutaneous reinforced osteoplasty for use in correcting long bone fractures. Materials and methods Fifteen explanted swine femora were randomly assigned into three groups. Group 1 (n = 5) was native (intact) bones without any intervention (control), group 2 (n = 5) received cementoplasty, and group 3 (n = 5) received stent and wire scaffolding ("rebar") in addition to cementoplasty. All treatment procedures were performed under fluoroscopic guidance. Mechanical strength of fracture fixation was quantified by peak load to failure, stiffness, work done to fracture, and fatigue testing with four-point bend test. Results Percutaneous osteoplasty with or without reinforcement was successfully achieved in all specimens. The respective peak load at failure, flexural stiffness, and work done to fracture (mean +/- SEM) for group 1 was 2245 +/- 168 N, 14.77 +/- 1.3 Nm/degree, and 4854 +/- 541 Nmm; group 2 was 468 +/- 81 N, 3.9 +/- 0.5 Nm/degree, and 401 +/- 56 Nmm; and group 3 was 594 +/- 90 N, 4.42 +/- 0.4 Nm/degree, and 522 +/- 54 Nmm. The mean cyclic displacement for groups 1, 2, and 3 were 0.15, 0.58, and 0.48 mm, respectively, at 220-240 N loading. Conclusions While percutaneous reinforced osteoplasty with stent, wire, and cement augmentation resulted in improved mechanical strength in restored bones, it did not differ significantly from specimens that underwent exclusive cementoplasty. With the improvement of fracture strength, the concept may be applicable for prevention or treatment of pathological fractures.