Feasibility study of using viscoplastic bone cement for vertebroplasty: an in vivo clinical trial and in vitro cadaveric biomechanical examination.
METHODS
An in vivo clinical trial, and an in vitro cadaveric biomechanical and micromorphologic analysis.


OBJECTIVE
To find the feasibility of using viscoplastic bone cement for vertebroplasty.


BACKGROUND
Vertebroplasty involved in bone cement reinforcement of fractured vertebra has shown promising clinical results. The most frequently observed complication of vertebroplasty is the cement leakage during surgery. Many methods were proposed and were successful at reducing the risk of leakage, such as creating a void within vertebra to reduce the injection pressure, increasing the cement viscosity to reduce the cement infiltration, etc. Nevertheless, a more cost-effective and safer surgery method is still the goal for many spine surgeons and researchers.


METHODS
To deliver the viscoplastic bone cement into the vertebra, a unipedicular tract and a void in the vertebra was created using a curette. The viscoplastic bone cement was then delivered into the void piece by piece and tamped for compactness with a blunt end tool. For the in vitro biomechanical test, 7 thoracic vertebrae were used. The intact specimens were compressed to lose 25% of its intact height, and then augmented with viscoplastic bone cement. Postaugmentation CT scanning was taken to examine the cement distribution, leakage path, and cement filling ratio within the vertebra. Postaugmentation compression test was conducted to examine the vertebral strength and stiffness, and then compared with the intact ones. Finally, the vertebrae were cut into slices for micromorphologic analysis.


RESULTS
The 6 in vivo clinical trials were all successfully operated with significant pain relief and showed no leakage during and after the surgery. The in vitro biomechanical test showed the cement augmentation significantly increased the vertebral strength (pre 3164 (229) N vs. post 3905 (484) N, P < 0.003), but tentatively decreased the vertebral stiffness (pre 1074 (74) N/mm vs. post 801 (370) N/mm, P = 0.081). The postaugmentation CT scanning showed the cement was well confined within the vertebra and the cement filling ratio was 21% (ranged from 15% to 29%). The depth that the viscoplastic bone cement infiltrated into the cancellous bone was 3.5 (0.6) mm, which is less than the depth [8.3 (2.2) mm, P < 0.001] of standard viscous bone cement vertebroplasty.


CONCLUSIONS
Vertebroplasty using viscoplastic bone cement is clinically feasible and can effectively improve the vertebral strength and reduce the cement infiltration depth. The risk of cement leakage can also be decreased by using viscoplastic bone cement.
Lin
Shih-Wei
SW
Institute of Biomedical Engineering, College of Engineering & College of Medicine, National Taiwan University, Taipei, Taiwan.
Chiang
Chun-Kai
CK
Yang
Chi-Lin
CL
Wang
Jaw-Lin
JL
D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena / Q000502:physiology; D001843:Bone Cements / Q000009:adverse effects / Q000737:chemistry / Q000494:pharmacology*; D002102:Cadaver; D005260:Female; D050815:Fractures, Compression / Q000601:surgery; D006801:Humans; D008297:Male; D008953:Models, Anatomic; D019635:Neurosurgical Procedures / Q000295:instrumentation / Q000379:methods; D010024:Osteoporosis / Q000150:complications; D010969:Plastics / Q000009:adverse effects / Q000737:chemistry / Q000494:pharmacology*; D011183:Postoperative Complications / Q000209:etiology / Q000517:prevention & control; D016103:Spinal Fractures / Q000601:surgery*; D013314:Stress, Mechanical; D013904:Thoracic Vertebrae / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000601:surgery; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D054854:Vertebroplasty / Q000295:instrumentation / Q000379:methods*; D055682:Viscoelastic Substances / Q000009:adverse effects / Q000737:chemistry / Q000494:pharmacology*; D014783:Viscosity; D016474:Weight-Bearing / Q000502:physiology
D001843:Bone Cements; D010969:Plastics; D055682:Viscoelastic Substances