STUDY DESIGN: Cadaver motion segments were used to evaluate the effects of vertebroplasty on spinal loading following vertebral fracture. OBJECTIVES: To determine if vertebroplasty reverses fracture-induced changes in the distribution of compressive stress in cadaver motion segments. SUMMARY OF BACKGROUND DATA: Vertebroplasty involves reinforcement of vertebrae by injection of cement and is now being used increasingly to treat osteoporotic vertebral fractures. However, its effects on spinal load-bearing are largely unknown. We hypothesize that vertebroplasty, following vertebral fracture, helps to equalize stress acting on the intervertebral disc and adjacent vertebral bodies. METHODS: Nineteen cadaver thoracolumbar motion segments (age 64-90 years) were induced to fracture by compressive overload. Specimens were then subjected to vertebroplasty, and subsequently creep loaded for 1 hour at 1.5 kN. The compressive stress acting on the intervertebral disc was measured before and after fracture, after vertebroplasty, and after creep, by pulling a pressure transducer mounted in a 1.3-mm needle across the disc's midsagittal diameter. This information was then used to calculate neural arch load-bearing. At each time point, measurements were also made of compressive stiffness. RESULTS: Vertebral fracture reduced motion segment compressive stiffness, decompressed the adjacent nucleus, increased stress concentrations in the posterior anulus, and increased neural arch load-bearing, all by a significant amount. Vertebroplasty partially, but significantly, reversed all of these fracture-induced changes. CONCLUSIONS: Vertebroplasty reduces stress concentrations in the anulus and neural arch resulting in a more even distribution of compressive stress on the intervertebral disc and adjacent vertebral bodies.
STUDY DESIGN: Cadaver motion segments were used to evaluate the effects of vertebroplasty on spinal loading following vertebral fracture. OBJECTIVES: To determine if vertebroplasty reverses fracture-induced changes in the distribution of compressive stress in cadaver motion segments. SUMMARY OF BACKGROUND DATA: Vertebroplasty involves reinforcement of vertebrae by injection of cement and is now being used increasingly to treat osteoporotic vertebral fractures. However, its effects on spinal load-bearing are largely unknown. We hypothesize that vertebroplasty, following vertebral fracture, helps to equalize stress acting on the intervertebral disc and adjacent vertebral bodies. METHODS: Nineteen cadaver thoracolumbar motion segments (age 64-90 years) were induced to fracture by compressive overload. Specimens were then subjected to vertebroplasty, and subsequently creep loaded for 1 hour at 1.5 kN. The compressive stress acting on the intervertebral disc was measured before and after fracture, after vertebroplasty, and after creep, by pulling a pressure transducer mounted in a 1.3-mm needle across the disc's midsagittal diameter. This information was then used to calculate neural arch load-bearing. At each time point, measurements were also made of compressive stiffness. RESULTS:Vertebral fracture reduced motion segment compressive stiffness, decompressed the adjacent nucleus, increased stress concentrations in the posterior anulus, and increased neural arch load-bearing, all by a significant amount. Vertebroplasty partially, but significantly, reversed all of these fracture-induced changes. CONCLUSIONS: Vertebroplasty reduces stress concentrations in the anulus and neural arch resulting in a more even distribution of compressive stress on the intervertebral disc and adjacent vertebral bodies.
Authors: Andrew M Briggs; Tim V Wrigley; Jaap H van Dieën; Bev Phillips; Sing Kai Lo; Alison M Greig; Kim L Bennell Journal: Eur Spine J Date: 2006-07-04 Impact factor: 3.134
Authors: Michael N Tzermiadianos; Susan M Renner; Frank M Phillips; Alexander G Hadjipavlou; Michael R Zindrick; Robert M Havey; Michael Voronov; Avinash G Patwardhan Journal: Eur Spine J Date: 2008-09-16 Impact factor: 3.134