Showing papers by "Hervé Deramond published in 2001"

The biomechanics of vertebroplasty. The effect of cement volume on mechanical behavior.

Abstract: Study Design. Ex vivo biomechanical study using osreoporotic cadavetic vertebral bodies. Objective. To determine the association between the volume of compent injected during percutaneous vertebroplasty and the restoration of strength and stiffness in osteoporotic vertebral bodies, two investigational cements were studied: Orthocomp (Orthovita, Malvern, PA) and Simplex 20 (Simplex P with 20% by weight barium sulfate content: Stryker-Howmedica-Osteonics, Rutherford, NJ). Summary of Background Data. Previous biomechanical studies have shown that injections of 8-10 mL of cement during vertebroplasty restore or increase vertebral body strength and stiffness; however, the doseresponse association between cement volume and restoration of strength and stiffness is unknown. Methods. Compression fractures were experimentally created in 144 vertebral bodies (T6-L5) obtained from 12 osteoporotic spines harvested from female cadavers. After initial strength and stiffness were determined, the vertebral bodies were stabilized using bipedicular injections of cement totaling 2, 4, 6, or 8 mL and recompressed, after which post-treatment strength and stiffness were measured. Strength and stiffness were considered restored when post-treatment values were not significantly different from initial values. Results. Strength was restored for all regions when 2 mL of either cement was injected. To restore stiffness with Orthocomp, the thoracic and thoracolumbar regions required 4 mL, but the lumbar region required 6 mL. To restore stiffness with Simplex 20, the thoracic and lumbar regions required 4 mL, but the thoracolumbar region required 8 mL. Conclusion. These data provide guidance on the cement volumes needed to restore biomechanical integrity to compressed osteoporotic vertebral bodies.

Percutaneous vertebroplasty : a developing standard of care for vertebral compression fractures

Abstract: Acrylic cements have been used for the augmentation of weakened or partially destroyed bones for decades [(1)][1]. The term vertebroplasty originally described an open surgical procedure that introduces bone graft or acrylic cement to mechanically augment weakened vertebral bodies.

An ex vivo biomechanical evaluation of a hydroxyapatite cement for use with vertebroplasty.

Abstract: STUDY DESIGN: Comparative ex vivo biomechanical study. OBJECTIVE: To determine the strength and stiffness of osteoporotic vertebral bodies subjected to compression fractures and stabilized via bipedicular injections of the following: 1) Simplex P (Stryker-Howmedica-Osteonics, Rutherford, NJ), 2) Simplex P formulated consistent with the practice of vertebroplasty (F2), or 3) BoneSource (Stryker-Howmedica-Osteonics). SUMMARY OF BACKGROUND DATA: Little is known about the mechanical stabilization afforded by new materials proposed for use with vertebroplasty. METHODS: Vertebral bodies (T8-T10 and L2-L4) from each of 10 fresh spines were harvested from female cadavers (81 +/- 12 years), screened for bone density (t score, -3.8 +/- 1.1; bone mineral density, 0.75 +/- 15 g/cm2), disarticulated, and compressed to determine initial strength and stiffness. The fractured vertebral bodies were stabilized via bipedicular injections of 4 mL (thoracic) or 6 mL (lumbar) and then recrushed. RESULTS: Vertebral bodies repaired with Simplex P resulted in significantly greater strength (P < 0.05) relative to their prefracture states, those repaired with BoneSource resulted in the restoration of initial strength for both the thoracic and lumbar level, and those repaired with F2 resulted in significantly greater strength (P < 0.05) in the thoracic region and restoration of strength in the lumbar region. All cement treatments resulted in significantly less stiffness compared with initial values. CONCLUSIONS: All three materials tested restored or increased vertebral body strength, but none restored stiffness. Both new materials show promise for use in percutaneous vertebroplasty, but they need clinical evaluation.

An ex vivo biomechanical evaluation of a hydroxyapatite cement for use with kyphoplasty.

Abstract: BACKGROUND AND PURPOSE: Previous ex vivo biomechanical studies have shown that kyphoplasty with polymethylmethacrylate cement increases vertebral body (VB) strength and restores VB stiffness and height after compression fracture. The purpose of the current study was to determine if a hydroxyapatite cement used as a void filler during kyphoplasty provides mechanical stabilization similar to that of a polymethylmethacrylate cement. METHODS: Simulated compression fractures were experimentally created in 33 osteoporotic VBs harvested from female cadaver spines. VBs were assigned to one of three groups: 1) kyphoplasty with a custom mixture of Simplex P; 2) kyphoplasty with BoneSource; and 3) no treatment. The kyphoplasty treatment consisted of inserting a balloon-like device into the VB via both pedicles, inflating the tamp, and filling the created void with Simplex P bone cement or BoneSource. VBs in the no-treatment group received no interventions. Pre- and posttreatment heights were measured, and the repaired VBs were recompressed to determine posttreatment strength and stiffness values. RESULTS: Kyphoplasty with altered Simplex P restored strength, whereas kyphoplasty with BoneSource and the no-treatment protocol both resulted in significantly weaker VBs relative to initial strength. All treatments resulted in significantly less stiff VBs relative to their initial condition. All VBs lost significant height after initial compression, but a significant amount of lost height was restored by kyphoplasty with either cement. CONCLUSION: Kyphoplasty with either cement significantly restored VB height. Kyphoplasty with altered Simplex P resulted in stronger repairs than did no treatment or kyphoplasty with BoneSource.