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Biomechanical Evaluation of the Vertebral Jack Tool and the Inflatable Bone Tamp for Reduction of Osteoporotic Spine Fractures

Sietsma, Maurits S., MD*; Hosman, Allard J. F., MD, PhD; Verdonschot, N J. J., PhD; Aalsma, Arthur M. M., MSc, PhD§; Veldhuizen, Albert G., MD, PhD

doi: 10.1097/BRS.0b013e3181b1fed8

Study Design. Controlled in vitro study.

Objective. To compare two kyphoplasty techniques in cadaveric fractured vertebrae: an experimental vertebral jack tool (VJT) and an inflatable bone tamp (IBT).

Summary of Background Data. A previous biomechanical study showed restored strength and stiffness after height restoration in cadaveric-fractured osteoporotic vertebrae using a new device for reduction of osteoporotic vertebral fractures.

Methods. Anterior wedge fractures (AO type A1.2) were created in 8 (4 lumbar, 4 thoracic) vertebrae by displacement eccentric external forces. In all vertebrae the amount of height reduction was 35%. After compression, 4 vertebrae were restored in height using the VJT procedure. Four vertebrae were restored in height using the IBT procedure. Posttreatment strength and stiffness of the vertebrae were determined by a compression test identical to the pretreatment compression protocol.

Results. In the VJT group the postrestoration strength was 81% ± 13% of the original strength and in the IBT group it was 96% ± 32%. The postrestoration stiffness in the VJT group was 61% ± 42% of the original stiffness and in the IBT group 76% ± 62% of the original stiffness. The vertebrae in the VJT group were restored to 101% ± 2% of their original height whereas this was 104% ± 14% in the IBT group. In this study, no cases of cement leakage were found. No cases of damaging of the end plates, new fractures or perforations were seen in both groups. The mean amount of cement inserted for the VJT group was 3.6 ± 0.9 cm3 and for the IBT group 5.9 ± 0.8 cm3.

Conclusion. Both kyphoplasty procedures were able to restore height in this in vitro study, while strength and stiffness were partially restored, with no significant differences. In this study on average significant less cement was used in the VJT procedure. No complications were noted in both groups. This new end plate-to-end plate laminar augmentation technique may be of clinical advantage.

Controlled in vitro study to compare 2 kyphoplasty techniques in osteoporotic wedge fractures: an experimental vertebral jack tool and an inflatable bone tamp. Both techniques restored height. Significant less cement was used in the vertebral jack tool procedure, while comparable postoperative strength and stiffness values were gained among both groups.

From the *Department of Orthopaedic Surgery, Martini Hospital, Groningen, The Netherlands; †Departments of Orthopedic Surgery and ‡Orthopedic Research Laboratory, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands; §Baat Medical BV, Hengelo, The Netherlands; and ¶Department of Orthopedic Surgery, University Groningen Medical Center UMCG, Groningen, The Netherlands.

Acknowledgment date: February 27, 2008. First revision date: August 27, 2008. Second revision date: December 4, 2008. Acceptance date: December 4, 2008.

The manuscript submitted does not contain information about medical device(s)/drug(s).

No funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.

Supported by Surgicraft Ltd., Worcestershire, UK.

Address correspondence and reprint requests to M. S. Sietsma, MD, Department of Orthopedic Surgery, Martinihospital, Postbus 30033, 9700RM Groningen, The Netherlands; E-mail:

© 2009 Lippincott Williams & Wilkins, Inc.