Grafts bone substitutes devices internal fixation

Dorn Spinal Therapy

Spine Healing Therapy

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Structural autografts harvested from the anterior iliac crest or from the fibula are used in anterior fusion of the cervical spine. The grafts must enhance stability and substitute for the regenerative capacity of bone. Fresh autolo-gous grafts posess some osteogenic potential and have os-teoinductive and osteoconductive properties [62]. Structural corticocancellous grafts from the anterior iliac crest are commonly used, and their mechanical strength is greater than that of the posterior crest [89]. Iliac crest grafts are used in mono- and bisegmental interbody fusion and also after corpectomy involving no more then two levels. They are considered the biological and biomechan-ical standard for mono- and bisegmental reconstruction of the anterior cervical spine [3, 11, 17, 73, 75, 86, 98, 102, 103, 107]. In longer fusions after corpectomies a structural fibula graft is appropriate. There are different techniques for stabilizing the strut graft within the decompressed site [7, 47, 78, 105, 106]. Vascularized fibula grafts may accelerate the process of fusion in the case of multiple vertebrectomies [80, 100]. Additional internal fixation may provide immediate intrinsic stability in long strut graft constructs [15, 16, 46, 67, 92]. There are disadvantages when using autologous grafts such as potential donor site morbidity, increased operative time, and hospital stay.

To avoid these disadvantages allografts may be considered. There are also disadvantages concerning the use of allografts, such as risk of transmitting infections from the donor, prolonged healing, and compatibility problems [26, 30, 34, 49, 74, 82, 88, 99, 107]. The use of allografts in multilevel reconstructions is associated with a nonunion rate up to 41%. This nonunion rate is significantly higher than that with autologous grafts, which is estimated at 27% [24]. Allografts may be preserved as fresh-frozen or freeze-dried [27, 52, 87]. Both processes are effective in suppressing antigenicity and retain some osteoinductive ability and osteoconductive properties [62]. Other methods, including sterilization with ethylene oxide gas and highdose y-irradiation are effective but decrease significantly the osteoinductive properties and mechanical integrity of the graft [69, 81].

Demineralized bone matrix is composed material, consisting from some collagen proteins and bone growth factors [45]. There are some osteoinductive and osteoconductive properties established [81]. Since demineralized bone matrix lacks mechanical properties that resist forces, it is not suitable for reconstruction of large defects in the cervical spine.

Fig. 2 Computed tomography 6 months after C5-C6 segmental fusion with cage (Cervios, Mathys, Bettlach, Switzerland) prefilled with P-tricalcium phosphate. Note the restitution of P-tricalcium phosphate by bone. a Sagittal plane. b Coronal plane

Fig. 2 Computed tomography 6 months after C5-C6 segmental fusion with cage (Cervios, Mathys, Bettlach, Switzerland) prefilled with P-tricalcium phosphate. Note the restitution of P-tricalcium phosphate by bone. a Sagittal plane. b Coronal plane

Bioceramics are calcium phosphate materials processed by sintering. Hydroxyapatite and P-tricalcium phosphate are examples of the ceramics which may be used in reconstructive surgery. Hydroxyapatite is almost unresorb-able while P-tricalcium phosphate degrades and resorbs 6-12 weeks after surgery [40, 70]. The bioceramics are mechanically stable, but the material is brittle and not suitable for use as a stand-alone device. Combined with a rigid anterior fixation bioceramics may be very successful in anterior interbody fusion [91].

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