Hydroxyapatite-coating of pedicle screws improves resistance against pull-out force in the osteoporotic canine lumbar spine model: a pilot study

In patients with spinal osteoporosis, the early achievement and maintenance of a biological bond between the pedicle screw and bone is important to avoid screw loosening complications. There are few reports of in vivo investigations involving biomechanical and histological evaluations in the osteopo...

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Bibliographic Details
Published in:The spine journal 2005-05, Vol.5 (3), p.239-243
Main Authors: Hasegawa, Toru, Inufusa, Akihiko, Imai, Yoshiyuki, Mikawa, Yoshihiro, Lim, Tae-Hong, An, Howard S.
Format: Article
Language:English
Subjects:
Absorptiometry, Photon
Animals
Bone Density
Bone Screws
Coated Materials, Biocompatible
Dogs
Durapatite
Female
Hydroxyapatite
Lumbar Vertebrae - surgery
Osteointegration
Osteoporosis
Osteoporosis - surgery
Ovariectomy
Pedicular fixation
Pilot Projects
Spinal Fusion - instrumentation
Stress, Mechanical
Titanium
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Summary:In patients with spinal osteoporosis, the early achievement and maintenance of a biological bond between the pedicle screw and bone is important to avoid screw loosening complications. There are few reports of in vivo investigations involving biomechanical and histological evaluations in the osteoporotic spine. To evaluate the effect of hydroxyapatite (HA)-coating on the pedicle screw in the osteoporotic lumbar spine and to investigate the relationship between resistance against the screw pull-out force and bone mineral density (BMD) of the vertebral body. Mechanical and pathological investigations in the lumbar spine. Two 24-month-old female beagle dogs were fed a calcium-free dog chow for 6 months after ovariectomy (OVX). BMD (in g/cm 2) was measured by dual energy X-ray absorptiometry at pre-OVX and 6 months after OVX. Pedicle screws were placed from L1 to L6 at 6 months after OVX. Twenty-four pure titanium cortical screws (Synthes, #401-114) were used as pedicle screws (Ti-PS). Of these, 12 screws had HA-coating (HA-PS). The HA-PS screws were inserted into the right pedicles and the Ti-PS were inserted into the left pedicles. Ten days after this procedure, the lumbar spines were removed en bloc for screw pull-out testing and histological evaluation. The mean BMD value of the lumbar vertebrae 6 months after the OVX was 0.549±0.087 g/cm 2, which was significantly less than the pre-OVX mean BMD of 0.603±0.092 g/cm 2 (p
ISSN:1529-9430
1878-1632
DOI:10.1016/j.spinee.2004.11.010