Article

Intermittent administration of parathyroid hormone (PTH)
has an anabolic effect on bone, as confirmed in human osteoporosis studies,
distraction osteogenesis, and fracture healing.
PTH in rat models leads to
improved fixation of implants in low-density bone or screw insertion
transcortically. Material and methods We examined the effect of human PTH (1-34)
on the cancellous osseointegration of unloaded implants inserted press-fit in
intact bone of higher animal species. 20 dogs were randomized to treatment with
human PTH (1-34), 5 mug/kg/day subcutaneously, or placebo for 4 weeks starting on
the day after insertion of a cylindrical porous coated plasma-sprayed titanium
alloy implant in the proximal metaphyseal cancellous bone of tibia.
Osseointegration was evaluated by histomorphometry and fixation by push-out test
to failure. Results Surface fraction of woven bone at the implant interface was
statistically significantly higher in the PTH group by 1.4 fold with (median
(interquartile range) 15% (13-18)) in the PTH group and 11% (7-13) in control.
The fraction of lamellar bone was unaltered. No significant difference in bone or
fibrous tissue was observed in the circumferential regions
of 0-500, 500-1,000,
and 1,000-2,000 mum around the implant. Mechanically, the implants treated with
PTH showed no significant differences in total energy absorption, maximum shear
stiffness, or maximum shear strength. Interpretation Intermittent treatment with
PTH (1-34) improved histological osseointegration of a prosthesis inserted
press-fit at surgery in cancellous bone, with no additional improvement of the
initial mechanical fixation at this time point.

Langue : ANGLAIS