title: Systemic intermittent parathyroid hormone treatment improves osseointegration of press-fit inserted implants in cancellous bone.
abstract: OBJECTIVE
  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.
  
  
  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 μg/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 μm around the implant. Mechanically, the implants treated with PTH showed no significant differences in total energy absorption, maximum shear stiffness, or maximum shear strength.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Orthopaedic Research Laboratory, Department of Orthopedic Surgery, Aarhus University Hospital, Denmark. h.daugaard@dadlnet.dk
authors.forename: Henrik
authors.initials: H
authors.lastname: Daugaard
authors.forename: Brian
authors.initials: B
authors.lastname: Elmengaard
authors.forename: Troels Torp
authors.initials: TT
authors.lastname: Andreassen
authors.forename: Anders
authors.initials: A
authors.lastname: Lamberg
authors.forename: Joan Elisabeth
authors.initials: JE
authors.lastname: Bechtold
authors.forename: Kjeld
authors.initials: K
authors.lastname: Soballe
mesh_terms: D000497:Alloys / Q000627:therapeutic use; D000818:Animals; D001696:Biomechanical Phenomena; D020099:Coated Materials, Biocompatible; D004195:Disease Models, Animal; D004285:Dogs; D004334:Drug Administration Schedule; D006801:Humans; D007279:Injections, Subcutaneous; D008297:Male; D016348:Osseointegration / Q000187:drug effects* / Q000502:physiology; D010281:Parathyroid Hormone / Q000008:administration & dosage*; D010784:Photomicrography; D019736:Prostheses and Implants; D011474:Prosthesis Design; D019919:Prosthesis Implantation / Q000379:methods; D011897:Random Allocation; D012016:Reference Values; D033081:Shear Strength; D013977:Tibia / Q000473:pathology / Q000601:surgery*; D014025:Titanium / Q000627:therapeutic use; D016896:Treatment Outcome
chemical_list: D000497:Alloys; D020099:Coated Materials, Biocompatible; D010281:Parathyroid Hormone; D014025:Titanium