Parathyroid hormone PTH(1-34) increases the volume, mineral content, and mechanical properties of regenerated mineralizing tissue after distraction osteogenesis in rabbits.
OBJECTIVE
Parathyroid hormone (PTH) has attracted considerable interest as a bone anabolic agent. Recently, it has been suggested that PTH can also enhance bone repair after fracture and distraction osteogenesis. We analyzed bone density and strength of the newly regenerated mineralized tissue after intermittent treatment with PTH in rabbits, which undergo Haversian bone remodeling similar to that in humans.


METHODS
72 New Zealand White rabbits underwent tibial mid-diaphyseal osteotomy and the callus was distracted 1 mm/day for 10 days. The rabbits were divided into 3 groups, which received injections of PTH 25 microg/kg/day for 30 days, saline for 10 days and PTH 25 microg/kg/day for 20 days, or saline for 30 days. At the end of the study, the rabbits were killed and the bone density was evaluated with DEXA. The mechanical bone strength was determined by use of a 3-point bending test.


RESULTS
In the 2 PTH-treated groups the regenerate callus ultimate load was 33% and 30% higher, absorbed energy was 100% and 65% higher, BMC was 61% and 60% higher, and callus tissue volume was 179% and 197% higher than for the control group.


CONCLUSIONS
We found that treatment with PTH during distraction osteogenesis resulted in substantially higher mineralized tissue volume, mineral content, and bending strength. This suggests that treatment with PTH may benefit new bone formation during distraction osteogenesis and could form a basis for clinical application of this therapy in humans.
Aleksyniene
Ramune
R
Orthopaedic Division of Northern Denmark, Aalborg University Hospital, University of Aarhus, Aalborg, Denmark. raa@rn.dk
Thomsen
Jesper Skovhus
JS
Eckardt
Henrik
H
Bundgaard
Kristian G
KG
Lind
Martin
M
Hvid
Ivan
I
D000818:Animals; D001696:Biomechanical Phenomena; D015519:Bone Density / Q000187:drug effects*; D001861:Bone Regeneration / Q000187:drug effects*; D002146:Bony Callus / Q000187:drug effects; D005260:Female; D017102:Fracture Healing / Q000187:drug effects; D019857:Osteogenesis, Distraction; D010281:Parathyroid Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D011817:Rabbits
D010281:Parathyroid Hormone