Defective implant osseointegration under protein undernutrition: prevention by PTH or pamidronate.
Protein deficiency is associated with impaired titanium osseointegration. We studied whether systemic treatment with PTH or pamidronate could influence the resistance to pull-out of titanium rods implanted into rats proximal tibia under normal and isocaloric low protein intake. PTH or pamidronate prevented the deleterious effects of protein undernutrition on bone microarchitecture close to the implant and on mechanical fixation. PTH even significantly improved implant osseointegration.


BACKGROUND
Protein deficiency is highly prevalent among elderly patients hospitalized in orthopedic wards. Reduced protein intake impairs titanium osseointegration in rats. Whether stimulator of bone formation or inhibitor of bone resorption could improve implant osseointegration under protein deprivation is not known. We studied the effects of systemic treatment with PTH or pamidronate on the resistance to pull-out of titanium rods implanted into rats proximal tibia under normal and isocaloric low protein intake.


METHODS
We measured the resistance to pull-out 1-mm-diameter titanium rods implanted into the proximal tibias of 49 adult female rats receiving a normal or an isocaloric low protein diet. After 2 wk on either diet, the implants were inserted, and the rats received PTH(1-34), pamidronate or saline vehicle for 8 wk. The tibias were removed for microCT morphometry, followed by the evaluation of pull-out strength.


RESULTS
Pull-out strength was lower in rats fed an isocaloric low protein diet compared with rats fed a normal protein intake (-29%). PTH and pamidronate significantly increased pull-out strength in animals fed a normal or a low protein diet, the effect of PTH being of higher magnitude. The PTH- or pamidronate-mediated increase in pull-out strength was associated with significant increases of relative bone volume, bone-to-implant contact, and trabecular thickness, whereas trabecular spacing was reduced, in the vicinity of the implants.


CONCLUSIONS
We confirmed that isocaloric low protein intake impairs titanium implant osseointegration. PTH or pamidronate prevented the deleterious effects of protein undernutrition and even significantly improved the implant osseointegration. These results indicate that systemic administration of PTH or pamidronate could be considered for preventing uncemented arthroplasty loosening in protein undernourished patients.
Dayer
Romain
R
Division of Bone Diseases (WHO Collaborating Center for Osteoporosis Prevention), Department of Rehabilitation and Geriatrics, University Hospitals of Geneva, Geneva, Switzerland.
Badoud
Isabelle
I
Rizzoli
René
R
Ammann
Patrick
P
D000821:Animal Feed; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D004164:Diphosphonates / Q000494:pharmacology*; D005260:Female; D020007:Implants, Experimental; D016348:Osseointegration / Q000187:drug effects* / Q000502:physiology*; D000077268:Pamidronate; D010281:Parathyroid Hormone / Q000494:pharmacology*; D011506:Proteins / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013718:Tensile Strength; D015898:Tomography Scanners, X-Ray Computed
D004164:Diphosphonates; D010281:Parathyroid Hormone; D011506:Proteins; D000077268:Pamidronate