Forteo stimulates bone formation within femoral neck after total hip replacement
Forteo promotes rapid bone formation in the femoral neck, with pronounced effects in cancellous and endocortical bone envelopes, according to recent findings.
Felicia Cosman, MD, an endocrinologist at Helen Hayes Hospital Regional Bone Center in West Haverstraw, New York, and professor of medicine at Columbia University, and colleagues evaluated 25 women (mean age, 71.5 years) and 15 men (mean age, 68.9 years) to determine the effect of Forteo (teriparatide, Eli Lilly) on the femoral neck of the proximal femur.
Participants were randomly assigned a regimen of daily subcutaneous teriparatide (20 µg) or placebo for approximately 40 days before undergoing total hip replacement surgery. During surgery, femoral neck tissue was removed and then stained and sectioned. The researchers analyzed four bone envelopes for standard histomorphometric parameters. The study’s primary outcome was defined as bone formation rate of the femoral neck.
The main finding was that there was a much more extensive bone surface engaged in active bone formation in both cancellous bone (120% group difference; P < 0.01) and endocortical bone (85% group difference; P <0.05) in teriparatide-treated patients compared with placebo-treated patients. Consistent with the histomorphometric data, there were no significant changes in any of the biochemical markers analyzed, while the teriparatide group demonstrated increases in all bone turnover markers: a nearly 100% increase for the bone formation markers procollagen type I N-terminal propeptide (PINP) and osteocalcin (OC), and a 25% increase for the bone resorption marker cross-linked C-terminal telopeptide (CTX; all P < .01).
Significant correlations were seen between bone formation marker levels on the day of total hip replacement and bone formation rate in the femoral neck in cancellous and endocortical bone envelopes. These associations were seen within the overall population and the teriparatide group alone. In the teriparatide group (n = 17), serum OC and PINP were associated with cancellous bone formation rate (R = .53; P = .013 for serum OC; R = .59; P = .008 for PINP), as well as endocortical bone formation rate (R = .54; P = .012 for serum OC; R = .64; P = .003 for PINP). In the overall population, associations were seen between cancellous bone formation rate and OC (R = .61; P < .0001) and PINP (R = .67; P < .001). The same was true for endocortical bone reformation rate (R = .61-.68; P < .001 for both).
“This study is important because hip fractures cause the greatest morbidity and mortality in osteoporosis. Our data demonstrate, for the first time, that teriparatide stimulates bone formation quickly in the hip region. The increase in bone formation is expected to produce an increase in bone strength and reduced risk of hip fracture,” Cosman told Endocrine Today. – by Jennifer Byrne
Disclosure: Cosman reports consulting for Amgen, Eli Lilly, Merck and Radius, and receiving lecture fees and grant support from Amgen and Eli Lilly. Please see the full study for a list of all other authors’ relevant financial disclosures.
Editor’s note: On March 17, we made changes to the fourth paragraph to reflect correct data. The Editors regret this error.