A study presented by Jose B. Toro, MD, at the 2007 annual meeting of the Orthopaedic Trauma Association (OTA) examined the effects of bisphosphonates and PTH in the treatment of diaphyseal fractures in the osteoporotic population.
Published 2/1/2008
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Annie Hayashi
Study demonstrates fracture healing enhanced by pharmacologic intervention
A large body of clinical data exists to support the efficacy of bisphosphonates and parathyroid hormones (PTH) in treating osteoporosis. Whether these same medications could be equally effective in treating fractures in those with osteoporosis, however, is not well-researched.
Jose B. Toro, MD |
“PTH has become a very popular substitute when alendronate cannot be used,” Dr. Toro told the OTA audience. “Previous studies suggested that alendronate may prevent fracture healing due to its mechanism of action. We believe that PTH may reverse the mechanism of action behavior of the fracture callus and improve the mechanical behavior of fracture callus formation after fracture.”
Testing all options
The study involved 126 rats, divided into two groups, to test the effectiveness of preoperative treatment with alendronate. The groups were later subdivided to test the effectiveness of PTH and alendronate on healing after osteotomies (Fig. 1). Six weeks following surgery, researchers tested the rats’ femurs. The union rate was based on “callus qualitative observation from a single observer for all samples.”
“Those bones that were held in a horizontal plane to the floor and presented with deformations secondary to gravity were marked nonunited,” Dr. Toro explained. “We also took radiographs (Fig. 2) to evaluate the bone formation rate and did biomechanical analysis and microcomputed tomography analysis to measure bone mineral density and bone volume.”
“At 6 weeks, estrogen-deficient rats from the control group had a 41 percent union rate,” Dr. Toro explained. “The rats that received pharmacologic intervention before the osteotomy had a union rate of 44 percent—statistically insignificant compared to the control group.”
A study presented by Jose B. Toro, MD, at the 2007 annual meeting of the Orthopaedic Trauma Association (OTA) examined the effects of bisphosphonates and PTH in the treatment of diaphyseal fractures in the osteoporotic population.
Fig. 2 Radiographs showing union (left) and nonunion (right). Photos
courtesy of Jose B. Toro, MD
The rats that received pretreatment and alendronate or rhPTH (Group 1a and 1b) after osteotomy had much higher union rates (82 percent and 78 percent) than those in Group 1c (44 percent), which received alendronate but no postoperative treatment (Fig. 3).
Dr. Toro and his colleagues identified an interesting finding from the mechanical testing.
The groups that received alendronate or alendronate and
PTH after osteotomy had stronger callus when compared to the rats that did not receive any pharmacologic intervention. The difference in strength between the two groups was statistically significant.
PTH, alendronate equally effective
“Osteotomy healing was enhanced,” Dr. Toro concluded, “by pharmacologic intervention with alendronate or PTH, providing a superior effect when the rodents were treated with alendronate before osteotomy. Pharmacologic intervention may improve mechanical response for failure moment and bending stiffness based on our data.
“The key message of the study is that pretreatment with PTH or alendronate is equally effective.”
Disclosure information for Dr. Toro was not available. Annie Hayashi is the senior science writer for AAOS Now. She can be reached at hayashi@aaos.org