Do estrogen and alendronate improve metaphyseal fracture healing when applied as osteoporosis prophylaxis?
Osteoporosis is accompanied by predominantly metaphyseal fractures with a delayed and qualitatively reduced healing process. This study addressed the question of whether fracture healing in the context of osteoporosis prophylaxis is improved with estrogen (E) or alendronate (ALN). Thirty-six ovariectomized and 12 sham-operated 12-week-old rats received soy-free (osteoporotic C, sham), E-, or ALN- supplemented diets. After 10 weeks, a metaphyseal tibia osteotomy and standardized T-plate fixation were performed. After a 5-week healing process, the fracture callus was evaluated qualitatively by biomechanical bending test and quantitatively in microradiographic sections. The time course of callus formation was examined using fluorochrome-labeled histological sections. Administration of E improved the biomechanical properties of callus (stiffness [N/mm]: sham: 110.2 + or - 76.07, C: 41.28 + or - 33.70, E: 85.72 + or - 47.24, ALN: 72.07 + or - 34.68). The resistance to microfracturing seen in E-treated animals was significantly enhanced and even superior to sham (yield load [N] sham: 27.44 + or - 9.72, C: 21.04 + or - 12.47, E: 42.85 + or - 13.74(Delta), ALN: 25.28 + or - 6.4(.)) (* P < 0.05 vs. sham group, (Delta) P < 0.05 vs. C group, (*) P < 0.05 vs. E group). Trabecular bone in particular was improved, indicating the presence of physiological endosteal bridging (Tr.Dn [%] sham: 10.53 + or - 18.9, C: 1.01 + or - 0.14, E: 24.13 + or - 34.09(Delta), ALN: 3.99 + or - 8.3(.)). ALN did not help bone healing, as shown by mechanical tests. Compared to the C group, statistically, ALN did not show worse properties. The induction of callus formation under ALN treatment was slightly delayed (Tt.Cl [mm(2)] sham: 3.68 + or - 0.66, C: 3.44 + or - 0.42, E: 3.69 + or - 0.58, ALN: 3.06 + or - 0.56). Osteoporotic metaphyseal fracture healing was qualitatively and quantitatively improved by E prophylaxis. The process of fracture healing occurred nearly physiologically (shamlike). Notably, ALN hardly improved metaphyseal callus properties when assessed as osteoporosis prophylaxis, but to a lesser extent than E.
Kolios
Leila
L
Department of Trauma and Reconstructive Surgery, Georg-August-University of Goettingen, Robert-Koch-Str. 40, 37075 Goettingen, Germany. leilakolios@freenet.de
Hoerster
Ann Kristin
AK
Sehmisch
Stephan
S
Malcherek
Marie Christin
MC
Rack
Thomas
T
Tezval
Mohammed
M
Seidlova-Wuttke
Dana
D
Wuttke
Wolfgang
W
Stuermer
Klaus Michael
KM
Stuermer
Ewa Klara
EK
D019386:Alendronate / Q000494:pharmacology*; D000818:Animals; D050071:Bone Density Conservation Agents / Q000494:pharmacology*; D001860:Bone Plates; D001861:Bone Regeneration / Q000187:drug effects / Q000502:physiology; D002146:Bony Callus / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D004195:Disease Models, Animal; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D005592:Fracture Fixation / Q000295:instrumentation / Q000379:methods; D050723:Fractures, Bone / Q000188:drug therapy* / Q000503:physiopathology / Q000517:prevention & control; D010024:Osteoporosis / Q000188:drug therapy* / Q000503:physiopathology / Q000517:prevention & control; D010027:Osteotomy; D051381:Rats; D017207:Rats, Sprague-Dawley; D020127:Recovery of Function / Q000187:drug effects / Q000502:physiology; D013977:Tibia / Q000187:drug effects / Q000293:injuries / Q000473:pathology; D016896:Treatment Outcome; D014945:Wound Healing / Q000187:drug effects* / Q000502:physiology
D050071:Bone Density Conservation Agents; D004967:Estrogens; D019386:Alendronate