TY - JOUR
T1 - Differential fracture healing resulting from fixation stiffness variability
T2 - A mouse model
AU - Gardner, Michael J.
AU - Putnam, Sara M.
AU - Wong, Ambrose
AU - Streubel, Philipp N.
AU - Kotiya, Akhilesh
AU - Silva, Matthew J.
N1 - Funding Information:
Acknowledgments We thank Tarpit Patel, M.S., for assistance with microCT analysis and mechanical testing, which were supported in part by NIH/NIAMS grants P30AR057235 (Washington University Core Center for Musculoskeletal Biology and Medicine).
PY - 2011/5
Y1 - 2011/5
N2 - Background The mechanisms underlying the interaction between the local mechanical environment and fracture healing are not known. We developed a mouse femoral fracture model with implants of different stiffness, and hypothesized that differential fracture healing would result. Methods Femoral shaft fractures were created in 70 mice, and were treated with an intramedullary nail made of either tungsten (Young's modulus = 410 GPa) or aluminium (Young's modulus = 70 GPa). Mice were then sacrificed at 2 or 5 weeks. Fracture calluses were analyzed using standard microCT, histological, and biomechanical methods. Results At 2 weeks, callus volume was significantly greater in the aluminium group than in the tungsten group (61.2 vs. 40.5 mm3, p = 0.016), yet bone volume within the calluses was no different between the groups (13.2 vs. 12.3 mm 3, ). Calluses from the tungsten group were stiffer on mechanical testing (18.7 vs. 9.7 N/mm, p = 0.01). The percent cartilage in the callus was 31.6% in the aluminium group and 22.9% in the tungsten group (p = 0.40). At 5 weeks, there were no differences between any of the healed femora. Conclusions In this study, fracture implants of different stiffness led to different fracture healing in this mouse fracture model. Fractures treated with a stiffer implant had more advanced healing at 2 weeks, but still healed by callus formation. Although this concept has been well documented previously, this particular model could be a valuable research tool to study the healing consequences of altered fixation stiffness, which may provide insight into the pathogenesis and ideal treatment of fractures and non-unions.
AB - Background The mechanisms underlying the interaction between the local mechanical environment and fracture healing are not known. We developed a mouse femoral fracture model with implants of different stiffness, and hypothesized that differential fracture healing would result. Methods Femoral shaft fractures were created in 70 mice, and were treated with an intramedullary nail made of either tungsten (Young's modulus = 410 GPa) or aluminium (Young's modulus = 70 GPa). Mice were then sacrificed at 2 or 5 weeks. Fracture calluses were analyzed using standard microCT, histological, and biomechanical methods. Results At 2 weeks, callus volume was significantly greater in the aluminium group than in the tungsten group (61.2 vs. 40.5 mm3, p = 0.016), yet bone volume within the calluses was no different between the groups (13.2 vs. 12.3 mm 3, ). Calluses from the tungsten group were stiffer on mechanical testing (18.7 vs. 9.7 N/mm, p = 0.01). The percent cartilage in the callus was 31.6% in the aluminium group and 22.9% in the tungsten group (p = 0.40). At 5 weeks, there were no differences between any of the healed femora. Conclusions In this study, fracture implants of different stiffness led to different fracture healing in this mouse fracture model. Fractures treated with a stiffer implant had more advanced healing at 2 weeks, but still healed by callus formation. Although this concept has been well documented previously, this particular model could be a valuable research tool to study the healing consequences of altered fixation stiffness, which may provide insight into the pathogenesis and ideal treatment of fractures and non-unions.
UR - http://www.scopus.com/inward/record.url?scp=80052442532&partnerID=8YFLogxK
U2 - 10.1007/s00776-011-0051-5
DO - 10.1007/s00776-011-0051-5
M3 - Article
C2 - 21451972
AN - SCOPUS:80052442532
SN - 0949-2658
VL - 16
SP - 298
EP - 303
JO - Journal of Orthopaedic Science
JF - Journal of Orthopaedic Science
IS - 3
ER -