Mechanical strength of fracture callus in osteopenic bone at different phases of healing
D L Wheeler1, E J Eschbach, M J Montfort
1Department of Orthopaedics, University of Florida, Gainesville 32610, USA.
Objectives:
To quantify and compare peak bending force and stiffness of fractured femurs during healing of ovariectomized (OVX) and sham-operated (SHAM) rats.
Design:
Temporal biomechanical animal study.
Setting:
Rat femurs were fractured and surgically fixed by a qualified surgeon. The inherent instability of the fixation system employed produced delayed union of the fracture. All biomechanical assessments were performed with servohydraulic test machines (Instron Inc., Canton, MA, U.S.A.; and MTS Corp., Eden Prairie, MN, U.S.A.).
Intervention:
OVX was performed sixteen weeks before femur fracture, and the effect of OVX on healing fractures was determined.
Main Outcomes:
Peak bending force and stiffness of the healing femurs at four, six, and eight weeks after fracture.
Results:
Peak bending loads of the healing fractured femurs in the OVX and SHAM animals were not significantly different. Peak bending loads for the OVX animals at four and six weeks were significantly lower than the peak load at eight weeks (p < 0.05), whereas no difference was found in the peak load with respect to time for the SHAM animals. Both SHAM and OVX animals had greater bending stiffness of the healing fractured femur after eight weeks of healing than at four weeks (p < 0.05).
Conclusions:
OVX is known to reduce cancellous bone mass and strength, but the effect of OVX on healing of fractures in cortical bone is controversial. This study, using a delayed-union model, found no significant differences between OVX and SHAM animals in the breaking strength of healing fractures.
Related Concept Videos
01:40Bone Remodeling
01:31Osteoclasts in Bone Remodeling
01:28Phases of Wound Repair
Formation of Blood Clot
In case of deep injuries, trauma to blood vessels results in blood loss. In the meantime, phospholipids released from the ruptured endothelial cellular membrane are converted into arachidonic...
01:27Fractures: Bone Repair
Minor fractures with no bone displacement are treated by immobilizing the fractured bone using a cast or splint. However, in the case of fractures with displaced bones, the broken bones are repositioned before immobilization to ensure successful healing without deformation and loss of function. The realignment of fractured bone ends is performed through a process called reduction. If the procedure...
01:29Bone Disorders
Bone deposition is also affected by the levels of sex hormones like estrogen and testosterone that promote osteoblast activity and bone matrix synthesis. When the level of these hormones decreases due to aging, it causes a reduction in bone deposition. As a result, bone resorption by osteoclasts...
01:31Bone Remodeling and Repair