Calvarial Bone Defects Heal Better in Short-Term Ovariectomized Rats Compared to Healthy Rats

Postmenopausal women develop estrogen deficiency which produces a pro-resorptive bone environment, leading to osteoporosis and increased fracture risk. Craniectomies are a common clinical procedure, especially in older populations, where calvarial bone is removed to relieve intracranial pressure (i.e., in the case of traumatic brain injury or stroke). Cranial reconstruction surgeries often result in failure due to infection or resorption of autograft material. Despite the need for calvarial bone graft alternatives for older patients, there is limited literature available on the effects of estrogen deficiency on skull bone metabolism and healing.

The purpose of this work was to assess the effects of short-term ovariectomy (OVX) on calvarial bone properties and on the healing of 3.5 mm unilateral calvarial defects.

Surprisingly, the intact calvarial bone of OVX rats had higher bone volume, thickness, and number of remodeling cavities than intact calvaria of sham rats. Normalized measures of bone volume showed consistently more calvarial defect healing in OVX compared to sham rats at 4-, 8-, and 12-weeks post-surgery.

These findings have implications for future investigations on therapies for treating calvarial bone defects in ovariectomy-induced osteoporotic rats.