header advert
You currently have no access to view or download this content. Please log in with your institutional or personal account if you should have access to through either of these
The Bone & Joint Journal Logo

Receive monthly Table of Contents alerts from The Bone & Joint Journal

Comprehensive article alerts can be set up and managed through your account settings

View my account settings

Get Access locked padlock


Factors affecting the stability of screws in human cortical osteoporotic bone


Download PDF


We investigated several factors which affect the stability of cortical screws in osteoporotic bone using 18 femora from cadavers of women aged between 45 and 96 years (mean 76). We performed bone densitometry to measure the bone mineral density of the cortical and cancellous bone of the shaft and head of the femur, respectively. The thickness and overall bone mass of the cortical layer of the shaft of the femur were measured using a microCT scanner. The force required to pull-out a 3.5 mm titanium cortical bone screw was determined after standardised insertion into specimens of the cortex of the femoral shaft.

A significant correlation was found between the pull-out strength and the overall bone mass of the cortical layer (r2 = 0.867, p < 0.01) and also between its thickness (r2 = 0.826, p < 0.01) and bone mineral density (r2 = 0.861, p < 0.01). There was no statistically significant correlation between the age of the donor and the pull-out force (p = 0.246), the cortical thickness (p = 0.199), the bone mineral density (p = 0.697) or the level of osteoporosis (p = 0.378).

We conclude that the overall bone mass, the thickness and the bone mineral density of the cortical layer, are the main factors which affect the stability of a screw in human female osteoporotic cortical bone.

Correspondence should be sent to Dr O. C. Thiele at the Department of Oral and Maxillo-Facial Surgery, University Hospital, INF 400, 69120 Heidelberg, Germany; e-mail: oliver.thiele@med.uni-heidelberg.de

For access options please click here