The clinical survival of joint prostheses depends on the quality of the surrounding bone. BMD (bone mass density) is an important measurement for bone strenght and quality.

The bone mass density surrounding joint prostheses is quantified by use of Dual Energy X-ray Absorptiometry (DEXA), which is an exact method for measuring even small changes in the BMD surrounding hip and knee joint prostheses.

The patients are exposed to a very small dose of radiation and the scan takes only a few minutes. Normally we do three to four scans over a follow-up period of two years. When analyzing changes in the bone mass the patient functions as his own "controller".

With a variation coefficiency of 2% we normally expect to find a significant change in the body mass; i.e. higher than 3% over a period of two years.

The Orthopaedic Surgical Research Group has a Luna Prodigy DEXA scanner at its disposal. The scanner is used in several clinical projects detecting changes in the periprosthetic bone mass. 

We know that BMD is reduced in the three months that follow the operation, but the bone mass is stabilized and remodeled after approx. two years.

It has not yet been clarified whether migration can be correlated directly to the bone density. We hope that our clinical studies can contribute to answering this question.