[Lumbar inter-apophyseal arthrosis and bone mineral content: prospective study versus controls with dual photonic...

Dual photon absorptiometry (DPA) is a non invasive and repeatable technique to measure vertebral bone mineral content (BMC). This method can be altered, in frontal incidence, by superposition of abnormal calcifications as calcified aorta or interapophyseal arthrosis. The authors studied nineteen females with lumbar apophyseal arthrosis compared with twenty one controls matched by age. Bone densitometry was performed by Am-Ba DPA and monoenergetic computerised tomodensitometry (CT) from L2 to L4. Arthrosis was studied by standard X ray radiographs and CT. Our results showed that inter-apophyseal arthrosis does increase BMC determined by DPA, especially when expressed as linear BMC (g/cm). The body mass index [weight (kg)/size (m2)] also increased these measures by DPA. CT results were, at the opposite, not influenced by osteo-arthrosis nor body mass index. Detailed analysis of DPA pictures allowed to recognize most of patients with osteo-arthrosis and to correct their results by using adjacent vertebral measures (L1) or abandoning pictures of unusual aspect. The authors mentionned necessity to match populations for age and body mass index and to include L1 in routine vertebral bone mineral content determination. By this way they supposed that osteo-arthrosis may not alter lumbar BMC measured with DPA technique.