Bone Abstracts

Vertebral fractures are one of the most common and disabling manifestation in osteoporosis. The relationship between bone mass and muscle strength has already been shown in the literature, but only a few studies argues the relationship between BMD and erector spinae muscles. Simple biomechanical considerations suggest that the loss of trunk muscle mass may contribute in vertebral fractures. In the literature, the Soerensen and isokinetic tests are often reported for the evaluation of the spine extensors strength, but their there are doubts about safety, usability.

The BET (Back Extensor Test) is a test, created in 2005. The protocol execution has been standardized: it consists in flexing your fully extended torso forward with an angle of 45° with the thighs and in measuring, in seconds, the time that the patients can maintain that position. The test ends when the patient reports pain and when he flexes the torso more than 10°. The extensor muscles are in anti-gravitary position, and are evaluated without hazards for osteoporotic patients.

To validate the BET different studies have been performed in the last 8 years. The subjects under investigation (229) were volontary subjects randomly selected (in several sports clubs, at the S.Paolo Hospital Osteoporosis clinic, at the S. Paolo Hospital volunteers AVO) and divided in three categories: healthy, low back pain and osteoporosis.

We found good reproducibility but the variability interoperator, even thought seems to be statistically acceptable (P=0.002), needs further study. Good sensitivity and significance (P <0.001) and statistically correlations with other common tests (Shoeber, Owestry, VAS, Back Pain Function Test) were found.

The BET proved to be a good predictor to identifying pathologies of the spine and also a good indicator of athletic training (P<0.01). We demonstrated a correlation between time and the BET area of the multifidus sonographically determined (P<0.001).

Future developments concern more studies of BET in osteoporotic patients and the resolution of some BIAS emerged regarding the interoperator reproducibility.