Lumbar central canal stenosis (CCS) is one of the common diseases, which increases by aging. We used quantitative image processing program to assess fat infiltration in paraspinal muscles especially multifidus as a diagnostic tool and its correlation with severity of CCS.

About 59 women with focal L4-L5 CCS as case group and 64 women as control group were enrolled. The bilateral multifidus innervated by L5 was assessed by image processing program. Moreover, Oswestry disability index (ODI) questionnaire was filled out by individuals.

The mean±standard deviation (SD) of fat tissue deposition percentile in multifidus muscle of case and control group were 45.87±23.42% and 36.48±13.05%, respectively (P-value<0.05). Besides, it correlated with severity of canal stenosis. A cut-off value of 46.7% fat percentile were measured for clinical diagnosis of canal stenosis severity. The fat infiltration did not correlated with weight of the participants in both case and control groups. We showed that age had effect on the fat degeneration totally, however it did not correlate with fat deposition in case and control group separately (Pearson correlation coefficient r=0.19 for case and r=0.18 for control group and P-value>0.05).

It has been suggested that percentile of fat infiltration by our image processing program is a good diagnostic tool of CCS besides clinical symptoms of the patients. 46.7% cut-off value can be used in clinical setting for diagnosis critical stage of CCS.