[The quality of a manual method for the identification of the lumbar vertebrae]

In order to identify the spinous processes in the lumbar region, we employ the following rule: that "the line between the iliac crests passes through the spinous process of L4 or the intervertebral space between the 4th and 5th lumbar vertebrae". Three anaesthetists (two junior staff and one consultant) identified a spinous process marked by lead-shot in 33 patients prior to radiological examination. No significant differences were found between the estimates made by the junior staff and the consultant and none of the following factors were of significance for the estimates: height, weight, weight index, sex or age of the patients. When the patients were subdivided according to the radiographic degree of pathological findings in the lumbar spine, only 48% of the estimates were found to be correct while where no or slight changes were present, 71% of the estimates were correct. The differences were significant. It is concluded that 40% of the estimates were incorrect but never by more than one segment. The method may be employed where unreliability of one segment is acceptable.