A study to determine the accuracy, reliability and validity of using the iliac crests to locate the fourth lumbar vertebra in the standing, seated and prone positions

M.Tech.Manual medicine practitioners rely on clinical skills to diagnose and treat patients with musculoskeletal complaints. Palpatory analysis of a patient is used to identify their problem, treat the problems found and evaluate the result of the treatment (Ward 1996). Despite this reliance on palpation as a clinical tool, the reliability of palpation remains to be proven (O'Haire & Gibbons 2000). Chiropractors' and other manual medicine practitioners' ability to accurately identify bony anatomical landmarks needs to be validated as static palpation, followed by motion palpation are based on the assumption of this ability (O'Haire & Gibbons 2000). The most common method of identifying lumbar interspaces is to use the intercrestal line, which is drawn between the two iliac crests (Reynolds 2000). The intercrestal line is reported to most frequently cross the vertebral column at the L4-5 disc (Mac Gibbon & Farfan 1979; Quinelle & Stockdale 1983), L4 spinous process (Cunningham & Romanes 1979; Nimmo et al 1994), or L4-5 interspinous space (Render 1996). From this it is clear that no clear consensus exists, at least not in the literature, as to where exactly the intercrestal line intersects the spine. This study aimed to determine whether palpation of the superior aspect of the iliac crest is a reliable, accurate and/or valid method of determining the location of the spinous process of the fourth lumbar vertebra in the standing, seated and prone positions. Thirty participants were marked by three examiners in the standing, seated and prone positions, using the iliac crests to locate the fourth lumbar vertebra. An X-ray was taken of each participant in each of the three positions, after being marked by all three examiners. Measurements were then made on the x-rays, as well as visual assessments by examiners to assess the location of the markers on the lumbar anatomy. The results demonstrated consistent inter-examiner reliability, however the accuracy of using the iliac crest to locate the fourth lumbar vertebra was poor. This is disappointing as the ability to palpate spinal levels is a basic skill and a pre-requisite to more complex palpatory tasks within manual medicine. As for the validity aspect of using the iliac crests to locate the fourth lumbar vertebra, this method was found to be valid in locating the spinous process of the fourth lumbar vertebra. However, it is not a very reliable method, considering that there is only a 53.3% chance of locating the spinous process of L4 once in three attempts in the standing and seated positions and only a 46.7% in the prone position. The reliability of palpation of anatomical landmarks needs to be validated further in future studies as motion palpation and the palpatory assessment of effectiveness of treatment applied to correct motion restriction are predicted upon accurate localization of anatomical landmarks The large variation in intersection points of the intercrestal line does however possibly explain the different opinions found in the literature, and it can be said that to a certain degree all of them are correct