Comparative Accuracy of Physician Palpation of Sacral Anatomical Landmarks versus Musculoskeletal Ultrasound Evaluation

Comparative Accuracy of Physician Palpation of Sacral Anatomical Landmarks versus Musculoskeletal Ultrasound Evaluation. Introduction Ultrasonography is useful for visualizing musculoskeletal structures due to its safety and capacity for real-time imaging. A recent publication shows the validity of ultrasonography to establish sacral base position and sacral sulcus depth. Our study will compare the palpatory examination of sacral landmarks by osteopathic physicians to sonographic findings. Methods This study has received institutional review board approval (#2015-188). Our enrollment goal is 40-60 subjects and we have currently recruited and collected data with 16 subjects. Each subject had an initial ultrasound measurement of each sacral sulcus and inferior lateral angle (ILA), both in a prone and extended (sphinx) position. Then 5 examiners comprised of 3 senior osteopathic physicians and 2 osteopathic residents, palpated and evaluated each landmark for symmetry, again in prone and sphinx positions. Finally, another ultrasound evaluation was performed to see if there was a change in the sacrum following the repeated examinations. Results The preliminary data collected with 16 enrolled subjects were analyzed thus far. Ultrasound measurements revealed mean left to right depth difference ranging from 0.38-0.26cm between the designated sacral bony landmarks. When the subjects were transitioned from prone to sphinx position, the mean depth difference ranged from 0.23-0.06cm (±0.46-0.68). Sonography before and after physician palpation showed a depth difference of the designated landmark range from 0.37-0.07cm (±0.6-0.42). Physician palpation data have not shown a high degree of interrator reliability with the 16 subjects studied. Comments/ Conclusions Our study is on going, but so far we are able to validate that ultrasound can identify depth differences of the sacral sulcus and the ILA. Sonography also has demonstrated that depth of the sacral landmarks change from prone to sphinx position. It is important to note that the ultrasound measurements we collected so far show that there may be relative anterior movement of the sacrum at both the sacral sulcus and ILA when the subjects are in a sphinx position. This is important to study further as standard osteopathic texts maintain that the sphinx position causes the sacral base to move anterior while the ILAs move posterior. Comparing ultrasound measurements before and after physician palpation demonstrated that repeated palpation of bony landmarks may change sacral positioning. Further data collection will be needed to adequately understand physician palpatory experience.