A novel and accurate palpation method for identification of the L4 spinous process
Authors: Cramer Gregory David , Selby Scott , Cantu Joe , Roytman Gregory 
Published: April 2020

Background

Effective physical examination of patients with back pain is essential for several clinical specialties, including rheumatology, orthopedics, neurology, anesthesiology, physical medicine, chiropractic, and physical therapy. Accurate identification of lumbar spinous process (SPs) as landmarks is fundamental to such examination; however, identifying lumbar SPs through manual palpation has been shown to be surprisingly inaccurate. During a clinical trial using precisely placed accelerometers to assess zygapophyseal joint cavitation, a novel method of palpation was used to improve palpation accuracy.

Methods

This case series was approved by the institutional IRB. Palpation to identify the L4 SP (primary landmark for the study) was performed by clinicians with a minimum of 5 years of practice experience, using either: 1) the standard/traditional method of identifying the L4 SP using the supracristal plane (n=14); or 2) a novel method that began by identifying the superior aspect of the sacrum through manually inducing sacral motion and then identifying the L5 SP and then the L4 SP (n=54). The clinicians worked independently on separate subjects and had no access to the results of one another during the palpation phase of the project. The clinicians applying either palpation method used a grease pencil to mark the location they identified as the L4 SP. An MRI high‐signal marker was then taped across this location. A mid‐sagittal scout MRI scan was then taken with the subject in the supine position. The de‐identified scans were assessed by a radiologist, blinded to the palpation method, who marked the superior and inferior extent of the L4 SP on the MRI scans and drew a line extending posteriorly through the skin and perpendicular to the lateral edge of the film (i.e., perpendicular to the MRI gantry table). The radiologist then determined if the high signal marker visible on the image was within the lines bordering the L4 SP (i.e., accurately identifying the SP, reported here as “on target”), on one of the lines (also considered to be “on target”), or too far superior or too far inferior. If too far superior or inferior, the radiologist assessed the extent of the discrepancy.

Results

Palpation by the traditional method showed a 35.7% accuracy, 5 of 14 on target [2 (40%) on a line]; and 9 of 14 off target, all off target being too superior (4 at the L3 SP, 5 at the L2‐L3 interspace). Palpation by the novel method showed 77.8% accuracy; 42 of 54 on target [9 (21%) on a line], and 12 of 54 off target, 3 off target being too superior (all at the L3 SP) and 9 too inferior (7 at the L5 SP, 2 at the L5‐S1 interspace).

Conclusions

The novel method performed better than the traditional method in this case series. We conclude that the novel method shows promise, and propose that additional prospective research be conducted to fully assess the accuracy of the novel method compared with traditional methods of palpation.

Support or Funding Information

NIH/NCCIH Grant# – 3R01AT000123‐06S2

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.