Mathematical Relationship Between Palpation Forces and Displacement Associated With Restriction

Based on the clinical data, a mathematical model was developed that characterized the palpation forces and the associated deformation/displacement of the surface of the body when osteopathic clinicians examine the low back or lumbar spine region. The purpose of this work was to better understand the haptic perception of clinicians who use palpation to assist in their assessment of patients with low back pain. Clinicians use palpation to identify areas of reduced tissue compliance thought to be associated with restriction of segmental vertebral motion. Using existing experimental data generated by multiple clinicians examining human volunteers, palpation forces and associated displacements were modeled by using three key variables: stiffness, damping, and inertia of the system. Of the total number of force application cycles analyzed, 92% had a goodness of fit, R², that was better than 95% (R²$≥$ 0.95). When comparing the experimental data to the response of the three-parameter force/displacement mathematical model, the mathematical model delivered an accurate representation of palpation forces and displacements. A normalized stiffness difference (NSD) was generated to compare to clinician assessments. Recommendations for design specifications of a palpation-training device were suggested.