Assessing palpation thresholds of osteopathic medical students using static models of the lumbar spine.

CONTEXT: Although spinal somatic dysfunction diagnosis is taught at all colleges of osteopathic medicine, few objective measures have been used to evaluate student accuracy.

OBJECTIVE: To assess the palpatory skills of osteopathic medical students in evaluating positional asymmetry in the transverse plane using static block transverse process and lumbar spine models.

METHODS: For this observational study, first-year osteopathic medical students completed 3 palpatory assessments using uncovered and covered block transverse process and lumbar spine models to simulate a range of positional asymmetries of the transverse processes. With use of logistic regression, 80%, 90%, and 95% thresholds were defined as the magnitude of asymmetry for which the predicted probability of students correctly determining the direction of asymmetry exceeded a specified amount (.80, .90, or .95).

RESULTS: A total of 346 students completed the assessments. For the uncovered block transverse process model (assessment 1), students correctly identified the direction of asymmetry with .89 probability at 1 mm of asymmetry (80% threshold), .94 probability at 2 mm (90% threshold), and .95 probability at 3 mm (95% threshold). For the covered block transverse process model, students correctly identified the direction of asymmetry with .80 probability at 1 mm (80% threshold), .92 probability at 2 mm (90% threshold), and .98 probability at 3 mm (95% threshold) by the third assessment. For the uncovered lumbar spine model (assessment 2), students correctly identified the direction of asymmetry with .93 probability at 2 mm (80% and 90% thresholds) and .95 probability at 3 mm (95% threshold). For the covered lumbar spine model (assessments 2 and 3), students correctly identified the direction of asymmetry with .87 probability at 4 mm (80% threshold); 90% and 95% thresholds were not reached with the range of asymmetries tested.

CONCLUSION: Most first-year osteopathic medical students were able to discern the direction of positional asymmetry of transverse processes on static models. Depending on the model type, student performance improved (block transverse process models) or declined (lumbar spine models) over time. Future studies should evaluate whether accuracy of palpating lumbar spine models translates to accuracy of palpating human lumbar spines.