Snider EJ, Pamperin K, Pazdernik V, Degenhardt BF. Influence of Transverse Process Landmark Localization on Palpation Accuracy of Lumbar Spine Models. J Am Osteopath Assoc 2018;118(3):151–158. doi: 10.7556/jaoa.2018.034.
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Accurate determination of transverse process displacement in the horizontal plane requires accurate transverse process landmark localization followed by accurate discrimination of asymmetry by the examiner's palpating digits.
To determine whether the accurate localization of transverse process landmarks influences overall accuracy of asymmetry determination in third-year osteopathic medical students evaluating covered lumbar spine models.
A class of third-year osteopathic medical students was split into 2 groups and asked to determine whether the right transverse processes of covered lumbar spine models were anterior or posterior relative to the left transverse process. The marked model group (group A) was provided covered models with black dots on the fabric covers over the transverse process landmarks, while the covered models given to the students in the unmarked model group (group B) had no markings. Both groups were asked to assess asymmetry differences from L1 to L5 on 2 models. Landmarks were randomized for asymmetry (ranging from 2 mm to 6 mm) and direction (anterior or posterior on the right side). The number of correct responses was modeled as a binomial random variable in a generalized linear model to compare the effects of marked vs unmarked models on accuracy of palpation. The predicted probability of correctly determining the direction of the asymmetry and 95% CIs were calculated.
The probability of correctly identifying the direction of asymmetry was 0.89 (95% CI, 0.87-0.91) for group A and 0.74 (95% CI, 0.71-0.78) for group B, a 15 percentage point difference (OR, 1.2; 95% CI, 1.1-1.3; P<.001). Assuming accurate perception of digit asymmetry and accurate localization of landmarks are independent and correct answers are given only if both events occur, then students were more likely to accurately perceive digit asymmetry (0.89) than accurately localize landmarks (0.83=0.74/0.89). Overall, more students accurately identified the direction of asymmetry when the right transverse process was anterior (0.87; 95% CI, 0.84-0.90) than when it was posterior (0.81; 95% CI, 0.77-0.84) (OR, 1.6; 95% CI, 1.2-2.1; P=.001).
Student palpation accuracy was better when transverse process landmark localization was provided on the lumbar spine models than when it was not. Students were more likely to accurately perceive digit asymmetry than accurately localize the landmarks. Improving palpation accuracy requires developing educational methods to improve both accurate landmark localization and accurate digit asymmetry perception.
a A blank cell indicates there was no assessment for that vertebra level or amount of asymmetry.
a Inverse-logit transformation of predicted population margins balanced across group.
a Group A (marked model): Pr(P | L) = 0.89. Group B (unmarked model): Pr(P ∩ L) = 0.74.
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