Can the Computerized Physical Examination Differentiate Normal Subjects from Abnormal Subjects with Benign Mechanical Low Back Pain?
Newman N, Gracovetsky SA, Itoi M, Zucherman J, Richards M, Durand P, Xeller C, Carr D.
Clinical Biomechanics
11(8) : 466-473, 1996.
Abstract
Inconsistencies among physicians in the evaluation of benign low back conditions make
standardization desirable. A computerized physical examination device was used to evaluate
low back pain patients and compare their results with a normative database obtained from a
selection of healthy subjects. A high-resolution motion analysis system tracked the
movement of skin markers placed on the midline and pelvis. Surface electromyography
electrodes placed above L5 collected data from multifidus. From the kinematics of skin
markers during flexion extension with lifts up to 32 kg, and lateral bending with lifts up
to 10 kg, the following parameters were estimated: lumbosacral angle and elongation,
contribution of each lumbar segment to the lordosis reduction, relative pelvic/spine
motion and trunk velocity. First, the average normal value for each estimated parameter
was determined using 40 normal subjects. For each subject, the difference between his
parameter and the normal was processed by an expert system generating a normality index
varying from zero (perfect abnormal) to one (perfect normal). To develop the expert
system's rules, a preliminary group of 20 very abnormal subjects were used, such that the
normality index separated them from the normals. For validation, a set of 29 WCB sprain
patients and another set of 42 discogram positive were selected. Each subject was tested
and his computerized normality index calculated without any clinicians' input. The
computerized normality index was compared with the clinicians' evaluation which was taken
to be the gold standard. The Receiver Operating Characteristic technique was used to
quantify the discrepancies. Results show that the expert system can detect clinically
abnormal subjects with accuracy (sensitivity 83-91% and specificity = 90%) while providing
quantitative information on workers' functional capacities.
Relevance
It is possible to automate the lumbar physical examination with an acceptable error rate.
This technique permits the objective consistent assessment of lumbar function and, thus,
allows the comparison of different treatment regimes for lumbar dysfunction.
