CAN THE COMPUTERIZED PHYSICAL-EXAMINATION DIFFERENTIATE NORMAL SUBJECTS FROM ABNORMAL SUBJECTS WITH BENIGN MECHANICAL LOW-BACK-PAIN

Inconsistencies among physicians in the evaluation of benign low back conditions make standardization desirable. A computerized physical exa mination device was used to evaluate low back pain patients and compar e their results with a normative database obtained from a selection of healthy subjects. A high-resolution motion analysis system tracked th e movement of skin markers placed on the midline and pelvis. Surface e lectromyography electrodes placed above L(5) collected data from multi fidus. From the kinematics of skin markers during flexion extension wi th lifts up to 32 kg, and lateral bending with lifts up to 4.6 kg, the following parameters were estimated: lumbosacral angle and elongation , contribution of each lumbar segment to the lordosis reduction, relat ive pelvic/spine motion and trunk velocity. First, the average normal value for each estimated parameter was determined using 40 normal subj ects. For each subject, the difference between his parameter and the n ormal was processed by an expert system generating a normality index v arying from zero (perfect abnormal) to one (perfect normal). To develo p the expert system's rules, a preliminary group of 20 very abnormal s ubjects were used, such that the normality index separated them from t he normals. For validation, a set of 29 WCB sprain patients and anothe r 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 clinic ians' evaluation which was taken to be the gold standard. The Receiver Operating Characteristic technique was used to quantify the discrepan cies. Results show that the expert system can detect clinically abnorm al subjects with accuracy (sensitivity 83-91% and specificity greater than or equal to 90%) while providing quantitative information on work ers' functional capacities. Relevance It is possible to automate the l umbar physical examination with an acceptable error rate. This techniq ue permits the objective consistent assessment of lumbar function, and thus allows the comparison of different treatment regimes for lumbar dysfunction. Copyright (C) 1996 Elsevier Science Ltd.