ABSTRACT
Background: Newly symptomatic chronic musculoskeletal illness is often misinterpreted as new pathology, particularly when symptoms are first noticed after an event. In this study, we were interested in the accuracy and reliability of identifying the symptomatic knee based on bilateral MRI reports. Methods: We selected a consecutive sample of 30 occupational injury claimants, presenting with unilateral knee symptoms who had bilateral MRI on the same date. A group of blinded musculoskeletal radiologists dictated diagnostic reports, and all members of the Science of Variation Group (SOVG) were asked to indicate the symptomatic side based on the blinded reports. We compared diagnostic accuracy in a multilevel mixed-effects logistic regression model, and calculated interobserver agreement using Fleiss' kappa. Results: Seventy-six surgeons completed the survey. The sensitivity of diagnosing the symptomatic side was 63%, the specificity was 58%, the positive predictive value was 70%, and the negative predictive value was 51%. There was slight agreement among observers (kappa= 0.17). Case descriptions did not improve diagnostic accuracy (Odds Ratio: 1.04; 95% CI: 0.87 to 1.3; P=0.65). Conclusion: Identifying the more symptomatic knee in adults based on MRI is unreliable and has limited accuracy, with or without information about demographics and mechanism of injury. When there is a dispute concerning the extent of the injury to a knee in a litigious, medico-legal setting such as Workers' Compensation, consideration should be given to obtaining a comparison MRI of the uninjured, asymptomatic extremity.
ABSTRACT
BACKGROUND: Minor events that occur in the workplace sometimes are evaluated with MRI, which may reveal age-related changes in the symptomatic body part. These age-related changes are often ascribed to the event. However, evidence of similar or worse pathophysiology in the contralateral joint would suggest that the symptoms might be new, but the pathophysiology is not. QUESTIONS/PURPOSES: Using a convenience sample of occupational injury claimants with bilateral MRI to evaluate unilateral knee or shoulder symptoms ascribed to a single event at work, we sought to determine whether MRI findings of the shoulder and knee are more often congruent or incongruent with new unilateral symptoms. METHODS: Two hundred ninety-four occupational injury claimants employed at companies throughout Texas that do not subscribe to workers' compensation insurance, who were older than 40 years, and with unilateral shoulder or knee symptoms, were studied. Starting in 2012, all patients seen by OccMD Group PA who present with unilateral symptoms ascribed to work undergo bilateral MRI, based on several previous occasions where bilateral MRI proved to be a compelling demonstration that perceived injuries are more likely age-related, previously well-adapted pathophysiology. MRI findings (anything described as abnormal by the radiologist; eg, defect size or signal change) was considered congruent if the abnormality of one or more structures on the symptomatic side was greater than that of the corresponding structures in the asymptomatic joint. Bivariate analysis was used to compare the frequency of MRI findings congruent and incongruent with symptoms. Logistic regression was used to evaluate factors associated with MRI findings of the shoulder or knee. RESULTS: Less than half of the patients with shoulder (90 of 189; 48%; p = 0.36) or knee (45 of 105; 43%; p = 0.038) symptoms had worse pathologic features on the symptomatic side. Older age was associated with disorders in the infraspinatus tendon (59 ± 8 versus 56 ± 8 years; p = 0.012), glenoid labrum (60 ± 9 versus 57 ± 8 years; p = 0.025), and biceps tendon (60 ± 8 versus 57 ± 8 years; p = 0.0038). Eighty-seven percent of patients (91 of 105) had structural changes in the medial meniscus described by the radiologist. CONCLUSIONS: Occupational injury claimants 40 years of age and older with unilateral knee and shoulder symptoms ascribed to a work event tend to have bilateral age-related MRI changes. Age-related disorders should be distinguished from acute injury. LEVEL OF EVIDENCE: Level IV, diagnostic study.
