Sensitivity and specificity of the Apley compression test were not correlated (Rs = 0.0) and no SROC curve was estimated. Sources of heterogeneity could not be identified. Only 3 studies, however, addressed this test.
Figure 2 shows the positive predictive value (PV+) and negative predictive value (PV-) for the assessment of joint effusion, the McMurray test, and JLT, according to varying prevalences of meniscal lesions. The summary estimate of sensitivity and accompanying specificity (derived from the SROC curve) were used for joint effusion (0.43 and 0.70), the McMurray test (0.48 and 0.86), and JLT (0.77 and 0.41). Only the McMurray test had a favorable estimated PV+. The PV+ of joint effusion and JLT exceeded the presumed prevalences only slightly, indicating poor additional diagnostic value. The PV- of all tests was poor.
Discussion
Our goal was to summarize the available evidence on the accuracy of various physical diagnostic tests for assessing meniscal lesions of the knee. The accuracy of those tests seems to be poor, and only a positive McMurray test result seems to be of some diagnostic significance.
However, because of the small number and poor quality of the studies found, we have significant concerns about the application of these results. Because of the methodologic flaws, the estimates of the various parameters of test accuracy probably will be biased, and the results of this meta-analysis should be interpreted with care. In view of the presence of review bias and verification bias in the various studies, the sensitivity of the various meniscal tests will be overestimated. The effect of those biases on specificity estimates, however, is less clear: Those specificities could be either overestimated or underestimated. Therefore, a rigorous conclusion regarding the diagnostic accuracy of the various meniscal tests cannot be made. Also, analysis of the influence of other potential sources of bias (like the type of gold standard, setting, and spectrum) was impeded by the low number of studies or the lack of information from studies.
The various physical diagnostic meniscal tests do not seem to be very helpful in guiding clinical decision making, and physicians should be aware of the very limited value of those tests. In the clinical determination of a meniscal lesion, however, meniscal tests are, of course, not applied in isolation. Combining the results of the various tests might improve accurate diagnosis of a meniscal lesion, and including other characteristics as well (eg, elements of history-taking) will further improve diagnosis setting. Those characteristics may even have more diagnostic power than the meniscal tests. Abdon and coworkers14 performed a discriminant analysis and addressed the McMurray test, JLT, and various other signs and symptoms jointly. Of the meniscal tests only, JLT resulted in some additional discriminative power (apart from various elements of history-taking). The results of their analysis, however, are not readily understandable, and the contribution of the individual items to improve the ability to diagnose meniscal lesions correctly remains obscure. Reanalysis of their results by multiple logistic regression might give results that are more directly applicable in clinical practice.
Because no study has been performed in primary care, and test characteristics are influenced by referral filters,27 one can only speculate what the effect will be of extrapolating the observed results to a primary care setting. If family physicians, who will be less experienced in performing those meniscal tests, apply as low a threshold for interpreting a test result as positive, the sensitivity of those tests will be higher, but the specificity will be lower. The predictive value of a negative test result will be affected only slightly, but the predictive value of a positive test result will decrease. On the other hand, when family physicians would apply a high threshold for test positivity, sensitivity decreases and specificity increases, resulting in an increased predictive value of a positive test result. Because of the case mix of patients with traumatic knee problems in primary care (ranging from vague minor knee disorders to clear-cut meniscal lesions), the prior probability (or prevalence) of having a meniscal lesion will be low in primary care, which means that the diagnostic gain will be low also Figure 2.
Recommendations For Future Research
Methodologically sound research on the diagnostic accuracy of the various physical diagnostic tests (determined both for each test separately and for all tests jointly) in combination with patient characteristics (eg, age, physical fitness, and functional demands) and elements of the medical history (eg, the type of trauma and the nature of the complaints) is needed. Such research will be more relevant to clinical practice and patient care if the effect of a correct early diagnosis on the functional outcome of the patient is assessed as well.