Clinical Diagnosis of Meniscal Tears in the Knee – Research Evidence

Hi all. This post continues on with the theme relating to the “usefulness” of clinical tests.

The time the topic of this post is “Clinical Diagnosis of Meniscal Tears in the Knee – Research Evidence”.

Once again this post throws values around for sensitivity, specificity, LR’s etc. So here is some information from a previous post regarding these figures.

For screening, triage, or ruling out disorders, a cut-off sensitivity of 90 and a negative likelihood ratio of less than 0.20 were considered as a necessity. Although there is no definitive cut-off score for screening or triage that is suggested for sensitivity, authors have advocated a sensitivity of 90 or greater for general musculoskeletal conditions (and higher numbers for more sinister conditions) (Cook and Hegedus, 2008).

For diagnosis, tests and measures with positive likelihood ratios of 5.0 or greater were considered useful (Jaeschke et al., 1989). 

Three of the more common tests (links to youtube videos) reported in the literature that I will cover in this post are:

1. McMurray’s Test
2. Apley’s Test
3. Thessaly Test

I think that most physiotherapists use these tests in clinical practice. But what does the research tell us about their ability to diagnose meniscal tears? 

Hegedus et al (2007) conducted a systematic review examining the ability of McMurray’s, Apley’s, and joint line tenderness to accurately diagnose a torn tibial meniscus. Results and conclusions were:

• Pooled sensitivity and specificity were 70% and 71% for McMurray’s, 60% and 70% for Apley’s, and 63% and 77% for joint line tenderness. Large between-study differences could not be explained by prevalence, study quality, or how well an index test was described.
• No single physical examination test appears to accurately diagnose a torn tibial meniscus and the value of history plus physical examination is unknown.

Rinonapoli et al (2011) conducted a study to investigate the reliability of two clinical meniscal tests, McMurray’s and Apley’s and the MRI imaging, in order to establish how to reduce unjustified arthroscopies. Key information:

• They assessed 102 patients, all of whom were submitted to a triple clinical examination, MRI and an arthroscopic procedure.
• The positivity or negativity of the tests and MRI were compared to arthroscopic findings. Arthroscopy is considered the gold standard for the diagnosis of meniscal lesions.
• The authors measured the length of the meniscal lesions in order to correlate it to the clinical findings.
• Results:
  • From the clinical examination the following numbers were produced:
    • McMurray’s test: sensitivity 79.7%, specificity 78.5%, accuracy 79.4%, positive likelihood ratio 3.7, negative likelihood ratio 0.2.
    • Apley’s test: sensitivity 83.7%, specificity 71.4%, accuracy 80.3%, positive likelihood ratio 2.9, negative likelihood ratio 0.2.
    • The assessment of the clinical tests was done even in relation to medial or lateral meniscal lesion.
    • No statistical difference was found about the length of the meniscal tear.
    • MRI gave the following results: sensitivity 78.3%, specificity 85.7%, accuracy 80.3%.
• Conclusions:
  • If used as as diagnostic means, McMurray’s and Apley’s clinical tests and MRI as imaging procedure, we have an accuracy of about 80%.
  • It is important to keep in mind that it is not possible to have the absolute certainty of make a correct diagnosis in case of meniscal lesions.

Yan et al (2011) also conducted a study in relation to meniscal tears in the knee.

• Their aims were to:
  • Identify sensitive and specific clinical tests and elements of patients’ history with a high predictive value, and;
  • To assess the combined diagnostic accuracy of sensitive and specific clinical tests and elements of patients’ history with MRI.
• The study group consisted  of 262 knees.
• The diagnostic values of MRI and the sensitive and specific clinical tests and elements of patients’ history with high predictive value for meniscal tears were calculated.
• Results:
  • Overall diagnostic value of MRI for meniscal tears was: accuracy, 88.8%; sensitivity, 95.7%; specificity, 75.8%; positive predictive value (PPV), 88.2%; and negative predictive value (NPV), 90.4%.
  • Giving way, locking and McMurray’s test were independent diagnostic factors with a predicted correct percentage of 80.0% (p <0.05) for the diagnosis of meniscal tears found during arthroscopy.
  • Locking, McMurray’s test and MRI increased the predicted correct percentage of meniscal tears found during arthroscopy to 91.6% (p <0.05).
  • For the diagnosis of meniscal tears found during arthroscopy, giving way, locking and McMurray’s test had the following values for accuracy (49.2, 60.9, 76), sensitivity (43.5, 55.2, 75.8), specificity (84, 96, 76.9), PPV (94.4, 98.8, 95.1) and NPV (19.4, 25.8, 35.1).
  • Combining MRI, the diagnostic values of giving way, locking, and McMurray’s test were: accuracy, 88.3,89.9,89.4; sensitivity, 95.7,97.4,97.4; specificity, 74.2,75.8,74.2; PPV, 87.5,88.4,87.7; and NPV, 90.2,94,93.9.

A lot of information in the above…….the conclusions summarise the information best:

• Conclusions:
  • Giving way, locking and McMurray’s test are independent clinical diagnostic factors for the diagnosis of meniscal tears.
  • MRI has higher accuracy, sensitivity and NPV for the diagnosis of meniscal tears than giving way, locking and McMurray’s test.
  • The combination of giving way, locking, McMurray’s test and MRI for confirmation is typical for a meniscal lesion diagnosis.

More on the Thessaly test to come below…….

To finish up I have am going to put up a table from Shier et al (2010) (All credit to the authors) that provides a nice summary of the research into this topic. Granted this information is only until 2010 so a couple of the article above don’t make it.

Interestingly the values for each test in the above table differ quite markedly in varying studies. Why might this be?

The key points (and I think these are important in all research into physical examinations) that Shrier et al (2010) make regarding factors that can result in varying values, such as in the above table, are:

• Reporting Bias:
  • Studies are more likely to be published if the findings are positive.
  • With the large amount of academic institutions, there probably are many studies showing a test is not good, and these would not be submitted for publication.
  • Even if a particular test is not very good, a few studies would have promising results by chance alone, and these would be published. This is why confirmatory evidence from independent sources is so important.
  • On the Thessaly test:
    • Note that the later studies report less promising results; “negative” studies become much more important (and publishable) if they suggest current practice is flawed or results from previous studies were exaggerated or biased.
• Selection Bias:
  • Although sensitivity and specificity are not affected by the prevalence of disease, they are affected by the choice of patients in the study.
• Heterogeneity of Pathology:
  • Diagnostic tests are designed to evaluate signs that are specific characteristics of the disease.
  • These characteristics are expected to be present in every patient (or almost every patient) and absent in subjects without disease. This fundamental principle must be present to have excellent diagnostic test properties.
  • In the physical examinations of musculoskeletal conditions (and many other conditions), this rarely applies.
• Summary:
  • The results of individual studies for the Thessaly Test are indicative of the problems associated with using meta-analyses of diagnostic test studies to evaluate the physical examination. Aside from the issue of reporting bias already mentioned, the Thessaly test appears superior to other tests in some studies but not others, suggesting that the populations or methods or heterogeneity of pathology of the different studies affect the sensitivity and specificity of the test.
  • The true value of any diagnostic test is the added information it provides in the context of what already is known about the patient.

My Thoughts:

Now I realise that there are many more articles available in relation to this topic, but in my opinion, the overall consensus from the above would be that, once again, we should interpret test results for Meniscal Tears with caution. The sensitivity, specificity and LR’s are variable and often not near the recommended “cut-offs”.

I admit the work by Yan et al (2011) looks promising, and worth considering for clinical practice, but whether subsequent research (like in the Thessaly test case) will show similar results or not, only time will tell.

Thanks for reading.

References:

Harrison BK, Abell BE, Gibson TW. The Thessaly test for detection of meniscal tears: validation of a new physical examination technique for primary care medicine. Clin J Sport Med. 2009 Jan;19(1):9-12.

Hegedus EJ, Cook C, Hasselblad V, Goode A, McCrory DC. Physical examination tests for assessing a torn meniscus in the knee: a systematic review with meta-analysis. J Orthop Sports Phys Ther. 2007 Sep;37(9):541-50.

Rinonapoli G, Carraro A, Delcogliano A. The clinical diagnosis of meniscal tear is not easy. Reliability of two clinical meniscal tests and magnetic resonance imaging. Int J Immunopathol Pharmacol. 2011 Jan-Mar;24(1 Suppl 2):39-44.

Shrier I, Boudier-Revéret M, Fahmy K. Understanding the different physical examination tests for suspected meniscal tears. Curr Sports Med Rep. 2010 Sep-Oct;9(5):284-9.

Yan R, Wang H, Yang Z, Ji ZH, Guo YM. Predicted probability of meniscus tears: comparing history and physical examination with MRI. Swiss Med Wkly. 2011 Dec 14;141:w13314. doi: 10.4414/smw.2011.13314.