Physical Therapy Haven

Diagnosing a meniscal tear using special tests.

With the correct diagnosis of a meniscal tear via special tests being between 60-95%, do we put too much trust into these special tests²? If so, how can we maximize clinical accuracy?

            A brief review of anatomy and biomechanics is needed to maximize clinical test sensitivity and specificity.  The menisci move with the tibia during flexion and extension and with the femur with rotation, thus part of their function is to limit extreme flexion or extension. It is important to also pay tribute to the fact that most of the tests are non-weight bearing yet they are used to assess an injury that often occurs in weight bearing. Take the McMurray test for example, during the test the client’s tibia is either internally or externally rotated in full flexion, which brings the lateral/medial tibial plateau anteriorly leaving the lateral/medial meniscus posteriorly respectively. Then the client’s knee is extended and the lateral/medial meniscus’ posterior horn will be tested and impinged respectively. In weight bearing, however, the motion is often driven from the bottom up, top down, or both and thus it is important to see/replicate the relative movement between the tibia and femur to understand the potential driving forces that occurred during the MOI.

            Of all the tests, it is interesting to note that Strobel and Stedtfeld¹ show joint palpation to be the most reliable. To maximize the reliability it is important to use the biomechanics to unveil the meniscus for palpation. To palpate the anterior medial aspect of the medial meniscus, place the knee in slight flexion and rotate the tibia internally; the opposite is true for the lateral meniscus.  Of the 20 tests Strobel and Stedtfeld² list for meniscal tears they encourage clinicians to use diagnosis by committee and by ruling out other diagnoses. After all, some of these clients may have tears despite having symptoms. A study by Kornick and associates found over 25% to have abnormal signals in their menisci, despite being asymptomatic¹.

            What tests have you used that have been verified to be a true-positive with an either an MRI or arthroscopy. If a client does have a meniscal tear how many weeks are they treated before they are able to return to full function or have to go through arthroscopy?

1. Kornick J. Meniscal abnormalities in the asymptomatic population at MR imaging. Radiology. 1990;177:463-465.

2. Strobel M, Stedtfeld HW: Diagnostic Evaluation of the Knee. New York: Springer-Verlag, pp 166-182, 1990.