No single test is diagnostic of a meniscal tear. A combination of clinical history with mechanism of injury, joint line tenderness and special tests help in the diagnosis.
If the clinical diagnosis is doubtful, MRI scans are 90-98% sensitive in making the diagnosis. There is limited role for diagnostic arthroscopy of the knee. Clinical tests for meniscal tears are less accurate in the presence of acute ligament injuries. preservation and even restoration
Tear of a healthy meniscus
Injury to a healthy meniscus occurs with a rotational force on a loaded knee. The meniscus follows the tibia with flexion and also follows the femur with rotation.
Medial meniscal tears are more common than lateral meniscal tears (Baker et al- 81% to 19% with sex ratio being 3:1 male:female) Lateral meniscal tears can more commonly occur with acute ACL ruptures as there is anterolateral rotatory translation of the tibia on the femur. Medial meniscal tears are as common with chronic ACL deficiency.
There is sports specific difference in type and location of tears. Medial meniscus posterior horn tears and longitudinal tears are more common with football, skiing and basketball. Lateral meniscal tears are as commoner in wrestling, gymnastics and volleyball. Most tears of the medial meniscus involve the posterior third whilst middle zone tears of the lateral meniscus are more common.
Tear of a degenerate meniscus
A degenerate meniscus can tear with no specific injury. There is a reduction in mucopolysacharides with fibrocartilage degeneration and it is more likely that the tear is due to degeneration rather than the tear causing degeneration (Noble 1975) Degenerate meniscal tears are often associated with arthritic knees. Calcific menisci have a two-fold higher association with degenerate meniscal tear. Degenerate meniscal tears are usually flap tears, horizontal cleavage or of complex pattern.
- Mechanism of injury
- Sporting history
- Presence of clicking or locking or giving way
- Pain on squatting or deep flexion
Tenderness along the joint line is more specific for lateral meniscal tears than medial meniscal tears. In the presence of an acute ligament injury, tenderness is not a useful sign. Careful evaluation by an experienced examiner identifies patients with surgically treatable meniscus lesions with equal or better reliability than MRI (Ryzewicz CORR 2007- Systematic Review). Numerous authors have reported that there is no significant difference in the accuracy of clinical examination and MRI in the diagnosis of meniscal or ACL tears. ( Rose Arthroscopy 1996, Kocabey Arthroscopy 2004, Thomas Knee Surg Sports Traumatol Arthrosc. 2007).
(1) a history of “catching” or “locking” as reported by the patient,
(2) pain with forced hyperextension,
(3) pain with maximum flexion,
(4) pain or an audible click with McMurray’s test, and
(5) joint line tenderness to palpation.
Five positive findings on composite examination yielded a positive predictive value of 92.3% (Lowery,Steadman et al). Positive predictive values remained greater than 75% with composite scores of at least 3 in the absence of ACL and DJD pathologies. The presence of an ACL injury decreased the positive predictive value of 5 composite findings to 67%, whereas the presence of DJD increased predictability to 100%.
- Deep flexion
- Steinman test
- Apley’s grinding test
- Thesally test
The negative predictive value (NPV) of clinical examination is no greater than 67%; therefore, about one third of meniscal tears are missed with clinical screening alone (Fowler, 1989; Spiers, 1993). In situations of multiple knee lesions, the accuracy of clinical examination in diagnosing meniscal tears decreases (Alseki 2003, Eren 2003, Shelbourne 1995, Oberlander, 1993). The negative predictive value of MRI scans is high and hence are useful to avoid unnecessary arthroscopy. The sensitivity of MRI scans to diagnose multiple injuries reaches almost 100% whilst for meniscal tears For MRI Scans to be more useful, there needs to be an integration of clinical findings with the Orthopaedic Surgeon’s review of the scans. (Luhmann JBJS-A 2005) Musculoskeletal radiologists have to be given enough clinical information when requests are made for MRI scans.
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