A comparison of accuracy of clinical tests and MRI in the diagnosis of meniscal and anterior cruciate ligament injuries

Abstract

Objective: To compare the accuracy of clinical examination versus Magnetic Resonance Imaging (MRI) in the diagnoses of meniscal and Anterior Cruciate Ligament (ACL) tears after trauma.
Methods: Between January 2011 and December 2015, 147 consecutive patients with previous history of knee injury were seen and evaluated clinically. One hundred and one were recruited for the study; out of these 52 knees were suspected to have meniscal tears while 36 knees were suspected to have ACL ruptures and 12 knees were unclear (equivocal). There were 68 males and 33 females. The average preoperative period for the patients was 3 months (range, 1 month to 2 years) and their mean age was 35 years (range, 15 to 49 years). After initial clinical diagnosis some patients underwent arthroscopy without MRI (34 cases) and some had MRI scanning before arthroscopy (67 cases). The final diagnosis was made at arthroscopy on all patients. Accuracy, sensitivity, specificity, and positive and negative predictive values were calculated comparing clinical examination and MRI reporting.
Results: There was a wide variance between clinical diagnosis and MRI reportage for meniscal tears. Clinical examination had negative predictive value of 25% against 6% for MRI. Both had high sensitivity of (87% and 92%) and low specificity (32% and 50%, respectively). The differences were statistically significant (P = 0.0164). On the contrary, there was little difference between clinical diagnosis and MRI diagnosis in the diagnosis of ACL raptures. There was a negative predictive value of 8% for clinical examination against 4% for MRI with a sensitivity of 92% and 96% respectively. Both have a high specificity (75% and 80%, respectively). There was no statistical difference between the two modes of diagnosis (P = 0.6177). MRI easily picked both injuries (ACL and meniscal) in the same knee which were difficult to differentiate clinically.
Conclusions: A careful clinical examination can safely diagnose almost all ACL injuries and most of the meniscal injuries. MRI should be reserved for more complicated and confusing cases. The routine ordering of an MRI scan of the knee before examination by a well-trained orthopaedic surgeon is not recommended. This is more so true in resource limited economies and public hospitals in the developing world.

Keywords: Accuracy, Clinical, MRI, Meniscal, ACL, Tears