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To determine the pattern of knee joint pathology as seen at five radiological imaging centers in Nairobi by MRI, the age and sex distribution and correlate these findings to the arthroscopic findings.


Study design


Retrospective-prospective study


Setting of study


The knee magnetic resonance imaging was carried out at five radiological centers providing MRI services in Nairobi.  These centers are: 1) Kenyatta National Hospital (KNH); 2) Medical Imaging and Therapeutic Centre-Nairobi (MITC); 3) Aga Khan University Hospital-Nairobi (AKUH); 4) MRI centre-Nairobi and 5) The Nairobi Hospital.


Subjects studied


MRI and arthroscopic findings of 46 knees with varied pathologies were reviewed between January 2006 and August 2007.


Results of the study


Males (58.7%) were more affected than females (41.3%).  Majority of the patients were in the 26-50 years age group, with the right knee (67.4%) being affected more than the left (32.6%).  The commonest findings encountered were meniscal tears and joint effusions constituting 78.3% and 65.2% of the cases respectively.  Both showed a male predilection.  Other pathologies seen included chondromalacia patellae, cruciate ligament tears, collateral ligament disruption, bone bruises, patella tendinosis, synovitis and intra-articular loose bodies.


MRI showed a high sensitivity in the medial meniscus, where it was sensitive in detecting a tear in 88.9% of cases.  Sensitivity for tears in the lateral meniscus was higher at 93.3%.  However, specificity for a meniscal tear was lower in the medial meniscus than in the lateral meniscus (36.1% and 63.3% respectively).  The sensitivity and specificity of the MRI for anterior cruciate ligament rupture (whether complete or partial) was 83.3% and 90.9% respectively.  For the articular cartilage, sensitivity was 46.2% and 16.7% for femoral and tibial articular cartilage abnormalities with a specificity of 81.8% and 75.0% respectively.  The sensitivity and specificity of the MRI for chondromalacia patellae was 26.7% and 81.8% respectively.




The results of this study support the use of MRI in the diagnosis of internal derangements of the knee.  However, it should always be used in conjunction with a full history and clinical examination.