Cross Sectional Study of The Pattern of Abnormalities in The Knee Joint Detected by Knee MRI in Patients Evaluated at Tikur Anbessa Specialized Hospital, Addis Ababa University, Addis Ababa, Ethiopia from April–August 2017

Introduction: The knee joint, the largest joint in the body, has several functions which are essential for human beings to walk, run and jump. Primarily, it enables flexion-extension of the lower limb in the sagittal plane. Joint stability during movement is attained by the shape of the articular surfaces, the collateral and cruciate ligaments, the menisci and tendons and muscles crossing the knee joint. (1) The vulnerability of the knee, the largest joint in the body, to direct trauma makes knee injuries very common throughout life. (2) MRI visualizes most components of the knee joint, including articular cartilage, menisci, intra-articular ligaments, synovium, bone marrow, subchondral cysts, and other periarticular and intra-articular lesions that are not detectable by radiography. (4). The prevalence of abnormalities of these different joint components as detected by MRI has been studied in different centers. Such types of studies, to date, have not been done in our country to our knowledge. The aim of this paper is to study prevalence of these abnormalities in the knee joint detected by knee MRI. Objective: To assess the prevalence of abnormalities in the knee joint detected by knee MRI. Methods: Hospital based prospective cross sectional study was conducted on 49 patients who had knee MRI at Tikur Anbessa Specialized Hospital in a period of 7 months from January 1 to August 2016.  Patients included here are those who had knee MRI and no history of knee surgery. Results: A total of 49 patients were included in the study out of which 26(53.1%) were male and 23 (46.9%) were female, with a mean age of 43 years (range 17 to 68 years). The three most common pathologies were joint effusion seen in 32(65.3%), bone marrow edema in 22(45.8%) and osteophytes in 22(44.9%). ACL tear was the commonest ligament abnormality occurring in 5 (10.4%) patients. Ten (20.8%) patients had meniscal tear, all involving the medial meniscus with the posterior horn being involved in 8(80%) of these patients. Conclusion: The mean age of our study population was higher than most referenced papers suggestive for possible delayed health seeking. The commonest knee pathologies were similar to other studies. Features of osteoarthritis were seen in higher frequency in our study population. Even though the higher mean age could be the possible cause, further study is recommended to look into the causes. Abnormalities which were seen with higher frequency in those with a history of trauma were also seen in higher frequency in the male population.