Prevalence and pattern of knee osteoarthritis in patients presenting at a rheumatology clinic of a tertiary hospital in north east Nigeria

Abstract

Background: Osteoarthritis (OA) is the most common joint disease in the world and a major cause of morbidity and activity limitation. It is among the top 5 causes of disability especially in people aged 45 years and above.

Objectives: This study aimed to determine the pattern and radiographic features of knee OA and its association with pain, age and BMI in patients presenting at the rheumatology clinic of the University of Maiduguri Teaching Hospital, Nigeria.

Method: This was a descriptive cross-sectional hospital-based study. Consecutively presenting adults satisfying the 1986 American College of Rheumatology criteria for knee OA were recruited from March to October 2015. Detailed history, physical examination of the knee and anthropometric measurements were obtained. Pain and functional status were assessed using Visual Analogue Score (VAS) and Steinbrocker’s criteria respectively. Blood samples for biochemical profiles were obtained. Standard radiographs of the knee in both anteroposterior and lateral views were taken.

Results: Four hundred and fifty-one patients with rheumatic complaints were seen at the clinic, out of whom 244 (54.1%) had knee OA. There were 63 (25.8%) males and 181 (74.2%) females with a male to female ratio of 1:2.9. The median age was 50 years (IQ range 45-57). All (100%) patients reported knee pain with a median duration of pain of 24 months (IQ range 12 -48) and mean VAS score 8.59±1.14. Two hundred (82%) had bilateral knee OA. The mean BMI was 32.20±5.95Kg/m². Two hundred and four (83.6%) were in functional class II and III. The median ESR was 13 (IQ range 5 - 29.5). One hundred and seventy-four (71.4%) patients’ radiographs showed KL grade III (48.4%) and grade IV (23%). The combined medial and patella femoral compartment OA was observed in 93  (38%) patients. There was a significant association between age, BMI, functional class, pain severity and the KL grading.

Conclusions: Knee osteoarthritis is the most common rheumatic disease in our clinic. The commonest radiographic pattern is the combined medial and patellofemoral compartments. There is significant correlation between age, pain severity and BMI with KL grading of the knee.

Keywords: Knee osteoarthritis, Prevalence, Pain, Kellgren-Lawrence grade