Correlation between functional disability grade and radiographic severity among Nigerian patients with knee osteoarthritis

Background: Knee osteoarthritis (OA) is the most common form of degenerative arthritis in human and a leading cause of functional disability in the middle aged and elderly. The diagnosis of knee OA is often based on clinicoradiographic criteria. And in spite of the widespread utilization of knee radiograph in the diagnosis of knee OA, studies on the correlation between clinical and radiographic findings have been discordant. Although most studies of knee OA patients in Nigeria have incorporated knee radiograph in the diagnosis of the disease, the contribution of radiographic severity to functional disability in Nigerian patients is not well described. Objective: The aim of this article is to determine the pattern of radiographic knee OA in Nigerian patients and the correlation between radiographic grades of knee OA and functional disability. Materials and Methods: One hundred forty consecutive patients with knee OA attending the Rheumatology Clinic of Ahmadu Bello University Teaching Hospital were recruited for the study. Patients biodata and anthropometric parameters were ascertained. Patients had general and musculoskeletal examination. Knee radiographs were done for all patients and graded using the Kellgren-Lawrence (K-L) grading system. Pain and functional disability grades were measured using Likert 3.0 Western Ontario McMaster University index. Results: All 140 patients had definite knee OA on radiograph (K-L grade 2 and above). Grade 2 radiographic knee OA was noted in 51 (36.4%) patients, grade 3 in 71 (50.7%) patients, and grade 4 in 18 (12.9%) patients. Eighty-nine (63%) patients had severe radiographic knee OA. The mean pain and disability scores were significantly higher in patients with grade 3 or 4 radiographic knee OA compared to those with grade 2 radiographic knee OA. Both pain and functional disability moderately correlated with radiographic grades (rs = 0.36, P = 0.000) and (rs = 0.48, P = 0.000), respectively. Conclusion: The point prevalence of severe radiographic knee OA (K-L grade 3 or 4) is 63% in Nigerian knee OA patients. There is a moderate correlation between radiographic severity and functional disability in knee OA patients, with radiographic severity being an independent predictor of functional disability.