Correlation between Kellgren-Lawrence classification of osteoarthritis and Knee Injury and Osteoarthritis Outcome Score

BACKGROUND Osteoarthritis (OA) is a common degenerative joint disease that considerably affects the quality of life (QoL) of individuals, especially the elderly. The Kellgren-Lawrence (KL) grading system assesses the severity of OA through radiographic evaluation, whereas the Knee Injury and Osteoarthritis Outcome Score (KOOS) measures clinical symptoms and functional status. AIM To analyze the relationship between KL grades and KOOS to elucidate the association between radiographic severity and clinical manifestations of knee OA. METHODS A cross-sectional study was performed at King Fahd Hospital of the University, involving 164 adult patients diagnosed with knee OA. Patients were evaluated using the KL system, based on standing knee X-rays performed within the last six months. The KOOS questionnaire was utilised for clinical assessment, evaluating five domains: (1) Pain; (2) Symptoms; (3) Activities of daily living; (4) Sport and recreation function; and (5) Knee-related QoL. Analysis of variance was utilised to examine variations in KOOS domain scores among different patient variables. The correlations between KOOS domains were determined using Pearson's correlation. RESULTS KOOS scores demonstrated a significant decline in patients with elevated KL grades, with Grade 4 exhibiting the lowest scores and grade 1 the highest (P < 0.001). The correlation between pain and activities of daily living was strong (r = 0.871, P < 0.001), as was the correlation with knee-related QoL (r = 0.754, P < 0.001). Notable age-related disparities were observed, as older patients (≥ 60 years) indicated poorer pain and functional outcomes. Gender differences were noted exclusively in symptoms, with females exhibiting lower scores than males (P = 0.022). CONCLUSION The association between radiographic severity and clinical impact is shown by the substantial correlation between KL grading and KOOS results, especially in later stages of OA. The results highlight the necessity for thorough assessments that integrate radiographic and clinical evaluations for individualized therapy choices for OA patients.