Reliability of a Proposed Ultrasonographic Grading Scale for Severity of Primary Knee Osteoarthritis

OBJECTIVES: The objective of this study was to examine the concordance of a grading scale (0–4) of medial femoral osteophytes in knee joint detected by ultrasound (US) compared with the corresponding grades (0–4) of Kellgren–Lawrence (K&L) scale of conventional radiography and clinical joint examination. PATIENTS AND METHODS: A cross-sectional observational study included 160 patients with knee pain who fulfilled the American College of Rheumatology (ACR) criteria for knee osteoarthritis (KOA) and 20 patients with knee pain who have not fulfilled the ACR criteria for KOA. All patients were subjected to clinical assessment (Western Ontario and McMaster Universities Index of Osteoarthritis and global visual analog scale) and radiological assessment in the form of X-ray grading according to K&L grading scale and ultrasonographic assessment of medial femoral osteophytes according to a scale that was proposed by the first author and consisted of five grades (0–4), where grade 0 denoted no osteoarthritis and grade 4 denoted the most advanced grade of KOA. Grade 2 was divided into two subgrades A and B with grade 2B considered as a more advanced stage than grade 2A. RESULTS: The proposed US grading scale had high sensitivity and specificity in detecting the different grades of KOA compared with K&L grading scale (a total sensitivity of 94.6% and a total specificity of 93.3%). Intra- and interreader reliability of US was excellent (kappa >0.93 and >0.85, respectively). CONCLUSIONS: US can reliably detect the severity of KOA. Good agreement was found between the proposed US grading scale and K&L grading scale. The proposed US grading scale is simple and reliable.