Background Conventional radiography (CR) is the standard imaging modality in the assessment of knee osteoarthritis (KOA), but Ultrasonography (US) is recognised as a useful imaging modality for the detection of synovitis and osteophytes .
Objectives to validate a proposed ultrasonographic grading scale for severity of primary knee osteoarthritis.
Methods The study included 160 knee primary osteoarthritis (KOA) patients with diagnosed according to the clinical or the radiological criteria for of the American College of Rheumatology (ACR) and 20 patients with knee pain but not fulfill ACR criteria for KOA.
All patients were subjected to clinical assessment (Western Ontario and McMaster Universities (WOMAC) Index of Osteoarthritis and global visual analogue scale VAS) and radiological assessment in the form of x ray grading according to Kellgren and Lawrence (KL) grading scale (0-4),2 and ultrasonographic assessment of medial femoral osteophytes according to a scale (0-4) that was proposed by the first author as follow: grade 0: No osteophytes; regular ends of both femoral condyle without any projections, grade 1: minor osteophyte; just a small projection from the femoral condyle, grade 2A: Small osteophytes; a projection from the femoral condyle that appears to have a downward part in joint space zone, grade 2B: Large osteophyte appears to be separated from femoral condyle and descending downwards in joint space zone, grade 3: Large osteophyte appears to be separated from femoral condyle and descending downwards in joint space zone with small horizontal extension parallel to femoral bone, grade 4: Mainly horizontal osteophyte parallel to femoral bone.
Results The proposed Ultrasound grading scale had high sensitivity and specificity in detecting the different grades of KOA compared with KL grading scale (a total sensitivity is 94.6% and a total specificity is 93.3%). Intra and inter-reader reliability of ultrasound was excellent (kappa >0.93 and >0.85 respectively). The proposed US grading scale was highly significantly correlated with age, disease duration and body mass index. While there was non-significant correlation between the proposed US grading scale and VAS and WOMAC subscales and total scale.
Conclusions Ultrasound can reliably detect the severity of knee osteoarthritis. Good agreement was found between the proposed US grading scale and KL grading scale. The proposed US grading scale is simple and reliable.
Abraham AM, et al. BMC Musculoskelet Disord. 2011;14:70.
Kellgren JH, Lawrence JS. Oxford: Blackwell Scientific; 1963.
Disclosure of Interest None declared