Ultrasonography of Primary Knee Osteoarthritis: Relation to Clinical and Radiographic Findings

Abstract Background Knee osteoarthritis (OA), also known as degenerative joint disease of the knee, is typically the result of wear and tear and progressive loss of articular cartilage. It is most common in the elderly. Knee osteoarthritis can be divided into two types, primary and secondary. Primary osteoarthritis is articular degeneration without any apparent underlying reason, Secondary osteoarthritis is the consequence of either abnormal concentration of force across the joint as with post traumatic causes or abnormal articular cartilage, such as rheumatoid arthritis. Aim of the Work To correlate ultrasonagraphic findings in primary knee osteoarthritis to Clinical, Function And Radiographic Scoring System. Patients and Methods This is cross-sectional study included 50 patients with primary knee osteoarthitis diagnosed according to ACR criteria 1990 that include pain in knee and at least three of the following: Age >50 years, Stiffness <30 minutes, Crepitus, Bony tenderness, Bony enlargement and no palpable warmth. Results In our study visual analogue scale was significantly positively correlated with; cartilage grade, osteophyte (medial, lateral) grade and medial meniscus extrusion. Also significantly negatively correlated with cartilage (medial, lateral) longitudinal thickness. We found that higher VAS score for pain is significantly related to a worse K-L grade. Our study revealed positive correlation between total WOMAC score and cartilage grade, osteophyte (lateral, medial grade) and medial meniscus extrusion. Also, significant negative correlation with cartilage (medial, lateral) longitudinal thickness. Regarding WOMAC score subclasses; pain, stiffness and function were significantly positively correlated with cartilage grade, osteophyte (medial, lateral grade) and medial meniscus extrusion and significantly negatively correlated with cartilage (medial, lateral) longitudinal thickness. In our study higher K& L grades were negatively correlated to cartilage medial longitudinal thickness and significantly positively correlated to cartilage grade, medial and lateral osteophyte grade and medial meniscus extrusion measured by US. Conclusion Musculoskeletal ultrasound is a useful tool in assessment and grading of severity in primary knee osteoarthritis that correlate well with clinical, functional and radiographic score. It could differentiate different grades of knee osteoarthritis severity at definite cutoff value specially those subset of patients who may required surgical intervention.