Ultrasound-guided intra-articular injection: Efficacy of hyaluronic acid compared to glucocorticoid in the treatment of knee osteoarthritis

BACKGROUND: Osteoarthritis (OA) is a degenerative joint disease which causes pain and functional impairment in adults over 50 years old with consequent important disability. Unfortunately, there is no definitive cure for OA, thus the approach is characterized by multiple treatments that can manage its symptoms. Even though data from randomized controlled trials and meta-analyses indicate that intra-articular hyaluronic acid (IAHA) offers the best benefit/risk balance among the various pharmacologic treatments to improve OA-related knee pain, there is a lack of agreement among national and international guidelines about such uses of IAHA for the medical management of symptomatic knee OA. To minimize confounding factors and biases, the aim of our study was to evaluate the efficacy of the different weight and concentration of IAHA treatment in patients suffering from knee OA comparing to glucocorticoids (GC) joint injections. Furthermore, to make the procedure more accurate and assessment more objective, we use ultrasonography (US) with power Doppler (PWD) to help us differentiate between active and inactive inflammation within joints and periarticular soft tissues. METHODS: We performed a retrospective evaluation of a cohort of patients with knee OA, diagnosed according to the ACR criteria, treated by US-guided joint injection of HA and GC. The patients were catalogued according to the type of treatment they underwent: group A, patients treated with HA (1.5%) >1500 kDa (three US-guided knee injections one week apart); group B, patients treated with HA (2%) 800-1200 kDa (three US-guided knee injections one week apart); group C, patients treated with glucocorticoids (three US-guided knee injections of triamcinolone acetate 40 mg one week apart). All patients were monitored for 6 months, evaluating: subjective pain using a 10-cm Visual Analogue Scale; pain, stiffness, and functionality using the Western Ontario and McMaster Universities Arthritis Index (WOMAC); the concomitant intake of anti-inflammatory and/or analgesic drugs through a questionnaire; and US results by grey scale and PWD. RESULTS: A total of 171 patients affected by knee OA were evaluated (women 72.3%) with a mean age of 69.3±4.1 years. All the subjects analyzed showed a pain reduction at 6 months after treatment (group A: -39.5; group B: -36.9; group C: -30.8). The difference between the three groups was statistically significant (Kruskall-Wallis P=0.001) and in particular between group A and group C (P=0.000) and between group B and group C (P=0.005), but not between A and B (P=0.258). WOMAC was statistically significantly improved from baseline in all groups examined (group A: -11.9; group B: -14.9; group C: -11.2). The PWD score showed a statistically significant improvement in group B (-0.64) even after 6 months (P=0.004). All patients in the different groups showed a statistically significant reduction of concomitant therapy compared to baseline with respect to paracetamol and non-steroidal anti-inflammatory drugs (NSAIDs)/COX2 therapy, while only group B showed a statistically significant reduction for opioids. CONCLUSIONS: This study demonstrated the efficacy of OA treatment with medium molecular weight HA in favor of the higher concentration of HA that may affect the reduction of pro-inflammatory mediators. Furthermore, US monitoring allowed to evaluate aspects related to synovial involvement, which cannot be appreciated with standard imaging.