Background/Purpose: A major challenge regarding intraarticular hyaluronic acid (IAHA) treatment in knee osteoarthritis (OA) is identifying patients who will benefit most. This study aimed to identify determinants associated with response level to IAHA treatment for symptomatic knee OA.

Methods: Data were from the Osteoarthritis Initiative (OAI) database. Subjects were selected based on the following question: “During the past 6 months, have you had an injection of HA in one or both knees for treatment of arthritis?” Included were subjects with radiographic OA who received a single treatment in one or both knees, and with data on demographics and WOMAC scores at visits before (T0) and after (T1; within 6 months) treatment. Data from the WOMAC pain scores were analyzed for demographic, clinical, and imaging (X-ray; Kellgren-Lawrence [KL] and joint space width [JSW], and MRI; cartilage volume [CV], bone marrow lesions [BML], and synovial fluid effusion size) at T0 and change (T1-T0) over time. Subjects with WOMAC ˃0 at T0 were included and subdivided based on WOMAC pain score tertile (first=lower pain). Analyses were also done on “responders” (improvement in pain score ≥20%) and “non-responders” (unchanged or worsening of pain score).

Results: Participants (n=310) received a total of 404 treatments (one/knee). WOMAC pain scores at T0 showed in the first and second vs. the third tertile, lower WOMAC score, BMI and KL grade, and greater JSW (p≤0.010), and in the first vs. the third tertile, significantly greater CV and effusion size (p≤0.033). Participants with decrease in pain score ≥20% were greater in the third tertile (p<0.001). Other WOMAC scores (function, stiffness, total) yielded similar results. These indicate a more severe disease in the third tertile. Analyses on participants in the third tertile, pain score ≥8 (greatest probability of improvement in pain with IAHA treatment), showed that responders vs. non-responders were usually younger (p=0.014), with greater medial compartment CV (p=0.046) and a trend toward lower BML score and greater JSW. In this group, differences between responders and non-responders in all WOMAC score changes were significant (p<0.001). The majority of responders had a reduction in WOMAC scores (except stiffness) of about 40%, while non-responders showed worsening of symptoms. The use of concomitant arthritis medication was similar in both groups.

Conclusion: This study has successfully allowed the identification of new reliable predictive factors that can identify patients who could best benefit from IAHA treatment. Patients with moderate to severe symptoms, younger, and with greater medial compartment CV are the most likely to respond to treatment with the greatest level of improvement. These predictive factors can potentially be implemented in daily clinical practice and will be a useful guide for physicians.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/exploring-determinants-predicting-response-to-intra-articular-hyaluronic-acid-treatment-in-symptomatic-knee-osteoarthritis/