Background/Purpose:

To investigate the potential predictors of response to a single intra-articular injection of mannitol-modified cross-linked hyaluronic acid (HANOX-M-XL) in patients with first metatarsophalangeal joint osteoarthritis (FMP-OA).

Methods:

Observational, single-arm, prospective multicentre trial, with a 3 month follow-up (N° EudraCT 2015-AO1904-45). Inclusion criteria: patients with symptomatic hallux rigidus, not relieved by analgesics and / or non-steroidal-anti-inflammatory drugs (NSAIDs) and / or foot orthotic) with radiological evidence of FMP-OA ( joint space narrowing and/or osteophyte). Main exclusion criteria: Patients with hallux valgus, microcrystalline or inflammatory arthritis, viscosupplementation of the target joint in the last 3 months, intra-articular corticosteroids in the previous month, planned surgery within the 3 months of follow-up. All patients received a single, imaging guided (ultrasonography or fluoroscopy), intra-articular injection, of 1 ml of HANOX-M-XL, in the FMP joint. Data obtained at baseline: age, sex, weight, height, symptoms duration, bilaterality, previous and current treatments for OA, concomitant therapies, patient self-assessment of pain ( 11-point numeric scale 0-10), Menz radiological classification (stage 1 to 4). Outcome measures: patient self-assessment of pain at day 90, patient’s perception of effectiveness ( ( 0=not effective to 3= very effective), changes in analgesic intake, safety. The primary endpoint was the pain variation between the date of injection and month 3. The secondary outcome measures were the patient assessment of effectiveness and the decrease in pain killer use. Predictors of efficacy were studied in uni-variate and multivariate analysis from the intent-to-treat (ITT) population.

Results:

Sixty-five subjects(72.3% women, mean age 60, mean symptom duration 24.9 months) were included in the trial. Nine (13.5%) were lost to follow-up. X-ray grade was 1 in 28 patients, 2 in 29, 3 in 6. There was no statistically significant correlation between the radiological stage and the pain score at baseline (p = 0.69). At baseline and end-point, the average pain was respectively 6.5 ± 1.8 and 2.8 ± 2.3. The pain score mean difference was highly significant (-3.1± 2.9 ; p <0.0001). The average pain score at end-point was 2.0 ± 1.9 in X-ray stage 1, 3.1 ± 2.3 in stage 2 and 3.3 ± 2.4 in stage 3. The between-group difference was statistically significant (p=0.001). In multivariate analysis, pain decrease was unrelated to age, gender, disease duration, pain score at baseline, bilaterality, and imaging guidance but remained related to X-ray stage (p=0.02). Adverse events (AEs) were reported by 15 patients (22.7%). All were a transient increase of the big toe pain, that occurred within the very next hours after injection and lasted a few days. All AEs have been resolved in 3 to 7 days.

Conclusion:

This prospective study, from the largest cohort ever published in FMP viscosupplementation, showed that the clinical outcome of a single injection of 1 ml of HANOX-M-XL, performed under imaging guidance, was significantly better in patients with mild joint space narrowing. However the majority of patients with more advanced OA were also significantly improved.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/predictors-of-response-to-a-single-intra-articular-injection-of-mannitol-modified-cross-linked-hyaluronic-acid-hanox-m-xl-in-patients-with-first-metatarsophalangeal-joint-osteoarthritis-hallux-rigi/