A prospective multi-centre, open study of the safety and efficacy of hylan G-F 20 (Synvisc^®) in patients with symptomatic ankle (talo-crural) osteoarthritis

Abstract

Background

To evaluate the safety and efficacy of hylan G-F 20 in patients with ankle osteoarthritis.

Methods

A prospective, open study in patients with symptomatic (≥50 mm and ≤90 mm on a 100 mm VAS) ankle osteoarthritis. Patients received 1 ml × 2 ml intra-articular injection of hylan G-F 20, plus an optional, second injection if pain remained at baseline levels after 1, 2 or 3 months. The primary efficacy endpoint was the change from baseline in the pain VAS score at 3 months.

Results

Fifty-five patients received the first injection; 24 patients received a second. There were no serious or severe adverse events (AEs) related to the treatment. Seventeen patients experienced mild or moderate local, treatment-related AEs. The mean pain VAS score decreased from 68.0 mm (baseline) to 33.8 mm at 3 months (p < 0.001), which was maintained to 6 months (34.2 mm, p < 0.001).

Conclusions

Hylan G-F 20 is well-tolerated and effective for up to 6 months in the treatment of symptomatic ankle osteoarthritis.

Introduction

Osteoarthritis (OA) is a chronic, degenerative disorder associated with joint pain and loss of joint function. It is the most common disease to affect synovial joints and is one of the most frequently occurring chronic conditions.

OA can affect any synovial joint but is most frequently found in the knee, hip and hand, and the majority of these patients present with primary (idiopathic) disease [1]. Reliable figures on the prevalence of OA in other joints are not readily available but estimates suggest that symptomatic ankle OA is found in <1% of the adult population [2]. In contrast to knee and hip OA, about 70% of patients with ankle OA present with secondary, post-traumatic disease [3]. As ankle trauma is often sports-related, patients suffering from OA are, on average, relatively young. Ankle OA can often prevent these young, otherwise healthy patients from working or participating in sports activities [3], [4].

The choice of treatment of ankle OA depends on the severity of the disease, the patient's age, medical and social history and the level of physical activity expected to be demanded of the joint.

A group that is difficult to treat are those patients suffering from milder, Grade II [5] ankle OA (joint space narrowing ≤50%). Although, usually, these patients are not yet surgical candidates, they are often relatively young and wish to be active without the burden of chronic pain medications with their associated adverse side-effects. Viscosupplementation (intra-articular supplementation of hyaluronic acid) could potentially provide a useful alternative in treating such patients with painful ankle OA.

Viscosupplementation is a well-established treatment option in knee OA and is included in the professional guidelines for treatment of the disease in this joint [6], [7]. The potential for treating osteoarthritis of the ankle joint by viscosupplementation has been suggested in the literature [8], [9]. Evidence for efficacy and safety in this setting is limited but two recent studies showed that five weekly HA injections in the ankle joint seem to be well-tolerated and can improve pain and function [10], [11].

Dosing in the ankle joint remains an area for discussion as no dosing studies have been published to date. Anecdotal evidence suggests that some clinicians simply follow the dosing regimen for knee OA, which varies from 3 to 5 weekly injections of 1–2 ml. However, published evidence on the use of hylan G-F 20 in hip OA shows that a single, 2 ml injection, with an optional second injection between 1 and 3 months after the first, can be safe and effective [12], [13].

The aim of this study was therefore to evaluate the safety and efficacy of a single, 2 ml injection of hylan G-F 20, with an optional, second injection between 1 and 3 months after the first, in patients with symptomatic ankle (talo-crural) OA.