The study was a prospective, multi-centre, randomised, open, five-arm trial conducted in France and Germany. The protocol and patient informed consent form were reviewed and approved by the appropriate independent ethics committee (IEC) and complied with the requirements of the international conference on harmonisation (ICH). Patient’s written, informed consent was required before enrolment in the study. Investigators complied with the Declaration of Helsinki, “Guidance for Good Clinical Practice” and the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use when developing the patient informed consent documents.
The main inclusion criteria were: Male or female patient aged 40 years or older with an active lifestyle, consulting for OA pain in one knee and scoring ≥50 and ≤80 mm on a 100 mm OA pain visual analogue scale (VAS) where 0 mm = no pain and 100 mm = worst possible pain; tibio-femoral OA (ACR criteria) , Kellgren–Lawrence grade II or III  diagnosed by standard X-rays taken within 3 months prior to enrolment; no surgical intervention planned in the study knee in the next 6 months. If taking analgesics (except permitted doses of paracetamol ≤3 g/day for rescue analgesia), NSAIDs or cyclooxygenase-2 inhibitors, patient were required to comply with a washout period of 1–3 weeks depending on the half-life of the medication.
The main exclusion criteria were: Patients with bilateral symptomatic knee OA or predominantly patello-femoral involvement of the study knee; knee OA flare with obvious tense effusion, diagnosed by clinical examination, at the study knee; clinical symptoms of meniscal instability or significant valgus/varus that required corrective osteotomy; significant ligamentous instability; any prior viscosupplementation therapy or history of sepsis in the study knee; systemic or intra-articular injection of corticosteroids in any joint within 3 months of enrolment; chondrocalcinosis and microcrystals-mediated arthritis, concomitant inflammatory or other rheumatologic, neurological or cardiovascular diseases which could affect the evaluation of knee pain.
Patients meeting the inclusion and exclusion criteria were randomised to 1 of 5 groups:
- Group 1:
: 1 intra-articular injection of 6 mL hylan G-F 20
- Group 2:
: 1 intra-articular injection of 4 mL hylan G-F 20
- Group 3:
: 2 intra-articular injections of 4 mL hylan G-F 20 administered 2 weeks apart
- Group 4:
: 3 intra-articular injections of 4 mL hylan G-F 20 administered 1 week apart
- Group 5:
: 3 intra-articular injections of 2 mL hylan G-F 20 administered 1 week apart
Intra-articular injections were performed under strict aseptic technique by a trained physician using a lateral, medial mid patellar or antero-medial injection route (according to the injector’s preference) after aspiration of any synovial fluid.
Patients were followed-up 7 days after each injection then at 3, 8, 16 and 24 weeks after the first injection. Safety and efficacy were assessed at each patient visit. At week 24, patients who scored ≥50 and ≤80 mm on the pain VAS, or patients who experienced a worsening of pain (>15 mm on VAS) compared to week 16, were eligible to receive a second cycle of treatment (Extension Study). Patients undergoing a second cycle of treatment received the same dosing regimen as that dictated by their original randomisation.
Target knee and systemic AE’s were monitored throughout the study. Additionally, patients assessed overall safety using a four point side-effect rating scale.
The primary efficacy endpoint was the patient-completed study knee OA pain score (VAS) 24 weeks after the first injection, compared to baseline.
The secondary endpoints were the patient-completed study knee OA pain score (VAS) at all other time points; improvement in pain, stiffness and functional impairment as measured by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC™) , and patient and physician global assessment of OA in the target knee using a 100 mm VAS at all visits. Concomitant use of permitted rescue medication (paracetamol ≤3 g/day) was also recorded.
The safety analysis was performed on all patients who underwent a first injection. Treatment-emergent AE’s were summarised by the number and percentage of patients for each MedDRA Preferred Term for each treatment group. Post-hoc analyses were performed using Fisher’s Exact Test to compared Incidence of Target Knee Treatment-Emergent AEs between Groups.
The primary efficacy hypothesis was evaluated by the change from baseline to the week 24 evaluation in the patient’s assessment of target knee OA pain during the previous 48 h on VAS. This endpoint was analysed for each treatment group in the ITT population (all patients who underwent the first injection and had at least one post-baseline efficacy assessment) using a paired t test. No statistical analysis was performed between treatment groups.
The secondary endpoints (patient-completed knee OA pain score on VAS at all other time points; total WOMAC score; WOMAC A (pain), B (stiffness), and C (physical function) sub-scores; patient global assessment (VAS) and physician global assessment (VAS)) were analysed similarly. The number and percentage of patients using paracetamol was tabulated for each treatment group at each visit. Paracetamol use was summarised by: number of patients, mean, median, standard deviation and range at each visit for each treatment group.