Background Anterior knee pain and patellofemoral osteoarthritis of the knee (POAK) are disabling and often difficult to manage. Intra-articular (IA) hyaluronate reduces pain in patients with tibiofemoral disease but its effect in POAK has not been studied prospectively.

Objectives To make a preliminary assessment of the potential effect of IA Hylan GF20 (Synvisc) on patients with isolated POAK.

Methods Out Patients aged more than 35 years with anterior knee pain and predominant POAK on plain radiographs, MRI or arthroscopy were recruited to an uncontrolled, prospective pilot study. Patients with significant tibiofemoral disease were excluded. Patients received 2 ml of IA Hylan GF20 on 3 successive weeks. The primary outcome was change in the patients’ global assessment of their disease on a 100 mm visual analogue scale (VAS). Secondary outcome included WOMAC, and Oxford Outcome Score. Data were collected at baseline, 5, 12 and 26 weeks.

Results Of the 39 enrolled patients 31 have radiographic (joint space narrowing) POAK and the remainder MRI (6) or arthroscopic (2) evidence of POAK but normal radiographs. The mean (95% CI) age is 56 (3.5) years and BMI 30 (1.9), 22 are women and 28 have currently reached 26 weeks. Mean patients’ global assessment was reduced from 64 (7.1) at entry to 47 (10.3), 37 (10.0) and 40 (11.7) at each time point and these changes were significantly different from baseline (paired T-test: P = 0.001, 0.00004, 0.006 respectively). 15/28 (54%) cases improved by >20 mm VAS at 26 weeks. Significant changes also occurred in pain on stair climbing (WOMAC Question A2: 77.6, 52.3, 51.3, 50.1) and Oxford Outcome Score (Total Score: 36.1, 32.9, 31.0, 30.9). Adverse knee events followed 16 of 116 injections but only two patients were unable to complete the course of injections.

Conclusion The apparent clinical benefit of Hylan GF20 persists to 26 weeks, beyond that expected of IA glucocorticoids. These positive data on the effect of Hylan GF20 in POAK suggest a randomised controlled trial be performed.