Safety and efficacy of retreatment with a bioengineered hyaluronate for painful osteoarthritis of the knee: Results of the open-label Extension Study of the FLEXX Trial

R. D. Altman, J. E. Rosen, D. A. Bloch, H. T. Hatoum

Research output: Contribution to journalArticle

25 Scopus citations


Objective: To evaluate the safety of repeated intra-articular (IA) injections of Euflexxa ® (1% sodium hyaluronate; IA--BioHA) for painful knee osteoarthritis (OA). Design: Participants who completed the randomized, double-blind, 26-week FLEXX Trial comparing IA-BioHA to IA saline (IA-SA) for knee OA. 1 received three weekly IA-BioHA injections in a 26-week Extension Study. Adverse events (AEs) were recorded and the effect of treatment on knee pain was measured immediately following a 50-foot walk test using a 100 mm visual analog scale (VAS). Responder rate, Medical Outcomes Study Short Form 36 scores, Patient's Global Assessment, and intake of rescue medication were also evaluated. Results: The Extension Study included 433 subjects, 219 who received IA-BioHA and 214 who received IA-SA during the FLEXX Trial. Safety results from the Extension Study indicated that 43.4% (188/433) of subjects had AEs, of which 4.8% (21/433) were deemed treatment-related AEs. Two AEs in the Extension Study led to discontinuation, and no joint effusion was reported. Patients who continued with IA-BioHA in the Extension Study maintained their improvement from baseline, with an average reduction in pain in the VAS score of -3.5 mm. Patients initially treated with IA-SA in the FLEXX Trial also had a reduction in VAS score of -9.0 mm. Secondary efficacy variables also improved during the Extension Study. Conclusions: Repeat injections of IA-BioHA were effective, safe, well tolerated, and not associated with an increase in AEs, such as synovial effusions. Additional symptom improvements were noted for subjects who received either IA-BioHA or IA-SA in the FLEXX Trial.Clinical Trial Registration Number: NCT00379236.

Original languageEnglish (US)
Pages (from-to)1169-1175
Number of pages7
JournalOsteoarthritis and Cartilage
Issue number10
StatePublished - Oct 1 2011



  • Bioengineered
  • FLEXX Trial
  • Intra-articular hyaluronate
  • Osteoarthritis

ASJC Scopus subject areas

  • Rheumatology
  • Biomedical Engineering
  • Orthopedics and Sports Medicine

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