APS injection relieves knee pain in osteoarthritis

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  • Intra-articular injection of autologous protein solution (APS) is safe and effective for the treatment of knee osteoarthritis (OA).

Why this matters

  • There has been an interest in injection treatments for OA to stave off the need for metal resurfacing.

Key results 

  • Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain scores were similar between groups at all time points until 12 mo, when the APS group had significantly higher scores (P=.02).
  • From baseline, both groups improved over time at 12 mo with WOMAC pain score (APS, P<.0001; control, P=.0012).
  • No significant differences between groups in visual analog scale (P=.05); difference observed at 12 mo (P=.06)
  • MRI data showed size increase from baseline in osteophytes (P=.032) and bone marrow lesions (P=.041) in control patients, whereas APS patients showed no changes.
  • No differences in adverse events between groups. 

Study design 

  • Randomized controlled trial of APS in 46 unilateral patients with knee OA.
  • Researchers recorded patient-reported outcomes and adverse events from 2 wk through 12 mo follow-up.
  • Funding: Biomet Zimmer. 


  • Small sample size.