Hypertonic dextrose injection (prolotherapy) for knee osteoarthritis: Long term outcomes

Objective: Knee osteoarthritis (OA) is a common, debilitating chronic disease. Prolotherapy is an injection therapy for chronic musculoskeletal pain. Recent 52-week randomized controlled and open label studies have reported improvement of knee OA-specific outcomes compared to baseline status, and blinded saline control injections and at-home exercise therapy (p < 0.05). However, long term effects of prolotherapy for knee OA are unknown. We therefore assessed long-term effects of prolotherapy on knee pain, function and stiffness among adults with knee OA. Design: Post clinical-trial, open-label follow-up study. Setting: Outpatient; adults with mild-to-severe knee OA completing a 52-week prolotherapy study were enrolled. Intervention and outcome measures: Participants received 3-5 monthly interventions and were assessed using the validated Western Ontario McMaster University Osteoarthritis Index, (WOMAC, 0-100 points), at baseline, 12, 26, 52 weeks, and 2.5 years. Results: 65 participants (58 ± 7.4 years old, 38 female) received 4.6 ± 0.69 injection sessions in the initial 17-week treatment period. They reported progressive improvement in WOMAC scores at all time points in excess of minimal clinical important improvement benchmarks during the initial 52-week study period, from 13.8 ± 17.4 points (23.6%) at 12 weeks, to 20.9 ± 2.8 points, (p < 0.05; 35.8% improvement) at 2.5 ± 0.6 years (range 1.6-3.5 years) in the current follow-up analysis. Among assessed covariates, none were predictive of improvement in the WOMAC score. Conclusions: Prolotherapy resulted in safe, significant, progressive improvement of knee pain, function and stiffness scores among most participants through a mean follow-up of 2.5 years and may be an appropriate therapy for patients with knee OA refractory to other conservative care.