Radial extracorporeal shock wave therapy for disabling pain due to severe primary knee osteoarthritis.

Objective: To assess the efficacy and safety of radial extracorporeal shock wave therapy (rESWT) for disabling pain due to primary knee osteoarthritis.
Design: Randomized, placebo-controlled trial (level of evidence, 1).
Subjects: A total of 105 women with disabling pain due to primary knee osteoarthritis lasting for a mean of 103 months (range 3-480 months).
Methods: Patients received either rESWT (3 sessions, each one week apart, 2,000 rESWT impulses per session, positive energy flux density 0.10-0.16 mJ/mm2) or placebo treatment. Primary outcome measure was pain on movement 3 months after the final treatment session. Secondary outcomes were pain, stiffness and limitations in physical function on the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) Index and the level of tolerance to pressure over muscles, tendons, ligaments and skin at both the treated and the untreated side at 1 week and 3 months follow-up examinations.
Results: Compared with placebo treatment, rESWT led to a statistically significant improvement only in mean WOMAC scores for pain and a few of the pressure measurements.
Conclusion: rESWT, as performed in the present study, is not efficient for treating patients with disabling pain due to primary knee osteoarthritis. Published data indicate that substantially higher energy flux densities are necessary for treatment success in this condition.