Shock wave therapy ineffective for plantar fasciitis

ABSTRACT

BACKGROUND: Plantar fasciitis is a common condition seen in primary care affecting up to 10% of the general population during their lifetime. Risk factors include middle age, obesity, prolonged walking, and running. Previous randomized-controlled studies of ultrasound-guided ESWT report efficacy in plantar fasciitis. A systematic review from the Cochrane Library reports limited evidence for ESWT, topical corticosteroids, corticosteroid injections, and dorsiflexion night splints. Interestingly, no evidence for effectiveness is reported for other commonly used interventions, including insoles, heel pads, strapping, and surgery.¹

POPULATION STUDIED: Participants in this study were 166 Australian patients diagnosed with clinical plantar fasciitis, defined as 6 weeks of pain over the plantar aspect of the heel, confirmed by plantar fascia thickening on ultrasound. Patients were referred to a radiology group from primary care, rheumatology, orthopedic surgery, and sports medicine practices. The patients were usually overweight and predominantly female (57%).

STUDY DESIGN AND VALIDITY: Overall this randomized, placebo-controlled, double-blind study was well designed. Patients were treated weekly for 3 consecutive weeks with a total shock wave dose of at least 1000 mJ/mm2 or place-bo (total dose 6.0 mJ/mm2). Symptoms were assessed at 6 and 12 weeks after treatment. The study used centralized randomization and controlled with low energy, low frequency “sham” ESWT. The intervention and control groups were similar and allocation of treatment was concealed (referring physicians, patients, and therapists did not know what therapy was going to be assigned before study enrollment). Patients and data evaluators were blind to treatment group assignment; however, physical therapists administering therapy were not blinded. Study subjects were surveyed after the study to determine whether they knew which therapy they had received. Blinding was moderately successful (the blinding index was 0.68, in which 1 represents complete blinding, 0 represents no blinding, and 0.5 represents random guessing about which therapy was received). Follow-up was complete with an intention-to-treat analysis (although dropouts were not included in the assessment). The study evaluated patients for 12 weeks, which seems a reasonable length of time to assess for clinical improvement in pain and function.

OUTCOMES MEASURED: The primary outcome measured was overall pain at 12 weeks. Secondary outcomes included overall, morning only, and activity pain; Maryland Foot Score ratings; walking ability; Short Form (SF-36) Health Survey quality-of-life score; and Problem Elicitation Technique score at 6 and 12 weeks. The Problem Elicitation Technique tracks changes in perceived disability and problems commonly reported by patients with plantar fasciitis, such as inability to participate in sports.

RESULTS: A total of 160 (96%) patients completed the 15-week study. Overall, both groups’ pain and function improved, but no statistically significant difference was noted in pain and function at 6 or 12 weeks. Only 1 outcome measure, the social function subset of the SF-36, showed statistically significant improvement in the placebo group at 6 weeks but not at 12 weeks. The power of the study was adequate for the primary outcome measure.