Short-term Benefits of Ultrasound-Guided Corticosteroid Injection in Plantar Fasciitis

Abstract

To determine the effectiveness of ultrasound (US)-guided corticosteroid injection in the treatment of plantar fasciitis. Randomized, placebo-controlled, double-blind trial with 12-week followup. Sample size was calculated with 80% power to show, after 4 weeks, a minimum clinically important difference of 13 points on the pain domain of the Foot Health Status Questionnaire (FHSQ) at P # 0.05. Community study at a university clinic in Melbourne, Australia between June 2010 and February 2011. Participants were recruited using local newspaper advertisements. Eligibility criteria were a history of inferior heel pain for $8 weeks, heel pain of $20 mm on a 100-mm visual analog scale, pain on palpation of the medial calcaneal tubercle or the proximal plantar fascia, and a dorsal plantar fascia thickness of $4.0 mm measured ata standard location by diagnostic US. Reasons for exclusion were pregnancy,a corticosteroid injection within 6 months or other treatment within 4 weeks, sensitivity to any of the substances used, additional conditions near the heel, a history of previous local surgery or trauma, systemic inflammatory disease or diabetes, and an inability to walk short distances unaided. All 82 participants were given a US-guided posterior tibial nerve block with 2% lidocaine. Patients then received either a US-guided injection of 1 mL of 4 mg/mL dexamethasone sodium phosphate (corticosteroid group) or 1 mL saline solution (placebo group). Both feet could be treated at the same appointment. Participants were advised not to do high-impact activities and to do stretching exercises for the first 8 weeks. The primary outcome measures at 4, 8, and 12 weeks were changes in pain scores on the FHSQ (0-100 points; worst pain to no pain) and plantar fascia thickness where the fascia crosses the anterior aspect of the inferior calcaneal border. In the case of bilateral fasciitis, the participant was asked to report pain for both feet together, and fascial thicknesses were averaged between the feet. Pain on first step in the morning and function were measured, and adverse events reported. The improvement in pain scores in the corticosteroid group was greater than that in the placebo group at 4 weeks (adjusted difference between change in group means, 10.9; 95% confidence interval [CI], 1.4-20.4),but at 8 and 12 weeks, the difference did not persist (difference, 5.6; 95% CI, 24.5-15.6 and difference, 5.3; 95% CI, 25.7-16.3, respectively). Plantar fascia thickness was reduced for the corticosteroid group compared with the placebo group at each time period (mean difference at 4 weeks, 20.35 mm; 95% CI, 20.67 to 20.03; at 8 weeks, 20.30 mm; 95% CI, 20.73 to 20.05; and at 12 weeks, 20.43 mm; 95% CI, 20.85 to 20.01). First-step pain was less for the corticosteroid group at 4 weeks, but function was not significantly different between groups. For participants in both groups, improvements in FHSQ pain scores at 12 weeks were correlated with reductions in plantar fascia swelling (r =20.30; P = 0.007). No adverse events such as nerve injury, postinjection flare, soft tissue infection, or rupture of the plantar fascia were reported. Adherence to the stretching program did not differ between groups. A single US-guided injection of dexamethasone reduced pain in plantar fasciitis at 4 weeks, without complications. Dexamethasone was effective in reducing plantar fascia swelling throughout the 12 weeks. Pain and swelling of the fascia subsided in both groups.