J.A. Ogden, R.Alvarez, R.Levitt, G.L.Cross
Atlanta Medical Center
The objective of this multicenter, randomized, placebo-controlled, FDA approved clinical study was to determine the safety and effectivencas of ESW (Extracorporeal Shockwave) treatment for chronic heel pain syndrom. The study was designed to demonstrate the initial success/failure of treatment results at 12 weeks post-treatment, and to provide sufficient preliminary safety and effectiveness data related to repeat ESW treatment in patients who failed to respond to initial treatment.
Between April 1998 and November 1999, 302 patients were treated for chronic heel pain syndrome using the OssaTron ESW System. 260 patients were randomizing to either active or placebo ESW treatment, an 42 patients were not randomized to ESW for investigator training purposes. The study was conducted at seven institutions throughout the U.S. For this study chronic heel pain syndrome was defined as symptoms of moderate to severe pain in this affected heel at the origin of the plantar fascia that had persisted for at least six months prior to study enrollment. Mean duration of symptoms for the subjects randomized to active treatment was 26 years, range 6 months to 13 years, and for subjects randomized to placebo treatment 29 years, range 6 months to 18 years. A subject had to have a pain score of 5.0 or greater on 10cm VAS based upon investigator assessment and must have failed 3 prior courses of non-operative treatment. Patients who failed to improve following the first procedure were aligible for retreatment with a nonrandomized ESW treatment.
Evaluations were obtained pre-treatment and 4,8 and 12 weeks post-treatment. An initial success/fail status was assigned based on findings at 12 weeks post-treatment. It was felt that the status assignment at the 12 weeks interval could help differnetiate improvement due to spontaneous healing rather than treatment effect. Subjects have continued follow-up to, determine durability of results at one year.
Study findings for the 234 randomized patients followed to 12 weeks showed a clinically as well as statistically significant difference in the treatment versus placebo groups (p-0.008). The average baseline Visual Analog Scale (VAS) score for Investigator Assessment improved from 7.7 (median 7.8) to 3.1(median 1.9); the average baseline Visual Analog Scale (VAS) score for Patient Self Assessment improved from 8.0 (median 8.1) to 3.4 (median 2.6). By grouping patients randomized to active treatment, nonrandomized patients, a small subset of active treatment patients who failed to ….success criteria following a primary OssaTron ESW treatment and elected to have a repeat treatment and subsequently treated placebo patients. 76% of all treated patients had good to excellent results, while 24% had poor or fai results. In a subset of patients undergoing repeat treatment following and unsatisfactory primary treatment, the success rate was 90,5% based on the Investigators Assessment.
This study showed that the OssaTron ESW System is a safe and effective non-invasive method for treating chronic, recalcitrant heel pain syndrome. The complication rate was low. Complications (usually petechiae) were mild and transient in nature.