Safety & Efficacy Study for the Use of Extracorporeal Shockwaves in the Treatment of Diabetic Foot Ulcers

Diabetic foot complications are the most common cause of nontraumatic lower extremity amputations in the industrialized world. The risk of lower extremity amputation ranges from 15 to 46 times higher in diabetics than in persons who do not have diabetes mellitus. Furthermore, foot complications are the most frequent reason for hospitalization in patients with diabetes, accounting for up to 25 percent of all diabetic admissions in the United States and Great Britain. The vast majority of diabetic foot complications resulting in amputation begin with the formation of skin ulcers. Early detection and appropriate treatment of these ulcers may prevent up to 85 percent of amputations. (Armstrong) The primary goal in the treatment of diabetic foot ulcers is to obtain wound closure. Rest, elevation of the affected foot, and relief of pressure are basic treatments that are usually initiated when the patient first presents with a foot ulcer. A postoperative shoe or another type of pressure-relieving footwear is also often prescribed. Crutches or a wheelchair might also be recommended to totally off-load pressure from the foot. Necrotic tissue is debrided to allow full visualization of the extent of the ulcer, to allow detect underlying abscesses or sinuses, and to support healing. Wet-to-wet dressings are used to provide a warm, moist environment that is protected from external contamination is most conducive to wound healing. Additional options include numerous topical medications and gels, and special dressings, including semipermeable films, foams, hydrocolloids, and calcium alginate swabs. When these more conservative treatments fail, another recently developed nonoperative option is available. The genetically engineered platelet-derived growth factor becaplermin (Regranex Gel, OMJ Pharmaceuticals, Inc.) is approved for use on neuropathic diabetic foot ulcers and can expedite healing. Growth factors stimulate chemotaxis and mitogenesis of neutrophils, fibroblasts, and monocytes, as well as other components that form the cellular basis of wound healing. When nonoperative treatments fail, skin grafting is often required to achieve wound closure. In addition to autologous donor tissue for the graft procedure, bioengineered skin (Apligraf, Organogenesis, P950032/S016) and human dermis (Dermagraft, Smith \& Nephew, P000036) are new types of biologically active implants approved for diabetic foot ulcers that are derived from fibroblasts of neonatal foreskins. These bioengineered products enhance healing by acting as delivery systems for growth factors and extracellular matrix components through the activity of live human fibroblasts contained in their dermal elements. (Frykberg) Despite the variety of modalities available to treat diabetic foot ulcers, the US Center for Disease Control reports that the age-adjusted lower extremity amputation rate for persons with diabetes is 5.5 per 1,000 persons with diabetes, which is was 28 times that of persons without diabetes. ESWT for Soft Tissue Indications The use of extracorporeal shock waves for clinical applications was introduced in the United States more than 20 years ago; the first indication for use approved by FDA was for treatment of renal calculi (kideny stones). Since that time, the clinical applications of extracorporeal shock wave therapy (ESWT) have been expanded to include treatment of chronic proximal plantar fasciitis (P990086, HealthTronics OssaTron; P000048, Dornier EPOS Ultra; P040026, Orthospec Extracorporeal Shock Wave Device; P040039, Orthometrix Orbasone Pain Relief System) and chronic lateral epicondylitis (P990086/S003, HealthTronics OssaTron; P010039, Siemens Sonocur Basic). In addition, there are numerous reports in the clinical and pre-clinical literature of shockwave therapy used to treat orthopedic conditions such as fracture non-unions, femoral head necrosis, and non-orthopedic conditions related to tissue healing. Treatment with extracorporeal shock waves has been shown to be associated with neovascularization in an animal model. Further, since several shockwave systems have been approved through the PMA process for treatment of chronic proximal plantar fasciitis and chronic lateral epicondylitis, there is a large amount of data regarding the safety of these devices in treating soft tissue. The research done by Meirer et al. (2005) and by Nishida et al. (2004) suggests that local delivery of shockwave therapy results in increased release of growth factors and improved circulation in the wound. Because of the promising association between ESWT and tissue healing, the favorable risk / benefit profile of the devices approved for treatment of soft tissue indications, and the European clinical experience with ESWT for wound healing, it is hypothesized that extracorporeal shock wave treatment (ESWT) could be beneficial in treating diabetic foot ulcers. Therefore, this IDE describes a clinical study designed to determine the safety and effectiveness of the DermaGold® ESW System when used to induce healing of chronic plantar foot ulcers in patients with diabetic foot ulcers.