• The primary outcomes measures will be changes in tissue health avariables and user satisfaction [ Time Frame: baseline, 4 weeks, and six months ] [ Designated as safety issue: No ]
  

• Progressive changes in muscle bulk and tissue blood flow will be evaluated using CT scanning and transcutaneous oxygen measurement [ Time Frame: baseline, 4 weeks, and six months ] [ Designated as safety issue: No ]
  
• Pressure distribution changes over the long-term (due to muscle changes) and over the short-term (due to muscle contractions) will be assessed by interface pressure measurement. [ Time Frame: baseline, 4 weeks, and six months ] [ Designated as safety issue: No ]
  

Within the scope of the study the aims will be to: (1. Develop the pre-implantation assessment protocol utilizing targeted CT to locate optimal gluteal motor points bilaterally.) CT assessment of the pelvic region in spinal cord injured subjects will be carried out to determine regional vascular and nervous anatomy. This will allow us to achieve optimal electode placement using a minimally invasive implantation procedure. (2. Develop the implanted gluteal stimulation system.) The fully implanted gluteal stimulation (GSTIM) system is envisioned as a marriage between the established technology of the implanted IM electrodes developed by the Cleveland FES Center and the newly developed Micropulse I 2-channel stimulator. The Micropulse I IPG is a small, rechargeable stimulator developed by NDI Medical as a platform technology for neuromodulation and neurostimulation applications. The device will be customized in order to provide two synchronized channels of stimulation for the GSTIM system. (3. Implement and evaluate implanted gluteal stimulation system in human volunteers.) A pilot clinical trial of the fully implanted gluteal stimulation system will be carried out using a two-arm crossover study of ten wheelchair users at risk for pressure ulcer development due to impaired mobility. Pre-defined selection criteria will be employed to screen potential participants physically and psychologically. All participants will receive a stimulation sytem consisting of implanted IM electrodes inserted bilaterally in the gluteaus maximus together with the Micropulse I stimulator implanted subcutaneously in the lower abdomen. Tissue health will be assessed at threemonth intervals during the 12-month period following implantation. The clinical application of this system is of great relevance to the veteran population at risk of pressure ulcer development. The project will add value to the continued improvement in health care provision for veterans, allowing them to benefit from the most recent advances in medical device technology. Although the initial target user group is veterans with SCI, the proposes system will have applications to other patient populations at risk due to reduced mobility, such as those with multiple sclerosis and the elderly.