Elevated vacuum (EV) is a promising technology in the field of prosthetics. It has been shown to improve the fit of the limb in the socket, resulting in many possible benefits to the function of a prosthesis. However, very little research has been done on its effect on patient function. This unique case report documents the effect on one patient's function of transitioning from a patella-tendon-bearing (PTB) socket with ischial weightbearing thigh cuff (IWBTC) to a prosthesis with an EV socket system. The patient underwent a transtibial amputation as a result of an avulsive trauma and used the PTB socket and thigh cuff for 16 years. In an effort to correct the patient's gait and improve his ability to perform the necessary tasks of his occupation, farming, the patient began using an EV prosthesis. He was interviewed and his functional status was evaluated 1 week, 1 month, and 1 year after receiving the prosthesis. After 1 week, the patient showed improvement in skin condition and expressed increased confidence in difficult locomotor tasks. At 1 month, he was no longer experiencing pain in his sound side knee and his gait symmetry had improved dramatically. After 1 year, the patient showed further improvement in gait and balance as well as the ability to wear the prosthesis comfortably for 24 hours at a time when necessary for his occupation. The transition from a PTB with IWBTC prosthesis to an EV system dramatically improved this patient's functional outcome and lessened the negative effects associated with wearing a prosthesis. (J Prosthet Orthot. 2011;23:184 -189.) KEY INDEXING TERMS: lower limb, prosthetics, function, outcomes, vacuum, subatmospheric I t is the goal of all prosthetic interventions to maximize patient function. Research has shown that physical mobility is the only independent factor that significantly affects quality of life in amputees when compared with nondisabled persons. 1 Although they theoretically have the highest probability of achieving normal functioning, 2 patients who have undergone amputation due to an avulsive trauma generally have secondary injuries that complicate their recoveries. For transtibial amputees, injuries typically include extensive damage to the patellar tendons and hamstring group. It is possible to accommodate for the resulting gait deficiencies with a patellatendon-bearing (PTB) socket connected to an ischial weightbearing thigh cuff (IWBTC) with external knee joints and check strap (Figure 1). In this type of prosthesis, the external knee joints and check strap combine to prevent knee hyperextension in the PTB socket, accommodating the hamstring group weakness. The forces responsible for hyperextension on the residuum are countered by the check strap. 3Alternatively, there is an emerging technology that shows promise as a replacement for traditional prosthesis designs: elevated vacuum (EV). Also known as subatmospheric, EV prostheses consist of an elastomeric liner, total surface bearing socket, mechanical or electronic vacuum pump, and a sealing sleeve. Des...