A custom designed Virtual Gait Retraining System (VGRS) is being adapted for balance and mobility rehabilitation in individuals with transtibial amputation. The system is composed of a treadmill that can simulate different environmental situations such as walking up stairs and hills and going around curves. The treadmill is synchronized with an immersive display and an avatar of the user. The combination of variable terrain and visual feedback is extremely promising as a means for amputee patients to achieve improved functional mobility after gait training. The proposed work is relevant to public health because it is the first step in developing a novel rehabilitation system that will use visual feedback for gait training in amputees and others with pathological gait disorders. The research is pertinent to the mission of the Department of Veterans Affairs which is committed to improve the quality of life of Veterans with disability.

Lower extremity amputation can cause impairments in gait and balance due to the loss of proprioception and motor control. The asymmetries present during amputee gait are thought to be one of the major contributors to secondary musculoskeletal problems such as osteoarthritis. After lower extremity amputation, physical rehabilitation is necessary to achieve functional ambulation; however, no an evidence-based standard of care exists for individuals who undergo transtibial (TT) amputations. The objective of this application is to determine the effectiveness of gait training in an immersive virtual environment in people with transtibial amputation. The investigators' custom designed Virtual Gait Retraining System (VGRS) is a virtual reality (VR) system which provides visual and motor challenges while treadmill walking. The VGRS immerses the user in a virtual world, provides additional feedback with an avatar and presents the user with challenging tasks such as inclines and stair climbing which are complemented by the movement of the treadmill. The central hypothesis is that people with amputations will achieve greater improvements in balance, mobility and gait function using the investigators' custom designed VGRS as compared to current conventional treadmill gait training. This objective will be accomplished by addressing the following specific aims:

• 1) Compare the efficacy of VGRS to conventional treadmill training.
• 2) Evaluate the rate of improvement over the course of each training program (VGRS and conventional treadmill).

The investigators will conduct a randomized clinical trial with twenty TT amputee subjects comparing 6 weeks of training with the VGRS to 6 weeks of training using a conventional treadmill protocol. The investigators will use gait analysis, postural sway and standard balance and mobility instruments including the 6-Minute Walk Test, Four Square Step Test, the Berg Balance Scale and the Dynamic Gait Index to assess improvements in gait and mobility. The investigators will evaluate subject pre- and post training and at an interim point 3 weeks into the training sessions. The investigators anticipate that the VGRS will deliver more effective training by creating a realistic and challenging environment with accurate visual perception of a motor task which is being simultaneously performed by the user. The investigators will also gain an understanding of the rate of improvement for TT amputees during treadmill training. The research design will demonstrate the need for immersive virtual reality that includes a rich visual display and affords the opportunity to train on a variety of terrain conditions and mobility tasks.

Inclusion Criteria:

• Subjects must be unilateral transtibial amputees (TTA) between the ages of 18 and 65 who have consistently used a prosthesis for at least one year.

• Subjects must be community ambulators at a K3 level,

  • which dictates that they have the ability or potential to walk with variable cadence,
  • to traverse most environmental barriers and may have vocational, therapeutic, or exercise activity that demands prosthetic utilization beyond simple locomotion.

Exclusion Criteria:

• History of surgical procedures on their intact limb.

• Subjects will be excluded from the study if they present with

  • cardiovascular,
  • neurological,
  • or balance disorders that can affect gait.
  • Rheumatoid arthritis,
  • knee joint replacement,
  • and the use of ambulatory aids will also exclude participation.

• Subjects with considerable pain in their knee joints, as measured by a visual analog scale will also be excluded due to the confounding effects of pain on gait patterns.

• A medical history screening will be used to identify subjects with pre-existing conditions that would compromise their gait.