The purpose of this industry-initiated research study is to test that a powered microprocessor controlled knee improves metabolic function during walking in level and sloped conditions as compared to the subject's physician prescribed prosthesis.

The Procedures include:

Initial Visit:

1. Informed consent
2. HIPAA authorization
3. Determine/verify ambulation potential
4. Take and record body measurements (height, weight, circumferences)
5. Activities-Specific Balance Confidence (ABC) scale
6. L.A.S.A.R. Posture alignment assessment with RxPx

Second Visit

1. Fit with heartrate monitor and metabolic analyzer mask
2. Treadmill Test (level-ground) with RxPx
3. Rest
4. Treadmill Test (incline) with RxPx
5. Fit subject with PMPK
6. L.A.S.A.R. Posture alignment assessment with PMPK
7. Subject uses PMPK for one week as their primary prosthesis

Third Visit (1 week later)

1. Fit with heartrate monitor and metabolic analyzer mask
2. Treadmill Test (level-ground) with PMPK
3. Rest
4. Treadmill Test (incline) with PMPK
5. Activities-Specific Balance Confidence (ABC) scale
6. Return PMPK and refit of RxPx
7. Verify alignment with L.A.S.A.R. Posture alignment
8. Check that all fasteners are secure

Inclusion Criteria:

• Males and Females with unilateral knee disarticulation or transfemoral (KD/TF) amputation.
• a body mass greater than 49Kg and less than 117Kg
• 18-75 years of age
• Have an ambulation potential of K3 or K4
• Use a prosthesis daily for walking or sports activities
• No less than six months of experience with a prosthesis
• No socket issues or changes in the last six weeks
• No residual limb pain affecting functional ability.

Exclusion Criteria:

• Cannot walk at different speeds (MCFL K0-K2)
• Limb-loss below the knee or through the hip
• More than one amputation.
• Uses an assistive device for walking
• Uncontrolled edema in leg compartments
• Compromised skin of the residual limb or contralateral foot
• Are 180 days or less post-amputation
• Pregnant (self-reported)