Patient outcomes following total knee replacement and standard physical therapy will be compared between subjects who use the Breg Flex study device vs those who do not. Subjects will be evaluated for knee range of motion, strength and patient reported outcomes.

Inclusion Criteria:

1. Individuals who are scheduled for Total Knee Arthroplasty by a single surgeon (Burnikel)
2. Individuals who are at least 55 years of age
3. Individuals with a body mass index (BMI) <45
4. Must be able and willing to complete all study assessments and to be followed for the full course of the study.
5. Must be able to read, write and follow instructions in English.
6. Must be able and willing to provide informed consent.
7. Must be willing and able to attend the pre-op assessment

Exclusion Criteria:

1. Individuals with a history of any underlying neurological conditions
2. Individuals with a history of stroke
3. Individuals with a history of neurological disorder that affects lower extremity function (stroke, peripheral neuropathy, Parkinson's disease, multiple sclerosis, etc.)
4. Individuals with physical conditions which would make them unable to perform study procedures
5. Pregnant women or inadequate precautions to prevent pregnancy
6. Diagnosis of a medical condition that would contraindicate treatment with the product, e.g. skin lesions at electrode site.
7. Individuals with a diagnosis of inflammatory arthritis (Rheumatoid arthritis, gout or psoriatic arthritis)?
8. Individuals with muscle diseases (i.e. muscular dystrophy)
9. Visible skin injury or disease on their legs
10. Principal investigator for this study, or member of study staff