It has been noted that patients "dramatically overestimate their functional ability early after surgery." Despite use of assistive devices increasing and functional testing scores decreasing post-surgery, the patient reported outcome scores fail to show worsening. Outcome questionnaires will be administered and functional testing will be conducted on all patients to capture these changes.

The functional testing used in this study consists of tests that physical therapists use daily as objective methods to assess patients' functional status. The testing is designed to closely mimic daily activities that the patients are familiar with.

Inclusion Criteria:

• Implant must be at least 6 months post-op and doing well
• Patient has had a total CR knee implant
• > 18 years of age

Exclusion Criteria:

• Simultaneous bilateral procedure occurred
• BMI > 40
• Other physical disability that requires an aid for walking or disability affecting the hips, spine, contralateral knee or other joint that limits function
• Participation in another clinical study which would confound results
• Inability to complete the protocol in the opinion of the clinical staff due to safety or other reasons

The study will include a 1:1 ratio of patients enrolled into both the iTotal arm and the off-the-shelf total knee arm.