 Patients who have elected to undergo surgery with one of the PIs, either a total knee replacement with Dr. Richard Scott or a partial knee replacement with Dr. Wolfgang Fitz, will be informed about the study and offered participation if they meet eligibility criteria. The PI will obtain written consent in the office for those who choose to participate. For participants, demographic data including height, weight, BMI, age and sex will be collected. Additionally, sit-to-stand, knee flexion, proprioception, strength and balance testing will be performed in the office by a physical therapist. Participant responses to the SF-36 physical and mental health surveys, knee function score, KSS and WOMAC questionnaires will also be collected. 