This is a single-institution, prospective, randomized study comparing the medial parapatellar and subvastus approaches in primary total knee arthroplasty using continuous, implant-based gait monitoring. Patients receiving a Zimmer Persona IQ smart implant will be followed preoperatively and through the first 30 days post-operatively, with extended follow-up to 6 months. Preoperative activity is captured using iPhone Health step-count data, while post-operative recovery is assessed using continuous tibial implant data, including step count, range of motion, cadence, walking speed, stride length, and distance. These objective metrics are correlated with PROMs. The primary outcome is daily step count. Secondary outcomes include early functional milestones, pain, and patient-reported functional scores. This study is designed to characterize early recovery trajectories and determine whether meaningful differences exist between surgical approaches.

Inclusion Criteria:

• All patients older than 18 years of age who plan to undergo medial congruent polyethylene bearing primary TKA with a PIQ
• Eligible for both approaches
• Have an iPhone and willing to "wear" it for two weeks preoperatively to get an estimated average stepcount
• Provide informed consent
• Willing to complete follow ups

Exclusion Criteria:

• Patients with TKA revisions
• Patients with insufficient pre-operative range of motion in the operative knee (flexion contracture of > 20 degrees or < 90° of knee flexion)
• Patients with Contralateral TKA within study time frame
• Patients with TKA other than medial congruent polyethylene bearing
• Patients with bilateral surgery
• Patients without a valid and active email address
• Patients not willing or able to participate in study and follow-ups
• Patients who use assisted devices to ambulate
• Rheumatoid arthritis

Individual participant data will only be used as necessary by the authorized research team and always secured, it will not be shared