The purpose of this study is to compare cemented and cementless versions of the Triathlon total knee arthroplasty/replacement (TKA) in terms of clinical outcomes, perioperative course, and outcome scores including function and patient satisfaction.

Patients who present to the clinical practices of Dr. Ryan Nunley, Dr. Robert Barrack, or Dr. Denis Nam and are suitable candidates for primary TKA will be screened for eligibility and invited to participate. Once enrolled participants will be randomized (1:1) to either receive a cemented or cementless Triathlon TKA. Data collected for the study will include standard of care clinical and radiographic evaluations collected during office visits and surgery, as well as study-specific patient questionnaires. Clinical, radiographic and questionnaire data will be collected pre-operatively, at the time of surgery, and at 6 weeks, 6 months, 1 year and beyond, and 2 years and beyond post-operatively. Patients will complete the following outcomes questionnaires preoperatively: New Knee Society Score, Oxford Knee Score, UCLA Activity Score, SF-12, and EQ-5D. The following questionnaires will be collected at four to six weeks, six months, one year and beyond, and two years and beyond postoperatively: New Knee Society Score, Forgotten Joint Score, Washington University Knee Satisfaction and Function Questionnaire, Oxford Knee Score, UCLA Activity Score, SF-12, and EQ-5D, and a Pain Drawing. In addition, a Pain Diary with a pain Visual Analog Scale (VAS) will be assessed once daily at home for 6 weeks after surgery.

The purpose of this study is to compare cemented and cementless versions of the Triathlon total knee arthroplasty/replacement (TKA) in terms of clinical outcomes, perioperative course, and outcome scores including function and patient satisfaction.

Patients who present to the clinical practices of Dr. Ryan Nunley, Dr. Robert Barrack, or Dr. Denis Nam and are suitable candidates for primary TKA will be screened for eligibility and invited to participate. Once enrolled participants will be randomized (1:1) to either receive a cemented or cementless Triathlon TKA. Data collected for the study will include standard of care clinical and radiographic evaluations collected during office visits and surgery, as well as study-specific patient questionnaires. Clinical, radiographic and questionnaire data will be collected pre-operatively, at the time of surgery, and at 6 weeks, 6 months, 1 year and beyond, and 2 years and beyond post-operatively. Patients will complete the following outcomes questionnaires preoperatively: New Knee Society Score, Oxford Knee Score, UCLA Activity Score, SF-12, and EQ-5D. The following questionnaires will be collected at four to six weeks, six months, one year and beyond, and two years and beyond postoperatively: New Knee Society Score, Forgotten Joint Score, Washington University Knee Satisfaction and Function Questionnaire, Oxford Knee Score, UCLA Activity Score, SF-12, and EQ-5D, and a Pain Drawing. In addition, a Pain Diary with a pain Visual Analog Scale (VAS) will be assessed once daily at home for 6 weeks after surgery.

Inclusion Criteria:

• Patients who qualify for a cementless primary total knee arthroplasty*
• 18 years of age but no more than 75 years of age
• Willing to be randomized
• Willing to sign informed consent
• Willing to return for all follow-up visits

Exclusion Criteria:

• Patients with inflammatory arthritis
• BMI equal to 40 or less.
• Patient with an active infection or suspected infection in the operative joint
• The absolute and relative contraindications stated in the FDA cleared labeling for the device
• Patients who have undergone osteotomy
• Patients who have had previous patella fracture or surgery
• Patients who have had previous healed tibia or femur fractures
• Patients who have had previous knee or hip replacement surgery on the ipsilateral side
• Patients who require patellar resurfacing
• Patients with major medical/muscular/orthopedic deformities

Patient between the ages of 18-75 getting a total knee surgery.