In this study the investigators propose to monitor subjects who have received Triathlon total knee components inserted with HV cement. The primary outcome will be fixation of the tibial implant component as assessed with RSA and to determine the functionality of patients after surgery using self-reported questionnaires. This is a historical control study, comparing the study cohort to a previous group with Triathlon implants and the long-standing Simplex T cement. The secondary outcomes are inducible displacements of the implants as well as a qualitative evaluation of the cement handling characteristics performed by the operating room staff.

Inclusion Criteria:

• Symptomatic arthritis of the knee indicating primary total knee arthroplasty
• Between the ages of 21 and 80 inclusive
• Patients willing and able to comply with follow-up requirements and self-evaluations
• Ability to give informed consent

Exclusion Criteria:

• Active or prior infection
• Medical condition precluding major surgery
• Severe osteoporosis or osteopenia
• Neuromuscular impairment
• Significant co-morbidity affecting ability to ambulate

Local ethics approval does not permit sharing of individual participant data