To compare the differences, if any, in clinical outcome, patient satisfaction and survivorship between cemented and uncemented Total Knee Replacements (TKR)? To investigate if there are health economic implications of using uncemented TKRs in the NHS?

The investigators propose to undertake a randomised controlled trial comparing Trabecular metal uncemented TKR with cemented TKR. The primary aim will be to determine whether there is a clinically significant difference in outcome between cemented and uncemented knee prosthesis over a 10-year period. The investigators will assess the patient's functional ability using two clinical knee scores the New Knee Society Score (NKSS) and Oxford knee score (OKS). In addition to employing these two standard clinical scores, the investigators will also utilise the Forgotten Joint Score (FJS). The FJS differentiates patients' awareness of the participant's artificial joint which is an important concept in knee arthroplasty. In contrast to hip arthroplasty where the majority of patients are unaware of their joint after surgery, knee arthroplasty patients rarely 'forget' that their joint is artificial. Given the difference in physical properties of trabecular metal and standard implants, the FJS scoring system may highlight potential differences that are important to patients and linked to patient satisfaction. Non-subjective assessment will be performed using Inertial Measuring Units (IMU), which measure the relative position of limbs in space and is a useful measure for clinical movement analysis. Participants will be asked to perform daily task such as walking, standing from a chair and walking up and down stairs, wearing the IMU, before and after surgery. This allows us to see functional improvements after surgery and if there are functional differences between the cemented and uncemented implant.

Clinical evaluation and radiological assessment will be carried out over a 10-year period recording complications and clinical performance of patients and implants.

In addition to carrying out a clinical evaluation of the trabecular metal uncemented knee and cemented knee systems, the investigators will also undertake a health economic assessment of the benefits of using uncemented trabecular metal prostheses.

The most expensive resources in a hospital theatre environment are the surgeon and anaesthetist and maximising their utilisation is essential. The removal of cement mixing and curing time from a TKR offers a potential time saving during the operation. However, the time saved using an uncemented prosthesis during a single operation is unlikely, in isolation, to be sufficient to allow additional clinical activity to be carried out. Nevertheless, by combining multiple uncemented knee replacement operations in a single theatre session it may be possible to save sufficient time during the entire day to facilitate an additional surgical procedure, thus increasing the utilisation of surgeons, anaesthetists and theatre staff. If this were achievable, it would add significant value for health care providers.

Despite the success of knee arthroplasty 18% of patients are dissatisfied with their outcome [16]. These are an important group of patients and understanding better the issues that these patients encounter is key in achieving better satisfaction rates and ensuring appropriate use of Orthopaedic implants. The investigators will therefore also study patient factors such as depression and ability to deal with pain/discomfort and correlate these with post-surgical outcome.

Trabecular metal uncemented implants potentially offer benefits to both patient and surgeon but as yet there is insufficient data available to support widespread use of this product. It is the investigators belief that uncemented knees are underutilised by surgeons because there are a number of areas of concern which have not been adequately addressed in clinical studies. The investigators hope to address these concerns in this study.

Inclusion Criteria:

• Male or female subjects may be recruited to the evaluation.
• Age - there are no restrictions relating to age of the patient.
• Subjects who are able to give voluntary, written informed consent to participate in this investigation and from whom consent has been obtained.
• Subjects who in the opinion of the Investigator, are able to understand this investigation, co-operate with the investigation procedures and are willing to return to the hospital for all the required post-operative follow-ups.
• Subjects with uni-lateral osteoarthritis of the knee or subjects with bi-lateral osteoarthritis of the knee, who have a well functioning and pain free knee replacement in the contralateral knee.
• Subjects who require a TKR for surgical management of osteoarthritis

Exclusion Criteria:

• Patients who, in the opinion of the Investigator, have an existing condition that would compromise their participation and follow-up in the study.
• Patients with bi-lateral disease that significantly impacts on their current function and pain.
• Patients who require revision knee arthroplasty surgery.
• Disorders of the feet, ankles, hips or spine causing significant abnormal gait or significant pain.
• Neurological conditions affecting movement.
• Patients with a pathology, which, in the opinion of the Chief Investigator, will adversely affect healing.
• Patients with other disorders which, in the opinion of the Chief Investigator, will/could impair rehabilitation.
• Subjects who in the opinion of the study investigator are unlikely to comply with the study follow-up protocol

all blind except surgeon, who will not take part in study or analysis after surgery