TRabecular Metal Economic and Clinical Knee Trial

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.

• Change in costs per quality adjusted life year (QALY) per participant. [Time frame: 1, 2 and 10 years post-operatively]
• Change in operation time (minutes) [Time frame: After last intervention is administered]
• Change in clinical movement: walking [Time frame: Baseline, 3 months, 1, 2 years post-operatively]
• Change in clinical movement: standing from sitting [Time frame: Baseline, 3 months, 1, 2 years post-operatively]
• Change in clinical movement: walking down stairs [Time frame: Baseline, 3 months, 1, 2 years post-operatively]
• Change in New Knee Society Score (Patient reported outcome measure of pain and function) [Time frame: Baseline, 3 months, 1, 2 years' post-operatively]
• Change in Forgotten Joint Score (Patient reported outcome measure of their awareness of their artificial knee) [Time frame: 3 months, 1, 2, 5 and 10 years post-operatively]
• Change in Patient Satisfaction (Patient reported outcome measure of post-operative satisfaction of the intervention) [Time frame: 3 months, 1, 2, 5 and 10 years post-operatively]
• Change in Hospital Anxiety and Depression Score (Patient reported outcome measure of depression and anxiety surrounding hospitalisation) [Time frame: Baseline, and 1, 2 years' post-operatively]
• Change in Short Form-12 (Patient reported outcome measure of general quality of life) [Time frame: Baseline and 1, 2 years post-operatively]
• Change in Pain Catastrophising Scale (Patient reported outcome measure of patients perceptions of pain) [Time frame: Baseline and 1, 2 years' post-operatively]
• Change in EuroQoL-5 Dimensions (EQ-5D) (Patient reported outcome measure of a patients perceptions of their overall health) [Time frame: Baseline, 3 months, 1, 2, 5 and 10 years post-operatively]