This study compares the use of sharp dissection with diathermy for the approach to a total knee replacement. Half of the patients will be randomly assigned each intervention.

The approach to the knee to carry out a total knee replacement (TKR) can either be carried out using a scalpel, sharp dissection, or using an electric current to divide tissue, monopoly electrocautery. Reducing blood loss is important. Blood loss can result in anaemia, which has a number of effects including shortness of breath, chest pain and lethargy. Blood loss into a newly replaced knee can also result in pain and stiffness in the joint. Total knee replacements are routinely carried out with a tourniquet inflated, which reduces the blood flow into to leg during the operation. Diathermy is applied to areas of bleeding to stop them from doing so during operations. With the tourniquet inflated, some areas that would bleed when this was deflated may not be noticed and continue to bleed. Using diathermy for the approach would be expected to reduce this bleeding compared to using a scalpel.

Inclusion Criteria:

• Primary knee osteoarthritis requiring TKA (total knee arthroplasty)
• Planned for cruciate retaining prosthesis without patella resurfacing
• Patient is able to give informed consent
• Patient resides locally and will be available for follow up

Exclusion Criteria:

• Cardiac pacemaker
• Inflammatory arthropathy
• Tourniquet contraindicated
• Thrombophilia/haemoglobinopathy
• Spinal anaesthetic not possible

Patients will be blinded to the intervention as they will be under anaesthetic whilst the procedure is being carried out.