Total knee Arthroplasty (TKA) is a highly effective treatment for knee osteoarthritis. Mid- to long-term follow-up studies have shown good clinical outcomes following TKA; despite these results, there is a high incidence of patient dissatisfaction; 20% of patients reporting dissatisfaction in otherwise uncomplicated procedures.

One reason for early dissatisfaction may be the trauma of surgery may lead to localised and systemic inflammatory responses that impair postoperative clinical recovery; this in turn influences long-term functional outcomes. Surgical techniques that limit the insult of surgery and help to restore the patient's native knee anatomy and kinematics may help to improve clinical outcomes, functional recovery, and patient satisfaction.

The technical objectives of surgery are to restore limb alignment, preserve the joint line, balance flexion and extension gaps, and maintain the normal Q angle for optimal patella tracking. Compromise to the periarticular soft tissue structures may compromise postoperative clinical and functional recovery, reduce stability, and decrease implant survivorship. In conventional jig-based (CO) TKA, bone cuts are most commonly performed using measured resection or gap balancing. The manual error associated with inadvertent soft tissue release during preparation for implantation or tissue damage from the saw blades is an accepted part of the procedure.

The evolution of surgical technology has led to the development of robotic-arm assisted TKA, which uses three dimensional images of the patient's native knee anatomy to guide bone resection and optimise implant positioning. The second-generation RIO Robotic Arm Interactive Orthopaedic system (Mako surgical) uses preoperative computerised tomography scans to build a computer-aided design (CAD) model of the patient's knee joint. The Mako robotic software processes this information to calculate the volume of bone requiring resection and creates a three-dimensional haptic window for the RIO robotic arm to resect.

In short, the robotic technology in TKA allows execution of the preoperative surgical plan without undue soft tissue release, inadvertent trauma from power tools, and minimal trauma to bone surfaces. Conceptually, this Mako TKA should have reduced soft tissue trauma and inflammatory response as assessed with inflammatory cytokines compared to CO TKA.

The overall aim of this single centre, prospective randomised controlled trial is to determine differences in the inflammatory response between CO TKA and Mako TKA.

A comprehensive range of local and systemic biochemical markers, thermal response, and macroscopic soft tissue injury outcomes between the two groups will be recorded and correlated to clinical and functional outcomes over 2-year postoperative. Patients undergoing CO TKA will form the control group and those undergoing Mako TKA will form the investigation group.

Inclusion Criteria:

• Patient has symptomatic knee osteoarthritis requiring primary TKA
• Patient and surgeon are in agreement that TKA is the most appropriate treatment
• Patient is fit for surgical intervention following review by surgeon and anaesthetist
• Patient is between 18-80 years of age at time of surgery
• Gender: male and female
• Patient must be capable of giving informed consent and agree to comply with the postoperative review program
• Patient must be a permanent resident in an area accessible to the study site
• Patient must have sufficient postoperative mobility to attend follow-up clinics and allow for radiographs to be taken

Exclusion Criteria:

• Patient is not suitable for routine primary TKA e.g. patient has ligament deficiency that requires a constrained prosthesis
• Patient has inflammatory arthritis e.g. Rheumatoid arthritis
• Patient has local or systemic autoimmune disease
• Past medical history of cancer or chronic illness
• Patient has symptomatic arthritis of the contralateral knee

No plan