Functionally Aligned vs Mechanical Axis Aligned Total Knee Arthroplasty

A Prospective Randomised Control Trial Comparing the Effect of Functional Alignment With Mechanical Axis Alignment on Outcomes After Total Knee Arthroplasty.

The objective of this study is to compare clinical and radiological outcomes in robotic-arm assisted TKA using mechanical alignment (MA TKA) versus robotic-arm assisted TKA with functional alignment (FA TKA).

These outcomes will be used to determine if patient recovery is better with functionally aligned Mako robotic-assisted total knee arthroplasty (FA TKA) or mechanically aligned Mako robotic-assisted total knee arthroplasty (MA TKA).

This project is being conducted by Perth Hip and Knee Clinic. The objective of this study is to compare clinical and radiological outcomes in robotic-arm assisted TKA using mechanical alignment (MA TKA) versus robotic-arm assisted TKA with functional alignment (FA TKA). Both FA TKA and MA TKA are performed through similar skin incisions, robotic-guidance, and use identical implants. In MA TKA, bone is prepared and implants positioned to ensure that the overall alignment of the leg is in neutral. In FA TKA, the bone is prepared and implants positioned to restore the natural alignment of the patient's leg. Both of these surgical techniques provide excellent outcomes in TKA but it is not known which of the two techniques is better for patient recovery. Mako robotic-assisted TKA is an established treatment for arthritis of the knee joint. The positions of the implants and overall alignment of the leg are important as they influence how quickly the implants wear out and need replacing. The aim of this study is to determine if patient recovery is better with functionally aligned Mako robotic-assisted total knee arthroplasty (FA TKA) or mechanically aligned Mako robotic-assisted total knee arthroplasty (MA TKA).

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
• Patient is between 45-75 years of age at time of surgery, computer literate, and able to complete patient-reported outcome measures independently.
• 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
• Patient has tried non-pharmacologic therapies including: patient education, self-management programs, aerobic exercise, weight loss, physiotherapy and occupational therapy
• Patient has tried appropriate pharmacologic therapies including: regular paracetamol and NSAIDS if appropriate

Exclusion Criteria:

• Patient is not suitable for routine primary TKA. E.g., patient has ligament deficiency that requires a constrained prosthesis
• Interoperative requirement for a more constrained implant.
• Intraoperative requirement for the Posterior Cruciate Ligament to be released. These patients will be still included in the study, but analyzed with an intention-to-treat principle.
• Patient has bone loss that requires augmentation
• Patient requires revision surgery following previously failed correctional osteotomy or ipsilateral TKA (e.g., post-high tibial or distal femoral osteotomy)
• Patient requires a polyethylene inset of 13mm or greater.
• Patient is immobile or has another neurological condition affecting musculoskeletal function
• Patient is less than 44 years of age or greater than 76 years of age
• Patient is a compensable patient. I.e., Worker's compensation claim or motor vehicle accident.
• Patient is already enrolled in another concurrent clinical trial
• Patient is unable or unwilling to sign the informed consent form specific to this study
• Patient is unable to attend the follow-up program
• Patient is non-resident in local area or expected to leave the catchment area postoperatively
• Patients who lacks capacity to provide consent, or the ability to understand the study protocol due to a cognitive condition (e.g., Dementia)
• Patient is unable to communicate effectively in English.