Functionally Aligned vs Mechanical Axis Aligned Total Knee Arthroplasty

NCT ID: NCT04748510

Last Updated: 2025-08-08

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 100 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2021-04-30
• Study Completion Date: 2024-11-14

Brief Summary

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).

Detailed Description

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).

Conditions

Osteoarthritis; Osteo Arthritis Knee

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: TREATMENT
• Blinding Strategy: DOUBLE

Study Groups

Functionally aligned Total Knee Arthroplasty

Knee arthroplasty performed using a functional alignment theory

Group Type: ACTIVE_COMPARATOR

Functionally Aligned Total Knee Arthroplasty

Intervention Type: PROCEDURE

Femoral + tibial osteotomy planned for equal resection of femoral condyles to replicate patient anatomy. In coronal plane, distal femoral resection of 6.5mm subchondral bone from medial + lateral condyles, adjusted 1-3mm for compensation of wear. Proximal tibia, 7mm resection from subchondral bone from medial + lateral tibial plateau. Sagittal plane, resection angle determined intraoperatively to closely match native femoral flexion + tibial slope. Axial plane: posterior femoral resection 6.5mm from the subchondral bone of medial and lateral posterior condyles. Tibial rotation aligned to Akagi's line. Adjustments will be made to bony alignment to balance soft tissues within boundaries of 6° varus/3° valgus HKA alignment. Femoral component alignment limited to 6° valgus/3° varus in coronal plane. Tibial alignment limited 6° varus/3° valgus in coronal plane. Combined flexion of components limited to 10° flexion. Soft tissue release if balance within boundaries not achieved.

Mechanical axis aligned Total Knee Arthroplasty

Knee arthroplasty performed using a mechanical alignment theory

Group Type: ACTIVE_COMPARATOR

Mechanically Aligned Total Knee Arthroplasty

Intervention Type: PROCEDURE

Tibial and femoral osteotomies in the coronal plane will be planned perpendicular to the tibial and femoral mechanical axes respectively to achieve neutral overall alignment. Soft tissue balance will be assessed and minor adjustments to bony alignment made to balance the knees with a maximal adjustment of two degrees valgus and two degrees varus of coronal alignment from neutral. Femoral rotation will be planned to surgical epicondylar axis and adjustments to rotation made to allow equal flexion and extension balance (to within 1mm). If balance can not be achieved within these boundaries then soft tissue release will be undertaken. In the sagittal plane, 0-3° degrees of posterior tibial slope and 0-5° of femoral component flexion will be used to optimise implant sizing whilst preventing notching. In the axial plane, the tibial component aligned to Akagi's line, which connects the medial border of the patellar tendon attachment to the middle of the posterior cruciate ligament.

Interventions

Functionally Aligned Total Knee Arthroplasty

Femoral + tibial osteotomy planned for equal resection of femoral condyles to replicate patient anatomy. In coronal plane, distal femoral resection of 6.5mm subchondral bone from medial + lateral condyles, adjusted 1-3mm for compensation of wear. Proximal tibia, 7mm resection from subchondral bone from medial + lateral tibial plateau. Sagittal plane, resection angle determined intraoperatively to closely match native femoral flexion + tibial slope. Axial plane: posterior femoral resection 6.5mm from the subchondral bone of medial and lateral posterior condyles. Tibial rotation aligned to Akagi's line. Adjustments will be made to bony alignment to balance soft tissues within boundaries of 6° varus/3° valgus HKA alignment. Femoral component alignment limited to 6° valgus/3° varus in coronal plane. Tibial alignment limited 6° varus/3° valgus in coronal plane. Combined flexion of components limited to 10° flexion. Soft tissue release if balance within boundaries not achieved.

Intervention Type: PROCEDURE

Mechanically Aligned Total Knee Arthroplasty

Tibial and femoral osteotomies in the coronal plane will be planned perpendicular to the tibial and femoral mechanical axes respectively to achieve neutral overall alignment. Soft tissue balance will be assessed and minor adjustments to bony alignment made to balance the knees with a maximal adjustment of two degrees valgus and two degrees varus of coronal alignment from neutral. Femoral rotation will be planned to surgical epicondylar axis and adjustments to rotation made to allow equal flexion and extension balance (to within 1mm). If balance can not be achieved within these boundaries then soft tissue release will be undertaken. In the sagittal plane, 0-3° degrees of posterior tibial slope and 0-5° of femoral component flexion will be used to optimise implant sizing whilst preventing notching. In the axial plane, the tibial component aligned to Akagi's line, which connects the medial border of the patellar tendon attachment to the middle of the posterior cruciate ligament.

Intervention Type: PROCEDURE

Eligibility Criteria

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.

• Minimum Eligible Age: 45 Years
• Maximum Eligible Age: 75 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

St John of God Private Hospital Subiaco

UNKNOWN

Sponsor Role: collaborator

Perth Hip and Knee

OTHER

Sponsor Role: lead

Responsible Party

Gavin Clark

Principal investigator

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Gavin Clark

Role: PRINCIPAL_INVESTIGATOR

Principal Investigator

Locations

Perth Hip and Knee

Subiaco, Western Australia, Australia

St John of God Private Hopsital

Subiaco, Western Australia, Australia

Countries

Australia

References

Steer R, Tippett B, Khan RN, Collopy D, Clark G. A prospective randomised control trial comparing functional with mechanical axis alignment in total knee arthroplasty: study protocol for an investigator initiated trial. Trials. 2021 Aug 9;22(1):523. doi: 10.1186/s13063-021-05433-z.

Reference Type: DERIVED

PMID: 34372888 (View on PubMed)

Provided Documents

Document Type: Study Protocol, Statistical Analysis Plan, and Informed Consent Form

View Document

Other Identifiers

ACTRN12621000060842

Identifier Type: -

Identifier Source: org_study_id