Functionally Aligned vs Mechanical Axis Aligned Total Knee Arthroplasty (FATKAvsMATKA)

July 22, 2025 updated by: Gavin Clark, Perth Hip and Knee

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).

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

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).

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
100

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

  • Australia
    • Western Australia
      • Subiaco, Western Australia, Australia, 6008
        • Perth Hip and Knee
      • Subiaco, Western Australia, Australia, 6008
        • St John of God Private Hopsital

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

45 years to 75 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

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.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Active Comparator: Functionally aligned Total Knee Arthroplasty
Knee arthroplasty performed using a functional alignment theory
Procedure: 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.
Active Comparator: Mechanical axis aligned Total Knee Arthroplasty
Knee arthroplasty performed using a mechanical alignment theory
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.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Change in Forgotten Joint Score After 2 Years From Baseline
Time Frame: Preoperatively and 2 years postoperatively
Difference in relative change in Forgotten Joint Score (2 years post-operatively compared to preoperatively) between FA and MA patients. Scale 0-100 with higher scores being a better outcome
Preoperatively and 2 years postoperatively
Change in Oxford Knee Score After 2 Years From Baseline
Time Frame: Preoperatively and 2 years postoperatively
Difference in relative change in Oxford Knee Score (2 years post-operatively compared to preoperatively) between FA and MA patients. Scale 0-48 with higher scores being a better outcome.
Preoperatively and 2 years postoperatively
Change in Range of Motion After 2 Years From Baseline
Time Frame: Preoperatively and 2 years postoperatively
Difference in relative change in range of motion via goniometry (2 years post-operatively compared to preoperatively) between FA and MA patients.
Preoperatively and 2 years postoperatively

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Determine Lower Limb Alignment Achieved With Both Alignment Techniques
Time Frame: 3 Months post-operatively
Lower limb alignment as assessed using standing long leg x-rays performed postoperatively at 3 months. Measurements of the hip-knee-angle (HKA), medial proximal tibial angle (MPTA) and lateral distal femoral angle (LDFA). Also evidence of imbalance with implant lift off will be measured.
3 Months post-operatively
Difference in Analgesia Requirements Between Patients in Alignment Groups
Time Frame: 6 weeks, 3 months, 1 year, 2 years

Determine if there are any differences in analgesic requirements based on alignment method used.

Inpatient medical records will be utilised to obtain analgesia requirements as inpatient Questionnaires will be used to obtain analgesia usage at remaining timepoints. Analgesia usage will be converted to morphine equivalent dosages for comparison
6 weeks, 3 months, 1 year, 2 years
Difference in Sagittal Stability of the Knee Post Replacement
Time Frame: Preop, and post-operatively at 3 months, 1 year and 2 years
Determine whether alignment method utilized has an effect on the sagittal stability of the knee post replacement, as measure with an arthrometer "Lachmeter"
Preop, and post-operatively at 3 months, 1 year and 2 years
Difference in Functional Outcomes (Measured as Maximal Voluntary Contraction) of Knee Flexion and Extension Between Alignment Groups
Time Frame: Preop, 3 months, 1 Year and 2 years

Determine whether alignment method utilized has an effect on functional outcomes.

Measured as Maximal voluntary isometric knee flexion and extension forces as measured via hand-held dynamometry.
Preop, 3 months, 1 Year and 2 years
Intra-operative Balance Achieved With Different Alignment Techniques.
Time Frame: Intraoperatively
Surgeon blinded measurement of intraoperative balance achieved with Verasense sensor (smaller cohort) Secondary outcome [6] To determine if there is a difference in knee kinematics between the two techniques. Measurement of knee kinematics with Verasense sensor to assess presence or absence of medial pivot (smaller cohort)
Intraoperatively
Difference in Clinical Outcomes as Measured in Knee Injury and Osteoarthritis Outcome Score for Joint Replacement Score (KoosJR)
Time Frame: Measured Pre-operatively and at 3 month, 1 year and 2 years post operatively.
Difference in operated knee outcome on Koos JR scale between FA and MA patients. Scale 0-100 where higher scores mean better outcome.
Measured Pre-operatively and at 3 month, 1 year and 2 years post operatively.
Difference in Clinical Outcomes as Measured in European Quality of Life Questionnaire With 5 Dimensions for Adults (EQ-5D-5L).
Time Frame: Measured Pre-operatively and at 3 month, 1 year and 2 years post operatively.
Difference in overall by Visual Analogue Scale for overall health (VAS). Scale: Five dimensions combined into a 5-digit number lower numbers represent better outcomes. Addition of overall health VAS Scale 0-100 with higher score being better outcome.
Measured Pre-operatively and at 3 month, 1 year and 2 years post operatively.
Difference in Operated Knee Pain as Measured by Visual Analogue Scale for Pain (VAS)
Time Frame: Measured Pre-operatively and at 3 month, 1 year and 2 years post operatively.
Difference in operated knee pain as measured by Visual Analogue Scale for pain (VAS). Scale 0-100 with higher scores meaning worse outcome.
Measured Pre-operatively and at 3 month, 1 year and 2 years post operatively.
Difference in Clinical Outcomes as Measured by Kujala Score- a Measure of Anterior Knee Pain and Best Clinical Score for Patellofemoral Function
Time Frame: Measured Pre-operatively and at 3 month, 1 year and 2 years post operatively.
Difference in clinical outcomes as measured by Kujala score between FA and MA patients. Scale 0-100, with higher scores indicating better outcome.
Measured Pre-operatively and at 3 month, 1 year and 2 years post operatively.

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Perth Hip and Knee

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
St John of God Private Hospital Subiaco

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Gavin Clark, Principal Investigator

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
April 30, 2021

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
October 8, 2024

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
November 14, 2024

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
February 4, 2021

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 8, 2021

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
February 10, 2021

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
August 8, 2025

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 22, 2025

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
July 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • ACTRN12621000060842

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Not shared - for confidentiality of participants

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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