Total Knee ArthroplastyPhase 4KMARTNCT06787417
Kinematic and Mechanical Alignment Randomized Trial
A Phase 4 study testing Restricted Kinematically-aligned Arthroplasty and Mechanically-Aligned Arthroplasty in people with Total Knee Arthroplasty and Osteoarthritis, run by McMaster University at 1 site in Canada.
Trial summary
Knee replacement surgery is the second most common surgery in Canada. People who have very painful knee arthritis usually receive a knee replacement where the surgeon aims to make everyone's knee as straight as possible (called mechanical alignment). Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Total Knee Arthroplasty, Osteoarthritis
- What is being tested?
- Restricted Kinematically-aligned Arthroplasty and Mechanically-Aligned Arthroplasty
- Type of treatment
- Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 260 participants
- Where
- 1 siteCanada
- Study dates
- 20 Feb 2025to Feb 2029
- Phase
- Phase 4
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Adult aged 18 years or older
- Knee osteoarthritis requiring total knee arthroplasty
- Provide informed consent
Who cannot join
- Inability to provide informed consent (e.g. cognitive disability, language barrier)
- Revision knee surgery
- Simultaneous bilateral knee surgery
- Recent lower extremity surgery or trauma interfering with gait assessment
- A CT scan cannot be obtained prior to surgery
- Inability or unwillingness to comply with the study protocol
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Canada1 site, 1 recruiting
- Recruiting
St. Joseph's Healthcare
Hamilton, Ontario, L8N 4A6
Kim Madden, PhD, 289-237-7380, maddenk@mcmaster.ca
Anthony Adili, MD, P.Eng, FRCSC
About this study
Official title: Kinematic and Mechanical Alignment Randomized Trial (KMART): A Technology-Focused Randomized Controlled Trial
Knee replacement surgery is the second most common surgery in Canada. People who have very painful knee arthritis usually receive a knee replacement where the surgeon aims to make everyone's knee as straight as possible (called mechanical alignment). Mechanical alignment focuses on making the implant last as long as possible. However, everybody's knee shape is different and we think that it is important to take individual differences into account. A newer technique that is more personalized is called restricted kinematic alignment. This technique customizes the placement of the new knee to reproduce each patient's unique knee shape, which may not be perfectly straight. We think this newer technique may feel more natural, be more stable, and lead to better knee function. Restricted kinematic alignment might last as long or longer than mechanical alignment, but the research that has been conducted to date is not clear. We are conducting this study to help surgeons better understand which technique is better. One of the reasons the existing research is not clear is because new developments in robotic technology now allow surgeons to place knee implants very precisely, which was not done in most previous research. In this study everyone will receive a robot-assisted knee surgery so we can be sure the implants are placed as precisely as possible.
The purpose of this trial is to determine whether there are differences in patient outcomes using restricted kinematic alignment rather than the traditionally used mechanical alignment for total knee replacements.
Participants who are having total knee replacements will be randomized to receive either a robot-assisted total knee replacement using mechanical alignment, or a robot-assisted total knee replacement using restricted kinematic alignment . We will ask participants to walk in a markerless motion capture system which will measure walking characteristics at pre-op, 6 months postop and 12 months postop. Participants will also complete a series of standardized questionnaires at preop and 6 months, 12 months, and 24 month postop.
Read the detailed description
Total Knee Arthroplasty (TKA) is recognized as a highly effective procedure for alleviating pain and restoring function in patients with knee arthritis. Despite its high success rate, approximately 20% of patients remain dissatisfied with the outcomes, primarily due to loss of functional outcomes, persistent pain, and reduced knee range of motion. This has sparked a debate on the optimal surgical alignment technique in TKA-whether mechanical alignment (MA), or personalized alignment philosophies such as kinematic alignment (KA) or restricted kinematic alignment (rKA) provides superior patient outcomes.
MA traditionally targets a neutral 180-degree hip-knee-ankle (HKA) axis, as it was taught traditionally that this approach focuses on the longevity and stability of the implant. However, this one-size-fits-all philosophy overlooks individual anatomical differences. Personalized alignments such as KA customize the placement of prosthetic components to replicate each patient's unique knee geometry and ligament tensions. Personalized alignment philosophies aim to achieve a more natural knee motion, which may enhance patient satisfaction. The precision provided by robotic-assisted surgery has increasingly facilitated the implementation of personalized alignment philosophies in TKA. Recent evidence suggests that while MA and KA yield comparable outcomes in terms of knee functionality and motion, KA may improve satisfaction and the natural feel of the knee in certain groups, particularly those without severe preoperative deformities. There is also the emerging approach of restricted kinematic alignment (rKA) which aims to provide a compromise by aligning the prosthesis within safe anatomical limits, thus avoiding the extremes of anatomical variation. This approach tailors the surgery more closely to the individual's anatomy without the risks associated with the broader variances permitted in pure KA. Hypothetically, KA and rKA techniques should more closely replicate natural knee biomechanics and improve waking gait. There are advantages and disadvantages to these alignment philosophies which should be addressed with high-quality research. While there have been several previous randomized trials on MA vs KA and its variations, the evidence is still unclear with meta-analyses having conflicting findings.
Patients will be randomly assigned to either mechanical alignment or restricted kinematic alignment. All participants will receive robot-assisted TKA using the Stryker Mako surgical robot and Stryker implants. Perioperative care, postoperative pain medications, and rehabilitation will be standardized according to local standard care.
- Conditions
- Total Knee Arthroplasty, Osteoarthritis
- Being tested
- Restricted Kinematically-aligned Arthroplasty, Mechanically-Aligned Arthroplasty
- Keywords
- Total Knee Arthroplasty, Kinematic Alignment, Mechanical Alignment, Osteoarthritis
- Medical subject headings
- Osteoarthritis
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Restricted Kinematically-aligned ArthroplastyProcedure or surgery
Robot Assisted with Restricted Kinematically-Aligned TKA.
Mechanically-Aligned ArthroplastyProcedure or surgery
Robot Assisted with Mechanically Aligned TKA.
| Study group | Role | What they receive |
|---|---|---|
| Mechanical Alignment | Active comparator | Not described Receives: Procedure: Mechanically-Aligned Arthroplasty |
| Restricted Kinematic Alignment | Experimental | Not described Receives: Procedure: Restricted Kinematically-aligned Arthroplasty |
What is being measured
The primary outcome is the main question the study is designed to answer.
Gait Biomechanics
The primary outcome will be joint angles and walking characteristics (speed, step length, number of steps, consistency between sides) collected using an in-clinic markerless motion capture system. The system uses 10 synchronized optical cameras (60 Hz, Sony RXOII) placed strategically along the clinic hallways to maximize the viewing volume to capture patient movement characteristics. Advanced AI-driven software (Theia Markerless) is used to predict limb segment poses dynamically as the person moves through the space, and, combined with biomechanical modelling algorithms (Visual3D, C-Motion) can be used to accurately represent patient lower extremity 3D joint angles and other kinematic stride characteristics.
Measured: 12 months
Secondary outcomes (4)
Knee function
We will measure knee function using the Forgotten Joint Score (FJS-Knee). The FJS-Knee is a well validated and well-used 12 item questionnaire specifically used to measure function in elation to how natural a knee feels after total knee replacement surgery
Measured: 24 months
Chronic post-surgical pain (CPSP)
We will use a modified version of the International Association for the Study of Pain's (IASP) definition of CPSP, to include a minimum threshold of pain severity: 1) Pain that developed after surgery; 2) Pain that lasts at least 3 months; 3) Other causes of pain have been excluded; 4) Pain caused by other conditions have been excluded; 5) Pain intensity at least 3/10 on a numeric rating score.
Measured: 24 months
Quality of life
We will use the Euro-Qol 5 Dimensions-5L (EQ-5D-5L) questionnaire to assess health-related quality of life (HRQoL). The EQ-5D-5L is a well-validated and well-used quality of life instrument that can assess health utilities
Measured: 24 months
Return to Function
We will use the Return To Function (RTF) questionnaire developed by Busse et al. at McMaster University. The RTF questionnaire is a 5 item questionnaire that has been used previously in orthopaedic trials to determine when a trial participant returns to work, leisure, and activities around the home after an injury or surgery
Measured: 24 months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted22 Jan 2025
- Study start20 Feb 2025
- Primary completionFeb 2028 (estimated)
- Study completionFeb 2029 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Total Knee ArthroplastyStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 4
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind
- Who is masked
- Participant, Outcomes assessor
- Enrolment
- 260 participants (estimated)
Sponsor and investigators
- Lead sponsor
- McMaster University
- Sponsor type
- University, hospital or other
- Collaborators
- Research Institute of St. Joseph's Hamilton, Canadian Orthopaedic Foundation (funding)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06787417
- Sponsor's protocol ID
- KMART
- Acronym
- KMART
- Status last verified
- May 2025
- First submitted
- 15 Jan 2025
- Last updated
- 8 May 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided
Study at a glance
From the registry record, last updated by the sponsor on 8 May 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Kinematic and Mechanical Alignment Randomized Trial (KMART): A Technology-Focused Randomized Controlled Trial
- ClinicalTrials.gov ID
- NCT06787417
- Acronym / sponsor ID
- KMART / KMART
- Conditions
- Total Knee Arthroplasty, Osteoarthritis
- Keywords
- Total Knee Arthroplasty, Kinematic Alignment, Mechanical Alignment, Osteoarthritis
- Phase
- Phase 4
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 260 participants (estimated)
- Lead sponsor
- McMaster UniversityUniversity, hospital or other
- Collaborators
- Research Institute of St. Joseph's Hamilton, Canadian Orthopaedic Foundation (funding)
- Study start
- 20 Feb 2025 (actual)
- Primary completion
- Feb 2028 (estimated)
- Study completion
- Feb 2029 (estimated)
- First posted
- 22 Jan 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Knee replacement surgery is the second most common surgery in Canada. People who have very painful knee arthritis usually receive a knee replacement where the surgeon aims to make everyone's knee as straight as possible (called mechanical alignment). Mechanical alignment focuses on making the implant last as long as possible. However, everybody's knee shape is different and we think that it is important to take individual differences into account. A newer technique that is more personalized is called restricted kinematic alignment. This technique customizes the placement of the new knee to reproduce each patient's unique knee shape, which may not be perfectly straight. We think this newer technique may feel more natural, be more stable, and lead to better knee function. Restricted kinematic alignment might last as long or longer than mechanical alignment, but the research that has been conducted to date is not clear. We are conducting this study to help surgeons better understand which technique is better. One of the reasons the existing research is not clear is because new developments in robotic technology now allow surgeons to place knee implants very precisely, which was not done in most previous research. In this study everyone will receive a robot-assisted knee surgery so we can be sure the implants are placed as precisely as possible.
The purpose of this trial is to determine whether there are differences in patient outcomes using restricted kinematic alignment rather than the traditionally used mechanical alignment for total knee replacements.
Participants who are having total knee replacements will be randomized to receive either a robot-assisted total knee replacement using mechanical alignment, or a robot-assisted total knee replacement using restricted kinematic alignment . We will ask participants to walk in a markerless motion capture system which will measure walking characteristics at pre-op, 6 months postop and 12 months postop. Participants will also complete a series of standardized questionnaires at preop and 6 months, 12 months, and 24 month postop.
Detailed description
Total Knee Arthroplasty (TKA) is recognized as a highly effective procedure for alleviating pain and restoring function in patients with knee arthritis. Despite its high success rate, approximately 20% of patients remain dissatisfied with the outcomes, primarily due to loss of functional outcomes, persistent pain, and reduced knee range of motion. This has sparked a debate on the optimal surgical alignment technique in TKA-whether mechanical alignment (MA), or personalized alignment philosophies such as kinematic alignment (KA) or restricted kinematic alignment (rKA) provides superior patient outcomes.
MA traditionally targets a neutral 180-degree hip-knee-ankle (HKA) axis, as it was taught traditionally that this approach focuses on the longevity and stability of the implant. However, this one-size-fits-all philosophy overlooks individual anatomical differences. Personalized alignments such as KA customize the placement of prosthetic components to replicate each patient's unique knee geometry and ligament tensions. Personalized alignment philosophies aim to achieve a more natural knee motion, which may enhance patient satisfaction. The precision provided by robotic-assisted surgery has increasingly facilitated the implementation of personalized alignment philosophies in TKA. Recent evidence suggests that while MA and KA yield comparable outcomes in terms of knee functionality and motion, KA may improve satisfaction and the natural feel of the knee in certain groups, particularly those without severe preoperative deformities. There is also the emerging approach of restricted kinematic alignment (rKA) which aims to provide a compromise by aligning the prosthesis within safe anatomical limits, thus avoiding the extremes of anatomical variation. This approach tailors the surgery more closely to the individual's anatomy without the risks associated with the broader variances permitted in pure KA. Hypothetically, KA and rKA techniques should more closely replicate natural knee biomechanics and improve waking gait. There are advantages and disadvantages to these alignment philosophies which should be addressed with high-quality research. While there have been several previous randomized trials on MA vs KA and its variations, the evidence is still unclear with meta-analyses having conflicting findings.
Patients will be randomly assigned to either mechanical alignment or restricted kinematic alignment. All participants will receive robot-assisted TKA using the Stryker Mako surgical robot and Stryker implants. Perioperative care, postoperative pain medications, and rehabilitation will be standardized according to local standard care.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind (participant, outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Mechanical Alignment | Active comparator | Procedure: Mechanically-Aligned Arthroplasty |
| Restricted Kinematic Alignment | Experimental | Procedure: Restricted Kinematically-aligned Arthroplasty |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (3 listed)
- Adult aged 18 years or older
- Knee osteoarthritis requiring total knee arthroplasty
- Provide informed consent
Key exclusion criteria (6 listed)
- Inability to provide informed consent (e.g. cognitive disability, language barrier)
- Revision knee surgery
- Simultaneous bilateral knee surgery
- Recent lower extremity surgery or trauma interfering with gait assessment
- A CT scan cannot be obtained prior to surgery
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Restricted Kinematically-aligned ArthroplastyRobot Assisted with Restricted Kinematically-Aligned TKA. | Procedure or surgery | Restricted Kinematic Alignment |
| Mechanically-Aligned ArthroplastyRobot Assisted with Mechanically Aligned TKA. | Procedure or surgery | Mechanical Alignment |
Primary outcome
Gait Biomechanics
Time frame: 12 months
The primary outcome will be joint angles and walking characteristics (speed, step length, number of steps, consistency between sides) collected using an in-clinic markerless motion capture system. The system uses 10 synchronized optical cameras (60 Hz, Sony RXOII) placed strategically along the clinic hallways to maximize the viewing volume to capture patient movement characteristics. Advanced AI-driven software (Theia Markerless) is used to predict limb segment poses dynamically as the person moves through the space, and, combined with biomechanical modelling algorithms (Visual3D, C-Motion) can be used to accurately represent patient lower extremity 3D joint angles and other kinematic stride characteristics.
4 secondary outcomes
Knee function
Time frame: 24 months
Chronic post-surgical pain (CPSP)
Time frame: 24 months
Quality of life
Time frame: 24 months
Return to Function
Time frame: 24 months
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 8 May 2025.
- Individual participant dataSharing planned: Undecided
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 4 study testing Restricted Kinematically-aligned Arthroplasty and Mechanically-Aligned Arthroplasty in people with Total Knee Arthroplasty and Osteoarthritis, run by McMaster University at 1 site in Canada.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 6 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 8 May 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Canada. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 4 studies take place after a treatment is approved, to learn more about its long-term benefits and risks in everyday use.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Kim Madden, PhD (289-237-7380, maddenk@mcmaster.ca), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Gait Biomechanics (time frame: 12 months). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 8 May 2025.