RObotic-assisted Versus Conventional Knee Endoprosthetic Techniques (ROCKETS)

September 16, 2026 updated by: Olof Skoldenberg, Danderyd Hospital

ROCKETS: RObotic-assisted Versus Conventional Knee Endoprosthetic Techniques in a Randomized, Multicenter, Preference-tolerant Study

Rationale for conducting the study:

The ROCKET study evaluates the clinical and economic outcomes of robot-assisted total knee arthroplasty (RTKR) compared with conventional total knee arthroplasty (TKR). The primary endpoint is the proportion of randomized participants achieving a Forgotten Joint Score (FJS) of ≥80 points at 24 months after surgery. Secondary outcomes include patient-reported knee function, health-related quality of life, self-reported instability, physical activity, radiographic alignment, surgical and technical outcomes, complications, reoperations, revisions, and health-economic outcomes.

Study design:

International multicentre, preference-tolerant, randomized, controlled superiority trial with two treatment arms comparing RTKR with conventional TKR. Participants in the randomized part are allocated 1:1. At selected centres where feasible, an optional participant-blinded randomized component may be implemented. Eligible patients who do not undergo randomization may participate in a parallel observational/preference cohort, which is analysed separately from the primary randomized comparison.

Study population:

Adults aged 18 years and older who are eligible for total knee arthroplasty according to local guidelines and who provide informed consent.

Number of patients:

Up to 1,600 randomized participants. Eligible non-randomized participants may additionally be included in the observational/preference cohort.

Primary outcome:

Proportion of randomized participants achieving FJS ≥80 points at 24 months after surgery.

Long-term follow-up:

Patient-reported and registry-based outcomes are planned at 5 and 10 years after surgery where feasible.

Study Overview

Status

Status

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

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

The ROCKET study is an international multicentre, prospective, preference-tolerant randomized controlled superiority trial comparing robot-assisted total knee arthroplasty with conventional total knee arthroplasty.

Participants in the randomized component are allocated 1:1 to robot-assisted or conventional total knee arthroplasty. Randomization is stratified by participating centre and sex. At selected centres where practical and approved, participants may remain blinded to treatment allocation until completion of the 24-month follow-up unless earlier unblinding is clinically required or requested by the participant. Surgeons and operating-room personnel cannot be blinded. Outcome assessment is performed blinded to treatment allocation whenever feasible.

Eligible patients who are unwilling to undergo randomization, or for whom treatment equipoise cannot be achieved, may enter a parallel observational/preference cohort. Treatment in this cohort follows patient and surgeon preference. The observational/preference cohort is analysed separately from the primary randomized comparison.

The primary endpoint is the proportion of randomized participants achieving a Forgotten Joint Score (FJS) of ≥80 points at 24 months after surgery. Follow-up includes patient-reported outcomes, activity, radiographic alignment, surgical and technical variables, complications, reoperations, revisions and health-economic outcomes. Long-term follow-up is planned at 5 and 10 years after surgery, including PROMs where available and registry-based outcomes such as reoperations, revisions, complications and mortality.

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 (Estimated)

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.
1600

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 Locations

  • Sweden
      • Hässleholm, Sweden, 281 38
        • Recruiting
        • Hässleholm Hospital
      • Stockholm, Sweden, 182 88
        • Recruiting
        • Danderyd Hospital
        • Contact:
        • Principal Investigator:
          • Olof Skoldenberg, MD, PhD

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

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Adults aged 18 years and older.
  • Eligible for total knee arthroplasty according to local guidelines and routines.
  • Willingness to participate in the study.

Exclusion Criteria:

  • Patients with extreme malalignment necessitating special implants or techniques.
  • Patients unfit for surgery due to other medical reasons.
  • Patients who, for other reasons such as alcohol or substance abuse, are deemed unsuitable to participate in the study.
  • Patients who, for other reasons, cannot fulfil the required patient-reported outcome measures.

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: Single

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.
Experimental: RTKR

Robot-assisted total knee arthroplasty (RTKR).
Procedure: Robot-assisted total knee arthroplasty

Robot-assisted total knee arthroplasty using an approved robotic surgical system to assist intraoperative planning, bone preparation, implant positioning and balancing according to the participating centre's approved technique.
Active Comparator: TKR

Conventional total knee arthroplasty (TKR).
Procedure: Conventional total knee arthroplasty

Conventional total knee arthroplasty using standard manual instrumentation according to local clinical routine.

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
Proportion of participants achieving a Forgotten Joint Score (FJS) ≥80 points
Time Frame: 24 months after surgery

The primary endpoint is the proportion of randomized participants achieving an FJS of ≥80 points at 24 months after surgery. The FJS ranges from 0 to 100, with higher scores indicating less awareness of the replaced knee during everyday activities.
24 months after surgery

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
Forgotten Joint Score (FJS), continuous score
Time Frame: Baseline, 6 weeks, 12 months, 24 months, 5 years and 10 years after surgery

FJS is scored from 0 to 100, with higher scores indicating less awareness of the replaced knee.
Baseline, 6 weeks, 12 months, 24 months, 5 years and 10 years after surgery
Knee injury and Osteoarthritis Outcome Score (KOOS)
Time Frame: Baseline, 6 weeks, 12 months, 24 months, 5 years and 10 years after surgery

KOOS assesses knee-related pain, symptoms, activities of daily living, sport/recreation and knee-related quality of life. Each subscale ranges from 0 to 100, with higher scores indicating better outcome.
Baseline, 6 weeks, 12 months, 24 months, 5 years and 10 years after surgery
Self-reported knee instability (ADLS items)
Time Frame: Baseline, 6 weeks, 12 months, 24 months, 5 years and 10 years after surgery

Self-reported slipping/partial giving way and buckling/full giving way are assessed using items from the Activities of Daily Living Scale of the Knee Outcome Survey.
Baseline, 6 weeks, 12 months, 24 months, 5 years and 10 years after surgery
EQ-5D and EQ VAS
Time Frame: Baseline, 6 weeks, 12 months, 24 months, 5 years and 10 years after surgery

Health-related quality of life is assessed using EQ-5D and EQ VAS.
Baseline, 6 weeks, 12 months, 24 months, 5 years and 10 years after surgery
Patient activity and walking distance
Time Frame: Baseline, 6 weeks, 12 months, 24 months, 5 years and 10 years after surgery

Patient activity and walking distance are assessed during follow-up using the study's prespecified activity measurements.
Baseline, 6 weeks, 12 months, 24 months, 5 years and 10 years after surgery
Knee alignment
Time Frame: Preoperative and approximately 6 weeks after surgery

Coronal knee alignment is assessed using long-standing radiographs, including Hip-Knee-Ankle alignment and Coronal Plane Alignment of the Knee (CPAK) classification.
Preoperative and approximately 6 weeks after surgery
Surgery time
Time Frame: During the index operation

Duration of the surgical procedure is recorded in minutes.
During the index operation
Technical and intraoperative surgical outcomes
Time Frame: During the index operation

Technical difficulties and prespecified intraoperative surgical details are recorded.
During the index operation
Range of motion (ROM)
Time Frame: 24 months after surgery

Knee range of motion is assessed at the 24-month follow-up.
24 months after surgery
Reoperations and revisions
Time Frame: Up to 24 months, with additional follow-up at 5 and 10 years

Reoperations and revisions of the index knee are recorded during the primary study period and assessed during long-term follow-up where data are available.
Up to 24 months, with additional follow-up at 5 and 10 years
Adverse events and complications
Time Frame: Up to 24 months, with additional long-term assessment at 5 and 10 years

Adverse events and complications related to the index knee arthroplasty are recorded. Long-term complications may additionally be assessed using approved registry or other data sources.
Up to 24 months, with additional long-term assessment at 5 and 10 years
Mortality
Time Frame: 90 days, 1 year, 5 years and 10 years after surgery

Mortality is assessed using available approved registry or other data sources.
90 days, 1 year, 5 years and 10 years after surgery
Health-economic outcomes
Time Frame: Up to 24 months; exploratory long-term analyses at 5 and 10 years where data are available

Health-economic analyses include direct and indirect costs and cost-effectiveness using health-related quality-of-life data.
Up to 24 months; exploratory long-term analyses at 5 and 10 years where data are available

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.
Danderyd Hospital

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.
Karolinska Institutet

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.
March 4, 2024

Primary Completion (Estimated)

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.
December 1, 2029

Study Completion (Estimated)

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.
December 1, 2037

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).
April 4, 2024

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.
April 26, 2024

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.
April 29, 2024

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.
September 21, 2026

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.
September 16, 2026

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.
September 1, 2026

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.
  • 2024DS
  • Knee (Other Identifier: Danderyds sjukhus)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

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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