Knee Positioning After Total Knee Replacement

July 30, 2026 updated by: Brett Hayden, Icahn School of Medicine at Mount Sinai

The Effects of Postoperative Positioning in Knee Flexion Versus Usual Care After Total Knee Arthroplasty: A Randomized Controlled Trial

Many total knee replacements are performed each year, but there is no clear recommendation regarding knee positioning following this surgery. While the surgical knee is usually positioned in a straight position immediately after surgery, there may be benefits of positioning it in a partially bent position. A trial will compare the outcomes of two groups of patients: a) those whose knees are positioned in a partially bent position for a few hours after surgery and b) those who receive usual care where the knee is most likely positioned in a straight position. The investigators are looking to see whether knee motion and pain differ for patients in the two groups.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet 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

This parallel two-arm randomized controlled trial will compare outcomes for knee flexion versus usual care in the immediate postoperative period after total knee arthroplasty. Patients who are scheduled for elective primary unilateral total knee arthroplasty will be recruited from an academic health system, screened for inclusion/exclusion criteria, and enrolled. The experimental group will have their surgical knee positioned in approximately 60° of flexion for 2-4 hours after surgery. The control group will receive usual care, where the knee will generally be positioned in extension. Other than the study intervention, both groups will receive standard perioperative, intraoperative, and postoperative care as determined by their treating clinical team. The co-primary endpoints are 6-week knee passive total arc of motion and 7-day maximum pain intensity. Secondary outcomes will be assessed throughout the 12 months after surgery and will include knee motion and pain intensity at other time points; oral opioid consumption; patient-reported questionnaires of knee health, quality of life, and satisfaction; healthcare utilization; and complications. Adverse events will also be monitored for the 12 months after surgery. Outcomes will be assessed via phone or electronic surveys; routine care visits at 2.5 weeks, 6 weeks, 3 months, 6 months, and 12 months after surgery; and chart review.

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.
150

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

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

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Provision of signed and dated informed consent form
  • Stated willingness to comply with all study procedures and availability for the duration of the study
  • Males and females; Age >18 years
  • Scheduled for elective primary unilateral total knee arthroplasty
  • The planned arthroplasty is secondary to physician-confirmed diagnosis of knee osteoarthritis
  • English- or Spanish-speaking

Exclusion Criteria:

  • Patients with a history of chronic opioid use or chronic pain disorders
  • Patients with a history of bleeding disorders/coagulopathy
  • Patients receiving a total knee replacement secondary to trauma, avascular necrosis, tumor, or Charcot arthropathy
  • Patients scheduled to undergo multiple procedures simultaneously
  • Patients with cognitive impairment or inability to consent independently

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: Knee Flexion
Participants in this arm will receive the knee flexion intervention.
Other: Knee Flexion
Participants will receive knee flexion postoperatively following primary total knee arthroplasty. The surgical knee will positioned at approximately 60° flexion using an abduction pillow as a jig underneath the knee during the immediate postoperative recovery period. Positioning will occur following surgery while the participant is still in the operating room. This is a soft construct and a noninvasive intervention. A goniometer will be used to approximate 60° of flexion as closely as possible. It is expected that the knee will be positioned for 2-4 postoperative hours until a physical therapist comes to mobilize the patient. However, the duration may vary because of the pragmatic context. There is no minimum or maximum positioning time that would make the intervention duration ineligible.
Active Comparator: Usual Care
Participants in this arm will receive usual care. No specific attention will be placed to knee positioning in the immediate period after surgery. However, the current usual practice in the health system is that the knee is positioned in extension.
Procedure: Standard Care
Participants in this arm will receive usual care. No specific attention will be placed to knee positioning in the immediate period after surgery. However, the current usual practice in the health system is that the knee is positioned in extension.

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
Knee Passive Total Arc of Motion
Time Frame: At 6 weeks after surgery
Passive total arc of motion will be evaluated through goniometric assessment of maximal passive knee flexion and passive knee extension. Both measures will be recorded, but a single endpoint will be derived by subtracting available extension from available flexion.
At 6 weeks after surgery
Maximum Pain Intensity
Time Frame: At 7 days after surgery
Pain intensity will be evaluated via the patient-reported Numeric Rating Scale (NRS) for pain. The rating is from 0 to 10, with a higher score indicating worse pain. The worst (i.e., maximum) pain intensity will be used.
At 7 days 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
Knee Passive Total Arc of Motion
Time Frame: At 2.5 weeks, 3 months, 6 months, and 12 months after surgery
Passive total arc of motion will be evaluated through goniometric assessment of maximal passive knee flexion and passive knee extension. Both measures will be recorded, but a single endpoint will be derived by subtracting available extension from available flexion.
At 2.5 weeks, 3 months, 6 months, and 12 months after surgery
Maximum Pain Intensity
Time Frame: At 0 days, 1 day, 2 days, 3 days, 10 days, 14 days, 2.5 weeks, 6 weeks, 3 months, 6 months, and 12 months after surgery
Pain intensity will be evaluated via the patient-reported Numeric Rating Scale (NRS) for pain. The rating is from 0 to 10, with a higher score indicating worse pain. The worst (i.e., maximum) pain intensity will be used.
At 0 days, 1 day, 2 days, 3 days, 10 days, 14 days, 2.5 weeks, 6 weeks, 3 months, 6 months, and 12 months after surgery
Total Opioid Consumption
Time Frame: Postoperative days 0 through 14
Consumption of opioids standardized in oral morphine milligram equivalents based on medical records for in-hospital administration, prescriptions, and patient report for at-home consumption. Consumption will be summed across days, with higher numbers indicating greater opioid consumption.
Postoperative days 0 through 14
Knee Injury and Osteoarthritis Outcome Score for Joint Replacement
Time Frame: At 6 weeks, 3 months, 6 months, and 12 months after surgery
The Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS, JR) is a patient-reported measure of knee health (i.e., pain and function). Scores range from 0 to 100, with higher scores indicating better health.
At 6 weeks, 3 months, 6 months, and 12 months after surgery
Veterans RAND 12-item Health Survey
Time Frame: At 6 weeks, 3 months, 6 months, and 12 months after surgery
The Veterans RAND 12-item Health Survey (VR-12) is a patient-reported measure of global physical and mental health. It provides a physical component summary score and a mental component summary score. These are T-scores with a mean of 50, and higher scores indicate better health.
At 6 weeks, 3 months, 6 months, and 12 months after surgery
Goodman Satisfaction Score
Time Frame: 12 months after surgery
The Goodman Satisfaction Score assesses patient satisfaction with total hip or knee arthroplasty outcomes. Scores range from 0 to 100, with higher scores indicating greater satisfaction.
12 months after surgery
Length of Hospital Stay
Time Frame: Through hospital discharge, average of 1 day, up to 30 days after surgery
Number of days the patient stays in the hospital after the index surgery. This information will be extracted from the medical record.
Through hospital discharge, average of 1 day, up to 30 days after surgery
Percentage of Participants with an Emergency Department Visit
Time Frame: Within 7 days, 30 days, and 90 days after surgery
Percentage of participants with an all-cause emergency department visit after surgery. This information will be extracted from the medical record, with supplementation by participant queries during the postoperative visit after the respective timepoint.
Within 7 days, 30 days, and 90 days after surgery
Percentage of Participants with a Hospital Readmission
Time Frame: Within 30 days and 90 days after surgery
Percentage of participants with an all-cause hospital readmission after surgery. This information will be extracted from the medical record, with supplementation by participant queries during the postoperative visit after the respective timepoint.
Within 30 days and 90 days after surgery
Percentage of Participants with Deep Vein Thrombosis
Time Frame: Within 30 days and 90 days after surgery
Percentage of participants who have deep vein thrombosis after surgery.
Within 30 days and 90 days after surgery
Percentage of Participants with a Pulmonary Embolism
Time Frame: Within 30 days and 90 days after surgery
Percentage of participants who have a pulmonary embolism after surgery. This information will be extracted from the medical record, with supplementation by participant queries during the postoperative visit after the respective timepoint.
Within 30 days and 90 days after surgery
Percentage of Participants with a Venous Thromboembolism
Time Frame: Within 30 days and 90 days after surgery
Percentage of participants who have a venous thromboembolism after surgery. This information will be extracted from the medical record, with supplementation by participant queries during the postoperative visit after the respective timepoint.
Within 30 days and 90 days after surgery
Percentage of Participants with a Coronary Event
Time Frame: Within 30 days and 90 days after surgery
Percentage of participants who have a myocardial infarction or other coronary event after surgery. This information will be extracted from the medical record, with supplementation by participant queries during the postoperative visit after the respective timepoint.
Within 30 days and 90 days after surgery
Percentage of Participants with a Stroke
Time Frame: Within 30 days and 90 days after surgery
Percentage of participants who have a stroke after surgery. This information will be extracted from the medical record, with supplementation by participant queries during the postoperative visit after the respective timepoint.
Within 30 days and 90 days after surgery
Percentage of Participants with a Blood Transfusion
Time Frame: Within 30 days after surgery
Percentage of participants who receive a blood transfusion after surgery. This information will be extracted from the medical record, with supplementation by participant queries during the postoperative visit after the respective timepoint.
Within 30 days after surgery
Percentage of Participants with a Wound Dehiscence
Time Frame: Within 30 days and 90 days after surgery
Percentage of participants who have a wound dehiscence after surgery. This information will be extracted from the medical record, with supplementation by participant queries during the postoperative visit after the respective timepoint.
Within 30 days and 90 days after surgery
Percentage of Participants with a Mechanical Complication
Time Frame: Within 30 days and 90 days after surgery
Percentage of participants who have a mechanical complication after surgery. This information will be extracted from the medical record, with supplementation by participant queries during the postoperative visit after the respective timepoint.
Within 30 days and 90 days after surgery
Percentage of Participants with a Manipulation under Anesthesia
Time Frame: Within 12 months after surgery
Percentage of participants who undergo a manipulation under anesthesia after surgery. This information will be extracted from the medical record, with supplementation by participant queries during the postoperative visit after the respective timepoint.
Within 12 months after surgery
Percentage of Participants with a Knee Revision Surgery
Time Frame: Within 12 months after surgery
Percentage of participants who undergo a knee revision surgery after the index surgery. This information will be extracted from the medical record, with supplementation by participant queries during the postoperative visit after the respective timepoint.
Within 12 months after surgery

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.
Icahn School of Medicine at Mount Sinai

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: Brett Hayden, MD, Icahn School of Medicine at Mount Sinai

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 (Estimated)

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.
September 1, 2026

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.
February 1, 2028

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.
February 1, 2029

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).
July 30, 2026

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.
July 30, 2026

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.
August 5, 2026

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 5, 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.
July 30, 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.
July 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.
  • Study 26-00680

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

No individual participant data is planned to be shared with other researchers.

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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