Knee Positioning After Total Knee Replacement

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: Not yet recruiting
• Conditions: Knee Arthroplasty
• Intervention / Treatment: Other: Knee Flexion; Procedure: Standard Care

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: Interventional
• Enrollment (Estimated): 150
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Brocha Stern; Phone Number: 212-659-9650; Email: brocha.stern@mountsinai.org

Study Locations

• United States
  • New York
    • New York, New York, United States, 10029
      • Mount Sinai Health System
      • Contact: Brocha Stern; Phone Number: (212) 659-9650; Email: brocha.stern@mountsinai.org

Participation Criteria

Eligibility Criteria

• 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

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
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

Outcome Measure	Measure Description	Time Frame
Knee Passive Total Arc of Motion	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	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

Outcome Measure	Measure Description	Time Frame
Knee Passive Total Arc of Motion	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	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	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	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	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	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	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	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	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	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	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	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	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	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	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	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	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	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	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

• Sponsor: Icahn School of Medicine at Mount Sinai
• Investigators: Principal Investigator: Brett Hayden, MD, Icahn School of Medicine at Mount Sinai

Study record dates

Study Major Dates

• Study Start (Estimated): September 1, 2026
• Primary Completion (Estimated): February 1, 2028
• Study Completion (Estimated): February 1, 2029

Study Registration Dates

• First Submitted: July 30, 2026
• First Submitted That Met QC Criteria: July 30, 2026
• First Posted (Actual): August 5, 2026

Study Record Updates

• Last Update Posted (Actual): August 5, 2026
• Last Update Submitted That Met QC Criteria: July 30, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: Knee Flexion
• Additional Relevant MeSH Terms: Health Services Administration; Health Care Quality, Access, and Evaluation; Quality of Health Care; Quality Indicators, Health Care; Standard of Care
• Other Study ID 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