Knee Flexionater to Avoid Motion Restoring Surgery

NCT07454356 | Recruiting FDA Device

• 1 other identifier: RCT-EF-225
• Study Type: interventional
• Target: 150
• Locations: 1 country
• Sites: 1

Brief Summary

The goal of this clinical trial is to learn whether adding a stretching device to standard physical therapy can help people regain knee bending after total knee replacement surgery. Some people have difficulty bending their knee during recovery. When this happens, doctors may recommend another procedure called motion-restoring surgery to improve knee movement. This study aims to answer two main questions. First, does adding a hydraulic high-intensity stretching device to physical therapy help people regain knee bending after surgery? Second, does using the device affect recovery, daily activities, or the chance of needing another procedure? Researchers will compare two treatment approaches. One group will receive standard physical therapy alone. The other group will receive standard physical therapy and will also use a hydraulic high-intensity stretching device called the Ermi Knee Flexionater at home. Participants who receive the device will use it at home each day in addition to attending their physical therapy sessions. Researchers will measure how well participants can bend their knee and will ask questions about pain, daily function, and activity level. Participants will also complete simple walking and mobility tests. Study visits will occur about four weeks after surgery when participants enroll, and again at about eight weeks, twelve weeks, six months, one year, and two years after surgery. Researchers will compare results between the two groups to see whether the stretching device improves recovery after knee replacement.

Conditions

Joint Contractures; Total Knee Anthroplasty; Knee Arthrofibrosis

Outcome Measures

Primary Outcomes (1)

• Change from Enrollment in Active and Passive Knee Flexion Range of Motion (Degrees)

  Change in active and passive knee flexion measured in degrees using a standard goniometer. Higher values indicate greater knee flexion and improved range of motion.

  Baseline (Enrollment at 4 weeks post-operative), 8 weeks post-operative, 12 weeks post-operative, 6 months post-operative, 1 year post-operative, and 2 years post-operative

Secondary Outcomes (6)

• Change from Enrollment in KOOS Score

  Baseline (Enrollment), 8 weeks, 12 weeks, 6 months, 1 year, and 2 years post-operative

• Change from Enrollment in WOMAC Score

  Baseline (Enrollment), 8 weeks, 12 weeks, 6 months, 1 year, and 2 years post-operative

• Change from Enrollment in Visual Analog Scale (VAS) Pain Score

  Baseline (Enrollment), 8 weeks, 12 weeks, 6 months, 1 year, and 2 years post-operative

• Change from Enrollment in Timed Up and Go (TUG) Test Time (Seconds)

  Baseline (Enrollment), 8 weeks, 12 weeks, 6 months, 1 year, and 2 years post-operative

• Change from Enrollment in Six-Minute Walk Test (6MWT) Distance (Meters)

  Baseline (Enrollment), 8 weeks, 12 weeks, 6 months, 1 year, and 2 years post-operative

Study Arms (2)

Physical Therapy Only

ACTIVE COMPARATOR

Participants will receive standard postoperative physical therapy following primary total knee arthroplasty according to the treating clinician's usual rehabilitation protocol.

Other: Standard Physical Therapy

Hydraulic high-Intensity Stretch Device Plus Standard Physical Therapy

EXPERIMENTAL

Participants will receive standard postoperative physical therapy and will use a hydraulic high-intensity stretch device (Ermi Knee Flexionater) at home in accordance with the study protocol.

Device: Hydraulic high Intensity Stretch Device

Interventions

Hydraulic high Intensity Stretch Device DEVICE

A hydraulic high-intensity mechanical stretch device (Ermi Knee Flexionater) used as an adjunct to standard postoperative physical therapy following primary total knee arthroplasty. The device is designed to apply controlled, patient-actuated stretch to increase knee flexion range of motion. Participants assigned to this intervention will use the device at home daily for approximately one hour, in addition to attending prescribed physical therapy sessions. Device use will begin at approximately four weeks postoperatively and continue for up to eight weeks, consistent with the study protocol. Participants will receive in-person instruction on device setup and operation and will record frequency and duration of use in a log. Compliance will be monitored through weekly check-ins.

Hydraulic high-Intensity Stretch Device Plus Standard Physical Therapy

Standard Physical Therapy OTHER

Supervised postoperative physical therapy following primary total knee arthroplasty. Therapy includes range of motion exercises, strengthening, neuromuscular re-education, manual therapy, and functional rehabilitation as determined by the treating clinician.

Physical Therapy Only

Eligibility Criteria

• Age: 40 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Age 40 years or older
• Undergoing primary total knee replacement surgery
• Knee flexion less than 105 degrees at approximately 4 weeks after surgery
• Considered a candidate for motion-restoring surgery, with any surgery delayed until after 2 months of nonoperative treatment

You may not qualify if:

• Not willing to participate
• Diagnosis of advanced rheumatoid arthritis
• Neurological deficit affecting the operative leg
• Revision total knee replacement or previous major surgery on the same knee
• Cognitive impairment
• Prior total hip replacement on the same side (ipsilateral total hip arthroplasty)
• Living more than 2 hours from the study site or unwilling to attend required local physical therapy visits

Sponsors & Collaborators

• Ermi LLC: lead

Study Sites (1)

INOV8 Orthopedics

Houston, Texas, 77043, United States

RECRUITING

Study Officials

• Shaun K Stinton, PhD

  Ermi LLC

  STUDY DIRECTOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: March 2, 2026
• First Posted: March 6, 2026
• Study Start: December 9, 2025
• Primary Completion (Estimated): December 1, 2029
• Study Completion (Estimated): December 1, 2029
• Last Updated: March 6, 2026

Record last verified: 2026-03

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)