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NCT Number: NCT07454356

Knee Flexionater to Avoid Motion Restoring Surgery

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.

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Key information

Conditions

Joint Contractures Knee Arthrofibrosis Total Knee Anthroplasty

Age range

40 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

INOV8 Orthopedics

Houston, Texas, 77043, United States

Location status: Recruiting

Location contact

Director of Research

CONTACT

[email protected]

832-240-5974

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • 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

Exclusion criteria

  • 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

Treatment and study plan

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.

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.

Primary outcomes

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

    Time frame: 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

    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.

Secondary outcomes

  1. Change from Enrollment in KOOS Score

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

    Change in Knee injury and Osteoarthritis Outcome Score (KOOS). Scores range from 0 to 100, where 0 represents extreme knee problems and 100 represents no knee problems. Higher scores indicate better knee function.

  2. Change from Enrollment in WOMAC Score

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

    Change in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Total scores range from 0 to 96, where higher scores indicate worse pain, stiffness, and functional limitation.

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

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

    Change in self-reported pain measured using a 0-10 scale, where 0 indicates no pain and 10 indicates the worst possible pain. Lower scores indicate less pain.

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

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

    Change in time required to complete the Timed Up and Go test. Lower times (seconds) indicate improved mobility.

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

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

    Change in distance walked during the Six-Minute Walk Test measured in meters. Greater distance indicates improved functional endurance.

  6. Number of Participants Experiencing Adverse Events

    Time frame: From enrollment to 2 years post-operative follow-up

    Number of participants experiencing any adverse event, including but not motion restoring surgery, limited to infection, pulmonary embolism, rehospitalization, revision surgery, or other complications following enrollment.

Sponsors and collaborators

Lead sponsor

Ermi LLC

Industry

Registry information

Official study title

Comparing High Intensity Stretch Device Combined With Physical Therapy Versus Physical Therapy Alone to Prevent Motion-Restoring Surgery Following Primary Total Knee Arthroplasty: Study Protocol for a Randomized Controlled Trial

Important dates

Study start
2025
Primary completion
2029
Study completion
2029
First posted
Mar 6, 2026
Registry last updated
Mar 6, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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