Ermi Knee Flexionater to help avoid motion-restoring surgery after knee replacement
Official 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
Run by Ermi LLC · NCT07454356 · Data updated 2026-11-12
This will test whether adding the Ermi Knee Flexionater to standard physical therapy helps people 40 and older who can't bend their knee enough after a total knee replacement.
Quick facts
| Study type | Interventional |
|---|---|
| Ages | 40 Years and up |
| Sex | All |
| Enrollment | 150 (estimated) |
| Sponsor | Ermi LLC Industry-sponsored |
| Locations | 1 site (Houston, Texas) |
| Status | Recruiting |
| Started | December 9, 2025 |
| Main results expected | December 2029 |
| Study ends | December 2029 |
| Registry record updated | March 6, 2026 |
| Trial ID | NCT07454356 on ClinicalTrials.gov |
Is this trial a fit for you?
✓Likely a good fit
Ideal candidates are adults aged 40 or older who had a primary total knee replacement, have knee flexion under 105 degrees about four weeks after surgery, and are considered candidates for motion‑restoring surgery but willing to try nonoperative treatment first.
✕Probably not a fit
Patients with advanced rheumatoid arthritis, neurologic deficits in the operative leg, prior revision or major knee surgery, ipsilateral hip replacement, cognitive impairment, or those unable to attend local PT visits or living more than two hours away are unlikely to benefit or be eligible.
A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.
What this trial studies
Adults 40 and older who have less than 105 degrees of knee flexion about four weeks after a primary total knee replacement and who are considered candidates for motion‑restoring surgery are enrolled. Participants are assigned to standard physical therapy alone or to standard physical therapy plus daily home use of a hydraulic high‑intensity stretching device (the Ermi Knee Flexionater), with device use added to clinic PT visits. Study outcomes include change in knee flexion, effects on daily activities and recovery, and the eventual need for motion‑restoring surgery, with follow‑up visits at the treating site in Houston. Exclusion criteria include advanced rheumatoid arthritis, neurologic deficits affecting the operative leg, prior major knee surgery or revision TKA, ipsilateral total hip replacement, cognitive impairment, or living more than two hours from the study site.
Why it matters
Potential benefit: If successful, the device could improve knee bending after replacement and reduce the need for additional motion‑restoring surgery.
How similar studies have gone: Prior research of high‑intensity stretching devices and intensive home therapy for post‑TKA stiffness has shown mixed results, with some small trials reporting benefit but no definitive large-scale evidence.
Who can join: the full rules
Show full inclusion / exclusion criteria
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
Where it's running
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INOV8 Orthopedics
Houston, Texas, United States Recruiting
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How to take part
- Review the eligibility criteria above with your treating physician.
- Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
- Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.