Blood Flow Restriction Training for Patellar Instability

This study is looking at whether a type of physical therapy called Blood Flow Restriction Training (BFRT) can help people recover from patellar instability (when the kneecap slips out of place). You could be eligible if you are between 14 and 40 years old and have been diagnosed with patellar instability by a doctor or physical therapist. Participants will be randomly assigned to one of two groups: either standard physical therapy alone, or standard physical therapy plus BFRT. BFRT uses a cuff on the thigh to temporarily limit blood flow, which may help muscles recover strength faster. The main goal is to see if BFRT improves your knee stability and function, measured by a special scale at the start, 5 weeks, and 9 weeks into the study. The study is currently recruiting 78 participants, but the overall status is unclear.

Study design
This is an interventional study where 78 participants will be randomly assigned to one of two treatment groups.
What's involved
Participants will undergo 8 weeks of either Blood Flow Restriction Training or Sham Blood Flow Restriction Training, along with a standardized physical therapy program. Measurements will be taken at the start, 5 weeks, and 9 weeks.
Compensation
Not stated in the trial record.
Follow-up
Your knee stability will be measured at 9 weeks after the start of the study.

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.

NCT04554212

Blood Flow Restriction Training After Patellar INStability

Recruiting
NAAges 14–40InterventionalTreatment
Caitlin Conley
~78 participants
Updated 2026-08-21 on ClinicalTrials.gov
What's tested:Blood Flow Restriction TrainingSham Blood Flow Restriction Training

At a glance

Recruiting sites
4 of 4 listed sites are recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
The Norwich Patellar Instability Scale
Measured over Baseline
+11 more outcomes measured
Patellar Dislocation
Knee Injuries
Leg Injury
Wounds and Injuries

NCT04554212

Where you'd take part

This study runs at 4 sites. They're the same protocol — you choose where, and that choice sets who your contact draft is addressed to.

  • Center for Sports Performance and Research

    Foxborough, Massachusettsstudy coordinator listed

    Recruiting

  • Foxboro Sports Medicine Clinic

    Foxborough, Massachusettsstudy coordinator listed

    Recruiting

  • UK Healthcare at Turfland

    Lexington, Kentuckystudy coordinator listed

    Recruiting

  • University of Kentucky Biomotion Laboratory

    Lexington, Kentuckystudy coordinator listed

    Recruiting

Sites open and close at different times, so the status above is per site — it can differ from the study's overall status.

  • Caitlin Conley, PhD · STUDY_DIRECTOR · University of Kentucky

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Eligibility criteria

Inclusion

Diagnosis of traumatic patellar instability (either primary or recurrent) determined by an American Board of Family Medicine certified physician with a Certificate of Added Qualifications in Sports Medicine or licensed Physical Therapist utilizing clinical examination, radiographic imaging, and patients' reports of instability
Age 14 to 40 years
Skeletally mature with closed growth plates visualized by radiograph
A score of 80 or more on the Sports Activity Scale, which corresponds to participating in "running, twisting, turning (tennis, racquetball, handball, ice hockey, field hockey, skiing, wrestling)" at least 1-3 times per week
Desire to resume pre-injury activity level

Exclusion

Concomitant osteochondral lesion requiring surgical fixation
Radiographic evidence of osteoarthritis (\< Kellgren-Lawrence Grade 2)
Previous ipsilateral or contralateral knee surgery
Most recent instability event more than 3 months before enrollment
History of any inflammatory disorder
BMI \> 35 kg/m2
Diabetes or uncontrolled hypertension
Varicose veins or a history of personal or immediate family history (parental or sibling) of deep vein thrombosis
Pre-existing conditions or previous surgeries that effect the ability to walk
Planned trips or vacations that will result in the inability to attend 4 consecutive physical therapy sessions
  • The Norwich Patellar Instability ScaleBaseline

    The Norwich Patellar Instability (NPI) Scale is a 19-item scale that asks subjects to rate their perceived patellar instability during different tasks, and has been demonstrated to be a valid and responsive tool for assessing patient-reported outcomes for those being treated conservatively or surgically following patellar dislocation. The NPI is scored on a scale of 0 to 100, with lower scores being indicative of less perceived instability

  • The Norwich Patellar Instability Scale5 Weeks

    The Norwich Patellar Instability (NPI) Scale is a 19-item scale that asks subjects to rate their perceived patellar instability during different tasks, and has been demonstrated to be a valid and responsive tool for assessing patient-reported outcomes for those being treated conservatively or surgically following patellar dislocation. The NPI is scored on a scale of 0 to 100, with lower scores being indicative of less perceived instability

  • The Norwich Patellar Instability Scale9 Weeks

    The Norwich Patellar Instability (NPI) Scale is a 19-item scale that asks subjects to rate their perceived patellar instability during different tasks, and has been demonstrated to be a valid and responsive tool for assessing patient-reported outcomes for those being treated conservatively or surgically following patellar dislocation. The NPI is scored on a scale of 0 to 100, with lower scores being indicative of less perceived instability

  • The Norwich Patellar Instability Scale6 Months

    The Norwich Patellar Instability (NPI) Scale is a 19-item scale that asks subjects to rate their perceived patellar instability during different tasks, and has been demonstrated to be a valid and responsive tool for assessing patient-reported outcomes for those being treated conservatively or surgically following patellar dislocation. The NPI is scored on a scale of 0 to 100, with lower scores being indicative of less perceived instability

  • The Norwich Patellar Instability Scale12 Months

    The Norwich Patellar Instability (NPI) Scale is a 19-item scale that asks subjects to rate their perceived patellar instability during different tasks, and has been demonstrated to be a valid and responsive tool for assessing patient-reported outcomes for those being treated conservatively or surgically following patellar dislocation. The NPI is scored on a scale of 0 to 100, with lower scores being indicative of less perceived instability

  • Quadriceps Strength Symmetry1 Week

    Isokinetic Dynamometer will be used. The primary analysis may include the comparison of these observations over multiple time points, with a particular interest in whether there are between-group or within-patient differences.

  • Quadriceps Strength Symmetry5 Weeks

    Isokinetic Dynamometer will be used. The primary analysis may include the comparison of these observations over multiple time points, with a particular interest in whether there are between-group or within-patient differences.

  • Quadriceps Strength Symmetry9 Weeks

    Isokinetic Dynamometer will be used. The primary analysis may include the comparison of these observations over multiple time points, with a particular interest in whether there are between-group or within-patient differences.

  • Quadriceps Strength Symmetry6 Months

    Isokinetic Dynamometer will be used. The primary analysis may include the comparison of these observations over multiple time points, with a particular interest in whether there are between-group or within-patient differences.

  • Quadriceps Strength Symmetry12 Months

    Isokinetic Dynamometer will be used. The primary analysis may include the comparison of these observations over multiple time points, with a particular interest in whether there are between-group or within-patient differences.

  • MRI T1rho1 Week

    Increased T1rho relaxation times have been associated with loss of proteoglycan content. This then corresponds with MRI changes associated with the loss of proteoglycan content. Patients with patellofemoral pain and maltracking have been demonstrated to have significantly greater T1rho relaxation times in the lateral facet of the patella when compared to healthy volunteers.

  • MRI T1rho12 Months

    Increased T1rho relaxation times have been associated with loss of proteoglycan content. This then corresponds with MRI changes associated with the loss of proteoglycan content. Patients with patellofemoral pain and maltracking have been demonstrated to have significantly greater T1rho relaxation times in the lateral facet of the patella when compared to healthy volunteers.