Blood Flow Restriction Training After Patellar INStability

Inclusion Criteria:

* 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 Criteria:

* 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