The Acute Effects of an Isometric Loading Intervention on Lower Extremity Landing Biomechanics in Individuals With Patellar Tendinopathy

University of North Carolina (UNC)

Status: Completed

Conditions: Tendinopathy

Treatments: Other: Sham Transcutaneous Electrical Nerve Stimulation; Other: Isometric Exercise

Study type: Interventional

Funder types: Other; Industry

Identifiers

NCT03262181

17-1731

Details and patient eligibility

About

The purpose of this study is to determine differences in lower extremity landing biomechanics and real-world physical activity between individuals with patellar tendinopathy compared to individuals without patellar tendinopathy,and to determine the acute effects of an isometric loading intervention on lower extremity landing biomechanics in individuals with patellar tendinopathy.

Enrollment: 43 patients

Sex: Male

Ages: 15 to 28 years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

The investigators will recruit a convenience sample of participants who meet the following overall criteria:

1. Age 15 and post-pubertal (confirmed by Pubertal Development Scale Questionnaire) - 28 years
2. Actively participating within an organized sport setting (high school, collegiate, club, competitive intramural sports) in their respective team's weekly training and competitions, quantified by a Tegner Activity Level Scale of at least 5.

Exclusion criteria

The following exclusion criteria will be applied to all participants:

1. Any anterior knee pain with no patellar tendon abnormality on ultrasound assessment.

2. History of any knee joint surgery ever.

3. History of other (non-knee) lower extremity surgery in the last 1 year.

4. History of lower extremity injury in last 6 months (other than patellar tendinopathy).

5. An injection (corticosteroids, plasma-rich-protein, etc.) to the patellar tendon in the last 3 months.

6. Known history of osteoarthritis or current symptoms related to osteoarthritis (i.e. stiffness, swelling).

7. Participation in formal rehabilitation for patellar tendinopathy in prior 3 months

8. Known neurological disorders, including: stroke, multiple sclerosis, ALS, diabetic neuropathy, epilepsy, traumatic brain injury resulting in loss of consciousness, concussion within the last 6 months, cranial neural surgery, balance disorders.

9. Use of pacemaker or another implantable electronic device.

10. History of cardiac arrhythmia or any cardiac condition.

11. History of psychiatric disorder. *

12. History of cancer in the brain or thigh musculature.

13. Pubertal Development Scale Score < 12 (Stages 1-4)

    • Note: Rationale for exclusion of individuals with a history of psychiatric disorders is that these individuals may have taken or be taking pharmacological agents that could affect pain or neuromuscular control.

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Double Blind

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43 participants in 2 patient groups

Isometric Exercise Condition

Experimental group

Description:

The participant will perform 5 sets of a 45-second isometric contractions at 70% of their maximum voluntary isometric contraction (MVIC). During the 45-second contraction, the participant will be provided with visual biofeedback on a computer screen (70% MVIC target line and +/- 5% error lines). The participant will be instructed to produce a level of isometric quadriceps contraction that maintains the isometric torque output line as close the target line as possible and always between the two error lines.

Treatment:

Other: Isometric Exercise

Sham TENS Condition

Sham Comparator group

Description:

Two electrodes of the Select System TENS unit (Empi, Inc., St. Paul, MN) will be placed on either side of the patellar tendon on the test limb. The same instruction script will be used for each participant, stating, "A surface electrode has been placed on either side of your patellar tendon. I will turn on the stimulation unit to emit a stimulus to your patellar tendon. This is a special sub-sensory stimulation treatment, so you will not feel anything during this period as the stimulus is set at a very low, non-detectable threshold. Please remain still during this 45-second period, letting your leg rest passively in the machine without contracting your leg muscles. After the 45-second period, the stimulation unit will be turned off and you will have a 2-minute rest period. We will repeat this same treatment/rest sequence 5 total times."

Treatment:

Other: Sham Transcutaneous Electrical Nerve Stimulation