Corticospinal Excitability and Rehab in Knee Osteoarthritis

To determine differences in thigh muscle function in individuals with and without knee arthritis, and also determine the effectiveness of common physical therapy interventions on clinical and patient oriented outcomes.

The primary objective of the proposed research evaluates the concurrent changes in corticospinal excitability and central sensitization of pain pathways for their influence on quadriceps voluntary activation. A secondary objective is to establish the feasibility of an intervention study to determine if changes in the excitability of these supraspinal motor and sensory processes can be modified by physical therapy interventions targeting pain and muscle strengthening. We hypothesize that patients with knee osteoarthritis will show measurable deficits in quadriceps voluntary activation that can be explained by lower levels of corticospinal excitability and increased pain sensitization. A 1 week physical therapy intervention will improve voluntary activation and reduce pain with concurrent changes in underlying motor and sensory processes. We further hypothesize that part of this improvement will be attributed to positive treatment expectation.

The physical therapist will read a script indicating that the intervention is an effective treatment for knee osteoarthritis and is expected to reduce pain and improve strength. Patients are then instructed on the home exercise program and how to operate the TENS (transcutaneous electrical nerve stimulation) unit. The duration of intervention is 1 week during which patients will wear then wear the TENS unit for 8 hours per day and perform no more than 3 sets of 10 repetitions of the physical therapy exercises daily.

The physical therapist will read a script indicating that the intervention may or may not be an effective treatment for knee osteoarthritis and may nor may not reduce pain and improve strength. Patients are then instructed on the home exercise program and how to operate the TENS unit. The duration of intervention is 1 week during which patients will wear then wear the TENS unit for 8 hours per day and perform no more than 3 sets of 10 repetitions of the physical therapy exercises daily.

The patients in the control group will be reminded of their appointment in 1 week and instructed to maintain their usual activity level during that time.

The TENS electrodes will be applied on the medial and lateral superior, as well as the medial and lateral inferior, borders of the patella. A continuous biphasic pulsatile current (150 Hz, phase duration 150 µs) will be applied at an intensity that produces a comfortable sensation but not a muscle contraction. The duration of intervention will be 8 hours per day for 1 week.

Patients will be given detailed verbal and hands-on instruction in a home exercise program. This program will consist of 6 exercises modeled from established protocols focuses on improving lower extremity strength. Patients will be instructed to do the exercises daily and to progress the exercises over the week for a maximum of 30 repetitions per day for 1 week.

Quadriceps activation will be estimated by utilizing the burst-superimposition technique on a maximum voluntary isometric contraction (MVIC) and during a resting condition. The burst-superimposition technique provides the muscle with a percutaneous stimulus to recruit any remaining muscle fibers which have not been stimulated.

Inclusion Criteria: Age 19-65 Grade I or II knee Osteoarthritis confirmed by radiographs or other imaging and at least one of the following: Age > 50 years old Morning stiffness < 30 minutes Crepitus Meet at least 3 of 6 diagnostic criteria for osteoarthritis: Age > 50 years old Morning stiffness < 30 minutes Crepitus Bony tenderness Bony enlargement No palpable warmth Exclusion Criteria: BMI > 30 History of traumatic spine or lower extremity injury within the last 6 months Previous adverse reaction to electrical stimulation (i.e. burns or hypersensitivity) Cardiac pacemaker Metal implants in head Current pregnancy Neurological disorders History of seizures Unable to give consent or understand the procedures of this study