An Intervention of Electrical Stimulation in Osteoarthritis

Patients with knee osteoarthritis (OA) often have decreased thigh muscle strength. This muscle weakness is thought to originate from centers in the brain and spinal cord that restrict recruitment of fibers responsible for muscle contraction. An inability to fully contract muscles surrounding the knee joint impairs patients' abilities to perform activities of daily living (i.e. walking, climbing stairs) and may even contribute to further joint degeneration.

Establishing therapies aimed at increasing muscle strength, restoring normal function, and possibly slowing the processes involved in the development of knee OA is essential in order to enhance the quality of life in the adult population plagued with this degenerative joint condition.

Electrical muscle stimulation applied to the thigh is a promising therapy that has been shown to successfully restore muscle strength, however how long the treatment lasts and its influence on functional outcomes remains unknown. In order for electrical muscle stimulation to be of value it must result in sustained improvements in muscle strength and functional outcomes. Therefore, the purpose of the proposed investigation is to determine if electrical muscle stimulation can restore thigh muscle strength and improve functional outcomes in patients with knee osteoarthritis.

A frequent clinical obstacle encountered in patients with knee osteoarthritis (OA) is an inability to achieve full voluntary activation of the quadriceps musculature. This phenomenon has been termed arthrogenic muscle inhibition (AMI) and is an ongoing reflex inhibition of musculature surrounding a joint following distension or damage to the structures of that joint. AMI is a limiting factor in joint rehabilitation as it restricts full muscle activation and therefore prevents restoration of strength. Thus, patients often participate in life activities deficient in strength and neuromuscular control resulting in altered lower extremity mechanics and potentially predisposing patients to further joint degeneration. Neuromuscular electrical stimulation (NMES) has been shown to be successful in reversing quadriceps AMI, however the duration of its effectiveness and its influence on functional outcomes remains elusive. Therefore, the purpose of the proposed study is to examine quadriceps activation and functional outcomes following a 4-week NMES protocol in patients with medial tibiofemoral osteoarthritis. To examine the efficacy of NMES in reversing AMI and improving functional outcomes, 38 subjects will be randomly assigned to either undergo a 4-week NMES program or to undergo no therapeutic intervention. Prior to treatment and at 1, 12, and 24 weeks following treatment, patients' quadriceps central activation ratios will be assessed. Additionally, subjects will undergo gait and stair climb analyses to determine if functional performance during these activities of daily living are improved when compared to the baseline assessment. Patients' perceived level of function will also be tested using the Western Ontario and McMasters Universities Osteoarthritis Index.

Eligibility Criteria:
Inclusion Criteria:

* All participants must be female
* Subjects must have radiographic osteoarthritis of grade 2 severity according to the Kellgren and Lawrence scale on the posterior-anterior semi-flexed view with definite osteophytes present in the medial and not lateral compartment.

Exclusion Criteria:

* Previous adverse reaction to electrical stimulation
* Inability to ambulate without the use of an assistive device (i.e cane, walker)
* Patients who have undergone a total knee arthroplasty
* Patients who have torn any knee ligament (ACL, PCL, MCL, LCL)
* Enrollees who have a demand-type cardiac pacemaker or are pregnant
* History of tibial osteotomy surgery
* Significant peripheral or central nervous system disease
* Concurrent clinically active arthritis of the hip, ankle, hindfoot or midfoot in either limb
* Concurrent bilateral radiographic evidence of tibiofemoral osteoarthritis
* Enrollees who are concurrently undergoing physical therapy for pain or OA
* Enrollees who are taking Cox-2 inhibitors or are receiving corticosteroid injections
* Subjects will be allowed to take buffered aspirin and naproxen sodium while enrolled in the study
* Enrollees who have a body mass index of greater than 40 (morbidly obese)
* Enrollees who have a CAR \> .95 (e.g. patients whose quadriceps are uninhibited)
* Enrollees who have previously undergone quadriceps NMES therapy