The Effect of Contralateral Isokinetic Lower Extremity Exercises in Unilateral Painful Knee Osteoarthritis

Patients with unilateral knee pain due to knee osteoarthritis presenting to our clinic will be included in a 20-session treatment program, either on an outpatient basis or as inpatients at our clinic. The patients will be divided into 2 groups, and conventional treatments including isometric exercises, TENS (Transcutaneous Electrical Nerve Stimulation) and hot pack therapy for the painful knee will be administered to both groups. In addition to these treatments, the intervention group will receive isokinetic exercise sessions using the Cybex 770 Norm isokinetic dynamometer system (Lumex Inc., Ronkonkoma, New York) at speeds of 60°/s and 180°/s according to the device's standard protocol, targeting the contralateral lower extremity. Subsequently, examinations and measurements will be conducted to evaluate patients for reduction in pain, increase in muscle strength, improvement in functionality, and increase in thigh muscle thickness.

Osteoartritis is the most common form of arthritis, originating from the failed repair of joint damage caused by stress initiated by any joint or periarticular tissue abnormality. Its most common symptom is pain. The long-term consequences of osteoarthritis include decreased physical activity, loss of conditioning, sleep disturbances, fatigue, depression, and disability. Factors associated with increased risk of knee osteoarthritis include advanced age, female gender, overweight or obesity, knee injury, occupational factors, and varus or valgus alignment of the knee.

With the increasing aging population, degenerative joint problems have become relevant to a large portion of society. Exercise is a fundamental component in the treatment of this chronic disease, which limits functionality and reduces quality of life.

A systematic review including 32 randomized controlled trials evaluating 5362 participants showed that various types of exercise provide improvement in pain, functionality, and quality of life in knee osteoarthritis.

Musculoskeletal pains can lead to cortical reorganization in both somatosensory and motor areas, which can reduce motor activity in both the affected and unaffected contralateral extremities. For example, a decrease in motor activity in both painful and pain-free contralateral extremities has been identified during acute pain and/or in the presence of chronic pain.

If exercise is performed to increase muscle strength on one side of the body, strength may also increase on the opposite side. This effect, called the contralateral exercise phenomenon, is typically measured in homologous muscles. Although known for over a century, most studies have not been well-designed to demonstrate the exact magnitude of the strength increase effect. However, an updated meta-analysis of 16 studies indicates that the size of the contralateral exercise effect is approximately 8% of baseline strength or about half of the increase in strength on the exercised side.

However, there are few studies examining the combined effects of contralateral lower extremity isokinetic exercises on pain, muscle thickness, and functionality. Therefore, the aim of this study is to demonstrate the effect of isokinetic exercises applied to the contralateral lower extremity added to routine treatment on muscle strength, muscle thickness, and functionality in the painful knee, and to show its potential relationship. We aim to provide clinicians with a new perspective on the treatment of knee osteoarthritis.

Eligibility Criteria:
Inclusion Criteria:

* To agree to participate in the study
* To be aged 50 years or older
* To have a clinically and radiographically confirmed diagnosis of knee osteoarthritis
* To have unilateral knee pain due to osteoarthritis (VAS \<2 in the contralateral knee, VAS \>2 in the painful knee)
* To have Kellgren-Lawrence Grade 1-3 in the painful knee and Kellgren-Lawrence Grade \<4 in the contralateral knee
* To have dominance of the right lower extremity

Exclusion Criteria:

* A history of previous lower extremity fractures or orthopedic surgery that would interfere with isokinetic and isometric exercises in both lower extremities
* The presence of significant sensorimotor deficits due to neurological diseases
* The presence of known inflammatory rheumatic diseases
* The presence of non-curable malignant tumors with bone metastasis
* The presence of neuropsychiatric diseases or conditions that would hinder cooperation
* Having undergone interventions such as injections for pain relief within the last 3 months