Osteoarthritis (OA) is a long-term chronic disease involving the thinning of cartilage in joints which results in bones rubbing together, creating stiffness, pain, and impaired movement. 1
Osteoarthritis is the most common joint disease with a prevalence of 22-39% in India. Primary osteoarthritis of the knee is a major cause of impairment of mobility of the lower limb. There is no known cure for this progressive and degenerative disease, making effective rehabilitation particularly important. 2
The knee joint consists of three compartments—the medial tibiofemoral, lateral tibiofemoral, and patellofemoral—all sharing a common synovial cavity. The tibio-femoral is the biggest articulation in the body. The condyles of the femur rest in an incongruent manner on the shallow convex surface of the tibia, thus the knee joint relies on other structures to provide both static and dynamic stability. This stability is accomplished by the various soft tissue structures, particularly the muscles crossing the joint. 18
Apart from pre-established factors like age, gender, bodyweight, height, activity level, the strength of quadriceps muscle has also been shown to influence pain and disability of the lower limbs.
The major clinical symptom of knee OA is knee pain. 4Symptomatic knee osteoarthritis is defined as a K/L scale of at least mild radiographic osteoarthritis and symptoms in the same knee. Symptomatic knee is significant in both clinical diagnosis as well as measuring the public health burden. It is a primary indication for most knee joint replacements. 3
One of the factors contributing to knee pain other than radiographic knee OA may be quadriceps muscle weakness. 5
The quadriceps muscle is the principal dynamic stabilizer of the knee joint since it offers ample shock absorption for the knee during gait by virtue of its eccentric contraction. 6
Quadriceps weakness is one of the initial clinical findings among persons with knee OA9-12 which appears even before patient-reported symptoms and observed disability, and may play a vital role in disease advancement. 16, 17 Quadriceps strength has found to be reduced in patients with higher grades of osteoarthritis in some studies. 8The inability to adequately attenuate large compressive forces at the knee can result in impulsive loading which has been credited to quadriceps weakness and inactivity and may be responsible for changes of osteoarthritis. 7
Quadriceps muscle weakness could, thus, predispose the knee joint to injury and cause further deterioration of the existing injury. 2Research has shown that higher quadriceps muscle strength leads to a reduced risk for incident symptomatic knee OA. However there is limited evidence to suggest that quadriceps muscle plays a significant role in the incidence of radiographic knee OA.6
Quadriceps muscle weakness forms a unique link with symptomatic and radiographic knee osteoarthritis. The present study is a major step towards analyzing these links especially in the chosen population of the hilly region of Sullia, Dakshina Karnataka. Progressive diminution of quadriceps strength with increase in radiological grades of osteoarthritis may substantiate the concept of increasing the strength of quadriceps muscle to halt the progression of the disease or at least, reduce the pain and disability associated with this severely debilitating disease.
1. To determine the isometric quadriceps strength in patients with painful symptomatic osteoarthritis of the knee
2. To compare the isometric quadriceps strength in patients with mild, moderate and severe radiological knee osteoarthritis
3. To identify the association of quadriceps strength with pain and disability in patients with knee osteoarthritis.
This study will be a cross-sectional type of study.
Sample size estimation- Considering the prevalence of knee OA to be __ in adults in India and an allowable error of 5%, sample size was calculated by the formula 4pq/l2 and found to be 50.
The participants are selected based on convenience sampling method and the sample size is determined by the influx of patients, with the specific conditions as mentioned later. This constitutes an average of 25 patients per month in K.V.G Medical College and Hospital, thus making the sample size 50 patients for 2 months of allotted study time.
The study population will be divided into two categories which are further divided into three groups each:
Kellgren-Lawrence grading (radiographic osteoarthritis)
Western Ontario McMaster Universities Osteoarthritis Index scoring for pain and disability (symptomatic osteoarthritis)
1. Mild osteoarthritis (K/L Grade I),
1. Mild pain and disability,
2. Severe osteoarthritis (K/L Grades III and IV)
2. Moderate pain and disability
3. Moderate osteoarthritis (K/L Grade II)
3. Severe pain and disability
In the duration of two months, patients visiting Orthopedics Outpatient Department with complaints of pain in knee joint and fulfilling the inclusion criteria will be taken for this study, till the goal of 50 subjects is reached.
1. Subjects aged above 40 years
2. Patients reporting pain in knee joint, which is insidious in onset and lasting for a duration more than 1 month
3. Patients with knee radiographs in standing position, showing features of osteoarthritis as per Kellgren-Lawrence (K/L) grade more than or equal to K/L grade I .
1. Those who are not willing to participate in the study and/or are not willing to give the required consent form.
2. Patients with history of recent or old trauma to the same painful knee, directly or indirectly causing severe bony or ligament injuries, which has been documented in their previous medical records
3. Patients with pain in multiple joints, indicating inflammatory origin of arthritis like rheumatoid arthritis, ankylosingspondylitis, etc.
4. Patients with history of previous surgeries on the same painful knee or history of infection, indicating septic arthritis
Informed consent will be taken from the subjects through a consent form. Confidentiality will be maintained. The subject’s choice to participate in the study will not be influenced under any circumstances.
1. Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) scoring for assessment of knee pain
2. Radiographic evaluation using Kellgren-Lawrence grading
3. Assessment of isometric quadriceps muscle strength by modified Hand Held Dynamometer
Ø Assessment of Knee Pain-
· All patients included, will be subjected to the questionnaire as per Western Ontario McMaster Universities Osteoarthritis Index scoring including Visual Analog scale for categorizing their pain.
· As per the scoring, patients will be sub-grouped into those with Mild pain and disability, Moderate pain and disability, and Severe pain and disability. 5
Ø Radiographic evaluation-
· Radiographic evaluations consist of anteroposterior radiograph of the patient’s knee in the standing position. The Kellgren and Lawrence scale of OA grading will be used.
· The patients will be sub- grouped as per Kellgren-Lawrence grading system into those with Mild osteoarthritis (K/L Grade I), Moderate osteoarthritis (K/L Grade II), Severe osteoarthritis (K/L Grades III and IV). 5
· Radiographs will be reported by an academically based bone and joint radiologist.
Ø Assessment of Quadriceps Muscle Strength-
All the patients will be subjected to isometric quadriceps strength measurement using a modified hand-held dynamometer.
ü The patients will be instructed about the procedure and guided to sit on a fixed chair with their hips and knees flexed to 90o.
ü They will place both hands on their upper legs to avoid compensation.
ü The patients will be instructed to extend the leg against the resistance offered by the dynamometer, leading to the contraction of the quadriceps muscle isometrically.
ü A hand-held dynamometer, modified with straps tied onto the affected leg over the ankle, will be used for the study. This is a measure of the quadriceps muscle strength and the reading from the dynamometer is documented.
ü Each patient will perform 3 trials, with resting time of about 5 minutes between each trial and the maximum reading of strength amongst the 3 trials are taken as the final reading. 13
The subjects will complete assessments for pain and functioning, strength, and radiographic examinations on the same day.
The association between knee pain, quadriceps strength and radiological features (K/L grading) will be determined using Multiple Logistics Regression Analysis. Analysis is done using SPSS Software package.
By determining the quadriceps strength at an early and late stage of osteoarthritis in reference to the levels of pain, this study intends to show the influence of quadriceps strength in the progress of the disease pattern.
Failing to address strength deficits may additionally hold serious complications which include further joint deterioration and continued functional decline. These deficits may persist following surgical intervention and restrict functional recovery. 14
Physical activity programs can lessen pain, enhance overall physical performance, reduce depressive symptoms, and prevent or postpone disability in knee osteoarthritis. 15 Rehabilitation therapists can introduce strengthening interventions at an appropriate stage to circumvent the devastating symptoms of this disease.
A large proportion exists as subthreshold population or borderline diagnoses. Awareness programmes should be initiated at community level for the prevention of or early diagnosis of osteoarthritis upon onset of symptoms. A long-term study will be suitable to achieve these goals.