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The isometric exercises for the Osteoarthritis of Knee

The isometric exercises for the Osteoarthritis of Knee have been designed to strengthen the thigh muscles without much movement around the knee joint. Strength of the quadriceps muscles affect the knee joint functions. It is evident that lower extremity strength has a major role in knee joint shock attenuation during weight bearing activities. There is increased risk of development or progression of osteoarthritis due to greater or uncontrolled loading on the knee joint. Reduction of pain and disability is the main aim of treatment approach in the management of knee osteoarthritis. 

Relevant anatomy
The quadriceps femoris (four-headed femoral muscle) forms the main bulk of the anterior thigh muscles, and collectively constitutes the largest and one of the most powerful muscles in the body. It covers almost all the anterior aspect and sides of the femur. 
The quadriceps consist of four parts:
(1) rectus femoris, 
(2) vastus lateralis, 
(3) vastus intermedius, and
(4) vastus medialis. 
Because of the drastically different orientation of the upper and lower fibers of the vastus medialis muscle, the upper fibers are commonly referred to as the vastus medialis longus (VML), and the lower fibers are referred to as the vastus medialis oblique (VMO).

The tendons of the four parts of the quadriceps unite in the distal portion of the thigh to form a single, strong, broad quadriceps tendon. The patellar ligament (ligamentum patellae), attached to the tibial tuberosity, is the continuation of the quadriceps tendon in which the patella is embedded. The patella is thus the largest sesamoid bone in the body.

Collectively, the quadriceps are a two-joint muscle capable of producing action at both the hip and knee. The quadriceps are the great extensor of the leg. Concentric contraction of the quadriceps to extend the knee against gravity is important during rising from sitting or squatting, climbing and walking up stairs, and for acceleration and projection (running and jumping) when it is lifting or moving the body’s weight. 
The quadriceps may be three times stronger than its antagonistic muscle group i.e. the hamstrings.In level walking, the quadriceps muscles become active during the termination of the swing phase, preparing the knee to accept weight. The quadriceps  are primarily responsible for absorbing the jarring shock of heel strike, and its activity continues as the weight is assumed during the early stance phase (loading response). It also functions as a fixator during bent-knee sports, such as skiing and tennis, and contracts eccentrically during downhill walking and descending stairs.

Quadriceps anatomy
Quadriceps anatomy

There are three types of basic therapeutic exercise: isotonic, isokinetic, and isometric exercise. Of these three, isometric exercise might be the most appropriate and easy to understand by the patients and can be easily and safely performed at home because it requires no or minimal apparatus. Isometric exercise is an active exercise performed against stable resistance, without change in the length of the muscle. Further, isometric exercise causes the least intra-articular inflammation, pressure, and bone destruction.

Knee isometrics sitting towel press
Knee isometrics sitting towel press

Knee isometrics sitting towel press

Sit with leg extended, knee supported with towel roll.

Tighten quad muscles on front of leg, trying to push back of knee downward.

Hold the contraction for 10 seconds Repeat the exercise for 10 times

Terminal knee extension
Terminal knee extension

Terminal knee extension

With the right knee over a bolster straighten the knee by tightening muscles on top of the thigh

Maintain the contraction for 10 seconds.

Repeat the exercise for 10 times

Note: If tolerated and the motion is not painful you can apply mild resistance at the ankle by way of weight cuffs. Strengthening in terminal extension trains the muscle to function where it is least efficient (because of its shortened position and where there is minimal patellar compression because it is superior to the femoral groove). End-range knee extension is needed when lifting the leg into bed and moving the covers, as well as when lifting the leg into a car.

Isometric knee exercise with ankle dorsiflexion
Isometric knee exercise with ankle dorsiflexion

Isometric knee exercise with ankle dorsiflexion

Begin in half sitting position full the toes and tense the muscles on the front of the thigh also squeeze your buttocks.

Maintain the leg and buttock flat on the floor

Hold the contraction for 10 seconds Repeat the exercise for 10 times

Straight leg raise supine
Straight leg raise supine

Straight leg raise supine

With the right leg straight, other leg bent, raise your legs 15 to 20 inches

Hold the position for 10 seconds

Repeat exercise for 10 times

Resisted knee extension in sitting
Resisted knee extension in sitting

Resisted knee extension in sitting

Start with sitting on a high chair with a band looped around your right ankle hold the other end of the loop under the other foot straighten the leg with the ankle loop

Keep the other leg bent to increase the resistance

Hold the position for 10 seconds

Repeat exercise for 10 times