Knee replacement is a surgical procedure in which the weight-bearing surfaces, which are also known as the articulating surfaces, are being replaced in order to relieve pain and discomfort at the knee joint.
Knee replacement procedures are usually done for patients with severe osteoarthritis or a severe knee injury.
People who undergo knee replacement are eager to get back to how they were before. However, to recover fast from knee replacement, some exercises need to be done. Recovery is usually based on how old the person is and how quickly physiotherapy sessions start after the surgery.
In order to fully understand the knee replacement procedure, we have to understand how the knee works and how these structures play a major role in recovery.
How Does The Knee Work?
The knee is made up of 4 bones:
The femur or thighbone
- The tibia or shin
- The fibula or calf bone
- The patella or kneecap
Ligaments join the bones to each other and tendons join the muscle to the bone.
For the knee to move effectively, the end of femur glides over the top of the tibia with the patella preventing them from over-pushing themselves out of the joint.
Muscles, which attach to the fibula, join the bones to bend and straighten the knee joint. The muscle that bends the knee is called the Hamstrings and they are found at the back of the thigh while the muscle that straightens the knee is found in front of the thigh and is called the Quadriceps.
There is a Synovial Membrane found at the knee that produces a fluid called the synovial fluid to lubricate the knee joint for easy movement of the femur on the tibia.
In between the bones, we have the Cartilage. It is a soft and firm connective tissue that is designed to bear and distribute weight. It covers the articulating surfaces of the bones at a joint and also allows for easy movement of the bones on top of each other.
Indications For Knee Replacement
Knee replacement is usually a last resort. It is done if medications and physiotherapy do not seem to ease off the pain and if the movement becomes more difficult. Here are some conditions that may lead to a knee replacement surgery:
This is a degenerative disease that involves the wearing off of the cartilage on the articulating surfaces of the bones that form the joint. It usually causes pain, swelling and reduced movement at the affected joint.
This is an auto-immune disorder that affects the lining of the joints which causes a painful swelling and then wearing off the cartilage.
Severe Knee Injury
Sometimes, serious injuries to the ligaments and tendons surrounding the knee can put a lot of pressure on the bones.
What Happens In Knee Replacement Surgery?
Knee prosthesis will be gotten for the surgery. The prosthesis has three components:
The top of the tibia bone
The end of the femur
The bottom of the patella that rubs against the femur
- The surgery is done under general anesthesia. An incision is made on the top of the knee to expose the damaged joint.
- The kneecap is moved aside to properly view the damaged femur and tibia bone.
- The surgeon makes precise cuts on the bone starting with the femur and then inserts the implant, which can either be metal or plastic.
- After the femur is done, the same procedure is carried out on the tibia. These implants are secured to the bones with the use of surgical cement.
- Once the tibia implant is secured, the surgeon will insert a medical grade plastic between the tibia and femur. This insert acts as a pseudo cartilage to support the body weight and reduce the shock received by the knee joint.
- After this, the patella will need to be refitted to fit the implant. Usually, a plastic component is cemented to the bottom of the kneecap to allow for easy movement of the kneecap on the femur.
- Before stitching up the skin. The surgeon will move the knee joint to ensure that it moves freely and the positioning is almost like a normal biological knee.
- Patients usually leave the theatre with their knee being moved continuously either by a medical personnel or a machine designed to do so.
- The surgery usually takes about 2 hours to complete.
Are There Any Factors That Influence The Recovery Time Of Knee Replacement?
Yes. There are factors that may affect the recovery time after knee replacement. these factors are:
1. How Soon Physiotherapy Starts
The earlier physiotherapy starts, the better the recovery time. Physiotherapy should start at least 24 hours after the surgery is performed. We will discuss later the role of physiotherapy in the recovery from knee replacement.
2. How Quickly The Patient Can Progress Through The Exercises
Exercises progress as the patient improves. No two patients are the same. Patient A may do isometric exercises for 1 week and progress to strengthening exercises using weights while Patient B may do isometric exercises for 2 weeks and progress to using weights.
It is usually stated that younger people recover faster than older people. younger people tend to be more eager to become independent while older people may take a while to go through the exercises to independence.
4. The Condition Of The Unaffected Leg
If the unaffected leg has some elements of arthritis, it can affect recovery as the unaffected leg may not be strong enough to carry the body weight alone. this can affect recovery time as exercises will need to be done on both legs to ensure that there will be even weight shared between the two legs.
How Do You Recover From Knee Replacement
After the surgery is done, surgeons usually suggest physiotherapy immediately to get the patient moving. starting physiotherapy immediately after the surgery or at least 24 hours after surgery helps to speed up the recovery process.
Physiotherapy management is very vital to recovering from knee replacement surgery because it helps to:
- Relieve Pain
- Reduce swelling
- Prevent joint stiffness at the knee
- Prevent muscle weakness
These are what physiotherapists do to help you move about properly with your new knee joint and also achieve the goals listed above:
In order to avoid any complication that may arise from bearing weight on the affected knee, physiotherapists usually advise the use of a walking aid such as crutches or a walking frame during the first few days of rehabilitation. As you gain confidence in walking with the walking aid, you will be gradually weaned off the walking aids.
Usually, patients do not spend so much time using walking aids. Like I mentioned earlier, it depends on how old the patient is and how quickly the patient is gotten out of bed. patients tend to go off walking aids after 3 weeks
This is also known as ice therapy. Ice is used to relieve pain and reduce any form of associated swelling on the operated knee. Ice reduces the flow of blood and any other fluid that causes swelling and also, in the same way, relieves pain by providing a form of numbness at the knee due to differences in temperature between the body and the ice.
The physiotherapist will encourage you not to always stay in bed but sit out of bed which will encourage knee flexion and helps to strengthen your back in order to avoid complications.
4. Strengthening exercises
While using walking aids, the muscles of the legs need to be strengthened. These exercises may not necessarily cause the knee to move fully but strengthen the muscles needed for bending and straightening the knee. Some of these exercises include:
Static Quadriceps Exercises
This is an isometric exercise to strengthen the quadriceps that is responsible for straightening the knee joint. This is how it is done:
- With your leg stretched out sitting up in bed, place a rolled up towel or a soft pillow under the knee or behind the knee.
- Use your knee joint to press the towel or pillow to the bed or
- Try and pull the towel or pillow from under your knee while still pressing it down with your knee
- Your quadriceps will contract against that resistance. This strengthens the quadriceps muscle.
Ankle Pump Exercises
This exercise helps reduce swelling in the ankle and also the knee joint. Because you aren’t moving your operated knee as you normally do, there is a tendency for the leg to swell up. This is because the muscles in our legs play an active role in pumping blood from the legs towards the heart against gravity.
Here is how to do it:
- Continuously move your ankle joint as if you are stepping on the accelerator in a car and taking your foot off the pedal.
- This pumping effect helps to pump blood against gravity towards the heart.
Isometric Buttock Contraction Exercises
This exercise strengthens the hip muscles and allows mobility from one point of the bed to the other.
It is a very simple exercise.
Stand or sit and squeeze your buttocks together. Hold for 10 seconds and repeat 10 times.
5. Mobilization Exercises
Mobilization exercises are basically exercises that strengthen the muscles and also encourage movement at the knee joint. The hip joint also has to be mobilized because it shares the weight distribution with the knee and needs to be strong as well and get used to the knee joint. These exercises may be painful and difficult at first. This is because you are not used to the new knee joint. Some of these exercises include:
Lying on your back, gradually bend your knee as far as you can and straighten. Repeat this 10 times. This will gradually increase the range of motion at the knee joint and also strengthen the muscles responsible for this action.
This exercise strengthens the muscles at the hip, back, and legs.
- Lie on your back and bend your two knees
- Lift your hips off the bed as if you want the top of your hips to touch the ceiling.
- Hold for 3 seconds and come back to the bed
- Repeat this 10 times
Straight Leg Raises
This is a hip mobilization exercise
- Lie on your back and lift your leg up with bending your knee
- Repeat this 10 times
This strengthens the hip muscles and quadriceps and also mobilizes the hip joint.
Hip Abduction And Adduction Exercises
This exercise can either be done in lying or standing
- Lie on the unaffected side and let the affected leg rest on it
- Lift the affected off the other leg towards the ceiling
- Return the leg to the starting point
- Repeat 10 times
- Stand against the wall or hold on to something with your feet slightly apart
- Take the unaffected leg away from the starting point
- Hold for 3 seconds
- Return the leg to the starting point
- Repeat 10 times
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