What is Knee Replacement Surgery?
What is knee replacement surgery?
Knee replacement surgery is removal of the diseased articular surface and resurfacing the knee with artificial components comprised of metal and polyethylene. The surgery is performed on an osteoarthritic knee whose articular surface, made up of cartilage, degenerates resulting in pain and decreased function.
How do I know I need Knee replacement surgery?
Knee replacement surgery is performed when you have pain and functional limitations due to knee osteoarthritis and all alternative treatment option such as weight reduction, physical therapy, analgesics, and injections has failed to relieve the pain. Patients may complain of nighttime pain or pain that limits their ability to walk, climb stairs, or perform high impact activities. If you have these symptoms, you may be a candidate for knee replacement surgery.
The ideal candidate for a partial knee replacement surgery rather than a total knee replacement are patients with osteoarthritis affecting only one compartment, with a bodyweight of less than 82kg, patients who have intact cruciate ligaments, and have well preserved motion of the knee. 
Why is there knee pain in knee arthritis?
Normally a knee joint has cartilage covering on the ends of the femur and tibia bone. The cartilage helps the bones to smoothly glide when bending the knee. Whenever the knee is damaged by osteoarthritis, rheumatoid arthritis, or post-traumatic arthritis the knee suffers from cartilage loss of the joint space. The cartilage which provides pain-free motion is lost and the bones, instead of cartilage, start to glide upon each other. This results in pain and limitation of motion.
How is partial knee replacement different from a total knee replacement?
The knee joint has a medial (inner) and lateral (outer) joint surface, also known as compartment. Commonly, the medial joint surface has to bear more load than the lateral joint so the medial joint suffers from arthritis more frequently. In the past, both the medial and lateral knee joint surface would be replaced during knee replacement surgery. Surgical techniques have become more advanced allowing for replacement of only the affected joint surface. Most commonly, the medial joint surface is replaced. Partial knee replacement surgery has been considered as an alternative surgery to total knee replacement surgery for the appropriate patient population. 
Replacing only the affected joint surface maintains the biomechanics of the knee joint. Partial knee joint replacement preserves the cruciate ligaments. These ligaments serve to provide stability while performing physical activities.
What can I expect after knee replacement surgery?
Any joint replacement surgery is performed with the goal to have a pain-free joint with near-normal movement and range of motion. You will be encouraged to weight bear as tolerated with an assistive device the day of surgery. Getting the knee back to full strength and movement requires physical therapy soon after the procedure. Physical therapy includes range of motion exercises and strengthening of knee stabilizers including quadriceps and hamstring muscles.
At 6-8 weeks postoperatively the patient may progress activities as tolerated with no restrictions. Sports involving running/jogging are limited in order to decrease the wear-and-tear of the implant inside the knee joint. Other recreational activities which you enjoy can be performed following knee replacement surgery. 
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