What is Arthritis?
Arthritis is the term used for inflammation of joints. It is the leading cause of knee pain and disability. The severity of the disease can be from mild to debilitating. It can cause a person to be crippled from performing routine daily activities like walking, standing, running, driving etc.
How it is Usually Treated?
The medical treatment for arthritis includes the following:
- Painkillers such as oral NSAIDS, opioids
- Local application of NSAIDS, intra-articular steroid injections, anesthetic gels and balms etc
- Physiotherapy, exercise and reduction of weight
- DMARDS such as methotrexate, cyclosporine, sulfalazine, azathioprine
- TNF alpha inhibitors such as rituximab, adalimumab etc
Knee Replacement Surgery
The large number of cases responding to one or more form of treatment modalities mentioned above. In some cases, however, due to the continued progression of disease, its increasing severity, lack of response to medical therapy or its harmful interaction with an existing medical condition, it has to be abandoned. The only resort in these cases is surgical replacement of knee. This has proven to be an extremely effective treatment that is being successfully performed since the late 1960’s. According to an estimate, more than 600,000 replacements of knee are performed in the U.S every year. Recent advancements in the medical arena have provided excellent techniques and materials to be used in this procedure.
What are The Main Causes Of Knee Replacement Surgery?
There are three leading causes of knee arthritis, joint deformity and its surgical correction:
This is the most common cause of knee replacement, and occurs due to a gradual wear and tear of the joints with increasing age. The cartilage in the joints gets worn out and reduced in amount and eventually leads to bones grinding against each other. This leads to stiffness, limited movement, joint pain and swelling. It doesn’t come as any surprise that the knee joint is the most commonly affected joint in this disease. This joint bears the weight of the entire body while walking and standing and is under constant stress. Osteoarthritis is mostly seen in older people after the fourth or fifth decade.
2. Rheumatoid Arthritis:
This is an autoimmune condition in which the body’s immune system attacks its own cells. It leads to destruction of joint cartilage and membranes. Symptoms include morning stiffness, redness, swelling, pain, deformity, fever, fatigue and weight loss. It affects other organs of the body such as the lungs, skin, and eyes. It is more common in women, in third to fourth decades of life and presents symmetrically in the joints.
3. Post-Traumatic Arthritis:
This is usually seen individuals leading an extremely active life such as athletes. These people are prone to injuries of the musculoskeletal system. The knee joint is commonly involved in such injuries. If severe enough, injury to knee joint can lead to permanent disability.
Structure of The Knee Joint
In order to have a better understanding of knee replacement therapy, it is essential to have a mild grasp of the structures that make up this joint. It is the most complicated joint in the body and comes under the classification of synovial joint. The articulating (joining) surfaces are made up of the lower end of the femur (thigh bone), upper end of the tibia (leg bone) and the circular patella. The femur and tibia have hyaline cartilage on their articulating surfaces to provide a frictionless moving surface. Surrounding the joint is a capsule, forming a cavity which is filled with a special kind of fluid known as the synovial fluid. This provides nourishment to the joint structures and act as a shock absorber. The joint capsule is strengthened by four major ligaments, the Anterior Cruciate Ligament, Posterior Cruciate Ligament, Medial Collateral Ligament and Lateral Collateral Ligament. The bones involved in the joint further provide attachment sites to muscle tendons which cause movements of the joint.
What is The Mechanism of Knee Replacement?
This procedure is medically termed as arthroplasty. The target is to get rid of the worn out and structures and restore form and function. It comprises of the following steps:
- The damaged pieces of cartilage are stripped away along with a little amount of bone
- Metal implants are inserted on the articulating surfaces to restore the joint surfaces. These can be press fit or cemented to the bone
- The undersurface of the patella (knee cap) is resurfaced and fixed to a plastic button. This step is optional
- A plastic spacer is then inserted between the metal implants to provide a frictionless gliding surface
The procedure is known to be quite effective and beneficial. However, it bears a large number of post-op complications. Some of them worth mentioning are:
- Wound Infection – This can occur immediately or delayed.
- Deep Venous Thrombosis and Pulmonary Embolism – This can be life threatening.
- Neurovascular Injury.