Bone and muscle loss is a common problem in the aging population, and it often leads to knee joint pains. Many patients with this problem have to replace their knee joints by undergoing knee replacement surgery. Currently, knee replacement surgery has one of the longest waiting times in public hospitals in Hong Kong, with a total of 32,074 pending cases as of September 30, 2021 and a waiting time of about 4 years.
When knee joints become diseased, many patients often choose to bear the pain until they are unable to perform normal daily activities. Diseased knee joints can affect a person in many ways:
- Decline in quality of life: As daily activities become more difficult, many patients choose to stay in, which significantly impacts their social life.
- Injury to other joints: Patients may attempt to relieve pressure on the diseased joint and inadvertently place added pressure on other joints, causing undue strain and injury.
- Sarcopenia: Lack of activity may lead to a gradual loss of muscle mass. This is especially common for patients over the age of 40, who can lose upwards of 8% of their muscle mass each decade. With less muscle strength, many people choose to become even less active, resulting in a vicious cycle of decline.
Knee replacement surgery is considered a safe and effective procedure. It involves cutting away damaged bone and cartilage and replacing it with an artificial joint composed of metal and plastic, which is affixed to the femur and tibia with bone cement. Following the procedure, most patients experience restored mobility in the knee joint, significant pain relief, and reduced stiffness and deformity.
If other forms of medical treatment have not been able to relieve pain, and it continues to affect a patient’s daily life, knee replacement surgery may be considered. Common conditions that may warrant the need for surgery include:
- Degenerative arthritis: a chronic condition caused by a breakdown of cartilage.
- Rheumatoid arthritis: an autoimmune disorder with an unknown cause.
- Post-traumatic arthritis: occurs following an injury to the joint which causes damage to the cartilage.
- Durable: Studies show that artificial joints can last up to 15 to 20 years.
- Small wound: Minimally invasive surgery reduces the wound size to about 7 to 10 cm, facilitating a faster recovery process.
- Quick recovery: With the help of medical staff, patients are usually able to stand the day after their surgery. Post-surgery pain gradually subsides within three to four days
- Highly precise: Patient specific instrumentation (PSI) is a modern technique in total knee arthroplasty (TKA), aiming to facilitate the implant of the prosthesis with the use of the pre-operative 3D model generated by computed tomography (CT) or magnetic resonance imaging (MRI) scan.
- Routine examination: A blood test, X-ray, and electrocardiogram are required.
- Management of pre-existing conditions: Any pre-existing condition such as heart disease, high blood pressure, diabetes, anemia, or anhelation must be stabilized prior to the surgery.
- Fasting: Patients must fast for at least eight hours before surgery.
- Anesthesia: Either general anesthesia or spinal anesthesia will be used depending on the patient’s condition.
- Intravenous antibiotics: Intravenous antibiotics may be administered to help prevent post-surgical infection.
- Pain medication: Medicine may be prescribed to manage post-surgery pain and symptoms.
- Physical therapy: Rehabilitation exercises will maintain mobility in the joint and encourage blood flow, reducing the risk of developing deep vein thrombosis (blood clot).
- Assistive devices: Walking with the help of an assistive device will allow the thigh muscles to regain strength and prevent overexertion of the knee joint.
With the continued advancement of technology, complications arising from knee replacement surgery are not common, though possible complications may include infection, poor wound healing, blood loss, blood clot, fracture, nerve damage, and loosening of the artificial joint.