Knee replacement surgery is a common orthopedic reconstructive procedure primarily used to repair severely damaged or degenerated knee joints. This surgery involves removing diseased bone and cartilage and implanting a prosthetic joint to restore joint mobility and alleviate pain. It is typically indicated for patients who do not respond to conservative treatments such as medication and physical therapy, significantly improving quality of life.
The procedure is divided into total knee replacement and partial replacement, with the surgeon selecting the appropriate option based on the extent of the lesion. Postoperative rehabilitation is necessary to regain muscle strength and joint function. This treatment has become well-established in Taiwan and is one of the standard options for end-stage arthritis.
Total Knee Arthroplasty (TKA) replaces the entire knee joint structure, including the femur, tibia, and patellar cartilage. The prosthetic components are made of titanium alloys and high-molecular-weight polyethylene, designed to mimic the natural joint function. Partial knee replacement involves only replacing the damaged medial or lateral compartment and is suitable for localized lesions.
The mechanism involves removing inflamed tissue and reconstructing joint alignment to reduce direct bone-on-bone friction. The biocompatibility design of the prosthesis prevents rejection, and surface coating technologies promote osseointegration. Modern techniques allow for customized implants based on patient anatomy, enhancing long-term stability.
Primarily indicated for diseases causing severe joint destruction, such as osteoarthritis and rheumatoid arthritis. When X-rays show disappearance of joint space, osteophyte formation, and pain unresponsive to medication, the patient qualifies for surgery. Common indications also include meniscal tears with degenerative changes due to sports injuries or joint deformities caused by severe trauma.
Typically recommended for patients aged 50 and above, but young patients with significant joint destruction due to trauma or congenital abnormalities may also be considered. Surgeons evaluate overall health, including cardiopulmonary function and control of metabolic diseases, before deciding on surgical eligibility.
The surgery is usually performed under general or spinal anesthesia, lasting approximately 1.5 to 3 hours. A surgical incision is made in front of the knee, diseased bone and cartilage are removed, and metal components are fixed to the femur and tibia. A polyethylene insert is then placed as a cushion. The wound is closed with sutures and dressed.
There is no concept of "dosage," but the choice of prosthesis must be adjusted according to patient weight, activity level, and anatomy. For example, overweight patients require high-strength materials, and active patients need prostheses designed for a broader range of motion. Rehabilitation begins the day after surgery, with hospitalization lasting about 3-7 days. The entire process includes preoperative assessment, surgery, and rehabilitation.
Compared to conservative treatments, surgery significantly improves functional indices such as stair climbing and squatting ability. Modern minimally invasive techniques shorten recovery time, with some patients able to resume light activities within 2-3 weeks. Long-term follow-up shows a 70% reduction in emergency visits related to arthritis.
Main risks include:
Short-term complications may include swelling, transient numbness, or joint stiffness. Rare cases may involve anesthesia complications or nerve injury. Strict adherence to postoperative rehabilitation is essential; otherwise, muscle atrophy or joint locking may occur.
Preoperative assessment of cardiopulmonary function is necessary. Patients with diabetes or coagulation disorders should have their treatment plans adjusted. Contraindications include:
Postoperative restrictions include avoiding high-impact activities (such as marathon running) and regular X-ray follow-ups. Patients should stop anticoagulants 6 weeks before surgery and control blood glucose to HbA1c<8%. Within 24 hours post-surgery, turning every 2 hours is recommended to prevent pressure ulcers.
Pre- and post-surgery, pain medications (such as COX-2 inhibitors) are used in conjunction, but anticoagulants should be avoided simultaneously. Physical therapy can start within 48 hours after surgery, but electrotherapy or heat application should be under medical supervision. If the patient is undergoing osteogenesis treatments (e.g., bisphosphonates), medication timing should be adjusted to avoid hindering osseointegration.
Regarding interactions with other surgeries, patients who recently had spinal surgery should have anesthesia plans adjusted accordingly. Acupuncture and other alternative therapies have no direct interactions but should not replace prescribed rehabilitation programs.
Randomized controlled trials show that 95% of patients experience a reduction of over 60% in pain scores (VAS) within one year post-surgery. The American Academy of Orthopaedic Surgeons reports that 85% of patients maintain good function after 10 years. Advances in prosthetic design have reduced the incidence of patellar maltracking from 15% to below 5%.
Analysis of Taiwan's National Health Insurance database indicates that 78% of patients regain stair-climbing ability within three months post-surgery, and the 10-year survival rate in patients over 65 is comparable to those who did not undergo surgery. Biomechanical studies confirm that modern prostheses have friction coefficients similar to natural joints under load.
Conservative treatments include:
Biologic agents for rheumatoid arthritis can delay the need for surgery. In Taiwan, some insurance plans cover bone marrow concentrate therapy as a central treatment. However, these methods are only suitable for patients with joint damage below grade 4 (Kellgren-Lawrence classification).
Pain management involves a combination of medication and non-pharmacological methods. Doctors typically prescribe analgesics and recommend ice packs to reduce swelling, while physical therapists guide gentle exercises to promote circulation. Patients should follow medical advice when using medications and use assistive devices during activities to reduce joint load, avoiding overexertion that may cause discomfort.
What physical assessments are necessary before surgery? Which health issues might affect surgical planning?Preoperative assessments include anesthesia evaluation, cardiopulmonary function tests, and blood tests to check for coagulation abnormalities or infections. Chronic conditions such as diabetes, cardiovascular disease, or severe obesity may increase risks and should be stabilized before scheduling surgery in consultation with the physician.
What is the average lifespan of a prosthetic joint? Is replacement needed periodically?Modern prosthetic joints typically last about 15 to 20 years, depending on patient weight, activity level, and postoperative care. If the prosthesis wears out causing pain or discomfort, revision surgery may be necessary. Regular X-ray follow-ups can detect abnormalities early, but proactive replacement is not usually required before the prosthesis reaches its end of life.
When should rehabilitation exercises start after surgery? What movements should be avoided?Light rehabilitation exercises, such as knee flexion and extension, and muscle strengthening, usually begin within 24 to 48 hours post-surgery to prevent joint stiffness. Deep squats, prolonged standing, and high-impact activities (like running) should be avoided for at least six months, with gradual resumption after medical evaluation.
Is surgery contraindicated for patients over 70 years old? What special precautions should be taken postoperatively?Age alone is not an absolute contraindication; overall health status is the key factor. Elderly patients should have their cardiopulmonary function and bone density evaluated. With manageable surgical risks, they can proceed with surgery. Postoperative precautions include fall prevention measures, such as non-slip equipment, and assistance from family members to prevent injuries due to balance issues.
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