Knee replacement has a finite expected survival that is adversely affected by activity level. Generally, it is indicated in older patients with more modest activities. It is also clearly indicated in younger patients who have limited function because of systemic arthritis with multiple joint involvement. Young patients requesting knee replacement, especially those with posttraumatic arthritis, are not excluded by age but must be significantly disabled and must understand the inherent longevity of joint replacement.
Absolute contraindications to total knee replacement include knee sepsis, a remote source of ongoing infection, extensor mechanism dysfunction, severe vascular disease and the presence of a well-functioning knee arthrodesis. Relative contraindications include medical conditions that preclude safe anesthesia and the demands of surgery and rehabilitation.
Work-up for this operation requires routine blood tests as in any major surgery, specific checkups for chronic diseases, urinalysis, radiographs and treatment of any septic focus. Most patients who undergo TKA are elderly with comorbid diseases. Patients must have good cardiopulmonary function to withstand anesthesia and to withstand a blood loss of 1000-1500 mL over the perioperative period. Patients with ischemic heart disease, congestive heart failure, and chronic obstructive airway disease should be seen by a medical specialist or anesthetist. Patients with significant peripheral vascular disease should be seen by a vascular surgeon.
The aim of total knee replacement is to resurface the deficient and damaged tibiofemoral joint surfaces with metal components and provide a low-friction articulation with a polyethylene bearing. The mechanical alignment and soft tissue balance around the knee should be anatomically restored for optimum function and longevity of the knee replacement.
Selection of regional or general anesthesia is made following preoperative discussion between the anesthetist, the patient and input from the surgical team.
A thigh tourniquet is generally used to aid surgical exposure , although it should be avoided in patients with a history of previous deep vein thrombosis or significant vascular disease. The operation should be performed in a laminar flow operating theatre with meticulous attention to detail to prevent contamination of the operation site.
The knee joint is usually approached anteriorly through a medial parapatellar approach. Osteophytes and intra-articular soft tissues are then cleared. Bone cuts in the distal femur are made perpendicular to the mechanical axis, usually using an intramedullary alignment system, which is then checked against the center of the hip. The proximal tibia is cut perpendicular to the mechanical axis of the tibia using either intramedullary or extramedullary alignment rods. Restoration of mechanical alignment is important to allow optimum load sharing and prevent eccentric loading through the prosthesis. Sufficient bone is removed so that the prosthesis re-creates the level of the joint line. This allows the ligaments around the knee to be balanced accurately and prevents alteration in patella height, which can have a deleterious effect on patellofemoral mechanics.
Patellofemoral tracking is assessed with trial components in situ and balanced if necessary with a lateral release or medial reefing procedure. If the patellofemoral joint is significantly diseased, it can be resurfaced with a polyethylene button. The original width of the patella must be recreated.
Once the definitive components have been selected, they are cemented into place with polymethyl methacrylate cement. If an uncemented system is being used, press-fit and bony ingrowth provides the short-term and long-term fixation of the component. The knee joint is usually drained and dressed in extension.
Post-operative care : The patient is recovered and usually observed for a 24-hour period in a high-dependency ward. Adequate hydration and analgesia are essential in this time of high physical stress. At this early stage, the patient begins knee movement sometimes using a continuous passive motion (CPM) machine and exercises. These are continued under the supervision of a physiotherapist until discharge.
Drains are usually removed within 24 hours, and the patient is encouraged to walk on the second postoperative day. Continual improvement is generally observed, and discharge occurs in 5-7 days. Discharge is only recommended once wound healing is satisfactory, knee flexion of 90 degrees has been achieved, the patient is considered to be safe and supported in the home environment, and no complications are present. Thromboembolism prophylaxis is often continued at home for a period of time. The first outpatient review generally is in 2 weeks for wound review, thereafter at 6 weeks and 3 months.
Follow-up care: Follow-up depends on the surgeon, the patient, and the health care system. A typical example would be a surgical follow-up appointment at 6 weeks, 3 months, 6 months and then every year. This is modified for each patient according to age, degree of activity, and presence of complications. We, at Medwin – Joint Replacement Center strive to provide exceptional & cost-effective medical care that improves the quality of life for patients who suffer from joint diseases and disorders. Here's what you can expect from us.
- Personalized services
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- Diligent Post-operative attention
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- Physiotherapy and Rehabilitation program
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