Why ‘new’ knee isn’t the final answer

Patients with painful, deformed, and unstable knees secondary to degenerative or inflammatory conditions need a prosthesis that provides reproducible pain relief and improvement in function.

Approximately 130,000 knee replacements are performed every year in the United States .

Osteoarthritis the knee is the most common reason for total knee replacement. This is a disease of synovial joints, characterized by degenerative and reparative processes. Osteoarthritis may be primary or secondary. Mechanical derangements (previous meniscal or cruciate ligament damage), pyogenic infection, ligamentous instability, fracture into a joint are among the common causes of the secondary type. Other causes of cartilage destruction include rheumatoid arthritis, hemophilia, seronegative arthritides, crystal deposition diseases, pigmented villonodular synovitis, idiopathic or steroid-induced avascular necrosis, and rare bone dysplasias.

Recent studies into risk factors for severe osteoarthritis of the hip and knee have revealed that siblings of individuals undergoing joint replacement are 3-5 times more likely to require similar surgery than age-matched controls. This means that genes contribute around 30% of the overall risk for severe osteoarthritis. Laboratory-based studies have shown that chromosome 11 is linked to severe osteoarthritis of the hip and chromosome 2 to severe osteoarthritis of the knee. The precise genes involved are as yet unknown. The exact cause of the degenerative process in primary osteoarthritis is unknown. It may represent a defect in cellular (chondrocyte) repair processes. Osteoarthritic cartilage contains increased amounts of water; alterations in the type of proteoglycan; type II collagen abnormalities; and increased levels of cathepsins, metalloproteinase, interleukin-1, and others as a complex cascade of enzymatic process. Changes in the synovium include synoviocyte hyperplasia, an increased leukocyte population in the membrane and fluid, occasional giant cells, neovascularization with increased vessel permeability, and altered matrix and cellular cytokine formation.

Clinical history in a patient with arthritis of the knee is dominated by pain. This predominantly occurs on weightbearing but in the end stages may be constant and unrelieved by rest. Night pain is a particularly disabling symptom. Pain may be localized or diffuse. Other symptoms include stiffness, swelling, locking, and giving way. Some patients may have considerable interference with social interaction, ADL, sexual function, and sleep and may experience exhaustion and even depression from their disease. Deformity can sometimes become the principal indication for knee replacement in patients with moderate arthritis.

Various structured outcome evaluations can be used to try to quantify this disability and dysfunction. Establish the integrity of the ligaments because deficiency may require use of a special prosthesis with intrinsic stability. Seek and systematically exclude other sources of knee and leg pain.

Xray findings must correlate with a clear clinical impression of knee arthritis. Knee roentgenography should include a standing anteroposterior (AP) view, a lateral view, a 45-degree posteroanterior (PA) view of the knee ( Rosenberg view), and a skyline view of the patella. Loss of joint space, cysts, subchondral sclerosis, and osteophytes confirm the diagnosis of osteoarthritis

Examination should include assessment of scars around the knee, vascular status to the limb and consultation with plastic surgeon.

The best predictor of range of motion following total knee replacement is the preoperative range of motion. This is an important factor when obtaining consent from the patient for surgery

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.

COMPLICATIONS of surgery:

Early complications include dislocation, improper placement, and cement extrusion, DVT, fractures. 

Late complications include implant failure, osseous fracture, heterotopic ossification, loosening, infection, and aggressive granulomatosis (or particle disease), implant failure, heterotopic ossification, loosening of a prosthesis and multiple surgeries with long term bracing.

Absolute contraindications to total hip replacement include sepsis, a remote source of ongoing infection, muscular dysfunction and severe vascular disease. 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 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
• Comprehensive diagnosis
• Effective treatment and surgery
• Diligent Post-operative attention
• Pain Management
• Physiotherapy and Rehabilitation program
• All these at very affordable prices