Knee Surgery

Causes and symptoms

Rheumatism, uneven loading, injury, fracture, age, overweight, and prolonged intensive activity can all increase wear.

• Pain and swelling, especially with weight bearing.
• Stiffness and reduced range of motion.
• Limited walking distance.
• In advanced stages: nocturnal pain and pain while resting.

When is knee replacement necessary?

When pain cannot be controlled and mobility is severely restricted, a partial or total knee prosthesis may be indicated.

• Partial knee replacement addresses wear in one compartment or patellofemoral region.
• Total replacement addresses the full knee joint.

Prosthesis materials and fixation

• A partial knee prosthesis may use oxinium (oxidized zirconium).
• A total knee prosthesis may use titanium with cobalt/chromium on articulating surfaces.
• Lower-leg component typically combines titanium with wear-resistant polyethylene.
• Fixation can be cemented, non-cemented, or a hybrid version, depending on bone quality.

Lifespan

The average knee prosthesis lifespan is 15 to 20 years. This is influenced by age at implantation, activity level, weight, implant type, surgical technique, and adherence to rehabilitation.

Knee prosthesis - the surgery

• Pre-op screening includes blood tests, chest X-ray, ECG, and a consultation with the anesthesiologist.
• Spinal anesthesia with sedation is common; general anesthesia when indicated.
• The damaged cartilage and bone are removed, the implant is positioned with proper alignment and stability checks.
• Local infiltration analgesia supports early recovery; surgery usually takes a little over an hour.

Recovery and rehabilitation

• Early mobilisation starts the day after surgery.
• Discharge follows once independent bed transfer and crutch walking are achieved.
• A blood thinner is often used for up to 30 days to prevent thrombosis.
• Stitches are removed around two weeks with progressive physiotherapy thereafter.
• Driving is often possible after 3 to 4 weeks.
• Outpatient X-ray review around six weeks.
• Full rehabilitation takes several months, with most gains in first three months.

Risks

Complications are uncommon, but individual risk depends on age, weight, comorbidities, previous surgeries, and adherence to prophylaxis and rehabilitation.

• Infection.
• Post-operative bleeding.
• Thrombosis and pulmonary embolism.
• Numbness around scar.
• Loosening of prosthesis.
• Stiffness.

Why revision may be needed

Patients who undergo primary knee replacement at younger ages are more likely to require a second operation over time.

• Component wear.
• Infection.
• Instability.
• Fracture around prosthesis.
• Stiffness.

Symptoms of failure

Symptoms of failure of the primary knee prosthesis can be

• Pain.
• Loss of function.
• Instability and limping.
• Swelling.
• Stiffness.

How a non-functioning prosthesis is treated

In most cases, treatment is a total knee revision, where malfunctioning components are replaced. Revision surgery is complex, takes longer than primary surgery, and requires careful planning, special implants, and experienced surgeons.

Diagnostic work-up

Extensive investigations are done to identify the cause of failure and plan surgery: X-rays, targeted procedures such as aspiration if infection is suspected; and, in selected cases, bone scan, CT, or MRI.

Revision strategies

• Single-component revision in selected cases.
• Full-component revision in most cases.
• Two-stage revision in case of infection when indicated, with spacer and IV antibiotics before reimplantation.

Treatment approach

Treatment depends on the cause, including infection, aseptic loosening, wear, dislocation, peri-prosthetic fracture, or mechanical problems.

Revision surgery is custom work and should be performed in experienced centres with specialized orthopedic teams, microbiology support, intensive care capacity, and multidisciplinary rehabilitation.