What Are The Risks Of Knee Surgery?

Knee replacements have been highly successful for more than 30 years. According to the US National Institutes of Health, 9 out of 10 patients who undergo the procedure report improved pain relief, knee function, and overall health-related quality of life.¹ And because medicine is always developing new materials and procedures, the results continue to get better. The complication rate following total knee replacement is low. Serious complications, such as knee-joint infection, occur in approximately 2.0% of patients.² Major medical complications, such as heart attack or stroke, occur even less frequently. (Of course, chronic illnesses may increase the potential for complications.)

Every surgical procedure has some risks and benefits. Your individual results will depend on your personal circumstances, and recovery takes time. While there can be no guarantee of success, benefits can include pain relief and return of normal use of the knee.

Each of the following reactions or complications can occur during and after surgery and may require medical attention (such as further surgery) and implant removal:

Blood clots

Blood clots in the leg veins are the most common complication of knee replacement surgery. Your surgeon will outline a prevention program. This may include periodic elevation of your legs, lower-leg exercises to increase circulation, support stockings, and medication to thin your blood.

Infection

Infection is a risk with any surgical procedure. According to the American Academy of Orthopedic Surgeons, approximately 2.0% of patients get an infection in the first two years.² When infection occurs after total knee replacement, it is most commonly caused by bacteria that enter the bloodstream during dental procedures or from urinary tract, skin, or fingernail infections. Although uncommon, when these complications occur, they can delay full recovery.

For the first two years after your knee replacement, you must take preventive antibiotics before dental or surgical procedures that could allow bacteria to enter your bloodstream. After two years, talk to your orthopedist and your dentist to see if you still need preventive antibiotics before other procedures.

Osteolysis

The bone next to the knee implant may break down (called osteolysis) because of your body’s reaction to particles that may be caused by:

• Direct contact of the metal and plastic components
• Contact between the knee components and the bone cement
• Contact between the knee components and your natural bone particles that exist between the knee’s moving parts, which can cause more particles or damage to the implant components

Implant fracture

Implant fracture has been reported following total knee replacement. This is typically caused by:

• Patients with unrealistic performance expectations
• Heavy and/or overweight patients
• Physically active patients

To minimize the possibility for implant fracture, it is important to follow medical instructions and to avoid excessive or inappropriate activity.

Other risks

• Removal and/or replacement of the device system or its components may be necessary at some point in the future
• Although rare, metal-allergy reactions from knee implants have been reported. Inform your doctor if you have any allergy symptoms
• Dislocation can result from improper positioning of the implant components
• Implant components can loosen or move due to improper cementing or shock from falls or collisions
• Cardiovascular disorders associated with the use of bone cement include blood clots; decreased blood pressure; heart attack; and, in rare instances, death

When knee replacement surgery is not appropriate

Given the risks, your doctor may decide that knee replacement surgery is not appropriate if:

• You have an infection or a history of infection
• You don’t have enough bone or the bone is not strong enough to support your new knee
• You have injured nerves in your knee area
• You have injured or nonfunctional knee muscles
• Your knee is severely unstable
• Your bones are not fully grown or developed
• You have noticeable bone loss or a severe decrease in bone mass (osteoporosis)
• Your knee joint has been previously fused and is stable, functional, and painless
• You have rheumatoid arthritis and active/history of skin lesions (because of increased risk of infection)

References

1. Consensus Statement on total knee replacement. NIH Consens State Sci Statements. 2003 Dec 8-10;20(1):1-34
2. Total Knee Replacement [Internet]. American Academy of Orthopaedic Surgeons; 2009 April [cited 2011 Nov 20]. Available from: http://orthoinfo.aaos.org/topic.cfm?topic=a00389