No surgical procedure is without risk, but the major risks associated with knee replacement surgery are minimal. It is best to know in advance what risks are possible so you can become familiar with possible remedies and continue your recovery process as smoothly as possible.
The most common surgical risk include urinary tract infection and development of blood clots in the leg (deep vein thrombosis), which occurs in up to 15 percent of patients. Risks related to the knee replacement surgery itself can typically be managed effectively. The most serious postoperative complication is infection of the knee joint, which occurs in less than 1 percent of patients.
Many people who undergo knee replacement surgery are concerned about postoperative pain. Pain management has become very sophisticated, with clinicians administering medications intra-operatively and postoperatively. This multilevel approach provides better pain control and also allows for better use and often lower dosages of medications, which in turn reduces side effects associated with pain relief drugs.
Most patients experience moderate pain following knee replacement surgery. About 90 percent of patients need narcotics for less than six weeks post-surgery, while 50 percent need them for less than four weeks and 20 percent take them for less than two weeks.
Loosening of the knee replacement components is the most common cause of failure in knee replacement surgery. The loosening rate for a total knee replacement is about 1 percent per year, which means after a decade, 10 percent of all patients will need to have a new knee prosthesis.
Instability of the total knee joint occurs in between 1 and 6 percent of all total knee replacements. The degree of instability can range from mild to severe. Left untreated, knee instability can cause the prosthesis to loosen and become damaged. Treatment may include use of a knee brace or an ankle-knee brace, use of walking aids, or surgery to exchange the plastic liner or replacement of the knee prosthesis.
Problems with the knee cap (patella) occur in about 6 to 30 percent of all total knee surgeries. Patients who have patellar problems experience pain in front of their new knee and may also feel clunking and instability. Treatment may include making cuts into the soft tissues around the knee cap to force it back on the right track.
Swelling of the knee joint is not uncommon, especially if patients try to do too much too soon. This type of swelling will disappear with rest. Chronic swelling may be a sign of an infection or excessive wear of the polyethylene knee components. A surgeon can take a sample of the fluid from the swollen area to identify the cause of the swelling. Damaged polyethylene components must be replaced, while an infection can be treated with appropriate medication.
Damage to the peroneal nerve (which crosses the knee joint on the outside of the knee) occurs in 0.3 to 4 percent of all total knee replacement operations. Patients typically feel tingling and numbness in their foot. In most cases, symptoms disappear after proper treatment, which includes removal of anything that may be putting pressure on the nerve (e.g., postoperative dressings), use of a protective brace, and physical therapy.