Kneecap removal

Definition

Kneecap removal, or patellectomy, is the partial or total surgical removal of the patella, commonly called the kneecap.

Purpose

Kneecap removal is performed under three circumstances:

• The kneecap is fractured or shattered.
• The kneecap dislocates easily and repeatedly.
• Degenerative arthritis of the kneecap causes extreme pain.

Demographics

A person of any age can break a kneecap in an accident. When the bone is shattered beyond repair, the kneecap has to be removed. No prosthesis or artificial replacement part is put in its place.

Dislocation of the kneecap is most common in young girls between the ages of 10–14. Initially, the kneecap will pop back into place of its own accord, but pain may continue. If dislocation occurs too often, or the kneecap does not go back into place correctly, the patella may rub the other bones in the knee, causing an arthritis-like condition. Some people are also born with birth defects that cause the kneecap to dislocate frequently.

Degenerative arthritis of the kneecap, also called patellar arthritis or chondromalacia patellae, can cause so much pain that it becomes necessary to remove the kneecap. As techniques of joint replacement have improved, arthritis in the knee is more frequently treated with total knee replacement .

People who have had their kneecap removed for degenerative arthritis and then later require a total knee replacement are more likely to have problems with the stability of their artificial knee than those who only have total knee replacement. This occurs because the realigned muscles and tendons provide less support once the kneecap is removed.

Description

General anesthesia is typically used for kneecap removal surgery, though in some cases a spinal or epidural anesthetic is used. The surgeon makes a linear incision over the front of the kneecap. The damaged kneecap is examined. If a part or the entire kneecap is so severely damaged that it cannot be repaired, it may be partially removed (partial patellectomy) or totally removed (full patellectomy). If kneecap removal is total, the muscles and tendons attached to the kneecap are cut and the kneecap is removed. However, the quadriceps tendon above the kneecap, the patellar tendon below, and the other soft tissues around the kneecap are preserved so that the patient may still be able to extend the knee after surgery. Next, the muscles are sewn together, and the skin is closed with sutures or clips that stay in place for about two weeks.

Diagnosis/Preparation

Prior to surgery, x rays and other diagnostic tests are done on the knee to determine if removing the kneecap is the appropriate treatment. Preoperative blood and urine tests are also done.

Patients are asked not to eat or drink anything after midnight on the night before surgery. On the day of surgery, patients are directed to the hospital or clinic holding area where the final preparations are made. The knee area is usually shaved and the patient is asked to change into a hospital gown and to remove all jewelry, watches, dentures, and glasses.

Aftercare

Pain medication may be prescribed for a few days. The patient will initially need to use a cane or crutches to walk. Physical therapy exercises to strengthen the knee should start as soon as tolerated after surgery. Driving should be avoided for several weeks. Full recovery can take months.

Risks

Risks involved with kneecap removal are similar to those associated with any surgical procedure, mainly allergic reaction to anesthesia, excessive bleeding, and infection.

Kneecap removal is very delicate surgery because the kneecap is part of the extensor mechanism of the leg, meaning the muscles and ligaments, the patella, the quadriceps tendon, and the patellar tendon; which all allow the knee to extend and remain stable when extended. When the kneecap is removed, the extensor assembly becomes more lax, and it may be impossible to ever regain full extension.

Normal results

People who undergo kneecap removal because of a broken bone or repeated dislocations have the best chance for complete recovery. Those who have this operation because of arthritis may have less successful results, and later need a total knee replacement.

Resources

BOOKS

Harner, C. D., K. G. Vince, and F. H. Fu, eds. Techniques in Knee Surgery. Philadelphia: Lippincott, Williams & Wilkins, 2001.

Winter Griffith, H., et al., eds. "Kneecap Removal." In The Complete Guide to Symptoms, Illness and Surgery, 3rd edition. New York: Berkeley Publishing, 1995.

PERIODICALS

Juni, P., et al. "Population Requirement for Primary Knee Replacement Surgery: A Cross-sectional Study." Rheumatology 42 (April 2003): 516–521.

Meijer, O. G., and Van Den Dikkenberg. "Levels of Analysis in Knee Surgery." Knee Surgery Sports Traumatology Arthroscopy 11 (January 2003): 53–54.

Petersen, W., C. Beske, V. Stein, and H. Laprell. "Arthroscopical Removal of a Projectile from the Intra-articular Cavity of the Knee Joint." Archives of Orthopaedic Trauma Surgery 122 (May 2002): 235–236.

ORGANIZATIONS

The American Academy of Orthopaedic Surgeons. 6300 North River Road, Rosemont, IL 60018-4262. (847) 823-7186, (800) 346-AAOS. http://www.aaos.org .

The American Association of Hip and Knee Surgeons (AAHKS). 704 Florence Drive, Park Ridge, IL 60068-2104. (847) 698-1200. http://hhtp://www.aahks.org .

OTHER

"Patellectomy." The Knee Guru Page. <http://www.kneeguru.co.uk/html/step_05_patella/step_05_patelle tomy.html> .

" Patellectomy or Partial Patellectomy." Pro Team Physicians. <http://www.proteamphysicians.com/Patient/Treat/knee/kneefractu e/patellectomy_procedure.asp> .

Tish Davidson, AM
Monique Laberge, PhD

WHO PERFORMS THE PROCEDURE AND WHERE IS IT PERFORMED?

Kneecap removal surgery is usually performed in an outpatient setting and hospital stays, if any, are short, not exceeding more than a day. An orthopedic surgeon performs the surgery. Orthopedics is the medical specialty that focuses on the diagnosis, care, and treatment of patients with disorders of the bones, joints, muscles, ligaments, tendons, nerves, and skin.

QUESTIONS TO ASK THE DOCTOR

• How is the kneecap removed?
• What type of anesthesia will be used?
• How long will it take for the knee to recover from the surgery?
• When will I be able to walk without crutches?
• What are the risks associated with kneecap removal surgery?
• How many kneecap removal procedures do you perform in a year?