Unicompartmental knee arthroplasty; Knee replacement - partial; Unicondylar knee replacement; Arthroplasty - unicompartmental knee; UKA; Minimally invasive partial knee replacement
A partial knee replacement is surgery to replace only one part of a damaged knee. It can replace either the inside (medial) part, the outside (lateral) part, or the kneecap part of the knee.
Surgery to replace the whole knee joint is called total knee replacement.
Partial knee replacement surgery removes damaged tissue and bone in the knee joint. It is done when arthritis is present in only part of the knee. The areas are replaced with an artificial implant, called a prosthetic. The rest of your knee is preserved. Partial knee replacements are most often done with smaller incisions, so there is less recovery time.
Before surgery, you will be given medicine that blocks pain (anesthesia). You will have one of two anesthesia types:
The surgeon will make a cut over your knee. This cut is about 3 to 5 inches (7.5 to 13 centimeters) long.
The most common reason to have a partial knee joint replaced is to ease severe arthritis pain.
Your health care provider may suggest knee joint replacement if:
You will need to understand what surgery and recovery will be like.
Partial knee arthroplasty may be a good choice if you have arthritis in only one side or part of the knee and:
However, most people with knee arthritis have a surgery called a total knee arthroplasty (TKA).
Knee replacement is most often done in people age 60 and older. Not all people can have a partial knee replacement. You may not be a good candidate if your condition is too severe. Also, your medical and physical condition may not allow you to have the procedure.
Risks for this surgery include:
Always tell your surgeon which medicines you are taking, including herbs, supplements, and medicines bought without a prescription.
During the 2 weeks before your surgery:
On the day of your surgery:
You may be able to go home the same day or need to stay in the hospital for a day.
You can put your full weight on your knee right away.
After you return home, you should try to do what your surgeon tells you. This includes going to the bathroom or taking walks in the hallways with help. You will also need physical therapy to improve range of motion and strengthen the muscles around the knee.
Most people recover quickly and have much less pain than they did before surgery. People who have a partial knee replacement recover faster than those who have a total knee replacement.
Many people are able to walk without a cane or walker within 3 to 4 weeks after surgery. You will need physical therapy for 3 to 4 months.
Most forms of exercise are OK after surgery, including walking, swimming, tennis, golf, and biking. However, you should avoid high-impact activities such as jogging.
Partial knee replacement can have good results for some people. However, the unreplaced part of the knee can still degenerate and you may need a full knee replacement down the road. Partial inside or outside replacement has good outcomes for up to 10 years after surgery. Partial patella or patellofemoral replacement does not have as good long-term results as the partial inside or outside replacements. You should discuss with your surgeon whether you are a candidate for partial knee replacement and what the success rate is for your condition.
Althaus A, Long WJ, Vigdorchik JM. Robotic unicompartmental knee arthroplasty. In: Scott WN, ed. Insall & Scott Surgery of the Knee. 6th ed. Philadelphia, PA: Elsevier; 2018:chap 163.
Jevsevar DS. Treatment of osteoarthritis of the knee: evidence-based guideline, 2nd edition. J Am Acad Orthop Surg. 2013;21(9):571-576. PMID: 23996988 pubmed.ncbi.nlm.nih.gov/23996988/.
Mihalko WM. Arthroplasty of the knee. In: Azar FM, Beaty JH, eds. Campbell's Operative Orthopaedics. 14th ed. Philadelphia, PA: Elsevier; 2021:chap 7.
Weber KL, Jevsevar DS, McGrory BJ. AAOS Clinical Practice Guideline: surgical management of osteoarthritis of the knee: evidence-based guideline. J Am Acad Orthop Surg. 2016;24(8):e94-6. PMID: 27355287 pubmed.ncbi.nlm.nih.gov/27355287/.BACK TO TOP
Review Date: 8/12/2023
Reviewed By: C. Benjamin Ma, MD, Professor, Chief, Sports Medicine and Shoulder Service, UCSF Department of Orthopaedic Surgery, San Francisco, CA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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