Arthroscopy involves a surgeon making a small incision in your knee and irrigating and removing loose pieces of cartilage. In the arthritic knee, there is a very limited role for an arthroscopy. Results of a “clean out” or a “wash out” are unpredictable at best and should be avoided.
This procedure involves cutting the bone and reorienting the alignment of the knee. It has traditionally been reserved for younger patients with mal-aligned knees who participate in high-demand activities such as sports. Osteotomy has fallen out of favor due to inferior results compared to knee replacements. There are some newer technologies that may improve outcomes, but currently osteotomy has a limited role in the treatment of osteoarthritis of the knee.
Partial Knee Replacement
A surgeon performing a partial knee replacement, also known as “unicompartmental” knee replacement, replaces only the part of the knee that is worn out. This can be either the knee cap-femur joint (patello-femoral) or more commonly – the femur-shin joint (femoral-tibial). These procedures are appealing because they are generally less invasive, more normal tissue is retained, and recovery is easier.
The ideal candidate for these procedures is an evolving topic. Issues of location and amount of disease as well as the amount of deformity present are important considerations. Newer technologies such as computers, robots and custom guides have been introduced to this concept in attempts to improve outcomes. The influence of these technologies has yet to be determined. Outcomes of partial knee replacements can be comparable to total knee replacements ten years after surgery.
Full vs. Partial Knee Replacement: What’s the difference?
While it may seem appealing to have half of a surgery compared to a full surgery, it is important to understand the differences between a unicompartmental (partial) and a total knee replacement surgery. Each type of knee replacement surgery is unique and has its own outcomes after surgery.
The knee is composed of three compartments: the inside (medial), outside (lateral) and underneath the knee cap (patellofemoral/anterior). Each of these compartments can be replaced individually in partial knee replacement surgery, or all three can be replaced in total knee replacement surgery*. A partial knee replacement is technically one-third of the surgery of a total knee replacement. If you have a partial knee replacement, you will find improvement in the function of your knee, but there are some long-term factors to consider.
Partial Knee Replacement
In the past, partial knee replacement was for patients over 60 years old whose ligaments were in good shape, had little knee deformity and could move their knee pretty well.1 Today, the procedure is being done on younger patients who have pain and other symptoms in one part of the knee.
Because a partial knee replacement is less surgery, it has often been reported to have an easier, quicker, more complete recovery and greater satisfaction than a full knee replacement.2 Complications during surgery like blood loss, transfusion and blood clots tend to be less with a partial replacement;3 however, long-term studies show the lifespan of partial knee replacement components is not as long as the lifespan of components used in a total knee replacement.4,5
Because partial knee replacement retains most of your knee tissue, you are still susceptible to meniscal tears and progression of arthritis in the rest of the knee. When a partial knee replacement fails, it can be converted to a full knee replacement with an excellent degree of success. The surgery and recovery may be more involved, but the overall outcomes are highly successful.6
Total Knee Replacement
This procedure has been revolutionary to orthopaedics giving many patients the ability to return to function and enjoy their lives with implants lasting about 10-15-years. While the surgery is longer, there is a higher rate of complications and greater cost, the lifetime of the implants is much greater than in partial knee replacements. Physical therapy is tougher early on, and the knee ultimately doesn’t quite feel the same as your own knee. Despite these potential limitations, patients who are good candidates for total knee replacement have greater patient satisfaction, higher functional scores and longer-lasting replacements. In the United States, over 90% of knee replacement surgeries are total knee replacements; while 10% or less are partial knee replacements.
Total Knee Replacement (TKR) is the gold standard when conservative treatment for arthritis of your knee has failed. This procedure involves resecting the ends of the bones of the knee and replacing them with a combination of metal and plastic. The procedure is one of the most successful of all surgical procedures. On average, TKR provides 90-95% pain relief and has a 1-2% complication rate. Approximately 90% of replaced knees will be satisfactory twenty years after surgery.
Both partial and total knee replacements can be highly successfully for patients who are good candidates. It is important to discuss the risks and benefits of each type of surgery with your surgeon so that your expectations are in line with the procedure you elect to have. Remember that both of these procedures are replacements, and you should follow the activity restrictions your surgeon provides you. Neither procedure is designed to hold up to the rigors of high-impact sports. If you take care of your total or partial knee replacement it will provide you with the greatest longevity possible.
- Kozinn SC, Marx C, Scott RD. Unicompartmental knee arthroplasty. A 4.5-6-year follow-up study with a metal-backed tibial component. J Arthroplasty. 1989;4 Suppl:S1-10.
- Kim MS, Koh IJ, Choi YJ, Lee JY, In Y. Differences in Patient-Reported Outcomes Between Unicompartmental and Total Knee Arthroplasties: A Propensity Score-Matched Analysis. J Arthroplasty. 2017;32(5):1453-1459.
- Siman H, Kamath AF, Carrillo N, Harmsen WS, Pagnano MW, Sierra RJ. Unicompartmental Knee Arthroplasty vs Total Knee Arthroplasty for Medial Compartment Arthritis in Patients Older Than 75 Years: Comparable Reoperation, Revision, and Complication Rates. J Arthroplasty. 2017.
- Dyrhovden GS, Lygre SH, Badawy M, Gothesen O, Furnes O. Have the Causes of Revision for Total and Unicompartmental Knee Arthroplasties Changed During the Past Two Decades? Clin Orthop Relat Res. 2017.
- Chawla H, van der List JP, Christ AB, Sobrero MR, Zuiderbaan HA, Pearle AD. Annual revision rates of partial versus total knee arthroplasty: A comparative meta-analysis. Knee. 2017;24(2):179-190.
- Thienpont E. Conversion of a unicompartmental knee arthroplasty to a total knee arthroplasty: can we achieve a primary result? Bone Joint J. 2017;99-B(1 Supple A):65-69.
- This article has been written and peer reviewed by the AAHKS Patient and Public Relations Committee and the AAHKS Evidence Based Medicine Committee. Links to these pages or content used from the articles must be given proper citation to the American Association of Hip and Knee Surgeons.
*In some instances the undersurface of the patella may not be resurfaced as selected by your surgeon.