Unicompartmental Knee Replacement

Unicompartmental knee replacement, also know as a partial knee replacement, is a solution for severe arthritis of the knee in a single compartment of the knee and its accompanying pain and deformity. Through this surgical process the damaged surfaces in the medial compartment of the knee, including the remaining meniscus, are removed and the new titanium components are precisely installed over the ends of the femur (thigh bone) and the tibia (shin bone) in the medial compartment. The resulting joint is now stable and the patient set on the path to recovery.

Planning for Unicompartmental Knee Replacement

When planning for possible unicompartmental knee replacement the patient is evaluated both physically and radiographically with x-ray and MRI to check the status of the cartilage in the three compartments of the knee. In addition, the patient’s history must be evaluated to determine whether they would be a good candidate for knee replacement or whether another treatment option would better suit them. In addition, the clinical staff will discuss options regarding location of surgery and whether the patient would benefit from inpatient or outpatient surgery. If the plan is then to move forward with knee replacement, the patient will be consented for surgery and given orders for pre-operative lab work. All lab work and medical clearances will then be completed within thirty days of surgery and the patient will return to clinic two weeks prior to surgery for their pre-operative appointment to further discuss details of the surgery. On the business day prior to surgery the patient is contacted by the hospital or surgical center to confirm the time of the surgical procedure and the time to arrive at the location of surgery. In addition, the patient’s prescription medications will be discussed and the patient will be instructed as to which medications they may and may not take on the morning of surgery, based on the anesthesia protocol.

Unicompartmental Knee Replacement Procedure

The knee will be accessed through an incision at the front of the knee. The incision length can vary but averages 8 inches. The incision will allow for preparation the ends of the femur and tibia to receive the new components. After the new components are applied to the femur and tibia, varied thicknesses of polyethylene spacers are inserted between the two components and the knee is then taken through a full range of motion by bending and straightening the knee to check for proper motion. When the proper fit has been achieved the incision is then closed and the patient awakened from anesthesia. All has been accomplished in one hour and the patient is ready to begin the recovery process.

Post-Operative Recovery

After the patient has awakened from anesthesia they are encouraged to begin walking. It is important to note that no muscles or tendons are cut during the procedure so the patient is capable of applying full weight to the joint and can begin walking with the help of assistive devices such as a walker or cane. Whether the surgery has been performed as an inpatient or outpatient procedure, the patient will work with a physical therapist prior to discharge. During this process the patient will learn the exercises they will perform as part of their recovery process, as well as how to navigate everyday obstacles such as going up and down stair or getting in and out of bed. Typically within a day of discharge the patient will begin at-home physical therapy which will continue for the first two weeks post-surgery, after which they will transition to outpatient physical therapy. In rare cases and depending on the patient’s homelife situation, the patient may require discharge from the hospital to a skilled nursing facility for post-operative care and rehabilitation. Upon discharge from the facility, the patient will then transition directly to outpatient physical therapy to continue their rehabilitation. In all cases the patient will return to clinic for a two-week post-operative evaluation and x-rays of the new prosthetic. After this visit the patient will continue with their outpatient physical therapy, as well as their home exercise program. The length of time from surgery to full mobility will, of course, vary from patient to patient, but by 4-6 weeks post-surgery the patient will be experiencing increased mobility, less pain, and may not require the use of assistive devices.


Jordan Gruskay, Shawn Richardson, William Schairer, Cynthia Kahlenberg, Michael Steinhaus, Ryan Rauck, Andrew Pearle,

Incidence and safety profile of outpatient unicompartmental knee arthroplasty,

The Knee, 2019, ,ISSN 0968-0160, https://doi.org/10.1016/j.knee.2019.02.002.

(http://www.sciencedirect.com/science/article/pii/S0968016018308962)


Wilson Hannah A, Middleton Rob, Abram Simon G F, Smith Stephanie, Alvand Abtin, Jackson William F et al. Patient relevant outcomes of unicompartmental versus total knee replacement: systematic review and meta-analysis BMJ 2019; 364 :l352