Not everyone with knee arthritis needs a total knee replacement. The knee has three compartments — the inside (medial), the outside (lateral), and the area behind the kneecap (patellofemoral). When arthritis has damaged only one of them and the ligaments are intact, a partial knee replacement can resurface that compartment alone and leave the rest of the joint untouched.
The orthopedic surgeons at Midwest Orthopaedics at Rush perform both partial and total knee replacement, and the evaluation that decides between them is the first thing that happens at your appointment. This page explains how that decision is made and what each path involves.
At a glance: Partial knee replacement, or unicompartmental knee arthroplasty, replaces only the damaged compartment of the knee and preserves healthy bone, cartilage, and ligaments. It is an option for people whose arthritis is confined to one compartment. Candidacy is determined by imaging and physical examination.
In a total knee replacement, all three compartments are resurfaced and the surgeon removes more bone and, in most designs, the cruciate ligaments. In a partial knee replacement, the surgeon resurfaces one compartment with a metal and polyethylene implant and leaves the remaining cartilage, bone, and ligaments — including the ACL — in place.
Because less of the joint is altered, patients often describe the knee as feeling closer to their own. The incision is typically smaller and hospital stays are generally shorter. These are surgical characteristics, not guarantees of how any individual will feel afterward; your surgeon will discuss what is realistic in your case.
Candidacy turns on a specific set of findings rather than on age alone. Your surgeon will look at:
Some patients arrive expecting a partial and learn during the evaluation that their arthritis is more widespread than they thought, and the reverse happens too. The imaging drives the recommendation.
Partial knee replacement is performed under regional or general anesthesia. The surgeon makes an incision over the affected compartment, removes the damaged cartilage and a thin layer of bone, and fits a metal component to the femur and tibia with a polyethylene bearing between them. Healthy structures elsewhere in the knee are left alone.
Some partial knee replacements at Midwest Orthopaedics at Rush are performed with robotic assistance, which uses a preoperative or intraoperative model of the knee to guide implant positioning. Robotic assistance is a tool for precision in component placement; whether it is used in your case depends on your anatomy and your surgeon's assessment.
Recovery is individual, and the timeline below describes a typical uncomplicated course rather than a promise.
Your surgeon and physical therapist will set the specific milestones for your knee.
Partial knee replacement carries the general risks of joint surgery, including infection, blood clots, stiffness, and persistent pain. There are also considerations specific to the procedure:
Your surgeon will discuss how these risks apply to your age, activity level, and the condition of your knee.
Implant longevity varies with age, weight, activity level, and implant position. Registry data on partial knee replacement shows meaningful survivorship at ten years and beyond, but no implant is permanent and individual results vary. Your surgeon can discuss what current evidence suggests for a patient in your situation.
Neither is better in the abstract — they treat different patterns of disease. A partial is appropriate when arthritis is confined to one compartment and the ligaments are intact. A total is appropriate when it is not. The imaging and examination determine which one fits.
Yes, if both knees meet the criteria. Whether they are done at the same time or staged is a decision your surgeon will make with you based on your overall health and recovery support.
Many patients can kneel comfortably after a partial knee replacement, and some cannot. Kneeling ability after knee replacement of any type is variable and is worth discussing with your surgeon before surgery.
Driving generally resumes once you are off narcotic pain medication and can control the vehicle safely, which most patients reach within a few weeks. Your surgeon will clear you individually.
If knee arthritis is limiting what you can do, a specialist evaluation is the first step in finding out which options are available to you. Schedule an appointment with the knee specialists at Midwest Orthopaedics at Rush.
This page is general information about a surgical procedure and is not medical advice. Talk with a physician about your own symptoms, imaging, and treatment options.