Partial Knee Replacement
What Is a Partial Knee Replacement?
A partial knee replacement, also called a unicompartmental knee arthroplasty, replaces only the damaged portion of the knee joint rather than the entire joint. The knee is divided into three compartments — the inner (medial), outer (lateral), and kneecap (patellofemoral) — and many patients with arthritis have damage concentrated in just one of these areas while the rest of the knee remains healthy. In these cases, resurfacing only the affected compartment can relieve pain while preserving the patient’s own healthy cartilage and ligaments elsewhere in the knee.
When Is a Partial Knee Replacement Needed?
A partial knee replacement may be recommended for patients who have:
- Arthritis or cartilage damage clearly confined to one compartment of the knee, confirmed on imaging and during surgical evaluation
- Intact ACL and healthy cartilage in the other compartments of the knee
- Pain and functional limitations that haven’t responded adequately to nonsurgical treatments like injections, bracing, and physical therapy
- A preference for a less invasive procedure with a generally quicker recovery than a total knee replacement, when they are an appropriate candidate
How Is a Partial Knee Replacement Performed?
Through a smaller incision than a total knee replacement, the surgeon removes the damaged cartilage and a thin layer of bone from only the affected compartment. Precisely sized metal and plastic implants are then fitted into this space — a metal component resurfaces the femur and tibia, while a durable plastic spacer sits between them, recreating a smooth, low-friction joint surface. Because the healthy ligaments and cartilage elsewhere in the knee are left undisturbed, the knee’s natural feel and motion are often better preserved compared to a total knee replacement.
Partial vs. Total Knee Replacement
The key difference comes down to how much of the joint is affected by arthritis. A partial replacement is only appropriate when damage is isolated to one compartment; if arthritis has progressed throughout the entire knee, a total knee replacement — which resurfaces all three compartments — is generally the more appropriate and durable option. Partial implants typically last 10 to 15 years, whereas total knee implants often last 25 to 30 years or more. Dr. Palsis will evaluate your age, activity level, arthritis location, and imaging to recommend the best personalized option for you.
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Recovery After a Partial Knee Replacement
Recovery from a partial knee replacement is generally faster than a total knee replacement, since less bone and tissue are involved:
- Many patients begin walking with assistance the same day as surgery
- Physical therapy typically starts within the first day or two
- Most patients progress from a walker or cane to walking independently within a few weeks
- Return to lower-impact daily activities often occurs within 4 to 6 weeks, with continued strengthening over the following months
As with any joint replacement, maintaining an active, healthy lifestyle helps protect the longevity of the implant over time.
Get back to what moves you
Dr. Palsis specializes in the treatment of knee, shoulder, and sports injuries.