What is a Unicompartmental Knee Replacement?
Unicompartmental knee replacement, also known as partial knee replacement or unicompartmental knee arthroplasty, is a minimally invasive procedure that replaces only the damaged part of the knee joint rather than the entire joint.
The knee is made up of three main compartments — the inner (medial), outer (lateral), and front (patellofemoral) — and in many cases, arthritis or damage affects only one of these areas. By replacing just the affected compartment, the surgery preserves healthy bone, cartilage, and ligaments, helping the knee feel and move more naturally.
Because it’s less invasive than a total knee replacement, patients often experience a quicker recovery, less pain, and improved flexibility after surgery.
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Who is Unicompartmental Knee Replacement For?
This procedure is best suited for patients with arthritis confined to one side of the knee, most commonly the inner (medial) compartment.
Candidates typically have:
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Pain and stiffness on only one side of the knee.
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Well-preserved cartilage and bone on the other side.
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Intact ligaments, especially the anterior cruciate ligament (ACL).
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Good overall knee stability and range of motion.
Unicompartmental replacement is generally suitable for about one in four people with osteoarthritis. We’ll assess your joint, overall health, and activity level to determine whether this approach is appropriate.
Benefits of Unicompartmental Knee Replacement
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Less invasive: Replaces only the damaged part of the knee, preserving more of your natural bone and tissue.
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Faster recovery: Smaller incision and less disruption to the knee allow for a quicker return to normal activity.
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Improved mobility: Retaining more of the natural joint helps the knee bend and move more smoothly.
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Less pain: Reduced tissue trauma results in less post-operative pain and swelling.
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Shorter hospital stay: Many patients go home within one to two days after surgery.
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Natural feel: Because the healthy ligaments are preserved, the knee often feels more “normal” compared to a total knee replacement.
Before and After Surgery
Before surgery
Patients undergo a thorough medical assessment, including x-rays or scans to confirm that the arthritis is limited to one compartment. Any infections should be treated before surgery, and certain medications may need to be adjusted. The surgeon and anaesthetist will discuss your anaesthesia options, typically either general or spinal.
Surgery
The procedure usually takes around one to two hours. The surgeon removes the damaged bone and cartilage from the affected compartment and replaces them with smooth metal and plastic components that function like natural cartilage. Because the rest of the joint remains untouched, recovery is typically quicker than with total knee replacement.
Recovery
Most patients begin walking with assistance within hours of surgery and can usually go home within a day or two. Physiotherapy starts soon after to help strengthen the leg and restore movement.
Swelling and stiffness gradually improve over several weeks, and most patients return to driving and light activities within three to four weeks. Full recovery and optimal strength typically develop over the next few months.
