A partial knee replacement surgery is an alternative to total knee replacement for some patients’ with osteoarthritis of the knee and can be done when the damage is confined to a particular compartment of the knee.Dr. Mir Zia Ur Rahman Ali, Consultant Orthopedic Surgeon & Advanced Revisional Joint Replacement Surgeon, Thumbay Hospital India Pvt Ltd. explains this groundbreaking technique.
BACKGROUND

In the past, partial knee replacement was reserved for older patients’, but Dr. Ali explains that now, partial knee replacement is often preferred in the younger population as recovery is quicker with less pain. He adds, “About five to six percent of patients’ with arthritic knees are estimated to be eligible for partial knee replacement.”

OSTEOARTHRITIS DEFINED

Osteoarthritis is the wearing away of the connective tissue, called articular cartilage, within the joint. As Dr. Ali reiterates, articular cartilage prevents one bone from scraping against another. The cartilage acts as a shock absorber in the joint and allows for smooth and stable movement within the joint. “When the cartilage thins, the joint can inflame and you may feel pain and stiffness in the joint and your range of motion may be limited,” he says. “Up to 30 percent of the population is believed to have knee osteoarthritis and until age 50, knee osteoarthritis is equally common in men and women, but after age 50, more women are affected.”

PARTIAL KNEE REPLACEMENT EXPLAINED

In a partial knee replacement, only the damaged part of the knee cartilage is replaced with a prosthesis. The healthy cartilage and bone, as well as all of the ligaments are preserved. Dr. Ali explains that candidates for partial knee replacement include patients with medial (the inside compartment of the joint) or lateral knee osteoarthritis (outside compartment farthest from the opposite knee.) “Medial knee joint degeneration is the most common deformity of arthritis,” he notes.

ADVANTAGES

Compared to total knee replacement, Dr. Ali points out that partial knee replacement better preserves a range of motion and knee function because it preserves healthy tissue and bone in the knee. “For these reasons, patients’ tend to be more satisfied with partial knee replacement compared with total knee replacement,” he narrates, and they are still candidates for total knee replacement should they ever need it in the future. Moreover, there is also less blood loss during surgery, and knee motion recovers faster with partial knee replacement. More importantly, according to Dr. Ali, because the bone, cartilage, and ligaments in the healthy parts of the knee are maintained, many patients’ report that a unicompartmental knee replacement feels more natural than a total knee replacement. A unicompartmental knee may also bend better.

INDICATIONS

The minimally invasive partial knee replacement is indicated in patients’ who have severe arthritis of the knee that have failed conservative treatments. The partial knee surgery may be possible if the arthritis in the knee is confined to a limited area, notes Dr. Ali, and if the arthritis is widespread, then the partial knee replacement is not appropriate, and should not be considered. In addition, the partial knee surgery is recommended in patients’ who are older than 55 years, not obese, relatively sedentary, and have intact ligaments. However, Dr. Ali explains that most patients’ who seek surgical management have arthritis that is too advanced for the minimally invasive partial knee replacement procedure. “Since surgical treatment is considered a ‘last-resort’ by most patients, by the time surgery is necessary, their arthritis is too advanced to consider this minimally invasive procedure,” he details, and if partial knee replacement is done in a patient who is a poor candidate, failure rates can be high, and conversion to a traditional total knee surgery may be more difficult.

• You may want to consider a knee replacement if your knee pain persists despite taking anti-inflammatory drugs and maintaining a healthy weight.
• Your doctor will ask you to identify the area of pain in your knee, and then check your range of motion and the knee’s stability. An X-ray of the knee will determine your eligibility for partial knee replacement. However, your surgeon may not know for certain if you are a good candidate until the surgery has begun.
• You must have an intact anterior cruciate ligament, a sufficient range of knee motion, damage to only one compartment, and a stable knee. The angulation of the deformity is also considered.
• In the past, a partial knee replacement was considered only in patients’ older than 60 years who were sedentary, but younger, more active patients’ are increasingly being considered.