Unicompartmental Knee Replacement
The goal of knee replacement surgery is to decrease pain and restore function. Although total knee replacement (also called “arthroplasty”) is an excellent option for patients with osteoarthritis of the knee, other surgical options exist. Patients with osteoarthritis that is limited to just one part of the knee may be candidates for unicompartmental knee replacement (also called a “partial” knee replacement).
Description
Unicompartmental knee replacement is an option for a small percentage of patients with osteoarthritis of the knee. Your doctor may recommend partial knee replacement if your arthritis is confined to a single part (compartment) of your knee.
Your knee is divided into three major compartments: The medial compartment (the inside part of the knee), the lateral compartment (the outside part), and the patellofemoral compartment (the front of the knee between the kneecap and thighbone).
In a unicompartmental knee replacement, only the damaged compartment is replaced with metal and plastic. The healthy cartilage and bone in the rest of the knee is left alone.
Advantages of Partial Knee Replacement
Multiple studies have shown that modern unicompartmental knee replacement performs very well in the vast majority of patients who are appropriate candidates.
The advantages of partial knee replacement over total knee replacement include:
- Quicker recovery
- Less pain after surgery
- Less blood loss
Also, because the bone, cartilage, and ligaments in the healthy parts of the knee are kept, most patients report that a unicompartmental knee replacement feels more “natural” than a total knee replacement. A unicompartmental knee may also bend better.
Disadvantages of Partial Knee Replacement
The disadvantages of partial knee replacement compared with total knee replacement include slightly less predictable pain relief, and the potential need for more surgery. For example, a total knee replacement may be necessary in the future if arthritis develops in the parts of the knee that have not been replaced.
Candidates for Surgery
Mr McKenna may recommend surgery if you have more advanced osteoarthritis and have exhausted the nonsurgical treatment options. Surgery should only be considered if your knee is significantly affecting the quality of your life and interfering with your normal activities.
In order to be a candidate for this procedure, your arthritis must be limited to one compartment of your knee. Patients with inflammatory arthritis, significant knee stiffness, or ligament damage are not be ideal candidates. Mr McKenna will determine if this procedure is suited for you. With proper patient selection, modern unicompartmental knee replacements have demonstrated excellent medium- and long-term results in both younger and older patients.
Orthopaedic Evaluation
Medical History
Mr McKenna will ask you several questions about your knee pain. He will be specifically concerned with the location of your pain. If your pain is located almost entirely on either the inside portion of your knee, then you may be a candidate for a partial knee replacement. If you have pain throughout your entire knee or pain in the front of your knee (under your kneecap) you may be better qualified for a total knee replacement.
Physical Examination
Mr McKenna will closely examine your knee. He will try to determine the location of your pain. He will also test your knee for range of motion and ligament quality. If your knee is too stiff, or if the ligaments in your knee feel weak or torn, then he will probably not recommend unicompartmental knee replacement (although you still may be a great candidate for total knee replacement).
Imaging Tests
Mr McKenna will order several x-rays of your knee to see the pattern of arthritis.
Your Surgery
The Day of Surgery
You will be admitted to Kilcreene Regional Orthopaedic Hospital on the day of surgery. Mr McKenna will meet you in the morning and confirm the surgical site and side with you.
Before your procedure, a doctor from the Department of Anaesthesia will evaluate you. He or she will review your medical history and discuss anesthesia choices with you. Anaesthesia will likely be a spinal anaesthetic (you are awake but your body is numb from the waist down).
Surgical Procedure
A partial knee replacement operation typically lasts between 1 and 2 hours.
Mr McKenna will make an incision at the front of your knee. He will then explore the three compartments of your knee to verify that the cartilage damage is, in fact, limited to one compartment and that your ligaments are intact. If your he feels that your knee is unsuitable for a partial knee replacement, he will instead perform a total knee replacement. He or she will discuss this contingency plan with you before your operation to make sure that you agree with this strategy.
After the surgery you will be taken to the recovery room, where you will be closely monitored by nurses as you recover from the anaesthesia.
Complications
As with any surgical procedure, there are risks involved with partial knee replacement. Mr. McKenna will discuss each of the risks with you and will take specific measures to help avoid potential complications.
Although rare, the most common risks include:
