WHO IS PARTIAL (UNICONDYLAR) KNEE PROSTHESIS SUITABLE FOR?
Unicondylar prostheses may be preferred in patients whose joint wear is only in a limited area of the knee. The patient's age is required to be 60 and above, but in recent years, unicondylar prostheses have been applied safely to patients in their 50s. The wear on the joint should only be in one area, the articular cartilage, menisci, cruciate ligaments and lateral ligaments in the rest of the knee should be intact. If there is a deformity in the knee (inward or outward curvature), this should be correctable during the examination. Unicondylar prostheses are not suitable for people with widespread cartilage erosion in the knee or common rheumatic diseases such as rheumatoid arthritis. Unicondylar prostheses can also be applied to patients who develop bone death and collapse as a result of occlusion of the vessels in a region of the knee, called osteonecrosis (Figure 3). Considering these limitations, unicondylar prosthesis can be used in approximately 15% of patients with knee arthrosis (calcification, wear).
WHAT ARE THE ADVANTAGES OF PARTIAL (UNICONDILAR) KNEE PROSTHESES?
Partial knee prosthesis has some advantages compared to total knee prosthesis.
After surgery The recovery period is faster and less painful. It takes a shorter time for knee range of motion to be regained and muscle strength to return. This is because the procedure is performed through smaller incisions and the structures around the knee are not damaged, except for the damaged area. The hospital stay after total knee prosthesis is 3 days, and after unicondylar prosthesis it is usually 2 days. It is possible for most patients to return to daily life without the need for physical therapy.
After the surgery, patients feel their knees more normal. This is because the ligaments and menisci of the knee are protected and the cartilage is intact except for the replaced surface. Deep sensory nerves within these structures are protected and continue to function normally.
Surgery is performed through smaller incisions, resulting in a smaller scar.
Both total and unicondylar scars are left. There is a significant improvement in knee pain after the prosthesis. On the other hand, there is a so-called "forgotten knee" and the patient has no knowledge of the knee. The situation in which there are no complaints is seen at a higher rate after unicondylar prosthesis. In addition, the activity levels of patients with unicondylar prosthesis are slightly higher than those with total prosthesis.
WHAT IS THE DURABILITY OF PARTIAL (UNICONDYLAR) KNEE PROSTHESES?
Designs of unicondylar knee prostheses 20 years ago had higher than expected failure rates due to premature wear and loosening issues and ongoing pain. Thanks to the development of modern prosthesis designs, accurate determination of patient selection criteria, and advances in surgical techniques, the durability of unicondylar knee prostheses is similar to total prostheses. In modern designs, the survival of the unicondylar prosthesis is over 90% at 10 years. It drops to around 80% in fifteen to twenty years of follow-up. In addition to the design features, the surgeon's experience is also very important in the success of unicondylar prostheses. Studies show that the results of surgeons who perform unicondylar prostheses more than once a month are better than those who perform them less frequently.
IS UNICONDYLAR PROSTHESIS SUITABLE FOR ME?
To decide whether the unicondylar prosthesis is suitable for you, your orthopedic doctor will first examine you, examine your x-rays, and use magnetic resonance imaging if necessary. In some cases, x-rays may also be required in special positions. After examining all these, your doctor will decide whether the unicondylar prosthesis is suitable for you. However, the final decision will be finalized during the surgery. Although very rare, if there is advanced damage that cannot be detected by pre-operative examinations in the areas of the knee that are thought to be healthy during the surgery, your doctor may give up on the unicondylar prosthesis and switch to total knee prosthesis. CAN I DO THE ACTIVITIES?
After the unicondylar prosthesis, all non-impact and non-challenging activities such as walking, going up and down stairs and squatting, which are necessary for daily life, can be done. Non-strenuous sports such as swimming, cycling, golf and bowling are recommended. Sports such as football, volleyball, tennis and basketball that involve sudden turns and jumps are not recommended. Skate well before There are also surgeons who allow patients to slide at low speeds on non-challenging slopes. The purpose of restricting impactful and challenging sports is to prevent premature wear and loosening of the prosthesis.
ARE THERE PROBLEMS WITH THE UNICONDYLAR PROSTHESIS?
The most important reason for the failure of the unicondylar prosthesis is the lack of surface replacement. The disease progresses in some parts of the body and there is a need to switch to total knee prosthesis. When a prosthesis is made on the inside of the knee, cartilage damage may progress on the outside, or when a prosthesis is made on the outside, on the inside, and a total prosthesis may be required. This rate is between 10-15% and increases as the time after surgery increases. The solution to this problem is total knee replacement and its results are very good. From another point of view, unicondylar knee prosthesis will delay total knee prosthesis by 10-15 years with very little bone loss.
Apart from this, prostheses that use a removable spacer will replace this part. separation and pushing out of the joint; In dentures with fixed spacers, problems such as premature wear of the plastic part may occur. These problems occur in less than 5% of patients and are usually due to technical difficulties during surgery.
As with all implants placed in the body, infection (inflammation) may occur after unicondylar prostheses. This rate is between 1-2% for total knee prostheses and is below 1% for unicondylar prostheses.
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