Professor Salmas performs unicompartmental knee replacement with excellent success: without postoperative pain, without blood loss, with immediate mobilisation and full range of motion from the first day after surgery, and with no more than 5 physiotherapy sessions needed. He uses a robotic system (robotic knee replacement) for precise preparation and accurate implant positioning. Together, these lead to a high level of satisfaction among his patients, as their online reviews also show.
Unicompartmental knee replacement
The aim of total knee replacement is to relieve the patient’s pain and restore the function of the joint. Although total knee replacement (arthroplasty) is an excellent option for patients with knee osteoarthritis, there are other options too. Patients whose osteoarthritis is limited to just one compartment of the knee may be candidates for unicompartmental knee replacement (also called partial knee replacement).
Description of the technique
Unicompartmental knee replacement is the right choice for a small proportion of patients with osteoarthritis. The orthopaedic surgeon recommends it when the arthritic changes are limited to just one compartment (part) of the knee.
The knee is divided into 3 main compartments: the medial compartment, the lateral compartment and the patellofemoral compartment (the front of the knee, between the kneecap and the thigh bone).
In unicompartmental knee replacement, only the damaged compartment of the knee is replaced with an artificial implant – or prosthesis – made of metal and plastic. The healthy cartilage surfaces of the rest of the knee are left as they are.
Advantages of unicompartmental knee replacement
A large number of studies have shown that unicompartmental knee replacement, when properly indicated, gives excellent results in the great majority of suitable patients.
The advantages of unicompartmental knee replacement compared with total knee replacement include:
- Faster recovery and rehabilitation
- Milder (less) pain after surgery
- Less blood loss during surgery
- In addition, because the bone, cartilage and ligaments in the healthy part of the joint are preserved, many patients report that after unicompartmental replacement their knee feels more “natural” than after total knee replacement.
Finally, with unicompartmental knee replacement patients achieve a greater range of motion of the joint (bending and straightening).
Disadvantages of unicompartmental knee replacement
The disadvantages of unicompartmental knee replacement compared with total knee replacement include less predictable results in terms of pain relief and, consequently, the possibility of a repeat operation (reoperation) to replace the other, non-operated part of the joint.
Candidates for surgical treatment / Patients who meet the criteria for surgery
The orthopaedic surgeon should propose surgical treatment in cases of advanced osteoarthritis, once all conservative (non-surgical) treatment options have been exhausted. Surgery should be recommended when the condition significantly affects the patient’s quality of life and prevents them from carrying out their daily activities. For unicompartmental knee replacement in particular, the arthritic changes must be limited to just one compartment of the knee. Patients with inflammatory arthritis, significant knee stiffness or ligament injuries are not ideal candidates. It is the surgeon’s responsibility to determine whether this operation is the most suitable for the patient. With correct patient selection, modern unicompartmental knee replacement techniques have shown excellent medium- and long-term results in both younger and older patients.
Orthopaedic assessment
To determine whether a patient can benefit from the advantages of unicompartmental knee replacement, the orthopaedic surgeon must assess the patient carefully and discuss all possible treatment options with them.
Medical history
Questions about the characteristics of the pain are important, as they help to pinpoint the exact area of tenderness. If the pain is located exclusively or mainly in one of the knee compartments (medial or lateral), the patient may be a candidate for unicompartmental knee replacement. If the pain involves the whole knee joint or its front part (below the kneecap), the orthopaedic surgeon may recommend total knee replacement.
Clinical examination
The orthopaedic surgeon should examine the knee carefully, looking for localised tenderness, swelling or redness of the joint. They also assess the joint’s range of motion and the integrity and quality of the ligaments. If the knee is stiff or unstable because of ligament weakness or a tear, unicompartmental knee replacement is not indicated. Instead, the patient may meet the criteria for total knee replacement.
Imaging
Imaging includes plain X-rays of both knees in anteroposterior and lateral views. The X-rays are taken with the patient standing, so that the knee joints bear the body’s weight. In certain cases, an MRI scan can give a better picture of the condition of the cartilage and soft tissues of the knee.
Before surgery
The patient is usually admitted to hospital on the day of surgery. Before the operation, the anaesthetist carries out a careful pre-operative assessment and discusses the anaesthesia options with the patient. These matters will already have been discussed with the orthopaedic surgeon in the clinic before surgery. Anaesthesia can be either general (the patient is asleep) or epidural (the patient’s body is numb from the waist down).
The operation
Unicompartmental knee replacement usually takes one to two hours. First, the surgeon makes an incision at the front of the knee. They then examine all 3 compartments of the knee to confirm that the cartilage damage is limited to one compartment and that the ligaments are stable and intact. If the surgeon feels that the patient’s knee is not suitable for unicompartmental replacement, they proceed with a total knee replacement. All of this will already have been discussed and agreed with the patient before surgery, with the patient’s consent.
If the knee is judged suitable for unicompartmental replacement, a special saw is used to remove the worn cartilage from the bone. The bone is then covered with metal components, which are held in place with special bone cement. A plastic polyethylene insert is placed between the metal surfaces so that they glide smoothly against each other. After the operation, the patient is taken to the recovery room, where they are closely monitored until they return to their room.
Complications
As with any surgical procedure, certain complications can occur with unicompartmental knee replacement. The orthopaedic surgeon should discuss all possible risks with the patient and take all the necessary precautions to prevent them.
Although rare, the most common complications are:
- Thrombosis. Thrombosis in the veins of the legs is the most common complication after unicompartmental knee replacement. It occurs after surgery in the deep veins of the legs or pelvis. Anticoagulants such as warfarin, low-molecular-weight heparin (LMWH) or aspirin can help prevent this complication.
- Infection. All patients are given antibiotics at the start of the operation, continued for a further 24 hours after surgery.
- Nerve or blood vessel damage. Although rare, nerves or blood vessels can be stretched during the operation.
- Persistent pain with no relief of symptoms.
- Complications related to anaesthesia.
Recovery
Because unicompartmental knee replacement is performed through a relatively small incision and, more generally, with a minimally invasive technique, the hospital stay is shorter and recovery takes less time.
Pain after surgery is milder and the joint is less swollen. In general, patients who have unicompartmental knee replacement recover faster than patients who have total knee replacement. In most cases, patients go home one to three days after surgery. Weight-bearing on the leg starts immediately after the operation. A walking frame, crutches or a walking stick may be needed for the first few days or even weeks, until the patient feels comfortable enough to walk unaided.
During the postoperative period, the surgeon, working with the physiotherapist, shows the patient the appropriate exercises to maintain range of motion and restore muscle strength.
Typically, the patient returns to their pre-surgery activities within 6 weeks of the operation.
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Patients with unicompartmental (partial) knee replacement
Medial compartment knee osteoarthritis – unicompartmental knee replacement
Unicompartmental knee replacement
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