Knee Surgeon
Partial Knee Replacement
What is a partial knee replacement?
A partial (or unicondylar) knee replacement is a type of surgery used when arthritis affects only one part of the knee. Like a total knee replacement, it is considered when knee pain is severe and is limiting daily activities and quality of life.
The knee joint is made up of three main compartments: the inner (medial) side, the outer (lateral) side, and the front of the knee (patellofemoral joint). If arthritis is isolated to just one of these compartments it is possible to replace that compartment alone. This is known as a partial knee replacement. When the inner or outer side of the knee is replaced, the procedure is called a unicondylar knee replacement. When only the front of the knee is replaced, it is called a patellofemoral replacement.
In up to half of patients with knee arthritis, only one compartment of the knee is affected. If arthritis is confined to a single compartment it is most commonly the inner (medial) compartment.
What are the advantages and disadvantages of a partial knee replacement?
Advantages:
The main advantage of a partial knee replacement is that only the damaged part of the knee is replaced. This allows the healthy parts of the knee and the important ligaments (including the cruciate ligaments) to be preserved. As a result, patients often experience:
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Faster recovery
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Better knee bending compared with a total knee replacement
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A more natural-feeling knee
Disadvantages:
One possible disadvantage is that arthritis can develop in the parts of the knee that have not been replaced. If arthritis progresses in these other compartments, further surgery may be required, and the knee can be converted to a total knee replacement in the future.
This risk needs to be carefully weighed against the potential benefits of improved knee movement and function that a partial knee replacement can offer.
Who may be suitable for a partial knee replacement?
A partial knee replacement may be an option if:
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Arthritis affects only one part of the knee
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Pain is mainly localised to the affected area of the knee
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The knee still has good movement and flexibility
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The cruciate and collateral ligaments are functioning well
Mr Gill will carefully assess these factors and discuss the advantages and disadvantages of all available treatment options to decide whether a partial knee replacement is the most appropriate treatment for you.
What are the steps of a medial unicondylar (partial) knee replacement?
The steps of a unicondylar knee replacement are similar to those of a total knee replacement, with a few important differences. In a partial knee replacement, only the damaged part of the knee is treated, allowing more of the normal knee to be preserved.
1. Anaesthetic
The operation can be performed under either a general anaesthetic (you are asleep) or a spinal anaesthetic (you are awake but numb from the waist down). This will be discussed with you before surgery.
2. Skin incision and access to the knee
A small vertical incision is made at the front, inner side of the knee. This incision is shorter than that used for a total knee replacement. The surgeon carefully opens the knee joint to gain access. The patella femoral and visible parts of the outer (lateral) compartment are checked to confirm that arthritis is limited to the medial side.
3. Preparation of the joint surfaces
Special instruments are used to remove the damaged joint surfaces from the affected part of the thigh bone (femur) and shin bone (tibia). The bone surfaces are shaped to fit the knee replacement components. Trial components are then inserted to check knee movement, stability, and ligament balance.
4. Implantation of the knee replacement
Once the correct fit has been confirmed, the final metal components are fixed into place using bone cement. A plastic spacer (polyethylene liner) is then secured onto the tibial component to allow smooth movement of the knee.
5. Wound closure
Local anaesthetic is injected into the tissues around the knee to help with pain relief after surgery. The deeper tissues are closed using dissolvable stitches, and the skin is closed with a buried dissolvable stitch and sealed with skin glue. A waterproof dressing is applied, and the knee is wrapped in a soft bandage to help reduce swelling and bruising.
The operation usually takes around 60 minutes.
Post-operative care
Once the operation has been completed, you will be transferred to the ward. A partial knee replacement is generally less painful than a total knee replacement. Pain is managed using strong pain relief medication and an ice cuff applied to the knee.
It is usually possible to stand and begin walking on the same day as surgery, using walking aids if needed. A physiotherapist will see you after the operation to help you get moving safely and to give you guidance on exercises and mobility. An X-ray of the knee will be taken to check the position of the knee replacement.
Discharge from hospital depends on:
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Passing a physiotherapy assessment, confirming you can mobilise safely
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Your pain being well controlled
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Most patients are able to go home the day after surgery. If the operation is performed in the morning and you feel well, you may be able to go home on the same day, if you wish.
Recovery and rehabilitation
Recovery from partial knee replacement tends to faster than recovery from a total knee replacement (Link). On average pain settles quicker. Patients are not reliant on mobility aids for as long and patients can return to their normal activities sooner.
Mr Gill's experience with unicondylar knee replacement surgery
When performed regularly, a partial knee replacement is a well-established and reliable procedure. Research has shown that outcomes are better when the operation is carried out by surgeons who perform this procedure frequently. This is likely due not only to greater technical expertise but also to careful patient selection, ensuring the procedure is offered to those most likely to benefit.
Mr James Gill is a high-volume unicondylar knee surgeon and a strong advocate of partial knee replacement because of the excellent functional outcomes it can provide for appropriately selected patients. His surgical volumes can be viewed on the National Joint Registry website.
Address
St Edmunds Hospital,
St Mary's Square, Bury Saint Edmunds
IP33 2AA
Contact
Medical secretary: 07598271034