Unicompartmental Knee Replacement
Why should I have a unicompartmental knee replacement?
Knee joint damage due to injury or arthritis results in pain and stiffness and can affect quality of life. Unicompartnmental knee replacement surgery involves partially replacing the joint, alleviating symptoms.
The knee is a hinge joint with cartilage covering the bone ends. The cartilage prevents the bones from rubbing together. If the cartilage is worn, the bone is exposed and the joint can become stiff and painful resulting in difficulty mobilizing and eventually deformity.
Unicompartmental knee replacement (partial knee replacement) may be considered when only one compartment of the knee has been damaged by osteoarthritis. By replacing only the most damaged areas of cartilage, a faster recovery is expected than traditional knee replacement, with a smaller incision, shorter in-patient stay and quicker return to function.
What should I do before my surgery?
Following consultation with Mr Hoad-Reddick and X-Ray investigation, total knee replacement may be suggested as the best form of treatment and the appropriate choice of prosthetic will be discussed. At this appointment you will receive a booklet ‘What you need to know about your joint replacement’ from Mr Hoad-Reddick containing more information.You can also download it here.
Once you have decided to proceed with surgery, please contact the HR Orthopaedics office on 0161 722 0007 to arrange a convenient date for your surgery.
If you are insured, you will need to contact your insurance company and obtain an authorisation number which you should take with you on admission. Your insurance company may ask you for a Procedure Code which isW4210. Prices for self- funding patients can be given on request and more information is on our information page for self pay patients. The hospital will contact you to attend for preoperative assessment approximately two weeks prior to surgery. At assessment, blood and urine tests will be performed along with a heart trace (ECG) to ensure you are healthy enough to undergo anaesthetic and surgery. The pre-operative nurse will advise whether you should stop taking any of your medication.
You will see a physiotherapist and occupational therapist, if possible on the same day as your preoperative assessment; you will be given advice on mobilization, postoperative exercise and rehabilitation. Home circumstances will be assessed and any necessary measures to assist you on discharge can be arranged. You will be required to fast for a period of time before your operation; this will be confirmed in writing along with your admission details.
What happens on the day of my surgery?
You will be admitted to hospital usually the same day as your operation. Mr Hoad-Reddick will explain the procedure again and consent forms will be signed. The operated leg will be marked and an expected position on the surgery list will be given, and is decided depending on medical conditions of all patients that day.
An anaesthetist will see you to discuss your anaesthetic and postoperative pain relief. Following surgery you will be taken to the recovery unit until your condition is stable. You will have an intravenous drip in your arm to administer fluids or drugs, you may have a catheter in-situ; these are both usually removed at twenty four hours following surgery.
Once stable you will be taken to the postoperative unit for close monitoring before returning to your room on the ward. The physiotherapist will visit you on the unit to institute basic exercises.
What happens during a unicompartmental knee replacement?
In a healthy knee the thigh and shin bone are covered with hard cartilage which allows the bones to move easily over each other. Arthritis damages the hard cartilage and can cause the bones to rub together. At surgery the worn ends of the bones and any remaining cartilage are removed and replaced with metal and plastic parts.
Unicompartmental knee replacement differs from total knee replacement in that only the most damaged areas of cartilage are removed and these surfaces replaced with metal and polyethylene components, these components are attached with cement to the ends of the shin bone (tibia) and thigh bone (femur). The joint will be inspected during surgery, if other parts of the knee are worn or damaged, then conversion to total knee replacement may be necessary. This decision will be made during the operation.
The procedure takes one to two hours. The wound is closed with a buried stitch and glue.
For more information please download our wound care booklet here.
What are the potential risks associated with a unicompartmental knee replacement?
As with any operation, knee replacement carries risks as well as benefits; the majority of patients undergoing such surgery will encounter no significant complications. 19 out of 20 patients are delighted with the outcome. 1 in 20 may experience dissatisfaction due to a variety of complications.
Infection: To reduce infection risk, surgery is performed in a specially ventilated ‘clean air’ operating theatre and most patients are given a short course of antibiotics at the time of surgery. Despite these measures deep infection can occur in 1:100 cases necessitating removal of the artificial joint until infection has cleared. This would also be treated with antibiotics.
Blood clot (DVT): Occasionally a blood clot can form in the deep veins of the leg causing pain or swelling in the calf, in a minority of cases this can break away and travel to the heart or lungs and become a risk to life. The overall risk of fatal lung clot is 1:600. To reduce this risk you will be given calf pumps to increase the blood flow and an anticoagulant drug to inject into your stomach for twenty eight days following surgery, in keeping with current recommendations from the National Institute for Clinical Excellence (NICE).
Residual pain: In the majority of cases, knee replacement significantly improves pain and mobility; residual pain and stiffness can occur and in most cases will resolve in time.
Neurovasuclar injury: Very rare occurrence of damage to vessels or nerves in the region of surgery.
Dislocation/Fracture: This is extremely rare and may require further surgery.
Failure requiring revision surgery: Wear of the implants or further degeneration of the knee over time can necessitate further surgery.
What happens when I am recovering from my surgery?
Exercise and mobility are an extremely important part of rehabilitation and require full patient participation for optimal recovery and outcome. A degree of pain and stiffness can be expected during the early days. You will commence mobilization with the aid of a walker, progressing onto crutches for approximately 2-4 weeks.
A physiotherapist will see you everyday during your stay, teaching you to climb stairs safely and providing you with an exercise regime to continue at home. 24 to 48 hours following surgery a routine check X-ray and blood tests will be performed.
What happens when I return home?
The majority of patients will be ready to return home two to three days post-surgery dependent upon wound healing and ability to mobilize safely. The nursing staff will advise on wound care and dressings. Mr Hoad-Reddick uses glue and a buried stitch; as such there are no stitches to be removed.
For further reference please download our wound care booklet.
A physiotherapy review appointment will be arranged for a week following discharge to monitor progress and adjust your exercise regime accordingly; you may require between four and six appointments. You can return to driving once safely off crutches and mobilizing without a limp, usually at six weeks post-operatively.
On discharge you will be sent a clinic appointment for six weeks following surgery by post. Patients will return to clinic for further clinical review at three months, one year, three years and five years post-operatively.
Reminder letters for these appointments will be sent by post.