Mr Mark Ashworth FRCS (Orth)
Consultant Orthopaedic Surgeon
HIP AND KNEE PAIN
Revision Knee Replacement Surgery
A revision knee replacement involves removing the previous prosthesis and replacing it with a new one.
In the absence of a complication, most knee replacements should last 20 years and potentially much longer. However, occasionally knee revision surgery is needed to remove and replace a worn, loosened or misaligned implant to relieve pain or improve function.
Reasons for revision surgery:
Increasing pain levels or your knee functionality is deteriorating.
Implant loosening or wearing of the plastic component, this is likely to happen sooner if you are overweight or play high-impact sports.
Occasionally trauma can occur to the knee, such as in a serious road accident or fall. This could result in a fracture of the lower end of the femur or upper tibia that may disrupt the stability of the knee and require surgery.
Instability, usually due to ligament laxity or stretching with time.
Component fractures occur very rarely.
Symptoms/signs your hip replacement may be in trouble:
Failure of the original operation to relieve your pain, a new pain developed since the initial operation or late recurrence of an aching pain particularly when you start walking (‘’start-up pain’’).
Limp, stiffness or weakness.
Instability and dislocation.
Recovery and outcomes from revision surgery:
The surgery is usually more complex and time consuming than the original operation, particularly where there is infection, a lack of adequate bone stock, or difficulty separating the implants from the bone.
The surgery can take longer to perform with specialized techniques and equipment being required. The extensive nature of revision surgery can affect recovery as the surgical trauma, scar tissue, and mechanical weakening of bone can reduce performance of the knee joint and muscles.
If the revision is due to an infection, the surgeon will have to perform the operation in two stages. The first stage involves taking out the previous components and inserting some bone cement with antibiotics into the joint. The second stage is carried out after 10-12 weeks if there is no more infection. Your surgeon will then remove the bone cement and place the new joint implants.
Care after knee revision surgery is similar to the care after total knee replacement, including physical therapy and pain medications as needed. Blood thinning medication will also be given to reduce the risk of blood clots. Usually you will be ‘’fully weightbearing’’ but occasionally a period of ‘’non- weightbearing’’ or ‘’partial- weightbearing’’ is necessary to protect the early healing. A Zimmer frame or crutches will be used early in your recovery period, then you will progress to a walking stick and eventually the vast majority will be walking without any assistance.
As this is complex surgery, occasionally complete pain relief and restoration of full function is not always possible. However, strength and mobility continue to improve over one to two years after knee revision surgery.
More than 90% of patients who undergo revision procedures can expect good to excellent results. It is important to ‘get it right’ during revision surgery to prevent the need for later remedial surgery. Mr Ashworth’s NJR results show he is in the top 25% for avoiding the need for any further surgery after a revision operation.
Complications of revision knee replacement surgery:
Generally, the risk involved with revision surgery are similar in nature to that of first-time knee replacement, but with higher magnitude.
The risks of revision knee replacement include (but are not limited to):
Infection – rare but potentially catastrophic. The infection rate in revision knee replacement surgery is reported to be around 2-4% (Mr Ashworth’s infection rate is lower than this). Infection may need further operations to wash out or revise the implants. In cases where the infection cannot be cleared despite removing the implants occasionally knee fusion or even amputation is needed (Mr Ashworth has never had to perform these in a case where he was the lead operating surgeon, although he has performed such surgery where the original operation was performed by other surgeons). In the case of infection, a staged procedure (two stage operation) is preferred by Mr Ashworth due to its higher success rate than a one stage operation. This involves a first operation to remove the existing implants and cement, and clean the knee thoroughly. An antibiotic spacer is then inserted to keep the joint under tension, to deliver antibiotics to the local area and permit knee movement to prevent stiffness. Intravenous antibiotics are then commenced for 6 weeks, and then ceased if the blood tests indicate the infection has cleared. The revision knee replacement is then inserted in a second operation usually 12 weeks after the first.
Wound irritation or numbness - Occasionally, there is some dull aching around the scar for many months, which can become worse in cold weather, but this is usually nowhere near as uncomfortable as the pain you had before the operation. The operation incision will always cut some skin nerves, so you will have numbness around the wound, particularly on the outside of the knee scar. This does not affect the function of your joint but may be irritating to you over the short to medium term. Eventually, this numb feeling improves and does not worry most people. Occasionally, instead of a numb sensation you may have burning or a hypersensitive sensation. This usually settles down over many months but occasionally, can be permanent and troublesome.
Stiffness – persistent stiffness following revision surgery may occur. Usually, stiffness before surgery determines whether the knee will be stiff afterwards. Some people form excessive scar tissue after total knee replacement (arthrofibrosis). The total knee replacement bend/flexion is 1200. If you are not bending past 90 0 by 6 weeks, you are likely to need readmission to hospital. Under spinal anaesthetic, the knee is forcibly manipulated to break the scar tissue which is stopping your bend. There is a very small risk of fracture with this procedure, so all efforts to regain flexion with the help of physiotherapy are encouraged.
Pain – Occasionally patients are left with pain after otherwise successful surgery.
Loosening – the bond between the metal implant and the bone can fail, leading to loosening due to bone loss (osteolysis) this can be painful. This requires repeat revision surgery.
Wear – the polyethylene in the knee can wear with time, requiring surgery. Sometimes a new polyethylene can be inserted, but usually the wear is associated with loosening of the metal components. In this situation, the knee replacement will have to be re-revised.
DVT/PE – Deep Vein Thrombosis (DVT) involves formation of blood clot in the deep calf veins. This may occur after surgery, trauma, or even spontaneously. Knee replacement revision is associated with a higher risk of DVT. Special precautions are taken, including pneumatic calf pumps and blood thinning injections followed by tablets. Despite these measures, DVT can occasionally occur. DVT causes calf pain and swelling, but its most concerning consequence is when the clot breaks free and travels to the lungs (called Pulmonary Embolism or PE), causing shortness of breath or chest pain. Very occasionally this can be serious or even life-threatening.
Injury to nearby nerves– rare, but may be associated with impaired long term function (e.g., a foot drop weakness with numbness – usually recovers within 6-9 months but a splint is used to prevent tripping up).
Injury to nearby blood vessels – exceptionally rare and requires emergency surgery to resolve. This has never happened to a case Mr Ashworth has operated on.
Bleeding – blood transfusion is rarely required following revision knee replacement surgery.
Dislocation or instability – the components of the knee replacement may jump or slide abnormally, leading to giving way of the joint. This almost always requires re-operation but usually only occurs many years after insertion of the prosthesis when there is a lot of wear. Re-revision of the knee replacement to a design with more intrinsic stability such as a rotating hinge design is usually successful.
Fracture – a rare complication. If this occurs, further surgery or splinting may be required.
Heterotopic ossification - This is rare, it means bone forms in the soft tissues surrounding the knee. This can cause discomfort and stiffness and occasionally needs to be excised.
Implant breakage - This is exceedingly rare and usually due to osteolysis causing loss of support to the implant. If this were to occur, reoperation to remove the broken implant and replace it with a new one would be required. Mr Ashworth has published on this topic whilst on his fellowship in Australia.
Anaesthetic problems - (these will be discussed by your anaesthetist when you meet them)– Anaesthetic agents have been associated with allergic and anaphylactic reactions. In addition, the medications can depress the function of the heart and lungs. In older or more prone patients this may lead to heart attack, stroke, or cardiac failure.