Consent for Surgery
No surgery is risk-free, but the likelihood of developing a problem (a "complication") following surgery is very small. It is important that patients are aware of the possibility of developing a complication, and that this is discussed in the course of the consent process with the surgeon and the anaesthetist.
As part of this consent process, patients having ANY orthopaedic surgery should read and understand the following sections 1-7. Patients having hip or knee joint replacement surgery should read and understand ALL sections.
Should any questions or difficulty understanding any of this information arise, this must be discussed with me and/or my anaesthetist prior to surgery.
1. Anaesthetic (Dr. Chris Elias, Anaethetist)
Modern anaesthesia is usually straightforward and safe. Fit people having minor surgery are probably more at risk on the way to the hospital then while under the care of the anaesthetist!
Minor side effects and complications do occur. A mild sore throat can result from use of the breathing tube (laryngeal mask). Bruising about the intravenous drip site is common. We try hard to prevent nausea, but a minority of patients will feel sick after the operation.
Severe allergic reactions occur in about 1 in 30,000 anaesthetics. Serious complications such as heart attacks, and stroke, even death, occur in 1 in 100,000 anaesthetics overall.
The risks are greater in complex operations, and they increase with age, and in those with heart disease, lung disease, obesity and smokers.
2. Infections
Infections following elective (non urgent) orthopaedic surgery are uncommon, but do occur statistically in less than 1:100-200 cases. This may be a devastating complication in a joint replacement and may occur "out of the blue". The risk is increased in patients with diabetes, on steroids or immunosuppressive drugs, or those who have had a previous infection in or around the joint. Any active infection anywhere else in the body (skin, teeth, chest, urinary tract) must be treated and cleared before surgery proceeds.
3. Nerve and Blood Vessel Damage
Nerve and blood vessel damage is a rare complication but as the structures are nearby (particularly in the knee) they can potentially be damaged. This should never happen, and major damage may result in serious problems.
Occasionally, a nerve may transiently lose function for unknown reasons and spontaneously recover. Electrical nerve conduction studies will define this. At "open" surgery (as opposed to arthroscopic surgery) damage to local sensory nerves is always a risk.
Despite careful surgical dissection and retraction, local nerve damage can occur, resulting in skin sensation loss in that nerve area. This is a particular problem with surgery through the top of the foot. Should this area be large, a nerve exploration and repair may be required, but this is not at all common.
4. Joint Stiffness
Joint stiffness can occur following any surgery, if the joint is not promptly and fully rehabilitated. If the perceived pain from the joint is such that the joint cannot be re-mobilised, this must be properly managed with drug treatment. In the knee, (less so in the ankle) an adverse pain condition, known as CRPS, can develop, resulting in ongoing pain, sensitivity and temperature changes. This must be identified, and specialised assessment and treatment applied. After arthroscopic knee surgery, an uncommon condition called "arthrofibrosis" can occur, resulting in internal scarring and movement restriction. Particularly following knee surgery, it is important to get a full range of movement back promptly, and to restore muscle strength about the knee.
5. Blood Clots
Blood clots can occur in the deep veins of the leg following any surgery, but the highest risk is following hip and knee joint replacement surgery. However, it is uncommon to find evidence of this, despite close observation for this problem following surgery. This is probably due to the fact that we get people up and moving as soon as possible after surgery, use anti-coagulant injection ("Clexane") and elastic stockings while in hospital. Good hydration is important. The big risk with a deep vein clot ("DVT") is if it gets loose and goes to the lung as a "pulmonary embolus" or "PE". This can be fatal, but the statistical risk of this (a non fatal PE ) is probably about 1:1000 cases.
6. Loss of Implant Fixation
Loss of implant fixation into bone is always a possibility when staples, screws, pins or plates are used to hold a bone or joint in position until bone forms. These fixation implants may move in the bone, or possibly break. If pain and swelling worsen or persists, and an infection has been excluded, loss of implant fixation and/or bone non-union is likely.
7. Failure of Bone to Fuse
Failure of bone to fuse is known as "non-union" and can occur following fracture, bone realignment (osteotomy) and attempted joint fusion (arthrodesis). Smoking seems to have a major adverse effect on bone formation in the context of joint fusion, particularly about the foot and ankle. The other major cause of non-union, as above, is loss of implant fixation.
8. Blood Transfusion
A blood transfusion may be needed after hip or knee joint replacement surgery depending on the losses into the tube drains. Modern cross matched blood is very safe, although minor allergic type reactions can occur. A major problem with a blood transfusion (mis-match, infection, incorrect blood) is rare (about 1:30,000) but blood will not be given unless deemed absolutely necessary.
9. Leg Length
Leg length difference after hip replacement surgery can occur. It does not occur with knee replacement surgery. The primary concern in hip replacement surgery is getting the hip stable, with proper surrounding soft tissue tensions. This is achieved by implanting the correct size head and restoring the "offset" distance the hip is from the pelvis. However, this may cause overall leg lengthening which may require correction by use of a full length shoe sole raise. Getting the leg length right (which is checked by an intra-operative measuring device) is of secondary concern to getting the hip stable. The majority of hip replacement patients have no awareness of leg length difference.
10. Fracture
A fracture as a complication of hip replacement surgery is a rare event, but may occur when a "press-fit" femoral component is inserted. Proper preparation of the bone canal prevents this problem, but if occurs, wire "cerclage" fixation of the fractured upper femur may be needed. Fracture of the ceramic bearing component of the hip replacement (if this type is used) is a rare event, with a reported incidence of 1: 5000-10,000 cases.
11. Squeaking of the Ceramic Bearings
Squeaking of the ceramic bearings of hip replacements can occur, but the risk of a ceramic hip generating noise is less than 1:100. Please see my web site post on this topic in the hip surgery section.
12. Early Loosening
Early loosening of implanted joint replacement components, can occur, though is uncommon. It may be caused by low-grade infection, but often no cause is found. The interface between the implant and bone (or the cement and bone) does not properly fill with bone after surgery and may hence require revision "re-do" surgery.
13. Late Wear and Loosening
Late wear and loosening of hip and knee joint replacement parts will occur when plastic bearing components are used. These components will fail in the second decade following implantation. In the knee, there is the option of a plastic spacer exchange procedure in an attempt to avoid a full revision, but in the hip, if the plastic hip cup wears out, a full revision will be needed. Patients who are likely to wear out a plastic hip cup in their projected life spans should have ceramic bearing surfaces in the hip replacement system.
14. Dislocations
Dislocations can occur following hip replacement surgery, due to the ball head jumping out of the hip socket. There is no hip replacement that will not dislocate, and this potential risk remains life long. The risk of a dislocation event is as high as 3-4 per 100 cases, and the risk is highest in the first 4-6 weeks following surgery. Scar tissue formation about the hip occurs which further stabilises it during that time. If a dislocation occurs, ambulance transfer to hospital is required, and the dislocation reduced (put back) under anaesthetic or sedation. Following an "early" dislocation event, there is only a 1 in 3 chance of having further dislocations. A dislocation can occur when the hip is flexed up and the leg turned inward.
Hence, the rule is, when the knee is brought up and the hip flexed: do not twist or turn the leg.
Recurrent dislocations may need further surgery to re-position the component parts.