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Total Knee Replacement |
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Your New Knee One of the most important orthopaedic surgical advances of this century,
knee replacement was first performed in 1968. Improvements in surgical
materials and techniques since then have greatly increased its effectiveness.
Total knee replacement means resurfacing the bones of your knee joint
with a Of the three surfaces in your knee that may become roughened and painful, you may need two or all three surfaces replaced. Like a normal knee, your implants have smooth weight-bearing surfaces. The femoral component covers your thighbone, the tibial component covers the top of your shinbone, and the patellar component (if used) covers the underside of your kneecap. All components are usually cemented to prepared bone surfaces. Total knee replacement is as safe and reliable as total hip surgery, although your knee is a more complex and less stable joint than your hip. The studies of modern knee arthroplasty report clinical survivorship of up to 96% of total knee implants at 10 to 15 years. The average survivorship of total knees is over 12 years. IndicationsIndications for knee replacement surgery have expanded during the last decade. During the 1970s and 1980s, knee replacement surgery was performed mainly for pain, disability or deformity. The expected benefit from the operation was reduced pain, limb realignment and functional improvement. However, pain was the primary reason for knee replacement surgery. As we enter a new century, function is a primary reason for knee replacement surgery. Patients are not satisfied with the reduced function that can accompany a stiff, painful arthritic knee and they are demanding knee replacement operations to improve their function. Increasingly, the desire for functional improvement includes recreational and sports activities. What Materials are Used for Implants?Joint implant manufacturers, orthopaedic surgeons and scientists continually strive to improve the durability of these devices. Current scientific advances in metallurgy have resulted in the use of titanium and cobalt-chrome alloys, which are used for femoral and tibial implants, and a low friction plastic component, made of ultra-high molecular weight polyethylene polymer, which acts as a spacer and articulating surface between two metal components. All materials used in moving surfaces are very durable, but they will eventually wear out. This is as true in surfaces of artificial joint implants as in those of car tires. Orthopaedic companies have been working hard to find better materials that will not wear out for a long time.
Benefits of a Knee ReplacementOnce your new joint has completely healed you should experience following benefits of the surgery: significantly reduced or no joint pain, increased movement and mobility, correction of angular leg deformity, increased leg strength (if you exercise!), improved quality of life and the ability to return to normal activities and pastimes. Obesity and a Knee ReplacementThere has been considerable discussion as to the influence of obesity on the indications for, and the outcome after, knee replacement. Although this is logistically, anaesthetically and surgically more difficult procedure, with additional risks involved, the functional outcomes of knee replacements in obese people appear to be satisfactory. However, attempts have been made in the east of England to withhold NHS funding for such procedures in those who are overweight. The editorial published in the British edition of the Journal of Bone and Joint Surgery examined the current evidence concerning the influence of obesity on joint replacement and it appears that it is only in the morbidly obese, with a body mass index (BMI) > 40 kg/m2, that significant contraindications to operation are present. The Editor concludes: "Overall, although there have been no controlled trials which have assessed the influence of obesity, the current evidence suggests that there is no statistically significant difference in outcome in hip and knee replacement as influenced by weight unless the patient is morbidly obese, when the results begin to worsen. However, in these patients the improvement in their quality of life is still considerable and, provided they have been made aware of the increased risks, operation should not be withheld." Source:
The research, published online in the journal Annals of the Rheumatic Diseases, shows that clinically obese people (those who have a body mass index of above 30 kg/m2) can benefit almost as much as anyone else from the procedure. Source:
Equally, there is substantial evidence of significantly increased risk of complications after lower limb joint surgery in patients who are morbidly obese and increasing evidence that obese patients too have a potentially increased risk of complications. Furthermore, evidence of implant failure after surgery in the morbidly obese, and increasing evidence of reduced implant survival in the obese population suggest that not only are there immediate dangers associated with surgery in this group of patients, but limitations with regard to longer term efficacy and durability. The clearly established links between obesity and other disorders such as cardiac disease and diabetes mellitus make it important for medical counselling prior to any surgery, and increasingly there is evidence that obesity itself should be discussed as not only an indirect, but a direct risk for complications and compromised results. Source:
Sports after a Knee ReplacementOur duty is to educate patients regarding risks associated with higher levels of activity after total knee replacement: implant loosening, accelerated wear of the articulating surfaces and injuries. We advise our patients to avoid recreational and athletic activities until their quadriceps and hamstring muscles are sufficiently rehabilitated. After muscle strength has been recovered, we try to help our patients to make reasonable choices regarding athletic activities. In general, we support and encourage low-impact activities: cycling, golf, dancing, riding, walking (but not jogging), swimming and tennis (but not squash). Please see The Knee Society recommendations for more information:
Orthopaedic articles on athletic activities after knee replacement:The orthopaedic literature on athletic activity after total joint arthroplasty is limited to small retrospective studies with short-term follow-up:
Further information on athletic activities after knee replacement:
ComplicationsKnee replacement surgery is generally very successful, and complications are relatively uncommon, considering the complexity of the procedure. However, complications can occur following a knee replacement, as with all major surgical procedures. They include excessive swelling or bleeding, blood clots (DVT or deep vein thrombosis), pulmonary embolism (PE), phlebitis, neurovascular damage, skin healing problems, subcutaneous stitch abscess, peri- and intra-articular infection, limited flexion or extension or both, stiff joint (arthrofibrosis), early loosening of implants, allergy to the metal parts of the implants, fracture of the knee bones, etc. There are also anaesthetic risks, both during and after the procedure. Further information:
When Can I Fly After a Knee Replacement?There is no universal agreement as to when it is safe to travel by plane after a knee replacement. It seems that most orthopaedic surgeons advise their patients not to fly for at least 4 to 6 weeks before and after a knee replacement. Although short flights do not seem to be a problem long intercontinental flights are a potential problem as there is an increased incidence of spontaneous DVT (deep venous thrombosis), even in the young and healthy passengers. It is possible that sitting for long period of time, in a confined space and with very little leg room, could predispose to the development of deep venous blood clots, especially in people following recent major knee surgery. The likelihood of developing postoperative leg blood clots depends on many different factors, including your general health, medical history, postoperative mobility and a number of risk factors (obesity, smoking, a history of DVT, etc.). If you have to travel by plane, before 4 weeks after your knee replacement, it would be wise to contact your airline’s Medical Department and to ask them for advice. Also, please discuss this issue with your GP, as you should take further prophylactic measures for several weeks. General advice on travel-related DVT prophylaxis:
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Site last updated on: 16 Oct 2008
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prosthesis. 
Disclaimer: This website is a source of information
and education resource for health professionals and individuals
with knee problems. Neither Chester Knee Clinic nor Vladimir Bobic
make any warranties or guarantees that the information contained
herein is accurate or complete, and are not responsible for
any errors or omissions therein, or for the results obtained from
the use of such information. Users of this information are encouraged
to confirm the accuracy and applicability thereof with other sources.
Not all knee conditions and treatment modalities are described
on this website. The opinions and methods of diagnosis and treatment
change inevitably and rapidly as new information becomes available,
and therefore the information in this website does not necessarily
represent the most current thoughts or methods. The content of
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you should promptly seek appropriate medical advice from your local
doctor. Any opinions or information,
unless otherwise stated, are those of Vladimir Bobic, and in no
way claim to represent the views of any other medical professionals
or institutions, including Nuffield Health and Spire Hospitals. Chester
Knee Clinic will not be liable for any direct, indirect,
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to persons which may occur by the user's reliance on any statements,
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