Osteoarthritis questions

Osteoarthritis is caused by wear of the cartilage in the knee joint. Several factors can be responsible for early osteoarthritic changes: previous cartilage injury caused by trauma, a history of ACL or meniscus injury, overload by axial leg deformities or high body mass, joint infection or systemic autoimmune diseases like rheumatoid arthritis. Do the ‘Knee Osteoarthritis Self Test’ (+linkje maken!) to find out whether you have osteoarthritic symptoms!

There are several things you can do yourself to prevent progression of osteoarthritic knee symptoms. Non-operative treatment consists of activity modification (more biking and less longer walking distances), quadriceps training (straight leg raising), weight reduction, and painkillers. Sometimes also knee braces, shoe inlays, medication (e.g. vitamin D) or injections can be effective.

Advantages of uni knee replacement are quick recovery with higher activity levels in daily life and sporting activities. Due to a smaller scar and less surgical trauma to other knee compartments also higher ‘forgotten joint’ scores can be reached in comparison with total knee replacement. Follow this link for more information.

Uni knee replacement has the same disadvantages as total knee replacement: it functions as an artificial joint, and the knee will not feel exactly the same as before or the same as the other knee that was not operated upon. Deep kneeling or sitting on the uni knee will feel uncomfortable around the knee cap in many patients as well. Follow this link for more information. 

Operation is indicated when osteoarthritic complaints of pain and stiffness become very incapacitating in daily life due to severely diminished walking distance and sleep disturbances. On X ray examination the knee joint must have a bone-on-bone appearance, and non-operative treatment guidelines should have been followed first.

Operation questions

Not every orthopedic surgeon had been trained to perform unicompartmental knee replacement. There is a learning curve to this specific procedure, and it has been shown that dedicated knee surgeons who operate more than 50 uni knees a year have better outcomes than low volume centers.

In the first couple of months a warm and swollen knee joint can be expected with pain around the medial scar, but also alleviation of  osteoarthritic pain and gradual functional improvement in daily life. Normal walking, bike riding, fitness, swimming, and golf or tennis will usually be possible after 6 to 12 months, but unicompartmental  knee replacements  are not meant for long distance running or heavy kneeling activities (often the knee cap will remain quite sensitive in deep knee flexion).

Studies have shown that unicompartmental knee replacement patients can flex their knees on average 10 to 15 degrees more than total knee replacement patients. Technically many people with unicompartmental knee replacements can actually sit on their knees, and will do this sometimes in daily life during house chores in the kitchen or bathroom for instance. The knee cap will often remain quite sensitive though in extreme knee flexion angles (but less than in comparison with total knee replacement), and more importantly repetitive deep kneeling motions are not advised to prevent early wear or loosening.

The operation procedure itself lasts less than 1 hour, but because of preparation procedures before and observation in recovery afterwards you will spend several hours at the operation theatre unit. Within a Rapid Recovery protocol you will be mobilized out of bed on the ward as soon as possible though with help of the physiotherapist and nursing staff.

Most people will stay one night in the hospital, but day care treatment is possible as well for patients without any past medical history and who are very motivated themselves to do so.

The operative risks of unicompartmental knee replacement are the same as for total knee replacement: wound leakage, infection, thrombosis, fractures, nerve or vascular injury and loosening. The very low mortality risk after knee replacement is significantly lower for uni knees in comparison with total knee replacements though.

Nerve damage is a very rare complication that can occur after knee replacement in general. Numbness of the skin around the scar is experienced quite often in the early rehabilitation, but loss of power in the foot and ankle because of damage to the peroneal nerve is only seen sometimes in people with very complex leg deformities that need to be corrected during the same procedure as well.

Operative treatment should not be planned in case of mild arthritic symptoms (X ray does not show ‘bone on bone’ yet), a non-functional anterior crucioid ligament, symptomatic arthritic wear in other knee compartments as well, severe arthritic angular knee deformities, and systemic disease like rheumatoid arthritis for instance.

No, in case of a correct pre-operative indication also 80 and 90 year old patients will experience the same positive effects of unicompartmental knee replacement. Because of shorter operation time with less bloodloss (and more rapid recovery afterwards) unicompartmental knee replacements even have lower risk for complications like myocardial infarction and deep venous thrombosis.

See also this article for more information: https://pubmed.ncbi.nlm.nih.gov/28215968/

Even lang als een hele kunstknie indien geplaatst door ervaren knie orthopeed. Na 15 jaar is minder dan 1 op de 10 patiënten voor een tweede keer aan dezelfde knie geopereerd om uiteenlopende redenen, zoals infectie, slijtage, botbreuk of loslating. Wilt u nog meer weten over hemi knie protheses? Lees dan dit Engelstalige wetenschappelijke artikel met een samenvatting van recent wetenschappelijk onderzoek op dit gebied.

Bij de juiste indicatiestelling voor een halve kunstknie is het zeldzaam dat het andere kniecompartiment in die mate slijt, dat ook die helft vervangen moet worden. Technisch is het dan ook mogelijk om aan de andere zijde van het gewricht een halve kunstknie te plaatsen met nog steeds het behoud van de eigen kruisbanden.

Bij een tweede ingreep is een goed geplaatste halve knieprothese meestal te vervangen door een ‘normale’ hele knieprothese.

Rehabilitation questions

Yes, the first couple of months after the operation the knee joint will always be swollen in some extent due to a resorbing hematoma. This can give a warm or pressured feeling above the knee cap, and activity level should be adjusted to this natural healing reaction.

This is very variable in between patients, but most people use crutches for at least 2 to 6 weeks after uni knee replacement for support. As soon as possible you can start walking just with one crutch, and gradually extend your activities guided by any reactive swelling of the knee.

Biking is possible as soon as the wound had healed and flexion is possible more than 100 degrees without complaints, but getting on and of the bike in a safe manner should be practiced first. Driving a car is allowed when walking without crutches is stable, and the driver should be capable of performing an emergency brake situation.

After the first 2 to 3 months most swelling and wound pain will gradually subside, but the end result with regards to recovery can be expected after 10 to 12 months in total.

Low intensity sporting activities like walking, biking, fitness, tennis and swimming are possible for most patients with uni compartmental knee replacements. Deep kneeling and high impact sports like long distance running should be avoided though. A subgroup of highly active uni knee patients are also able to perform more intensive sports like skiing, football, skating and field hockey.

No, not in case of standard dental treatment but only in the presence of deep tooth infections or dental abscess.

Yes, possibly but standard security procedure should be followed anyway.

Yes, there is no problem for MRI scans after uni knee replacement.