Myth busting: "window of opportunity" in TKR


Nurse Director
Jun 8, 2007
The North
United Kingdom United Kingdom
This "six week window of opportunity" surgeons often speak about is little more than a myth. It presupposes that all patients have the ability to create adhesions which is far from the truth. It also ignores the simple fact that in the first 3-4 weeks after surgery, swelling reactive to the surgery is inevitable and that sometimes it is excessive for no reason apparent to the patient.

What patients don't realise is how their knee is cut about, hammered and sawed, the soft tissues are pulled aside and stretched and that of course it is going to swell. But swelling acts like a plaster cast and prevents the leg from bending. So you might get 90 degrees the day or two after surgery and then become devastated that it drops to 80 or even 70 shortly afterwards. This is when PTs often come along and start telling you to fight hard to get your ROM back, even aggressively pushing on your knee to show that it can be done. All that then happens is that the knee swells even more and any increase the PT obtained is quickly lost again.

So here is a list of do's and don'ts:

Some Dos

Do read the thread on healing and understand why your knee is taking such a long time to settle down Healing: how long does it take?

Do follow the BoneSmart Guidelines, rest, elevate, ice and take your pain meds by the clock and read the thread Pain and swelling control: elevation is the key

Do accept that your sleep patterns and your emotional well being is going to be really upset by all this Post op blues is a reality - be prepared for it.​

Do be prepared to accept that this is all normal.​

Some Don'ts

Don't get depressed and anxious because you end up in pain after PT. It should be gentle, pain free and work on reducing the swelling, not punishing you.​

Don't think you should be getting on with housework, laundry and preparing meals for the family, etc., - this is YOU time and you should be resting not working. Getting up and going to the bathroom, getting yourself a drink or a snack and doing some gentle exercises - Home physio (PT) and activity progress: suggestions - on your own is quite sufficient in the first 3-4 weeks or until the swelling and pain are under control​

Don't think you should go for a one mile hike because the surgeon or PT said walking is good therapy! 5 mins several times a day around the house is good for the first week, up it to 10 mins 3-4 times a day in the garden for the second week and then start taking 15-30 mins o1-2 times a day in the road for week 3 and 4. All with walker, crutches or cane as you feel confident.​

Don't ever cut back on your pain meds because you are worried about getting addicted Myth busting: on getting addicted to pain meds

Now for some scientific papers on this problem.
Some key statements have been underlined for emphasis.

MUA (Manipulation under Anaesthetic) and Adhesions
Esler, Lock, Harper and Gregg JB&JS (UK)
NB. This was an unrandomised study conducted in 1999.
It should therefore be taken in the context of it being an old work.

As part of a prospective study of 476 total knee replacements, the use of MUA (manipulation under anaesthesia) was assessed in 47 knees. (incidence of 0.1%)
MUA was considered when intensive physiotherapy failed to increase flexion to more than 80°. Average time from surgery to MUA was 11 weeks.

Minimal ROM requirements
Laubenthal, Smidt and Kettelkamp assessed the amount of flexion necessary for everyday activities and found that the general degree of flexion required
to climb stairs was 83°
to sit 93°
to tie a shoelace 106°​

The long-term benefits of manipulation under anaesthesia (MUA) after TKR have been questioned.

The known complications of manipulation, including supracondylar fracture, avulsion of the patellar tendon, myositis ossificans and wound breakdown, and may further compromise poor results.

These occur, however, in fewer than 3% of patients.

Our aim was to evaluate the use of MUA in patients whose maximum flexion was less than 80° despite intensive physiotherapy.

At MUA, they achieved an average gain in flexion of 37° but after one week only 17° of this remained.

After one year, the average gain in flexion was only 13°.

A retrospective study of 17 patients who had bilateral TKRs but MUA in only one knee led them to conclude that the procedure did not increase the ultimate range of flexion after TKR.

CPM machines
Several studies have shown that the use of a CPM machine immediately after arthroplasty does not affect the end result ROM but may increase the rate at which flexion is regained.

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