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Dislocation risk and 90 degree rule

Discussion in '[library] Concerns after hip surgery' started by Josephine, Apr 4, 2011.

  1. Josephine

    Josephine NURSE DIRECTOR, BONESMART Administrator

    Member Since:
    Jun 8, 2007
    The North
    United Kingdom United Kingdom
    Generally, the 90 degree restrictions are for 6 weeks but don't take that as gospel! Some surgeons prefer more, some don't require any; so if you weren't told or have forgotten, please check with your surgeon .

    When a hip is replaced, for some time the muscles will be weak and have very little tone. This can cause the stability of the joint to be somewhat compromised and risk dislocations. In order of risk from day one, precautions includes the following:

    1. sleeping with a pillow between your legs - in abduction
    In hospital they will use a special triangular wedge sometimes called an abduction pillow or a Charnley wedge. This makes you keep your legs wide apart so lessening the risk of dislocation while your muscles are at their weakest. When you get home, you will be asked to substitute this with one or two pillows.

    2. The 90 degree restrictions
    This simply means not bringing your knee close to your body in order to reduce the risk of dislocation. Especially important if the approach used was posterior or lateral THR approaches or incisions.
    You can bend up to that point but not beyond it.

    This is 90 degrees of flexion at the hip

    If you're still confused, here's some comparisons to explain further

    flex to 0 a-horz.jpg

    And here is a chart explain some of the do's and don'ts!

    Retrieving things from the floor or feeding pets can still be done, just use the golfer's reach.

    As you can see, the operated leg is in a straight line with the body so not violating the rules. It's a very easy manoeuvre but do be careful the first few days and always hold on to something firm like the kitchen counter or an armchair until you are confident with it.

    3. no twisting
    This is also to avoid the risk of dislocation.
    When you want to turn round, don't spin on the ball of your foot but take many small steps to minimise risk.
    When you want to turn over in bed, try to keep your feet apart and avoid crossing one leg over the other

    4. no crossing legs
    This is always a good idea after any surgery, even an ENT job! Having an anaesthetic temporarily increases your risk of blood clots. Laying with one foot on the other ankle can restrict blood flow in the both legs so it's best avoided!
    However, in a hip replacement, this can also put the new hip at risk of dislocation

    5 Reaching to a bedside table
    This often involves half turning the body and causing the leg on the opposite side to roll inwards which puts the hip at risk of dislocating. For this reason, nurses will often place the bedside table on the same side as the operated hip.

    6. Sliding scale of dislocation risk
    The biggest worry THR patients have is that of dislocation. But the risk is simply that - a risk. And that risk, while worst in the first few days, reduces as the weeks of healing go by.

    Why is a hip at more risk of dislocating after a replacement than before?
    The surgery requires part of the joint capsule to be excised. The capsule is a fibrous bag which encompasses the joint and keeps all the joint fluid in place. It also contributes to the stability of the joint and, with the many small but strong muscles that surround it, keeps the joint from dislocating. When a new metal joint is put in place, eventually other fibrous material grows around the joint and takes the place of the excised capsule. This is known as 'psuedo' (or false) capsule.

    After about a couple of months, the muscles will have regained much of their strength and tone and the new 'pseudo' capsule has formed, the joint will be as secure as a normal one and you should be able to do pretty much do anything you want to.

    Getting in and out of a car without breaking the 90 degree rule
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