The 90% rule with hip replacement is actually the 90 degree rule, which is a crucial post operative precaution you should take after a hip replacement.
The 90 degree hip replacement rule states that you must not bend your hip past a right angle, which means that your thigh and your torso should never form an angle of less than 90 degrees.
The reason for this, is that it prevents excessive stress on your new joint after the hip replacement surgery and it also significantly reduces your risk of dislocation.
The 90 degree hip replacement rule applies and is often enforced for the first 6 weeks to 12 weeks after the hip replacement surgery.
The 90 degree hip replacement rule is also primarily standard for posterior approach.
And direct anterior hip replacements often don't require the restriction of the 90 degree hip replacement rule.
You should also avoid any deep bending, which is vital during early recovery from a hip replacement, to allow the surrounding muscles to heal.
After a hip replacement, you should also take other daily life precautions which include not sitting on or in low chairs, soft couches, or low toilet seats.
Instead use raised toilets seats and firm, elevated cushions so that the hips remain higher than your knees.
And never bend over at your waist past 90 degrees to pick things up or tie your shoes.
You should instead use what is known as the "golfers bend" which means to keep your leg that was operated on for the hip replacement straight back and then bend the good leg or use a grabber.
And never cross your legs or your ankles, whether you're sitting, standing or lying down and keep a pillow between your knees when sleeping.
When getting in and out of cars after a hip replacement, you should slide into the seat of the car with your legs extended, and avoid twisting your torso.
The 90-degree bending restriction after hip replacement surgery, typically lasts for 6 to 12 weeks post-surgery, depending on your surgeon’s guidelines and the surgical approach used.
This rule protects the new joint from dislocation while the surrounding muscles and soft tissues heal.
The safest position to sleep after a hip replacement is on your back with a pillow between your legs to prevent the hip from twisting or crossing the midline.
Avoid sleeping on your stomach or directly on the operated hip for at least 6 weeks, or until your surgeon clears you.