Hip replacement surgery is a common and successful procedure used to relieve pain and restore mobility in a damaged hip joint. Following this operation, patients are given a set of instructions known as hip precautions to protect the new joint from damage. These instructions are designed to prevent a complication called hip dislocation, where the ball of the new hip joint pops out of the socket. The need for these specific rules depends heavily on the surgical approach the surgeon used to access the joint. This article focuses on the specific instructions required after a posterior approach hip replacement.
Understanding Why the Posterior Approach Requires Restrictions
The hip joint is a ball-and-socket structure, and accessing it surgically requires moving or cutting surrounding muscles and soft tissues. The posterior approach involves making an incision along the back of the hip, near the buttocks. To reach the joint capsule, the surgeon must separate or release certain soft tissues, including the short external rotator muscles and the posterior capsule of the hip joint.
This necessary disruption temporarily weakens the posterior side of the joint, making it less stable immediately after surgery. The new joint is therefore at higher risk of dislocating backward until the soft tissues have had time to heal. The purpose of the precautions is to prevent the hip from entering the specific combination of movements that stress this newly repaired posterior capsule.
The Three Critical Movements to Avoid
To maintain the stability of the healing joint, patients must strictly avoid three distinct movements that are known to put the new hip at risk of dislocation. The first is avoiding hip flexion beyond 90 degrees, which means the angle between the torso and the thigh should not be less than 90 degrees. This restriction prevents the thigh bone from pushing the ball of the joint backward out of the socket.
Practically, this means patients must not lean forward while sitting, and they should not sit on low furniture, including low chairs, couches, or standard toilet seats. Bending down to tie shoes, pick up dropped items, or pull up blankets can also violate this rule and must be avoided. Using assistive devices like a reacher, a long-handled shoehorn, and a raised toilet seat is highly recommended to safely manage daily activities.
The second restricted movement is adduction past the midline, which is the act of crossing the operated leg over the other leg. Allowing the thigh to move across the center line of the body places excessive stress on the joint capsule. This applies when sitting, standing, and especially when lying down in bed.
Patients are often instructed to sleep on their back and use a pillow or wedge between their knees to ensure the legs remain separated and prevent accidental crossing. Even casually crossing the ankles while resting is considered a breach of this precaution and should be avoided.
The third movement to avoid is internal rotation, which is turning the operated leg and foot inward. This motion, particularly when combined with the other two restricted movements, positions the ball of the joint to slip out the back of the socket. Patients should consciously keep their toes pointed forward or slightly outward when walking, sitting, or rolling in bed.
Pivoting on the operated leg is also restricted, so patients should take small steps to turn their entire body rather than twisting at the hip. Performing all three movements—flexing the hip past 90 degrees, crossing the leg, and turning the foot inward—at the same time creates the highest risk for a posterior hip dislocation.
Duration and Clearance for Reducing Precautions
The duration for which a patient must follow these posterior hip precautions varies based on the surgeon’s protocol. Generally, the standard period of restriction is between six and twelve weeks after the operation. This timeframe is necessary for the soft tissues, including the repaired posterior capsule and external rotators, to achieve sufficient healing and stability.
Some surgeons may modify the timeline, sometimes reducing it to four weeks or extending it up to three months, depending on the surgical technique and the overall health of the patient. Patients should not make the decision to discontinue the precautions on their own. The final clearance to relax or completely stop the restrictions must come directly from the orthopedic surgeon or the physical therapy team, confirming the joint has achieved sufficient stability.