Total hip arthroplasty (hip replacement surgery) is a highly successful procedure that replaces a damaged hip joint with an artificial one. This surgery removes the painful, worn-out ball-and-socket joint and replaces it with prosthetic components to restore mobility and eliminate chronic pain. Following the operation, specific post-operative precautions are given to prevent the new joint from dislocating, a rare but serious complication. The instructions provided by your surgeon and physical therapist must always take precedence over any general advice.
Addressing the Need for Leg Elevation
The question of sitting with your legs up after a hip replacement involves two competing factors: comfort and joint protection. Many patients wish to elevate their legs to manage post-operative swelling (edema), which is common in the days and weeks following the procedure. Elevating the affected limb helps reduce this swelling by promoting the return of fluid toward the body’s core.
However, sitting in a standard chair and raising the legs usually forces the hip joint into excessive flexion (bending). Hip precautions strictly prohibit bending the hip past a 90-degree angle, known as the 90-degree rule. Propping your feet up on an ottoman or another surface almost always makes the angle between your torso and thigh less than 90 degrees, significantly increasing the risk of prosthetic joint dislocation.
Safe leg elevation must be achieved without violating the 90-degree angle. The safest method involves lying supine (on your back) in a bed with the foot slightly elevated, or by using a wedge cushion under the lower leg to achieve a gentle incline. If sitting, use a specialized recliner designed to keep the hip angle open and greater than 90 degrees, ensuring the knee never rises above the hip level. Any attempt to elevate the legs must maintain the principle that the hip joint should be positioned higher than the knee joint.
Essential Movement Restrictions
The restrictions placed on movement after hip replacement are known as hip precautions. They exist because certain movements can force the ball of the new joint out of the socket. The most widely known restriction is the 90-degree flexion limit, which prevents the hip from bending too far. This rule applies to all activities, including sitting, bending down, or leaning forward to pick up an object.
Another movement to strictly avoid is internal rotation, which means twisting the operated leg inward so the toes point toward the midline of the body. This twisting motion can destabilize the joint capsule and is a common mechanism for dislocation. Patients must also avoid crossing the operated leg over the other leg, either at the knee or the ankle, as this places leverage and rotational strain on the hip.
The specific set of precautions is influenced by the surgical approach used. Patients who undergo the posterior approach (the most common technique) typically have the strictest restrictions because this involves cutting through muscles and tendons that stabilize the back of the hip. Conversely, the anterior approach is a muscle-sparing technique that often results in fewer precautions, sometimes only requiring the patient to avoid moving the leg backward or into external rotation.
Creating a Safe Sitting Environment
Adhering to hip precautions requires significant adjustments to the physical environment, particularly regarding sitting. The height of the sitting surface is of utmost importance; the chair must be high enough to ensure the hips remain positioned higher than the knees. Use a firm, straight-backed chair, and avoid soft couches or low chairs, as they cause the hip to flex past the 90-degree limit.
If a chair is too low, the seat height can be increased by placing firm cushions or blocks on the seat. Assistive devices are necessary to prevent unsafe bending motions. These include long-handled reachers and shoehorns, which allow you to manage tasks without flexing the hip. An elevated toilet seat is also standard equipment to maintain the required open hip angle during bathroom use.
The technique for transitioning from sitting to standing is important for joint protection. When sitting down, back up until the chair touches the back of your non-operated leg. Then, extend the operated leg slightly forward before slowly lowering yourself. To stand up, keep the operated leg extended forward and use the armrests to push up, avoiding any forward lean of the torso.
The Timeline for Easing Restrictions
The duration for which hip precautions must be followed is not fixed and depends on the surgical approach and the surgeon’s preference. Generally, patients maintain these restrictions for six to twelve weeks post-surgery. This timeframe allows the soft tissues, ligaments, and muscles surrounding the new joint to heal and regain stability.
The six-week mark is a common checkpoint, with some surgeons lifting or modifying restrictions. The decision to ease precautions is based on a clinical assessment of the patient’s healing progress, muscle strength, and the overall stability of the new joint. Recovery progression is gradual, often involving a structured physical therapy program that slowly reintroduces greater ranges of motion.
A physical therapist guides the patient through a transition phase, gradually strengthening the muscles and ensuring the new joint can tolerate increased activity. Even after formal precautions are lifted, maximum improvement in function and strength may continue for up to a year following the operation. Following the specific guidance from your healthcare team is the best way to ensure long-term success and stability of the hip replacement.