Total hip replacement (THR) surgery is a common and effective procedure that relieves chronic pain and restores mobility. A successful long-term outcome relies heavily on strict adherence to post-operative guidelines, particularly in the initial recovery period. Daily activities, such as sitting on a sofa, must be approached with caution to protect the new hip joint. This careful navigation is necessary to allow the soft tissues surrounding the prosthetic joint time to stabilize fully.
Key Hip Movement Restrictions
The primary danger to a new hip joint in the early weeks is dislocation, where the ball component separates from the socket. Surgeons prescribe specific movement limitations, often called hip precautions, to prevent this. The most widely known restriction is the 90-degree rule, meaning the hip should never be bent more than 90 degrees. This angle is easily exceeded when sitting on a low surface, significantly increasing the risk of dislocation.
Patients must also actively avoid crossing the legs (hip adduction) and excessive internal rotation. These restrictions are particularly important for those who underwent the traditional posterior approach. The low height and soft cushions of a typical sofa encourage the very hip flexion and rotation movements that must be avoided.
Determining the Safe Timeline
The timeline for safely using a low sofa must be cleared by the surgical team. Most surgeons recommend strictly following hip precautions for the first six to twelve weeks after surgery, as this is when the risk of dislocation is highest. The exact duration depends on the specific surgical technique used, such as the muscle-sparing anterior approach versus the posterior approach.
Clearance to resume activities like using lower seating is often provided during a follow-up appointment after reviewing a post-operative X-ray. This imaging confirms the prosthetic components are stable and the surrounding bone is integrating. Until a doctor advises otherwise, all seating surfaces should be elevated to ensure the hips remain higher than the knees, preventing the 90-degree angle.
Techniques for Safe Seating
Modifying the Seating Surface
When the surgical team permits the use of a lower seating surface, modifications are necessary. The first step involves raising the seat height significantly, often requiring firm, dense cushions or blocks placed on the seat. This ensures the hips are higher than the knees. Avoid using soft, deep cushions or a recliner, as these surfaces cause the body to sink, violating the 90-degree rule and reducing stability.
Sitting Down Safely
Approach the modified sofa backward until the back of the non-operated leg touches the edge of the seat. The operated leg must be kept slightly extended forward throughout the process to prevent the hip from bending too much. Use the armrests or an assistive device like a walker to support the body weight and lower down slowly. Avoid leaning the torso forward, as this action can cause the hip to flex beyond the safe limit.
Standing Up Safely
To stand up, the process is reversed while maintaining hip precautions. Scoot forward to the very edge of the seat, ensuring the operated leg remains extended slightly forward. Push straight up using the armrests for leverage and support, keeping the weight on the non-operated leg as much as possible. This technique avoids flexing the hip joint excessively and maintains the necessary safe angle.
When to Contact Your Doctor
Symptoms require immediate medical attention, as they can signal a serious complication like joint dislocation or infection.
Signs of Dislocation
A sudden, severe pain in the hip or groin, sometimes accompanied by a popping or grinding sensation, is a warning sign. This may be followed by an inability to bear weight on the operated leg or a noticeable change in the leg’s position, such as appearing shorter or rotated.
Signs of Infection
Signs of infection at the surgical site should be reported immediately. These symptoms include:
- A fever
- Persistent or worsening pain that does not improve with rest
- Increased warmth or redness around the incision
- Pus or excessive drainage from the wound
Reporting these changes quickly allows for effective diagnosis and treatment to protect the new joint.