Total hip arthroplasty (THA) is a common and highly successful procedure designed to replace the damaged ball-and-socket structure of the hip joint. Patients often seek this surgery to eliminate chronic pain and restore mobility. A frequent concern is whether the procedure will alter their physical appearance by making their hips wider. The direct answer is that the surgery does not structurally widen the hips, as its purpose is to fix the internal mechanics of the joint.
How Hip Replacement Affects Skeletal Dimensions
Total hip replacement surgery involves removing the arthritic femoral head and resurfacing the acetabulum (hip socket) with prosthetic components. These implants are positioned deep within the hip joint, inside the pelvis and the upper femur bone. The surgeon’s goal is to precisely restore the original joint’s center of rotation and biomechanical alignment, not to increase the external size of the body.
The bony width of the hip is primarily determined by the distance between the two greater trochanters, the large bony knobs felt on the side of the upper thigh. During THA, the surgeon selects components that closely match the patient’s native anatomy using pre-operative X-rays. Although the new components are made of metal, ceramic, or plastic, they are sized specifically to fit the existing bone structure.
Surgeons aim to restore the femoral offset, which is the horizontal distance from the center of the hip joint to the center of the femur. This restoration ensures proper muscle tension and joint stability. This restoration of offset may sometimes result in minor leg lengthening of less than one centimeter, but it is done to prevent dislocation, not to intentionally widen the body. The bone structure itself, which dictates the long-term width, is maintained.
Addressing Post-Surgical Swelling and Temporary Appearance
Although the underlying bone structure does not widen, many patients experience a temporary increase in size around the hip and upper thigh immediately following the procedure. This is a normal part of the healing process caused by soft tissue response to surgical trauma. The fluid accumulation is known as edema, which is the body’s inflammatory reaction, along with potential hematoma formation.
This influx of fluids, including blood and lymph, causes visible swelling that can make the hip look or feel larger in the weeks and months after surgery. Swelling typically peaks a few days post-operation and then gradually subsides as the body reabsorbs the fluids. While most of the swelling resolves within a few weeks, mild to moderate inflammation can persist for up to three months. This temporary increase in dimension is entirely due to soft tissue changes, not the prosthetic hardware.
Correcting Gait and Changes in Perceived Width
A patient may perceive a change in their hip width due to the correction of long-standing physical compensations. Before surgery, chronic arthritis often causes patients to develop an antalgic gait (limp) to avoid pain. This gait can be accompanied by a pelvic tilt or functional leg length discrepancy, causing the patient’s posture to compensate for the joint damage.
The success of THA lies in restoring the correct mechanical axis, which allows for a straighter, more balanced posture and gait. When the new joint enables the pelvis to level out and the leg length to be equalized, the body moves differently, often eliminating a previous side-to-side sway or limp. This correction of pre-existing asymmetry can make the hip area feel or appear different to the patient. However, this is a return to a more natural alignment, not an anatomical widening. The perceived change results from improved walking mechanics and corrected posture.