The hip joint is a ball-and-socket structure, enabling a wide range of human movement. The femoral head, or ball, sits at the top of the thigh bone, while the acetabulum, or socket, is a cup-shaped part of the pelvis. Smooth cartilage covers these surfaces, allowing for effortless motion. However, conditions that disrupt this alignment can lead to pain and limitations. When the hip’s mechanics are compromised, individuals may experience discomfort and reduced mobility, prompting interventions to restore function and preserve joint health.
Understanding Periacetabular Osteotomy
Periacetabular osteotomy, often called PAO, is a surgical procedure that corrects issues from an improperly formed hip socket. “Periacetabular” means “around the acetabulum,” and “osteotomy” refers to a surgical cut in bone. This procedure primarily addresses hip dysplasia, also known as developmental dysplasia of the hip (DDH), where the acetabulum is too shallow or incorrectly oriented to adequately cover the femoral head.
In hip dysplasia, insufficient femoral head coverage leads to joint instability. This misalignment causes increased stress on the joint cartilage and the labrum, a ring of soft tissue around the socket, which can result in pain, limping, and tears. Over time, this abnormal loading accelerates wear and tear, potentially leading to early-onset osteoarthritis, a painful condition characterized by cartilage degeneration and reduced range of motion. PAO serves as a joint-preserving surgery, aiming to prevent or delay the progression of such degenerative changes by improving the hip’s biomechanics.
The purpose of PAO is to reorient the hip socket for better femoral head coverage, creating a more stable and functional hip joint. By repositioning the acetabulum, the surgery redistributes pressure across the joint surfaces, which alleviates pain and enhances hip function. This correction helps restore the hip’s natural mechanics, allowing the ball and socket to fit together more securely and reducing abnormal forces that contribute to joint damage.
The Surgical Procedure
During a periacetabular osteotomy, the patient receives general anesthesia. The surgeon makes an incision in the front of the hip, allowing access to the pelvic bone surrounding the hip socket. This approach involves carefully separating muscles to expose the bones while protecting nerves.
The procedure involves making precise cuts, known as osteotomies, in the pelvic bone around the acetabulum. These cuts are strategically made in three areas of the pelvis: the ischium, pubis, and ilium, freeing the hip socket from the rest of the pelvis while maintaining its blood supply. Real-time X-ray imaging guides the surgeon for accuracy during these bone cuts.
Once detached, the surgeon reorients the acetabulum to achieve optimal femoral head coverage. This repositioning is critical for improving hip joint stability and addressing underlying dysplasia. After the ideal position is established, the reoriented acetabulum is secured to the pelvis using specialized screws, which hold the bone in its new alignment while it heals. Bone graft material may be added to fill spaces, facilitating bone regrowth. The surgical team may also address other hip issues, such as labral tears, during the same procedure.
Recovery and Rehabilitation
Following a periacetabular osteotomy, patients typically remain in the hospital for two to five days. Pain management begins immediately, often with an epidural catheter for the first 24 hours, followed by oral pain medication. Early mobilization is encouraged, with physical therapy often starting the day after surgery.
Patients learn to walk with assistive devices, such as crutches or a walker. Partial weight-bearing, often limited to around 20-25% of body weight, is maintained for approximately six to eight weeks to allow the newly positioned bone to heal. During this period, physical therapy focuses on gentle range-of-motion exercises and protecting the hip flexor muscles.
As healing progresses, patients gradually advance to full weight-bearing and can often walk without crutches. Outpatient physical therapy, which may last four to six months, is crucial for regaining strength, restoring full range of motion, and improving overall hip function. The rehabilitation program emphasizes strengthening the muscles around the hip and pelvis to ensure proper integration of the realigned joint into daily activities.
Expected Long-Term Results
Patients undergoing periacetabular osteotomy can anticipate significant improvements in their hip health in the years following surgery. A primary outcome is a substantial reduction in hip pain, which often allows individuals to return to various activities, including sports. The procedure aims to enhance overall hip function and improve quality of life.
The long-term goal of PAO is to preserve the natural hip joint and deter the development or progression of hip osteoarthritis, a common consequence of untreated hip dysplasia. By correcting the underlying mechanical instability, the surgery reduces abnormal forces on the joint cartilage, thereby extending the life of the native hip. Studies indicate that a high percentage of patients report satisfaction with their pain relief and ability to perform daily and recreational activities many years post-surgery.
While PAO is highly effective in preserving the joint, some individuals may still develop osteoarthritis over time, potentially necessitating a total hip replacement later in life. However, the surgery is considered successful if it delays this outcome, especially in younger patients. The durability of the procedure is generally favorable, with high survivorship rates of the native hip for 10 to 15 years or more after the operation.