A Periacetabular Osteotomy (PAO) is a complex surgical procedure designed to correct structural abnormalities within the hip joint. The primary goal of a PAO is hip preservation, aiming to prevent or significantly delay the onset of hip osteoarthritis, particularly in young adults. This surgery focuses on reorienting the hip socket, the acetabulum, to improve its relationship with the ball of the joint, the femoral head. It addresses the underlying cause of mechanical instability and pain.
Understanding Hip Dysplasia
The condition most frequently addressed by a PAO is hip dysplasia, also called acetabular dysplasia. This structural abnormality means the acetabulum, the cup-shaped socket, is too shallow or incorrectly angled. This insufficient coverage means the femoral head does not sit securely within the socket.
The lack of proper coverage leads to abnormal mechanical forces and instability. Instead of the weight-bearing load being distributed evenly across the cartilage, it becomes concentrated on a small area, often the rim. This focused stress causes increased wear and tear on the joint cartilage and can lead to tears in the labrum, the thick ring of cartilage surrounding the socket.
This abnormal wear accelerates the breakdown of the joint’s protective tissues, resulting in painful osteoarthritis at a younger age. PAO corrects the underlying mechanical problem before advanced, irreversible arthritis sets in.
The PAO Procedure Explained
The PAO surgery involves precisely cutting and repositioning the entire acetabulum. The procedure is typically performed through a single incision over the hip.
The surgeon performs a series of controlled bone cuts in the pelvis to completely free the socket from the surrounding bones. These cuts are strategically made in the ilium, ischium, and pubis, the three bones that form the hip socket. This process ensures the blood supply to the freed acetabular fragment remains intact.
Once the acetabulum is mobilized, the surgeon rotates and repositions the socket into a more favorable position. This adjustment is guided by X-ray imaging in real-time, ensuring the new position provides optimal coverage and stability for the femoral head. The goal is to redistribute the weight-bearing forces over a larger surface area of the joint cartilage.
The re-positioned acetabulum is then secured to the rest of the pelvis. Fixation is typically accomplished using three or four specialized screws. These screws hold the bone fragment firmly in its new alignment while the cut bone surfaces heal and fuse together, a process that can take several weeks to months.
The Recovery and Rehabilitation Process
The recovery following a PAO is a multi-stage process that begins immediately after the surgery. Patients typically require a hospital stay of three to five days for initial pain management and mobilization. Pain control is managed with a combination of medications, including nerve blocks and oral analgesics, to facilitate early movement.
Initial mobility is restricted, and patients are instructed to use crutches. Weight-bearing on the operated leg is usually restricted for the first six to eight weeks to protect the bone cuts while they heal. During this period, physical therapy (PT) begins with gentle range-of-motion exercises.
The intermediate phase of rehabilitation, starting around four to six weeks, focuses on gradually increasing weight-bearing and strengthening the surrounding hip muscles. PT is a necessary component of the recovery, aiming to restore muscle strength and full range of motion. Patients typically transition to unassisted walking between six and twelve weeks post-surgery.
Returning to daily activities, such as driving or light work, can take approximately two to four months. For athletes, the full recovery and return to high-impact sports often takes six to twelve months. Follow-up appointments and X-rays monitor the bone healing and ensure the successful integration of the repositioned socket.