Though still uncommonly used in the United States, the popularity of the anterior approach for total hip replacement is rapidly growing because of its definite advantages for patients, even those in need of bilateral procedures. Rehabilitation is simplified and accelerated, dislocation risk is reduced, leg length is more accurately controlled, and the incision is small.
Why, then, is this approach not more widely used by U.S. surgeons? There are several reasons: lack of familiarity, traditional teaching, and lack of the necessary instrumentation and equipment. The anterior approach is especially facilitated by the HANA and PROfx operating tables. The unique functions of these tables enhance access to the hip through this small, soft tissue preserving incision.
The anterior approach is an approach to the front of the hip joint as opposed to a lateral (side) approach to the hip or posterior (back) approach. This anterior approach follows the lower half of the interval of the Smith-Peterson approach, making it a true anterior approach to the hip. It should not be confused with the Harding approach, which is often referred to as an anterior approach, but involves a lateral incision.
Rehabilitation is accelerated and hospital time decreased because the
hip is replaced without detachment of muscle from the pelvis or femur. Other surgical approaches necessitate detachment of muscle from the femur during surgery. In the anterior approach, by contrast, the hip is approached and replaced through a natural interval between muscles. The most important muscles for hip function, the gluteal muscles that attach to the posterior and lateral pelvis and femur, are left undisturbed.
Lack of disturbance of the lateral and posterior soft tissues also accounts for immediate stability of the hip and a low risk of dislocation. It is normal for patients undergoing lateral or posterior incisions to follow strict precautions that limit hip motion for the first two months after surgery. Most importantly, they are instructed to limit hip flexion to no more than 90 degrees. These limitations complicate a patient's simple daily activities such as sitting in a chair or on the toilet or getting in a car. Following the anterior approach, however, patients are immediately allowed to bend their hip freely and avoid these cumbersome restrictions. They are instructed to use their hip. Additionally, if patients are sexually active before surgery, there are no limitations on resumption of normal sexual activity after surgery.
Another advantage of the anterior approach is that for patients who require bilateral hip replacement, this can be performed during a single operative session. With the patient in the supine position (as opposed to lateral with standard techniques) both hips are simultaneously prepared and then the hips replaced successively. The muscle preservation and absent post operative restrictions also makes bilateral replacement more possible. Patients often prefer the one hospitalization and one visit to the operating room over staged hospitalizations and procedures.
The normal incision is about 4 inches but may vary (shorter or longer) according to a patient's body size. Though small incisions are often considered desirable by patients, it should be kept in mind that the degree and type of
tissue disturbance beneath the skin is a more important factor. Incisions of
adequate length allow the necessary side-to-side separation of the incision without undue force. Too small an
incision can be more traumatic to the tissues, particularly to muscles that can be damaged by stretching too hard.
With the anterior approach the patient lies supine (on their back) during surgery. X-rays taken during surgery with a fluoroscope ensure correct position, sizing and fit of the artificial hip components, as well as correct leg length.
The anterior approach does not limit the patient's and surgeon's options regarding type of hip prosthesis. Hip prostheses that are implanted with or without cement are applicable as well as all modern bearing surfaces including ultra high density polyethylene, metal and ceramic. Surface replacement arthroplasty is also possible through the anterior approach.
Possible complications of anterior hip replacement surgery include infection, injury to nerves or blood vessels, fractures, hip dislocation and the need for revision surgery.
Evaluation and treatment by a physical therapist begins following
surgery and leads to walking and functional activities. Patients may go home after achieving an initial degree of independence in walking with crutches or a walker, as well as capabilities in basic day to day activities. Patients are commonly discharged 1 to 3 days following surgery depending on their degree of disability prior to surgery and their overall capabilities.