Direct Anterior Hip Replacement

Hip replacement is considered one of the most successful procedures in orthopaedic surgery today. The vast majority of patients notice much less pain, with improved function, once they have recovered.

During hip replacement the worn out ball and socket of the hip joint are replaced with a titanium prosthetic device. The bearing surface is usually ceramic on plastic. This eliminates the bone on bone pain which is typical of the worn hip.

The “traditional” method of inserting a hip prosthesis involves a long incision over the backside of the hip. The gluteus muscle is separated, and the cuff of tendons called the “short external rotators” are cut off the back of the hip joint. The hip is then dislocated and the surgery is performed. After the prosthesis is in, there is an attempt to repair the rotator muscles back to the hip, and the gluteus muscle is repaired. This approach is called the “posterior” approach. The patients are laying on their sides during this procedure, which can also make it difficult to obtain reproducible positioning of the implants.

Because of the muscle releases, movement precautions are necessary during the recovery phase to avoid dislocation of the hip. Postoperative dislocations will occur in anywhere from 2 to 5 percent of patients with posterior approaches. Over the course of the lifetime of the replaced hip, it is thought that the chance of a dislocation occurring is close to 7 percent.

A different approach, called the “anterior” approach, was developed to try and improve on the results of traditional hip replacement. The anterior approach utilizes a natural separation between two muscles in front of the hip. The two muscles are the tensor fascia lata, and the rectus femoris. No muscles have to be cut off the hip in this approach. We use a modification of the operating room table in order to gain exposure to the hip joint. Because the patient is laying flat on the operating room table we are able to utilize a special X-ray device called a “C-arm”. The implants are placed while watching with the C-arm. This allows very accurate and reproducible positioning of the hip components. Once the implants are in, the hip is extremely stable, and dislocation is difficult. No movement precautions are necessary after surgery. The postoperative dislocation rate is somewhere in the 0.2 percent range.

In addition to the improved stability of the hip and the improved implant position, the orthopedic literature suggests that the recovery can be quicker with the anterior approach. My impression of how patients do after surgery mirrors a study done recently at the mayo clinic. They found the following differences between the anterior and posterior approach in regards to recovery:

Discontinuing use of a walker (10 days after surgery versus 14.5 days)
Discontinuing use of all gait aids (17.3 versus 23.6 days)
Discontinuing use of narcotics (9.1 versus 14 days)
Ascending stairs with gait aid (5.4 versus 10.3 days)
Walking six blocks (20.5 versus 26 days)

This tendency for a quicker recovery is a nice bonus for the anterior approach, in addition to the other benefits that I noted above.

Of course complications can occur with any surgical procedure, and hip surgery is not immune to these. Infection, dislocation, fracture, blood clots, and medical problems are rare, but can occur with surgery.

However, my overall complication rate for hip surgery is one of the lowest in the west Michigan area. In fact, I have found that I am able to perform the minimally invasive anterior approach safely as an outpatient for younger, healthy patients with no increase of complications.

Having performed hundreds of direct anterior hip replacements, I'm convinced that my patients do better with this technique. I believe that as more surgeons are trained in the technique, most hip surgeries in the future will be done anteriorly.

Incision made over the interval
between the tensor fascia lata muscle
and the rectus femoris. The interval
is then separated, leaving the
muscle attachments intact.

Templating measurements taken.

Completed hip surgery.