Anterior Hip Replacment
Anterior total hip arthroplasty offers significant advantages over standard hip replacement. Although the implants are similar and designed with the same goal in mind, the manner in which they are placed benefits the patient and their recovery. This technique simply allows an accelerated recovery with less need for rehabilitation after surgery. Additionally, the risk of a hip dislocation is less and finally the accuracy of reproducing symmetric leg lengths is improved.
The anterior approach for total hip replacement is performed through an 11cm incision on the front of the hip joint as opposed to a lateral approach to the hip or posterior approach. The anterior approach utilizes the inferior limb of a surgical approach described by Smith-Peterson. This is different from the Harding approach, which has been commonly called an anterior approach that uses a lateral-based incision.
One might then ask then, how come this approach not more commonly performed? The primary reason is due to lack of familiarity and of the necessary instrumentation and equipment. In order to effectively and properly perform the surgery, the PRO-fx operating table is essential. The table has specific attachments to assist the surgeon in peforming the hip replacement via a minimal incision surgery which is muscle preserving.
- Implant ComponentsIn the total hip replacement procedure, each prosthesis is made up of two major parts. The femoral component is a metal shaft with a ball on the end and replaces the top of the femur. The acetabular component replaces the socket side of the joint and is made of a metal cup and plastic liner
- <strong">The ProcedureBefore you are taken to the operating room you'll be given medication to help you relax, and the anesthesiologist will talk with you about the medications he'll be using. In the operating room, you will be placed under full anesthesia
Once you are "under" the surgeon will begin by making an incision in your leg to allow access to the hip joint. He'll then expose the joint and place a cutting jig or template on the end of the femur, or thigh bone. This jig allows the surgeon to cut the bone precisely so that the prosthesis fits exactly. Once the femur is cut, the inside of the bone will be prepared so that it closely matches the shape of the femoral shaft your surgeon has selected. Then the the cup portion of the pelvis is prepared with cutting tools so that the metal cup will fit exactly
Now it's time to place the prostheses. This begins with the femoral prosthesis. For some patients, an acrylic cement called Polymethylmethacrylate (PMMA) will be used for the fixation. This cement has been used successfully by orthopedists for over 25 years. It is a strong material, well-tolerated by the body and sets or cures within 15 minutes after it is mixed. Before curing, the cement is pressure-injected and the implants are seated.
For other patients, the implants are able to be affixed to the bones without cement. Special surgical instruments are used to precisely prepare the bones so as to enable a press fit. To supplement this joining, suportive screws or pegs are often used. Bone is a living and growing tissue. If an implant coated with metallic beads to form a porous undersurface is placed in very close contact to living bone, tissues can grow into the pores, further locking the implant in place. Porous-coated hip prostheses have been used for many years and have shown excellent results in many patients.
Finally, the incision is closed, a drain is put in, and the post-operative bandaging is applied.
The standard surgical incision is about 11 centimeters in length. It may vary, however, depending on the patient's body habitus. Today, many patients and surgeons alike are concerned about the size of the incision. It is important to know and realize that even more important that the length of the incision is the gentle treatment of the muscles and tissues underneath that correlates directly to a good result.
During the surgery for an anterior total hip replacement, the patient is supine (lying flat on one's back). Intraoperatively, the surgeon uses x-rays to properly place the implants in the exact position to correctly reproduce the patients hip and leg lengths.
The same kinds of implants and bearing surfaces are employed via this approach. The most common types of bearing surfaces are metal on metal or metal on polyethylene (plastic). Occasionally, a ceramic on ceramic bearing surface is used.
Any time a surgery is performed, there is a risk for complications. The six most common risks for anterior hip replacement are:
- Blood clots (Deep venous thrombosis or DVT)
- Leg-length inequality
- Numbness over the lateral thigh
You will be discharged when you can get out of bed on your own and walk with a walker or crutches, walk up and down three steps, bend your knee 90 degrees and straighten your knee.
At home you should begin ambulation with a cane as tolerated. Keep your incision clean and dry and watch closely for any signs of infection.
You'll continue your home exercise program and go to outpatient physical therapy, where you will work on an advanced strengthening regimen and such programs as stationary cycling, walking, and aquatic therapy.
Your long-term rehabilitation goals are a range of motion from 100-120 degrees of knee flexion, mild or no pain with walking or other functional activities, and independence in all activities of daily living.
Post-operatively, the patient has a much quicker period of rehabilitation and frequently discharge from the hospital occurs after only one to three days. The key to this faster recovery is the fact that no muscles or tendons are cut or removed during the surgery. In contrast, during a standard total hip replacement it is necessary to divide and detach muscles from the hip in order to perform the surgery. One of the key muscles about the hip is the gluteus medius which is one of the major hip flexor muscles. A well functioning gluteus muscle prevents the patient from limping and this muscle is completely untouched during the anterior total hip replacement.
Dislocation of the hip after total hip replacement is always a concern for both patients and the surgeons. Fortunately, the anterior approach offers a lower risk of dislocation because the protective muscles and tendons on the side and back of the hip joint are preserved. In fact, the anterior approach total hip is intrinsically stable and post-operatively patients are not required to follow any specific hip precautions. Traditional hip replacement mandates that patients not bend their hips past 90 degrees or cross their legs for up to 3 to 6 months. This can interfere significantly with a patient's daily life. There are no limitations during the post-operative course after total hip replacement from an anterior approach. A major concern for many patients relates to sexual activity. Patients may resume a normal sexual activity after surgery when they feel ready to do so.
After surgery, physical therapy begins the very next day. It begins with the patient sitting and standing by the bedside and progresses rapidly to walking up and down the hall. Often, the patients need to use a walker or crutches for several days to weeks after surgery. Most commonly patients are ready to go home within one to three days after the procedure. All of the patients have home therapy during the early post-operative period to assist them in their recovery. Some of the time, patients need to stay in a rehab facility for a short period of time after leaving the hospital. This assists them in their recovery until they are ready to be independent again.