Minimally Invasive Hip Replacement

Is hip replacement a major operation?

• Hip replacement surgery is one of the most successful modern orthopedic surgical procedures. (Orthopedics is the branch of medicine dealing with bones.)
• Hip replacement surgeries use modern biomaterials. Biomaterials are synthetic or partially synthetic materials that are used to take the place of parts within the body. Use of these modern materials has allowed hip replacements to last well in appropriately selected patients.
• However, pain and other side effects associated with the surgical procedures remain a concern for many people.

How painful is a hip replacement?

• New and improved anesthesia techniques, as well as pain management medications and methods, have reduced pain and improved recovery after hip replacement surgery. Any method of speeding up recovery after surgery is desirable, as many people are anxious to return to their day-to-day activities.

What is the recovery time for a hip replacement?

• Minimally invasive hip replacement surgery is a general term that describes several variations of existing surgeries. Minimally invasive techniques are designed to reduce the tissue trauma associated with hip replacement. The surgery is performed with smaller incisions. Less trauma to the tissues results in less postoperative discomfort and quicker recovery.

Being educated about what to expect is important after minimally invasive hip replacement surgery. Candidates for the procedure are educated on both the benefits and the risks of minimally invasive hip replacement surgery. The patient and his or her doctor determine if this procedure is right for them.

The term minimally invasive surgery is somewhat misleading. It is still a surgery, and any type of surgery is invasive. The human response to injury is predictable, and it includes discomfort, altered emotions, and a period of recovery until healing occurs. Minimally invasive surgery can reduce, but not eliminate, these normal responses to the trauma of surgery. Minimally invasive surgery also does not mean risk-free surgery. Hip replacement surgery, regardless of technique, is associated with risk of infection, nerve injury, deep blood clots, premature implant loosening and failure, unpredictable medical complications, and even death. While these complications are uncommon, one needs to be aware of them before embarking on any type of hip reconstructive procedure.

Usually, minimally invasive surgery simply means performing a big operation through a small incision. In other words, the deep tissue and muscle injury is often unchanged, but the physical appearance of the scar is smaller. Surgeons who typically perform at least 100 hip replacement procedures per year are most able to adopt minimally invasive surgery. They progressively shorten the incision while keeping the procedure the same. Using special instruments, the surgeon can shorten the incision of a standard hip replacement from 8-12 inches to about 4 inches. This person only spent two days in the hospital.

Many orthopedic implant companies (who manufacture the biomaterials used in hip replacements) have developed special instruments and training for surgeons. Reviewing the patient educational material provided on an orthopedic implant company's Web site, such as Zimmer, Inc., can be useful in learning more about the procedure. The Web site can help identify the surgeons in an area who use a particular company's implants, including those who have attended special seminars on minimally invasive surgery and are therefore qualified to safely perform the procedures.

One of the methods used to perform minimally invasive hip replacement is a procedure called the MIS-2-incision hip replacement. Hip replacement procedures performed with a shorter incision are considerably different from MIS-2-incision hip replacements. The MIS-2-incision hip replacement is often described as same-day hip replacement. It is a different way of performing hip replacement surgery.

The approach is not new. Several decades ago, pioneer hip surgeons described the surgical pathway to the hip joint from the skin. What is new is using two incisions that are only 1-2 inches in length. Importantly, once the surgeon makes the cuts, the rest of the procedure involves moving around the muscle layers without cutting them. Special instruments, implants, and fluoroscopic guidance are needed to perform an MIS-2-incision hip replacement. Fluoroscopic guidance requires an x-ray machine and computer to project the image on a video monitor. MIS-2-incision hip replacement is a technically demanding technique that is best left to very capable surgeons.

Besides greatly reduced pain after surgery, the MIS-2-incision technique offers a very early return to walking. The overall recovery is faster than that for hip replacements that are done through a 4-inch incision using standard techniques.

During some minimally invasive hip replacement surgery procedures, the person lies on one side. However, in the MIS-2-incision hip replacement procedure, the person lies flat on his or her back. Fluoroscopy is used to precisely guide the placement of the incision. Special instruments are used to make the small incisions. Also, the implants are slightly different in design than the implants that are used during a standard hip replacement surgery.

Traditional Hip Replacement Surgery

Standard total hip surgery involves an 8- to 12-inch incision. This helps the surgeon to align the implants and assess leg lengths. The instruments are designed for an opening of this size. Once the skin is opened, the surgeon dissects between the muscles, tendons, and nerves to reach the joint. This is known as the surgical approach. In North America, two types of approaches are used: the posterior approach and the lateral (anterior) approach.

• The posterior approach is usually made by using an incision that curves backward into the buttock area. The hip is reached by creating an incision and splitting the buttocks muscle and cutting the tendons of the small rotator of the hip. The arthritic hip ball (femoral head) is then taken out from the socket (acetabulum) by twisting the leg. The ball is cut off. The thigh bone and socket are hollowed out for the artificial implants. At the end of the operation, the muscles, fat layer, and skin are stitched back together.



• In the lateral, or anterior, approach, the skin is cut over the bony prominence on the side of the hipbone, the part that lies against the mattress when one sleeps on one's side. The thick fibrous tissue layer, called the fascia lata, which envelops and contains the large muscles of the thigh, must be cut to reach the muscle layer. The lateral buttocks muscle is split, allowing access to the front of the hip joint. The hip ball is removed. The thigh bone and socket are hollowed out. The implants are placed. At the end of the operation, the muscle, fat layer, and skin are repaired with stitches.

Until the muscles and the fascia lata heal and scar tissue forms, a person whose hip is replaced using either approach will continue to have soreness and weakness in that hip.

The posterior and lateral standard approaches are reliable, predictable, and safe in the hands of most orthopedic surgeons. The long-term results of these traditional hip replacements are well recorded, and outcomes after newer hip replacement techniques must be measured against these results.

Minimally Invasive Hip Replacement Surgery

Both the posterior approach and the lateral (anterior) approach have been adapted for use in minimally invasive techniques. Using a standard approach, a surgeon can transition to a minimally invasive approach by gradually shortening the incision to 4 inches or less. As the incision is shortened, the surgeon adapts to more restricted views of the anatomy. The incision can be moved from one site to another site without enlarging the length of the cut. The surgeon must learn to use methods that accommodate the smaller incision.

• Special instruments that are lower in profile and can fit through smaller skin openings are needed.



• Computer navigation techniques and fluoroscopy facilitate implant orientation, limb alignment, and other critical factors associated with the operation through these smaller openings. The skin, fascia lata, and underlying muscles are not cut as extensively. However, the underlying structures must still be divided to replace the hip.

MIS-2-incision hip replacement does not require the cutting of muscles and tendons. In addition, the fascia is cut toward the front of the thigh, where it is usually weaker and less developed and, therefore, not as critical for walking, unlike the thick and well-developed fascia on the side of the thigh.

If a person is choosing minimally invasive surgery, the specific approach used by the surgeon is important for the patient to understand. If the surgeon uses the posterior or the lateral (anterior) approach, then the only differences between the minimally invasive surgery and the traditional surgery are the size of the incision and the extent of deep muscle trauma; the surgeries are nearly identical in every other way. If the surgeon specifically uses the MIS-2-incision technique, the muscle trauma is significantly less and the recovery is much quicker.

Many surgeons combine a small incision with spinal and epidural anesthetics to facilitate recovery. Newer anesthesia drugs reduce the nausea and confusion experienced upon awakening. Local anesthesia injected into the surgical site relieves pain after surgery.

With current minimally invasive techniques, the person is encouraged to become mobile much earlier than with standard methods of hip replacements. Many people are able to get out of bed either the same day or the next day, with the help of a physical therapist.

Pain pumps that infuse painkillers into the incision, patient-controlled analgesics, and newer antiinflammatory drugs may all be combined to speed recovery.

Even though modern surgery can facilitate recovery and reduce the risk of blood clots, minimally invasive procedures cannot eliminate the risk of a clot. Some method or a combination of methods for reducing the likelihood of blood clots after surgery is still necessary. Draining the wound, medications that prevent blood clots (anticoagulants) that are given by mouth or injection, and even leg-squeezing devices that provide constant intermittent pressure are used to decrease the risk of developing deep blood clots. Additionally, medical support stockings, such as TED hose (tight elastic stockings that help prevent blood clots in the legs), may also be used. People who are prescribed certain anticoagulant medications (blood thinners) are required to have their blood drawn to measure their protime (prothrombin time, or how fast the blood clots). Measuring the protime guides the doctor in adjusting the anticoagulant to the optimal dose.

Traditional Hip Replacement Surgery

A person can expect to be on crutches or to use a walker for six to eight weeks. The person should not support full weight on the affected hip. Repaired muscles should not be exercised. The newly implanted hip ball can come out of the socket until the muscles have healed. Specific hip precautions must be followed, in some instances, for a person's lifetime. A hospital stay of three to six days is typical for traditional hip procedures.

Minimally Invasive Hip Replacement Surgery

With minimally invasive surgery, reasonable precautions are still necessary for the first six to eight weeks while the tissue is healing and uncemented implants are bonding to the person's bone. Since less tissue is traumatized, fewer precautions may apply. With the MIS-2-incision technique, restrictions apply for the first six weeks, after which a person can gradually resume full activities without any hip precautions. Most surgeons restrict driving for about four weeks following any type of procedure.

Some of the accelerated recovery can be attributed to better anesthetic techniques and newer medications that improve recovery. Research is underway to determine what role anesthetic techniques and decreased surgical trauma have in aiding recovery. Even with the traditional procedures, newer anesthetic techniques improve recovery and lead to a faster return of function.

A person who is contemplating hip replacement surgery should become informed. Ask friends who have had a similar procedure about their experience. This may help in choosing a hospital and a surgeon. Then, spend some time exploring the World Wide Web. A wealth of information concerning minimally invasive hip replacement surgery is available on the Internet. Be a smart consumer and keep in mind that the Internet is largely unregulated in terms of the quality of information. Some of this information may amount to self-promotion by surgeons, implant companies, hospitals, and other parties. An intelligent health-care consumer must decide the quality of the information. See Web Links for some trusted sources.

After researching on the Internet, discuss the procedure with a physician and orthopedist. They will know who in the community offers the newer minimally invasive techniques. Every community is also served by teaching hospitals, where orthopedic surgeons who specialize in hip or knee replacement often receive inquiries from far away, including other countries, and enjoy exchanging their opinions and perspectives.

Procedures like minimally invasive joint replacement surgery are first developed and tested at academic medical centers. There are excellent private practice groups that are fully versed in new methods of surgery and testing their effectiveness as well.

Once prepared, make an appointment with a doctor. If the doctor has a Web site, review it before the office visit. Make a list of questions ahead of time, so that all concerns are addressed. Make sure to be comfortable with the doctor you choose. The doctor should encourage you to ask questions. Because many questions may arise after the office visit, the doctor should encourage communication regarding any additional questions or concerns. Keep in mind that privacy may be compromised if you are asking questions via email.

Every surgery has risks. Minimally invasive surgery is still associated with complications, such as the following:

• Improper placement of the components
• Nerve injury
• Fractures during the procedure
• Blood loss
• Blood clots after surgery
• Infection after surgery

In addition, minimally invasive procedures may take longer to perform than traditional surgery. A person who undergoes any type of hip replacement surgery still needs to follow certain precautions and adjust to a lifestyle that accommodates the prosthetic device in the body. Be sure to ask the doctor about these complications. The doctor will know about complications specifically associated with minimally invasive hip replacement surgery. If a person considering a minimally invasive hip replacement is not comfortable with communications from the doctor, he or she should seek a second opinion. Unrealistic expectations, a lack of information and preparation, and a failure to become an active and intelligent participant in the surgical procedure can lead to disappointment after any surgery.

Different people react very differently to the same procedure, depending on their body weight, associated medical conditions, family support, mental health, and other unpredictable factors. Therefore, deciding to undergo minimally invasive hip replacement surgery must be an informed decision made with the guidance of the doctor, after all the facts are taken into consideration.

Minimally invasive hip replacement surgery is a new procedure. Short-term results are promising. Surgeons are gaining more experience with these new techniques. If the implants are placed properly, the new hip should last through several decades of reasonable use, as long as precautions and activity recommendations given by the surgeon are followed.

Minimally invasive hip replacements allow earlier discharge from the hospital, less pain, and faster return to the activities of daily living. Less physical therapy is needed after discharge. However, there are specific complications for any new procedure. The experience of the surgeon is also a factor. Surgeon selection and patient education are very important when it comes to new technology in surgery.

In general, hip replacement surgery should be sought only for debilitating pain that does not improve with pain medications, exercise, weight loss, and reasonable activity modification. Hip replacement, regardless of surgical technique, is a major operation for a worn-out joint that cannot function any longer. Hip replacement surgery involves lifestyle changes and an artificial joint. No artificial hip can ever be a perfect substitute for a real hip. Optional surgery, such as hip replacement, should be avoided until other treatment options have failed.