In this article:
- Smaller Incisions
- During the Procedure
- After the Procedure
- What are “surgical approaches”?
- What newer methods are available?
- Recovery Times
- Next Steps
- When to Seek Medical Care
Hip replacement surgery is among the most successful of surgical innovations in orthopedic surgery. Because of modern materials, the results of hip replacements in appropriate recipients are predictably lasting. Nonetheless, pain and morbidity associated with the surgical procedures remain a concern for many people.
Advances in anesthesia techniques and modern pain-management methods, including the use of newer analgesics, have reduced pain and improved recovery following hip replacement surgery. With the emphasis on shorter hospital stays, and a desire to return to work and day-to-day activities sooner, any method of speeding recovery after surgery is desirable.
“Minimally invasive hip replacement surgery” is a general term that describes several variations of existing surgical techniques that are designed to reduce the tissue trauma associated with hip replacement. The goals of minimally invasive hip replacement surgery are to perform the operation with a smaller incision and less trauma to the deep tissues, to reduce postoperative discomfort, and to speed discharge from the hospital. This article is designed to give you a comprehensive review of what minimally invasive hip replacement surgery is all about.
Patient education is a very important component of success after minimally invasive hip replacement surgery. Experience shows that a person who takes the time to learn and investigate surgical options, and who makes informed choices, typically ends up satisfied after joint replacement surgery. You should be aware of both the benefits and risks of minimally invasive hip replacement surgery in order to properly decide if the procedure is right for you.
The term “minimally invasive surgery” is misleading. This term is over-used by hospitals and doctors who are driven by economic interests and competitive pressures. Nearly everyone claims to be an expert in minimally invasive surgery to avoid being left behind. But, you should know that all surgery is inherently invasive to the body and to the human psyche. The response to injury is predictable, and it includes discomfort, emotional swings, unpleasant sensations like constipation and nausea, and a period of recovery until the body and mind heal. Minimally invasive surgery can reduce, but not eliminate, these normal physiological and psychological responses to the trauma induced by surgery.
It is also important to keep in mind that minimally invasive surgery does not mean risk-free surgery. Hip replacement surgery, regardless of technique, is associated with a small risk of infection, nerve injury, deep blood clots, premature implant loosening and failure, and unpredictable medical complications. While these complications are rare, you need to be aware of them, no matter how small the cut, and how minimally invasive your doctor claims the procedure will be.
Hip Replacement Performed with Smaller Incisions
In the majority of cases, all that “minimally invasive surgery” means is that the surgeon can do the same operation through a smaller cut. Redesigned instruments, and surgeon education make this possible. Keep in mind that in these cases, the nature of surgery to cut deep into the skin is unchanged, but the physical appearance of the scar is smaller. Surgeons who typically perform at least 100 hip replacement procedures per year are in the best position to adopt shorter incisions, while keeping the procedure the same. In many cases, well-trained surgeons using special instruments can shorten the incision of a standard hip replacement to about 4 inches. An example of such an incision is illustrated in Figure 1. This shorter scar is obviously preferable to the standard 8- to 12-inch scar on the side of the thigh associated with traditional hip replacement.
Several orthopedic implant companies have developed special instruments to facilitate making shorter incisions and have provided training seminars for surgeons. It can be useful to review the patient educational material provided on an orthopedic implant company’s Web site to learn more about the procedure. The Web site can usually identify surgeons in your area who use a particular company’s implants and have attended special seminars on minimally invasive surgery, and are therefore qualified to safely perform the procedures.
Micro-Posterior Tissue Sparing Approach
This is a posterior tissue-sparing procedure which aims to get patients back on their feet within days (possibly hours) instead of weeks. Patients who have undergone this procedure are able to walk unassisted the day after surgery, and leave the hospital without the typical restrictions (such as crossing their legs) associated with total hip replacement. Patients can also have as little as a 3-inch incision. It is important to understand that “less invasive” does not only refer to the incision but also means less trauma to the muscles and tendons under the skin. Replacement is designed to precisely reconstruct the hip without stretching or traumatizing muscles that are important to hip function.
There are two small incisions made in this approach, one being the main access to the joint and through which nearly all the work is performed. The other is a small stab wound in the thigh through which a special instrument is employed to work on the acetabulum (socket). This is a unique and innovative method of carrying out the replacement and unlike other MIS approaches, allows full vision for the surgeon throughout the procedure.2
MIS-2 Incision Method
One of the radically new methods to perform minimally invasive hip replacement is by using a procedure called the MIS-2-incision hip replacement. The MIS refers to “minimally invasive surgery.” There is a significant difference between hip replacement procedures done through a smaller skin incision, and those done using the MIS-2-incision hip replacement. The MIS-2-incision hip replacement, is often described as same day hip replacement, and it is a different way of performing hip replacement surgery. The surgical pathway to reaching the hip joint from the skin was described by pioneer hip surgeons several decades ago.
What is new is the adaptation of this previously described pathway of reaching the hip joint to a new method of performing hip replacement surgery using two incisions that are very small. More important than the incision size or number is the fact that under the skin, the muscles are spread in their natural planes. The surgeon navigates a path around the muscles, without cutting into them. Sometimes x-ray guidance is used to assist the surgeon in locating the hip joint. Special instruments, implants, and surgical education are needed to do this type of procedure, which is best left to very capable, high-volume surgeons with special training in the procedure.
Besides greatly reduced pain following surgery with the MIS-2-incision technique, the early results are drastically superior in terms of early return to functioning and walking. MIS-2-incision hip replacements are associated with a markedly different recovery overall than even those hip replacements that are done through a 4-inch incision using standard techniques, such as the one shown in Figure 1 above. The size and location of the two incisions used with the MIS- 2-incision hip replacement surgery are illustrated in a person who had the surgery in Figure 2.
During the Procedure
You’re placed on your side for most minimally invasive hip replacement surgery procedures, and placed on your back for the MIS-2-incision hip replacement procedure. X-ray imaging is often used to precisely guide your surgeon to the place where the incision must be made. With this type of surgery, the instruments used to approach the hip joint are specially designed by the implant companies to facilitate the use of small exposures. Also, the implants that are used during an MIS-2-incision hip replacement procedure may be slightly different, although no less durable, than the implants that are used during a standard hip replacement procedure.
After the Procedure
Many surgeons combine a small incision with other methods to relieve pain and to facilitate recovery. For example, spinal and epidural anesthetics can speed up recovery. Newer anesthetic agents can reduce the incidence of nausea and confusion associated with older drugs. The use of non-narcotic pain relievers and injections of painkillers into the tissues during the surgery make for a more pleasant experience afterwards.
With modern hip replacement surgeries, you are encouraged to become mobile as soon as possible. Many people are able to get out of bed either the same day or the next day, with the help of a physical therapist. In many cases outpatient therapy is not needed, although it may be necessary for certain patients.
Pain pumps that infuse painkillers into the incision, patient-controlled analgesics, and newer anti-inflammatory drugs may all be combined to speed up recovery. Analgesic drugs, anti-constipation, and anti-nausea medications can be started just before the surgery, so that the post-surgery experience is much more pleasant.
Even though modern surgery can facilitate faster recovery and reduce the risk of blood clots, minimally invasive procedures cannot eliminate the risk of a clot. Some method of reducing the likelihood of blood clots after surgery is still necessary, regardless of how small an incision your surgeon used to replace your hip. Surgeons may use a combination of methods to reduce the risk of blood clots. Your surgeon may prescribe blood-thinning medications by mouth, or via injections for several weeks after hip replacement surgery to reduce the risk of deep blood clots.
What are “surgical approaches”?
Traditional hip replacement surgery involves an incision of typically 8-12 inches in length; and the instruments that your surgeon uses are designed for the exposure made possible through an opening of this size. Once the skin is opened, the anatomic route that your surgeon takes to access the diseased joint is called a surgical approach. Two types of surgical approaches are commonly used in North America. The posterior approach is usually made by using an incision that curves backwards into the buttock area. The hip is reached by cutting several tendons that come out of the pelvis; these are called the short external rotator muscles. The arthritic hip ball (also called the femoral head) is then dislocated out from the socket (called the acetabulum) by twisting the leg. The ball is removed, and artificial implants are placed under direct visualization by the surgeon. At the conclusion, the short external rotator muscles are repaired using stitches.
The lateral approach (also called the ‘anterior’ or ‘direct anterior’ approach) is the second commonly used surgical approach for performing hip replacements in the U.S. Instead of the incision curving backwards toward the buttock, the skin cut is directly to the side, over the bony prominence that is against the mattress when you sleep on your side. In this variation, a large muscle called the gluteus medius is split in order to access the hip joint from the front side, as opposed to the back side during the posterior approach described above. Again, the hip ball is dislocated from the socket, and the operation is completed by repairing the gluteus medius muscle with stitches.
In both approaches above, a heavy, strong fibrous tissue layer called the fascia lata must be cut. This fascia layer envelopes and contains the large muscles of the thigh. At the conclusion of hip surgery using the above approaches, the fascia layer must be stitched together. The cutting and repair of the fascia and the underlying muscles contributes to the soreness and weakness after traditional hip replacement procedures.
The two approaches described above are reliable, predictable, and safe in the hands of most orthopedic surgeons. The long term results of hip replacements with these traditional techniques are the accepted standard today. Satisfactory surgical exposure helps the surgeon align the hip components, judge implant position, and assess leg lengths with confidence.
Minimally invasive surgery variations of both the posterior approach and the lateral approach are popular today, and these involve re-training surgeons to learn how to do the same approach using a smaller skin opening. Most surgeons refer to an incision that is 4 inches or less in length as “minimally invasive.” Surgeon training, redesigned instruments, x-ray imaging, and computer navigation can help your surgeon insert hip implants safely through a small skin cut, and maintaining the same muscle dissection below the skin as traditional approaches to hip replacement.
Because the skin cut is smaller with minimally invasive hip surgery, the fascia lata and underlying muscles also are cut less. But, keep in mind that even with minimally invasive surgery the underlying anatomy must still be invaded, although to a lesser extent, in order to insert a new hip. The exception is the MIS-2-incision operation because the surgical approach is designed to go around muscles. With the MIS-2-incision method, the fascia lata on the side of the thigh is spared from any cutting. Instead, the fascia is cut toward the front of the thigh, where it is usually weaker and less developed and therefore not as critical to walking ability as the thick and well-developed fascia to the side of the thigh. This is why patients tend to feel better and recover faster after the MIS-2-incision hip replacement.
It is in your best interest to inquire about the specific approach your surgeon plans to use for your hip replacement. If it is the posterior approach, or the lateral approach (also called the anterior approach by some surgeons) then the only difference between the minimally invasive surgery and the traditional methods is the size of the incision, and the extent of deep muscle trauma; the operation is nearly identical in every other way. If the surgeon uses the MIS-2-incision technique, the muscle trauma is significantly less and the recovery is usually much quicker.
At this time, few surgeons perform the MIS-2-incision hip procedure because the surgery is difficult to learn, and requires a surgeon willing to commit to learning and refining this method. It takes a lot of commitment for an established surgeon to learn new methods, and not too many surgeons take the concept of minimally invasive surgery beyond a simple shortening of the incision.
What newer methods are available?
By using a special table and yet more refined instruments, it is possible to eliminate even the second incision from the MIS-2-incision approach. This makes it possible to do the entire operation through one incision, cut no muscle or tendon, and avoid cutting the fascia on the side of the thigh. This newer third approach is called the “G-3 anterior approach” which also involves no muscle trauma, and the use of special instruments.
With traditional types of hip replacement, you can expect to be on crutches or a walker for 6-8 weeks, with limited weight-bearing. Certain exercises that stress the newly repaired muscles may be prohibited during that time. Also, hip precautions may be specified, to prevent the newly implanted hip ball from coming out of the socket until healed muscles can stabilize the hip joint. In some instances, the hip precautions have to be followed for a lifetime. A hospital stay from 4-7 days is typical for the traditional hip procedures.
With minimally invasive surgery to replace the hip joint, cautious surgeons will still prescribe reasonable precautions for the first 6-8 weeks while tissue healing is taking place, and uncemented implants have a chance to bond to the patient’s bone. Since less tissue is traumatized, fewer hip precautions may apply. With the MIS-2-incision procedures, it is reasonable to restrict the patient for the first six weeks, after which full activities can be progressively resumed, with few hip precautions. Driving with either type of procedure is usually restricted for about 4 weeks by most surgeons.
Some of the accelerated recovery following hip surgery can be attributed to better anesthesia techniques, and newer medications that improve recovery regardless of the surgical technique. Studies are in progress that will differentiate the contribution of special anesthetic techniques from the decreased surgical trauma of minimally invasive surgical techniques to improved recovery from hip replacement. Patients should recognize that even with traditional surgical approaches to hip replacement, newer anesthetic techniques that include methods of anesthetizing the surgical site improve recovery and lead to a faster return of function.
If you are contemplating hip replacement surgery, ask friends or relative who have had a similar procedure about their experience. This may help in choosing a hospital and a surgeon. Another very useful resource is to discuss the procedure with experts at a teaching hospital. Even if an academic medical center is far away, orthopedic surgeons who specialize in hip or knee replacement and are on the teaching faculty can be contacted via e-mail. These surgeons often receive inquiries from far away, including other countries, and enjoy exchanging their opinions and perspectives. This is free, expert advice and often invaluable in presenting the pros and cons of surgery relevant to your situation.
Consider consulting with joint replacement surgeons at your local academic medical center because procedures such as minimally invasive joint replacement surgery are first developed and tested in such institutions. Surgeons in academic practice also write about these techniques and present data in peer forums. Community doctors may be just as talented, but they cannot match the resources or extent of exposure available at university-based hospitals when it comes to developing new methods of surgery and testing their effectiveness.
Once prepared, make an appointment with a doctor. Ask if the doctor has a web site, and review it before the office visit. Make a list of questions ahead of time, because actual face time with the doctor is usually at a premium.
Because of competitive pressures, many surgeons may feel rushed and pressured to adopt minimally invasive hip replacement surgery. Make sure that the surgeon is one who specializes only in joint replacement surgery. Use the information in this article to ask critical questions of your doctor.
Make sure the chemistry and the comfort level with your doctor feel right. Questions should be encouraged. Because many questions may arise after the office visit, the doctor should encourage emails or calls with any additional questions and concerns. Even though privacy is a concern with email communications, this method allows quick and direct communication with the doctor.
Keep in mind that there is a downside to minimally invasive surgery. At least early in the surgical experience, small incisions are associated with improper placement of the components, nerve injury, fractures, and a longer duration of surgery. Ask about these complications, since they have been documented in peer-reviewed literature. If your doctor does not address these concerns, or is unaware of these complications, seek a different doctor.
Even the smallest of cuts is traumatic. Blood loss, the possibility of blood clots or infection after surgery, and the need to follow certain precautions to adjust to a lifestyle with a prosthetic device are still a reality after minimally invasive surgery. It is worth keeping in mind that unrealistic expectations, a lack of information and preparation, and a failure to become an active and intelligent participant in the surgical procedure will lead to disappointing results, regardless of incision size.
People react very differently to the same procedure, depending on their body weight, associated medical conditions, family support, psychosocial factors, and other unpredictable factors. Therefore, deciding to undergo minimally invasive hip replacement surgery must be an informed decision made with the guidance of your doctor, after all the facts are known.
Long-term results of minimally invasive hip replacement surgery are still unknown, and will be published as surgeons gain more experience with these new techniques. If the implants are placed properly, the new hip should last through several decades of reasonable use. This assumes that any precautions and activity recommendations given by your surgeon are followed.
The short-term results of minimally invasive hip replacements are very favorable in terms of earlier discharge from the hospital, less pain, and faster return to the activities of daily living. The need for physical therapy after discharge is minimized by techniques that reduce the trauma to the skin, muscles, and tendons. The complications reported by many studies describing the early results of minimally invasive hip replacement are inherent in any new procedure. This is why surgeon selection and patient education are so important when it comes to new technology in surgery.
When to Seek Medical Care
Minimally invasive hip replacement surgery should not change the reasons why you might seek a hip replacement in the first place. Hip replacement surgery should be sought only for debilitating pain that is not responding to pain medications, exercise, weight loss, and reasonable activity modification. Hip replacement, regardless of surgical technique, is a salvage operation for a worn-out joint that cannot properly function any longer. No artificial hip, regardless of how expertly it is implanted, can ever be a perfect substitute for a real hip. Hip replacement involves some lifestyle alterations and certain considerations that apply to any skeletal prosthesis. The golden rule is that elective surgery, such as hip replacement, should be avoided until all other reasonable treatment options have been exhausted.
- University of Missouri Medical School department of Orthopedic Surgery provided original text for publication on BoneSmart.org
- Fox, Josephine – Orthopaedic Nurse, Lead Forum Administrator at BoneSmart.org