Minimally Invasive Hip Replacement (cont.)
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During the Procedure
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.
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.
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.
B Sonny Bal, MD
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