Minimally Invasive Hip Replacement Surgery
In the last three-to-four years there has been a lot of talk and publicity concerning “minimally invasive” hip replacement. There is great confusion amongst patients regarding the definition of minimally invasive surgery and how it may or may not benefit them.
The following will explain the differences in current hip replacement procedures, define minimally invasive hip replacement surgery, discuss risks and benefits and describe the anterior approach currently being utilized.
Methods for total hip replacement
Common approaches to total hip arthroplasty in the western region of the United States include the well-known posterior approach, which likely represents some 80-90% of hip replacements.The anterolateral surgical approach represents the majority of the remaining procedures. Both of these techniques can be implemented using smaller incisions, which limit the amount of muscle split on the lateral side of the hip; however, they do not significantly change or limit the muscles released during the deeper dissection. These approaches should be referred to as “mini approaches.”
The two-incision approach is a novel minimally invasive surgical technique, combining an anterior incision and a superoposterior incision to avoid muscle detachment, but it does split the gluteus maximus muscle during the second incision. Furthermore, there are other technical limitations which restrict the approach to a certain subset of patients and implant types.
The anterior approach to hip replacement surgery has some variants (Smith-Peterson, Hueter) and is much less commonly used in the United States, especially on the West Coast. In fact, the anterior approach is more frequently utilized in Europe. When used as a Hueter variant, and with a special orthopedic table, it is a valid minimally invasive approach, thus avoiding muscle detachment (or muscle splitting) and allowing access for excellent component positioning.
Unlike the two-incision approach, the anterior approach is applicable to nearly all patients presenting for primary hip replacement and allows the vast majority of implant types, cement less and cemented, to be used. Originally brought to the U.S. six years ago by Dr. Joel Matta, the anterior approach is my current approach for nearly all primary hip replacements.
What is minimally invasive hip replacement surgery?
A minimally invasive approach is considered “valid” when it significantly decreases recovery time and increases early function by minimizing deep and superficial tissue trauma. It must also be able to retain all the principles of bone-implant fixation and preserve the long-term results of traditional approaches.
Minimally invasive approaches accomplish the above definition by avoiding or limiting the detachment of muscles and ligaments from bone and also limiting the splitting of muscles during the surgery. The basic principles of hip replacement must remain the same; these include: fixation, stability and maintenance of leg length.
These procedures also employ small incisions-between three and five inches-as larger incisions are no longer necessary. It should be emphasized that the size of the incision has little to do with how “minimally invasive” the procedure is. A surgical procedure is classified as “minimally invasive” by what is done subcutaneously, or under the skin. The avoidance of muscle detachment or muscle splitting is what allows the patient to enjoy the benefits of facilitated rehabilitation and a speedy return to normal activities
What is not considered minimally invasive hip replacement surgery
“Small incision,” or “mini incision,” hip replacement is not minimally invasive surgery. Again, the emphasis in minimally invasive surgery is on the deeper dissection and what is being affected beneath the skin that allows patients the postoperative benefits of this type of surgery. The length of the skin incision does not determine the patient’s postoperative recovery time, pain, function or limitations.
Benefits of minimally invasive hip replacement
- Decreased hip pain
- Decreased physical therapy
- Minimal motion restrictions
- Decreased hospital stay
- Early return to function
- Improved stability
- Precise leg length analysis
- Decreased limp
Other potential benefits
- Decreased blood loss
- Decreased use of extended care facilities
- Decreased use of home care, home physical therapy and adaptive equipment
Disadvantages of minimally invasive hip replacement
- Lower surgeon familiarity and experience with procedures
- Procedure is more difficult to perform
- Greater potential for intraoperative mechanical complications
Summary of minimally invasive anterior approach
This approach is currently the primary procedure used for all total hip replacement patients at Muir Orthopaedic Specialists. The benefit of early return to normal functions, such as driving, personal hygiene and exercise, is greatly appreciated by patients. The technical benefits of the surgical exposure allows any implant type to be used, facilitating the matching of patient characteristics and implant type.
The minimally invasive anterior approach for total hip replacement is performed with an incision, which is positioned, anywhere from 3.5 – 4.5 inches over the anterior aspect of the hip.The thin fascia over the fascia lata muscle is opened and the interval between sartorius medially and tensor fascia lata laterally is developed. The interval between rectus femoris medially and gluteus medius laterally is developed to reach the anterior hip capsule. A special operating room table is used to position the operate leg to access the femur.
Benefits of the anterior approach
- It is applicable to the vast majority of patients.
- It allows the use of cemented or cement less implants.
- No muscle releases or muscle splitting are necessary,
- There is a low incidence of lateral-sided hip pain.
- There is no abductor weakness
- There are no significant motion restrictions.
- The dislocation rates are far less with approximately 0-2 percent.
- There is a very fast return to function and normal gait.
- There is significantly less pain.
- There are no strengthening limits.
- No abductor pillows are used.
Limitations of this procedure
- A special operating room table is required to keep the incision 3.5-4.5″ and to access the femur without releasing posterior muscles.
- There is risk of thigh numbness from lateral femoral cutaneous nerve palsy.
- The use of intraoperative X-ray is common-on average, 20-30 seconds.