What is “MIS” Joint Replacement Surgery?

Fig 1: X-Ray of Right Hip Osteoarthritis Pre-OP
Fig 1: X-Ray of Right Hip Osteoarthritis Pre-OP

MIS stands for “Minimally Invasive Surgery.” The objective of MIS surgery is to allow for faster recovery, and the ability to return to normal activities quicker. This is accomplished through smaller and less painful incisions. Recent technological advances in implants and instruments used in performing the surgery have allowed for the development of MIS procedures.

In recent history, MIS surgery has evolved to encompass a wider array of procedures and meanings. In my application of the term, and in modern day practice, a more appropriate phrase is “MSS” otherwise known as “muscle-sparing surgery.” In this technique the surgical approach is performed through a region of the body where no muscles or tendons need to be cut or separated from the bone. This approach has led to faster recovery and improved patient satisfaction. The MSS technique is utilized in both hip and knee replacement surgery.

Fig 2: X-Ray of Right Total Hip Replacement through Direct Anterior Approach
Fig 2: X-Ray of Right Total Hip Replacement
through Direct Anterior Approach

In hip replacement surgery, the “direct anterior approach” has been a significant advancement in the realm of MSS. A total hip replacement is traditionally performed via a relatively large incision on the back or the side of the hip. The traditional technique requires releasing the muscle tendon which put the patient at risk for dislocation of the joint and/or limp. In the direct anterior approach, a small incision in the front of the hip is utilized. This small incision is strategically placed in front of the hip and allows for muscle sparing. This technique is beneficial to the patient for a multitude of reasons. There is less risk of dislocation of the joint and/or limp. This translates to no range of motion or activity restrictions after the surgery while being able to place full weight on their leg after the surgery. Ultimately the patient benefits as they are able to return to their daily life activities quicker due to being able to rehabilitate faster after surgery.

Hana® Radiolucent Surgical Table
Fig 3: Picture of Hana® Radiolucent Surgical Table

A special surgical table is utilized during the direct anterior approach. X-ray imaging during the surgery allows for the surgeon to accurately reconstruct the patient’s natural anatomy by making changes where necessary with the implant size and position. The end result produces a more natural feeling hip after the surgery. Finally, the orientation and size of the surgical incision are cosmetically appealing with the added benefit of being less painful.

For knee replacements, there are also muscle sparing techniques. The quadriceps is one of the integral muscles of the thigh needed for extending the knee and ambulation. The “sub-vastus approach” is one where a total knee replacement can be performed without having to cut any muscles or tendons. In this approach, the quadriceps muscle and tendon are moved to the side to allow the replacement to be performed. Post-operatively this allows a faster and improved recovery.

However, MSS total hip and knee replacement is not for everyone. Certain body types and pathology might not be appropriate for these techniques. If you are experiencing arthritis symptoms, or are considering a hip or knee replacement, make an appointment with Dr. Stanat who is fellowship trained in adult hip and knee replacement surgery.