Hip Prosthetics with the AMIS Method
The implantation of an artificial hip joint, otherwise known as a total hip endoprosthesis (or Hip-TEP), is one of the most common surgical procedures performed today. A hip replacement or hip prosthetic is required in cases of joint degeneration and arthritic hip joint deterioration, also known as coxarthrosis, if conservative forms of therapy do not lead to improvement.
The AMIS method is the gentlest and most conservative method for hip surgery, as no muscles, tendons, or nerves are severed or nicked on the way to the hip joint. The results are significantly shorter recuperation periods, a quicker return to daily doing, and unchanged muscular function for work and sport-related tasks.
What is the AMIS Method?
One of the major benefits of the AMIS method is that muscles, nerves, and tendons remain intact during the surgical procedure when making a path to the hip joint, because these tissues are only moved to one side instead of being severed.
The surgeon has several different approaches to the implementation of a hip prosthetic at his disposal. These access routes are also known as surgical access paths. Many of the surgical access paths used while performing a hip joint replacement procedure are touted as minimally invasive, because small incisions are made in the skin in order to reach the deeper lying muscles, tendons, and the joint itself.
In most traditional surgical techniques, the surgeon must bypass the short lateral hip muscles or the posterior muscles in order to reach the hip joint. These muscles and tendons, which are immensely important for proper hip function, may tear or be deliberately severed in the course of the surgical procedure.
The AMIS method is distinguished by a reduced skin incision and the preservation of all muscles, sinews and nerves on the way to the hip joint. Thus, the AMIS method is the procedure which best protects and preserves muscle and other soft tissue.
What happens during hip surgery?
Surgical methods for the implantation of a hip prosthetics are numerous and varied. Anyone who received an artificial hip in the past was forced to take a long convalescence period into account. The traditional surgical access path for the implantation of an artificial hip joint took place from behind via the gluteus or buttock muscles or laterally, either through the splayed hip musculature or by bypassing the musculature itself.
In order to obtain surgical access to the hip joint from behind, numerous muscles (known as the outer rotator muscles) had to be severed. These muscles then had to be sutured and subsequently go through the healing process.
Likewise, when gaining surgical access laterally, nicked or torn muscles (known as pelvitrochant musculature or abductors) have to heal after surgery and complete recovery is not the case for many patients. This results in a longer convalescence, sometimes coupled with ongoing pain and limping. Using the AMIS method, these things belong the past.
How is an AMIS hip operation carried out?
AMIS stands for „Anterior Minimally Invasive Surgery“ and describes the optimal path of surgical access to the hip from the front, resulting in a minimal amount of damaged muscle and tissue: this is an anatomically logical and very gentle method. During the procedure the patient lies on his/her back. The hip prosthetic is inserted via a small incision on the front side of the thigh. In the course of the surgery, muscle groups are not severed or detached, but merely moved to one side.
The AMIS method is so successful because the surrounding muscles are all longer muscles which reach from the pelvis to the knee joint, making it possible to these muscles to one side; similar to the strings on harp. In addition, no important motoric nerves cross the area to be operated on, as the surgical access area is located directly between the gluteus maximus nerves and the femoral nerves.
After the prosthetic is inserted, the hip capsule – the hip joint connective tissue capsule – is closed. Using the AMIS method, muscles do not need to be sewn back place, but instead are simply returned to their normal anatomic position, causing the surgical access route to close much as the curtains in a theater. Only the fascia and the skin must be sutured when using the AMIS method.
The benefits of using the AMIS method are enormous for patients: during the procedure, patients experience less blood loss, and immediately after the procedure less pain is experienced, leading to reduced requirements for pain medication. Because hip and thigh musculature are not damaged, patients recover rapidly and can return to normal daily activities after a shorter rehabilitation period.
How does the AMIS method work?
After the artificial hip joint has been inserted, the hip joint capsule – the connective tissue sheath covering the hip joint – is closed. Using the AMIS method, muscles do not have to be sutured but instead return to their normal anatomical positions, closing and covering the surgical access route much like curtains closing on a theater backdrop. Only fascia and skin must be sutured after hip replacement using the AMIS method.
The AMIS method offers enormous benefits for the patient: blood loss is reduced, and immediately after the procedure patients experience less pain and thus require less pain medication. Because hip and thigh musculature remain intact, patients recover more rapidly and can return to normal daily activities after a shorter period of rehabilitation.
Advantages of using the AMIS method
In comparison to conventional methods, the AMIS method is far less drastic, as nerves and muscles are not severed but merely moved to one side. Benefits for the patient are numerous:
- Reduced blood loss:
Because muscles and tendons are protected from injury, blood loss is reduced.
———- - Less pain after the surgical procedure:
As no muscles are severed while using the AMIS method, less pain is experienced after the surgical procedure.
——– - Shorter hospitalization:
Thanks to the AMIS method, postoperative recovery time in hospital is reduced significantly.
——- - Faster rehabilitation:
Postoperative rehabilitation is much faster, and in many cases inpatient rehabilitation is unnecessary.
———- - Reduced scarring:
When using the AMIS method, the dermal incision is shorter than that which is required when using traditional surgical procedures.
——— - Quicker return to everyday life:
Patients are able to return to normal daily activities faster, thanks to a shorter recuperation period.
——– - Reduced risk of dislocation:
The separation and/or indentation of tendons and muscles increase the risk of a hip prosthetic dislocation. Clinical studies have shown that the risk of dislocation is significantly reduced when using the AMIS method, as stabilizing muscles and musculature functions are fully preserved.
———- - Reduced limping:
Minimal damage to muscles and tendons reduce the risk of postoperative limping.
——– - Reduced long-term pain:
The AMIS method reduces the risk of chronic tendon injuries and painful lateral tendon inflammation and bursitis.
When is an AMIS hip prosthetic implemented?
Hip pain presents an immense limitation in daily life. In cases of hip arthrosis, the implementation of an artificial hip joint using the AMIS method is a feasible alternative should conservative therapeutic fail to produce an improvement or (as in some cases) result in more pain. This method frees the patient from continual pain and restores mobility which may have been thought lost.
The most common cause of hip pain is wear and tear on the hip joint. This condition is also known as hip osteoarthritis.
In cases of hip osteoarthritis, joint cartilage- the lubricating layer between the pelvic bones and the thigh bone- has been worn out. This damaged joint cartilage results in friction between the femoral bone and the hip socket. In turn, this friction results in infections, leading to an increase in discomfort or pain.
Root causes for hip arthrosis may be accidents, misalignment of the legs and/or hip sockets, excessive or inappropriate biomechanical stress to the joint, genetics, as well as age-related wear and tear.
Prof. Dr. med. Gollwitzer and Prof. Dr. med. Weber
Our hip specialists Prof. Dr. med. Hans Gollwitzer and Prof. Dr. med. Patrick Weber, as renowned specialists in orthopedics and trauma surgery, are international contacts for questions concerning diseases of the hip.
They have extensive knowledge and experience in hip and knee endoprosthetics and joint-preserving hip surgery. With several thousand hip operations, Prof. Dr. Gollwitzer and Prof. Dr. Weber are some of the few hip specialists who have sufficient experience in joint-preserving hip surgery as well as in hip joint replacement and prosthesis exchange.
Prof. Dr. med. Hans Gollwitzer was one of the first surgeons to use the AMIS method in Germany. Due to the advantages, our hip specialists Prof. Dr. Gollwitzer and Prof. Dr. Weber now use the AMIS method for all initial implantations of hip prostheses and also for replacement operations. In addition, Prof. Gollwitzer is a member of the international AMIS Educational Board.
Consultation and contact information for questions about the AMIS method
Do you have any questions regarding hip prosthetics using the AMIS method, or about hip disease and/ or dysfunction in general? Prof. Dr. Gollwitzer and Prof. Dr. Weber, our hip experts at ECOM® Excellent Center of Medicine, will be happy to inform and advise you in detail in a personal consultation. Please make an appointment here. We are looking forward to seeing you.