Joint Replacement Center
About Hip Replacement Surgery
Over time, the impact of joint disease, arthritis, or excessive body weight can erode the hip joint. Arthritis can be an inherited disease process that appears with age. One risk factor conversely that is under the control of the person is their body weight. Excessive body weight can wear out the normal knee and hip joints which were never intended to carry a human that is obese or morbidly obese.
The problem of obesity is growing, which in turn causes more joint problems. As of 2015, 34.9% of U.S. adults are obese or morbidly obese, according to the Journal of American Medicine (JAMA). The study also found that obesity worsens as a person enters their 40s and 50s. Obesity is higher among middle age adults, 40-59 years old (39.5%) than among younger adults, age 20-39 (30.3%) or adults over 60 or above (35.4%) adults.
Artificial hip joints
According to the American Academy of Orthopaedic Surgeons, each year in the United States, about 193,000 hip replacements are performed. With the aging of the post World War II baby boom generation (those born between 1946-1964), that number is expected to grow significantly as this large segment of the population now age into their 50s, 60s and 70s. It is estimated that more than 500,000 knee and hip replacements will be done each year by 2040.
Also, the joint implant technology involved is improving, enabling the artificial joint to last longer. This enables more surgeons to recommend hip replacement with the belief that the artificial hip joint may outlive the life of the patient, thereby eliminating the need for a revision surgery on an elderly patient in their 70s or 80s.
Traditional open hip replacement surgery lasts between two to three hours, although an extremely proficient hip surgeon who does a large volume of cases may be faster. The hip surgeon makes an eight-inch incision along the side of the hip and carefully moves the muscles at the top of the thighbone to reveal the hip joint. The surgeon then removes the ball portion of the joint. An artificial joint is inserted into the thighbone and fixed into position with a special bonding material that allows the remaining bone to attach to the artificial joint.
The life of the artificial joint
Like any mechanism, an artificial hip joint can wear out after 15 to 20 years, and outcomes of revisions are less ideal than original hip replacements. Consequently, surgeons try to delay hip replacement surgery as long as possible. In the United States, 65 percent of hip replacements are performed on those patients over the age of 65. It is also not recommended for the extremely obese, those with a terminal illness, those with nerve disease, or those lacking ample skin around the hip.
The pros and cons of anterior vs. posterior hip replacement surgery
About 70 percent of hip replacement surgeries today are performed through a traditional posterior approach through the buttock area. Most medical schools train orthopedic surgeons to use the traditional posterior approach as the primary approach.
Some hip surgeons favor an alternative approach from the anterior side, or front side of the hip.
Mini hip replacement
In the past 10 years, new instrumentation has enabled some specialized hip surgeons to perform “mini hip replacement” through a minimally invasive approach.
The “mini posterior approach” essentially is the same surgery as the traditional posterior approach, but done through a minimally invasive approach where a smaller incision is made and there is less disruption to soft tissue, muscles and ligaments.
In mini hip replacement the hip surgeon operates through a shorter incision about three to five inches long. Through minimally invasive instruments, the surgeon separates the muscle fibers of the large buttock muscle at the back of the hip. The same hip replacement process is then performed through the smaller opening.
Like any minimally invasive surgery, the benefit is typically less blood loss and less disruption to muscles and ligaments. Also, in theory, the hospital stay should be shorter and the recovery faster. The scar would also be shorter.
Advocates of the mini-posterior approach cite fewer complication rates than with a direct anterior approach, and a faster, more-consistent recovery. There is significantly less bleeding with the mini-posterior approach, which can reduce or eliminate the need for a blood from a blood bank during surgery.
Those who argue against mini hip replacement site some studies that some outcomes with the minimally-invasive approach may be worse than with standard hip replacement surgery if the surgeon is not very experienced with the minimally invasive technique.
Direct anterior hip replacement
Direct Anterior Hip Replacement is a new surgery method that is an alternative to the standard conventional hip replacement surgery and is growing in popularity. It’s only used in about 20% of cases in the U.S. currently. In the past, hip replacement surgery required cutting certain muscles and tendons in order to access the area being fixed. Conversely, direct anterior hip replacement does not require the cutting of muscles or tendons to expose the joint being treated. This new surgery can be more difficult and requires special equipment including surgical instruments and operating tables.
During direct anterior hip replacement the patient lies on the operating table on their back, which enables the surgeon to use a fluoroscope to help with the position of the prosthesis.
Some studies have shown that Direct Anterior Hip Replacement surgery patients may have a faster recovery and may have less post operative pain and discomfort than traditional hip replacement surgery. A 2014 study of 54 patients found that anterior hip replacement patients were able to walk unaided 6 days earlier than other hip replacement patients.
Direct Anterior Hip Replacement surgery, however, is not for all candidates. Some hip surgeons feel that anterior hip replacement has some issues: The nerve which supplies sensation to the front and side of the thigh can be more vulnerable to injury during surgery. Those patients who are obese, short, or the person with very muscular thighs are more challenging with an anterior approach.
In conclusion, there can be disagreement among hip surgeons as to what approach is the best one for a specific patient, and it’s important to listen to your surgeon’s recommendation rather than try to shop for an approach that may not be appropriate for you.
Abrasion Arthroplasty is a surgical procedure to reshape the joint by grinding down the damaged surface and removing rough areas, which allows blood and bone marrow cells to develop on the newly ground surface.
The raw bony surface may be stimulated to grow a new joint surface, albeit one which is not as perfect as the normal hyaline cartilage of a natural joint surface. The bone at the base of the crater is either picked or burred. This procedure is called abrasion arthroplasty. The aim is to expose small subsurface blood vessels, which will grow into the area and bring with them the growth factors that will eventually produce fibrocartilage. Although not as durable as hyaline cartilage, this substitute often works well especially if a patient is young and the defect small. It can be performed through an arthroscope and has been used for decades with reasonable success. However, the larger the hole the less likely it is to be successful.
Types of artificial hip joint prosthesis
Acrylic with Cement Fixation
This is the first type of hip prosthesis developed. Essentially, the prosthesis is secured to the hip with a cement adhesive. Over time (10 to 15 years) the cement will erode and need to be replaced. Usually these implants are used in older, less active adults or in people with weaker bones. The recovery time for this prosthesis is faster than other methods.
Without Cement Fixation
The difference between the cement and non-cemented version of the hip prosthesis is the lattice grid that comprises the socket part of the prosthesis. After the diseased bone and cartilage has been removed, the latticed grid is inserted into the socket. After a while during healing, the remaining hip bone will grow into the grid much like ivy grows into a trellis and suture itself to the prosthesis. The new bone grows into the implant, securing it in place. This is a much more natural cohesion and lasts longer than the traditional prosthesis. Also, it affords much more mobility to the active hip replacement recipient than the cemented type.
Scientists are currently in the process of developing joint replacement methods that will last much longer than the current prototype. While doctors now use a glue to bind the old bone with the new prosthesis, they one day hope to use ceramics as a bone substitute.
When a bone breaks in the body, the bone cells will form together to rejoin the broken bone. In the same way, bone cells can join with coral or ceramics forming one, continuous bone. While the glue or cement that doctors use will eventually deteriorate, ceramics will last much longer as they have better chances of being accepted by the cells. While recovery may take longer initially, the effects of surgery will last much longer than current replacement methods.
The hybrid fixation is where one part of the hip prosthesis (generally the stem) is cemented together while the other part of the hip (generally the socket) is inserted without cement.
Scientists are now working on using ceramics and coral to be used as joint replacements in the future. Hospital stay after surgery usually lasts for five days. After the hospital stay, the patient will probably require the aid of a walker for a few days before putting full weight on the leg.
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