Hip resurfacing has been developed as a surgical alternative to total hip
replacement. The procedure consists of placing a cobalt-chrome metal cap, which
is hollow and shaped like a mushroom, over the head of the femur while a
matching metal cup is placed in the acetabulum, replacing the articulating
surfaces of the patient's hip joint and removing very little bone compared to a
THR. When the patient moves the hip, the movement of the joint induces synovial
fluid to flow between the hard metal bearing surfaces lubricating them when
the components are placed in the correct position. The surgeon's level of
experience with hip resurfacing is most important; therefore, the selection of
the right surgeon is crucial for a successful outcome. Health-related
quality of life measures are markedly improved and patient satisfaction is
favorable after hip resurfacing arthroplasty.
Advantages and disadvantages The potential advantages of hip
resurfacing compared to THR include less bone removal, a reduced chance of hip
dislocation due to a relatively larger femoral head size, and easier revision
surgery for any subsequent revision to a THR device because a surgeon will have
more original bone stock available The potential disadvantages of hip
resurfacing are femoral neck fractures, aseptic loosening, and metal wear. Due
to the retention of the patient's complete femoral neck other advantages
exist: Surgeon induced discrepancies in leg length are now minimized. Also, the
toe-in or toe-out faults that could occur interoperatively with THR are now
over because the femoral neck that determines foot direction is left
undisturbed with hip resurfacing. On February 10, 2011, the U.S. FDA
issued a patient advisory on metal-metal hip implants, stating it was continuing
to gather and review all available information about metal-on-metal hip
systems. On June 27–28, 2012, an advisory panel met to decide whether to
impose new standards. No new standards, such as routine checking of blood metal
ion levels, were set, but guidance was updated.
Patient selection Patient suitability for hip resurfacing
is decided by the patient's anatomy and the patient's surgeon. Hip resurfacing
is intended for younger patients who are not morbidly obese, are clinically
qualified for a hip replacement, have been diagnosed with noninflammatory
degenerative joint disease, do not have an infection, and are not allergic to
the metals used in the implant. Hip resurfacing should not be used on
patients who have severe bone loss in their femoral head, those with large
femoral neck cysts present or cysts that are close to the head neck junction, or
patients who have poor bone stock or osteoporosis. Caution should be used for
patients who have rheumatoid arthritis, are tall, thin, or small boned, those
with osteonecrosis to the femoral head, or those with femoral head cysts > 1 cm
on an x-ray taken before surgery. Metal-on-metal resurfacing systems are
generally unsuitable for women of child-bearing age due to unknown effects
of metal ion release on the fetus. Patients with any of these conditions
may not be suitable candidates for hip resurfacing.
Devices In 2006, the United States FDA approved
hip resurfacing using the Birmingham Hip Resurfacing system, designed by British
Orthopaedic surgeon Derek McMinn. On July 3, 2007, the FDA approved the
Cormet hip resurfacing system made in the UK by Corin Group and marketed in
the U.S. by Stryker Corporation. On November 9, 2009 the FDA also approved
the Conserve-Plus hip resurfacing system made by Wright Medical Technology. There
are several other manufacturers of hip resurfacing systems, mainly in Europe.
Another THR and hip resurfacing system, the DePuy ASR, which had been undergoing
clinical trials for hip resurfacing in the United States and marketed overseas,
has been recalled as a result of having been proven to have abnormally high
revision rates. A prospective patient, therefore, needs to be cautious to
confirm the type of device being used has an acceptable track record. Subtle
differences among the devices in terms of design, manufacturing and surgical
technique can prove to be detrimental to clinical success.
Procedure The hip resurfacing devices are
metal-on-metal articulating devices which differ from total hip replacement
devices because they are more bone conserving and retain the natural
geometry. A THR requires that the upper portion of the femur bone be cut off to
accept the stem portion of a THR device. The femur cap of the hip resurfacing
devices does not require the femur bone be cut off; instead the top of the
femoral head is shaped to closely fit the underside of the cap. Both hip
resurfacing and hip replacement require that a cup is placed in the acetabulum
of the hip socket. The main advantage of the hip resurfacing surgery is that when
a revision is required, there is still an intact femur bone left for a THR
stem. When a THR stem requires a revision, the metal stem in the femur
has to be removed and often more bone is lost in the process of removal and
replacement with a larger diameter stem. Having a hip resurfacing at a younger
age means that a revision will likely be easier to perform when required.
Recent studies have shown that the outcome of a hip resurfacing is
dependent on surgeon experience and that proper positioning of hip resurfacing
components is crucial. Therefore, in addition to ensuring that a proven
device is used, patients should take care in selecting a surgeon with
experience and a good track record. Although formal labeling restrictions
exist in some countries, including the United States, hip resurfacing may allow
younger, active people to return to many activities they enjoyed prior to their
hip problems, which is an advantage over a traditional hip arthroplasty. The
large size cap and cup of the hip resurfacing devices are the same size as
a person's original ball and socket and thus are less prone to dislocation.
An often forgotten but very important advantage of hip resurfacing and thereby
the retention of the femoral neck is the fact that hip resurfacing has the least
measurable amount of "stress shielding" when compared to any type of THR. This
means that with hip resurfacing the femur's upper portion fully retains its
natural mechanical characteristics under load, also ensuring less disturbance of
the processes that place inside bone that is alive.
Notable athletes There are many athletes with resurfaced
hips that continue to compete at the personal and the professional level in a
myriad of activities. They include: Kay Glenn,won the high jump at the
national senior s.http:issuu.comdocs27?e=6499479/5415221
Ron Noreman, who on July 24, 2010 won the Masters Division of the NPC Empire
States Bodybuilding Championships only 5 months after hip resurfacing surgery.
Cory Foulk, who finished a marathon three months after his surgery, and
finished 11th in the Ultraman world championship eleven months later
Ian MacLaren, of the Torashin Karate Club, who is believed to be the first
5th dan Karate-ka in the world to have had both hips resurfaced
Floyd Landis, the 2006 Tour de France winner. His procedure was performed
after the Tour win. Joe Tierney completed the 2011, 2012,
and 2013 Syllamo's Revenge 50-mile endurance race 18, 30, and 42 months,
respectively, after resurfacing surgery on his left hip. This singletrack course
through the Ozark Mountains has been designated as "epic" by the
International Mountain Bike Association. Ed Jovanovski NHL Player - Defense
Florida Panthers. Only 9 months after having the procedure, Ed returned to the
NHL. He was the first athlete to return to a major professional team sport after
having the procedure done. Chase Poulsen - Olympic Tae Kwon DO
champion. Returned to training athletes only 6 months after the procedure.
Colby Lewis, MLB pitcher. Seven months after having the procedure, Colby
returned to baseball. He became the first player to return to MLB after hip
resurfacing. Gene Nelson of the Florida
Aikikai(Aikido) 5th Dan. Bilateral resurfaced hips. 2005 and 2009.
Recall In August 2010, DePuy Orthopaedics,
Inc., issued a voluntary recall of the ASR™ XL Acetabular System and ASR™ Hip
Resurfacing System after new information from the UK National Joint Registry
indicated that the number of patients who required a second hip replacement
procedure, called a revision surgery, was higher than previously reported
data. Potential complications include pseudotumors, metallosis, ALVAL, and
femoral neck fracture. See also
Minimally invasive hip resurfacing Total Hip Replacement
References