November 03, 2008
Rush University Medical Center
Study Finds More Complications in Women and in Males
Over the Age of 55
CHICAGO – Hip resurfacing is often seen as a modern
alternative to the more conventional total hip
replacement, but new data from a study led by Rush
University Medical Center suggest that a patient’s age
and gender are key to the operation’s success.
In a review of over 500 surgeries performed in the U.S.
using a hip resurfacing device recently approved by the
Food and Drug Administration (FDA), the researchers
found that the majority of serious complications
occurred in women of all ages and men over the age of
55. The most common complication, and the most serious,
was a fracture of the femoral neck, the slender area of
bone just beneath the head of the femur.
The study has just been published online and will appear
in the January 2009 issue of Clinical Orthopaedics and
"The ideal patients for hip resurfacing are males under
the age of 55. They have the fewest, and the least
serious, complications," said Dr. Craig Della Valle,
lead author and a specialist in joint reconstruction at
Rush University Medical Center. "Patients may be eager
to take advantage of technological innovations, but for
older individuals, a conventional hip replacement is
generally more appropriate."
The researchers analyzed data for the first 537 hip
resurfacing surgeries performed in the U.S. after the
Birmingham Hip Resurfacing implant, manufactured by
Smith & Nephew, was approved by the FDA in October 2006.
The majority of the patients suffered from severe
osteoarthritis. All 89 orthopedic surgeons involved in
the procedures had undergone training required by the
FDA before conducting their first cases. Their level of
experience with hip surgery varied. Some were joint
replacement specialists; others were general orthopedic
Serious complications occurred in 32 of the 537 cases,
including 10 cases in which the femoral neck fractured
after surgery, a problem not seen with conventional hip
replacements. Such fractures require additional surgery.
Nine of the fractures in the study occurred in patients
who were either female or older than 55 at the time of
the implant. Eight of the fractures occurred when the
surgeon was relatively inexperienced with the procedure
(within the surgeon’s first 10 cases).
According to Della Valle, age and sex are probably
linked to the incidence of such fractures because of
bone quality and quantity.
"Patients who are older or who are female tend to have
softer bone," he said. "Also, men on average have larger
bone structures, with a greater surface area for
securing the implant."
The study identified several other serious
complications, including nerve injury, joint
dislocation, fracture of the proximal femur (just below
the femoral neck), loosening of the metal component in
the joint socket, and deep infection.
The rate of complications, however, was similar to that
found in other studies involving only orthopedic
surgeons who had extensive experience with hip
resurfacing. As a result, the authors concluded that the
FDA-mandated training succeeded in teaching generalists
the skills needed to perform the technically challenging
hip resurfacing procedure, alerting them to possible
complications and ways to avoid those problems.
In a conventional total hip replacement, orthopedic
surgeons remove the head of the femur, or the ball of
the hip joint, and replace it with a metal stem inserted
into the thigh bone. They fit the socket of the joint
with a metal shell that typically includes a plastic
liner. In hip resurfacing, the femoral head remains, but
its surface is reshaped to accept a rounded cap with a
short stem that sits in the femur. A thin metal cup is
pressed into the hip socket. Both components are made
entirely of cobalt chrome, a metal.
Hip resurfacing is generally recommended for younger,
more active patients out of concern that the traditional
artificial hip might wear out during their lifetime and
require a second replacement, a far more complicated
"Hip resurfacing has certain advantages over the
conventional total hip replacement," said Della Valle.
"It preserves more bone because the head of the femur is
retained. It enables the patient to return to
high-impact sports because the metal components of the
implant resist wear and tear and can withstand the
forces associated with activities like running. Some
studies have also shown that hip resurfacing carries a
lower risk of dislocation because the size of the ball
component is larger."
"But despite its benefits, risks remain," Della Valle
added. "Our findings suggest that we need to be
cautious. This procedure is not ideal for everyone."