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AAOS Now

Published 12/1/2015

Studies Highlight Hip Care

A series of studies presented at the 2015 annual meeting of the American Association of Hip and Knee Surgeons examine various aspects of patient care surrounding total hip arthroplasty (THA).

The 3-day rule
In 1965, the Centers for Medicare and Medicaid Services (CMS) instituted a rule requiring Medicare patients to stay in the hospital for 3 days following THA before they can be admitted to a skilled nursing facility. The rule was intended to discourage excessive use of the skilled nursing benefit, but as care patterns have changed over time, it may now be having a greater impact on hospital costs.

According to presenter Victor H. Hernandez, MD, data collected between 2002 and 2011 on nearly 2 million hip replacements show a marked difference in the impact of rapid recovery protocols between patients with private insurance and those with Medicare.

"The change in patients discharged on day 1 went from 3 percent to 5.5 percent in the private group and from 1 percent to 1.9 percent in the Medicare group," said Dr. Hernandez. "The percentage of patients not discharged until the third day remained unchanged in the private group (approximately 50 percent), while for Medicare patients it went from 49 percent to 57 percent."

As a result, the changes in discharges associated with rapid recovery protocols after THA—including lower hospital costs—have been realized mostly in patients with private insurance.

"As the Medicare population increases in number and age, they are more likely to require inpatient rehabilitation after THA," said Dr. Hernandez. "Revision of this rule is critical to increase the cost effectiveness of THA."

How necessary is formal PT?
According to the results of a prospective randomized study, prescribed, patient-directed home exercises may be just as effective as formal outpatient PT is following total hip replacement surgery.

Matthew S. Austin, MD, presented the results of a study that followed two groups of patients for 6 months. Patients in one group followed a prescribed exercise program at home; those in the other group received two to three sessions of formal PT over 2 months after surgery.

"Preoperative functional scores and demographics between both groups were similar. We found no significant differences in any measured outcomes at 1 month or 6 months postoperatively," said Dr. Austin.

Direct anterior approach
The increasing popularity of the direct anterior approach prompted Joseph D. Maratt, MD, and colleagues to examine the risks and benefits of this approach in comparison to a modern posterior approach. They used data from the Michigan Arthroplasty Registry Collaborative Quality Initiative to compare the short-term outcomes and complications of 2,147 matched pairs of THA patients.

"We found no statistically significant difference in dislocation risk, fracture rate, blood loss, hematoma formation, length of hospital stay, or readmission," stated Dr. Maratt, "although the average operative time was 24 minutes longer when surgeons used the anterior approach." The study concluded that, based on these data, the two approaches "have no compelling advantage over each other."

10-year outcomes
In a multicenter study, a cohort of patients who received highly crosslinked polyethylene liners articulating against large diameter femoral heads was reassembled at a minimum of 10 years follow-up. Researchers sought to evaluate the radiographic and wear analysis of implants with highly-crosslinked polyethylene liners and femoral heads greater than 32 mm in diameter.

Wear analysis was performed using the Martell Hip Analysis software. Radiographic grading was performed on the longest follow-up AP hip films. The extent of radiolucency in each zone greater than 0.5 mm in thickness was recorded, along with the presence of sclerotic lines and osteolysis.

According to presenter Charles R. Bragdon, PhD, the wear rate of the implants "remained at levels lower than the detection limit of the software at minimum 10 year follow-up, and there was no identified osteolysis."

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