Saturday, December 29, 2012

Before Metal-on-Metal Hip Surgery, Consider Imaging, Symptoms

Healio

Researchers from the United Kingdom recommend patients who have received fatly metal-on-metal hip implants consider both MRI imaging and symptoms before undergoing revision surgeries.
“Although ultrasound and MRI are useful in the treating of metal-on-metal patients, there is a significant percentage of hips that have pain with negative radiology findings,” Naveed Ahmed, MBBS, MSc, of Prince Charles Hospital in Merthyr Tydfil, United Kingdom, stated in his presentation at the British Orthopaedic Association Congress, Healio.com said.

Ahmed and his team of researchers retrospectively studied imaging results from 25 hips between March 2011 and May 2012: 23 hips had ultrasound scans and 21 of these hips also had MRI scans preoperatively, Healio.com said. The patients’ average age range was 37 years to 69 years and ultrasound was conducted an average of 50 months after primary total hip replacement, Healio.com said.

Researchers examined fluid collected from patients during revision surgery in search of evidence of metallosis. MRIs were positive for fluid collection in 16 patients, and ultrasound was positive in 18 patients, Healio.com said. Four patients had both negative MRI and ultrasound results, but were still revised due to pain and were found to have histopathology positive metallosis. The histopathologist involved in the study defined metallosis as the presence of sheets of macrophages with dark brown pigmentation in the cytoplasm under polarized light, Healio.com said. The results also revealed that one patient had a positive ultrasound and negative MRI result. Likewise, one patient had a positive MRI with a normal ultrasound.

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