Imaging, patient symptoms should be considered before metal-on-metal THR revisions

MANCHESTER — Surgeons can use MRI and ultrasound equipment to detect metallosis in potential metal-on-metal total hip replacement revision patients, but researchers from the United Kingdom recommend taking patient symptoms into consideration as well, according to a recent presentation.

“Although ultrasound and MRI are useful in the treating of MoM patients, there is a significant percentage of hips that have pain with negative radiology findings,” Naveed Ahmed, of the Prince Charles Hospital in Merthyr Tydfil, United Kingdom, stated in his presentation at the British Orthopaedic Association Congress, here.

Naveed Ahmed

Ahmed and colleagues examined imaging results from 25 patients: 21 patients had MRI results and 23 patients had ultrasound results preoperatively. Patient imaging was taken on an average of 50 months after primary total hip replacement, Ahmed said.

The researchers analyzed the fluid collected from patients during revision surgery. MRIs were positive for metallosis in 16 patients, while ultrasound was positive in 18 patients. Four patients had both negative MRI and ultrasound results, but were still revised due to pain, Ahmed said.

“During surgery, multiple samples were taken from acetabulum, capsule as well as tissue lining the femoral neck and sent for histopathology,” Ahmed said.

The histopathologist defined metallosis as the “presence of sheets of macrophages with dark brown pigmentation in the cytoplasm under polarized light,” Ahmed said.

Reference:

Ahmed N. Paper #20. Presented at: British Orthopaedic Association Congress. Sept 11-14, 2012; Manchester.