BONE mineral density measurements obtained using radiofrequency echographic multispectrometry (REMS) were slightly lower after total hip replacement, according to a prospective study examining how surgery and patient characteristics may influence results.
REMS is an ultrasound-based technique used to estimate bone mineral density without ionizing radiation. Researchers investigated whether the presence of a hip prosthesis affected REMS measurements and explored the extent to which patient characteristics influenced the results.
REMS Measurements Before and After Surgery
The study included 50 people with advanced hip osteoarthritis who underwent REMS assessments before and 3 days after total hip arthroplasty. The cohort comprised 27 women and 23 men between 49 and 84 years of age.
Femoral neck bone mineral density was measured before and after surgery. Additional lumbar spine assessments were conducted in a subset of male participants to explore whether demographic information entered into the device influenced the measurements.
Femoral neck REMS-BMD measurements were strongly correlated before and after surgery. However, postoperative values were an average of 0.021 g/cm² lower than preoperative measurements, representing a reduction of approximately 2.8%. This difference was statistically significant, showing a systematic shift between the two assessments.
Patient Characteristics Influenced Measurements
Regression analysis indicated that age, sex, and BMI accounted for approximately 90% of the variation in femoral neck REMS-BMD measurements between participants in the study cohort.
The researchers also conducted additional assessments in which demographic inputs, including age, height, and weight, were altered while measurements were repeated. Changes in the information entered into the system were associated with differences in the resulting REMS-BMD values.
These findings suggest that REMS measurements may be influenced not only by the ultrasound signals collected during an assessment, but also by the demographic information used during analysis.
Further Research Needed on REMS-BMD
The study authors concluded that the hip prosthesis appeared to have a limited effect on REMS measurements, despite the small but statistically significant reduction observed after surgery.
However, they emphasized that further research is needed to determine exactly what REMS-BMD represents and whether it reflects areal or volumetric bone density. Additional investigation is also required to clarify how backscattered ultrasound signals and patient information contribute to the final measurement.
Reference
Bobelyak M et al. Bone mineral density assessment using radiofrequency echographic multispectrometry (REMS) in patients before and after total hip replacement. Osteoporos Int. 2025. doi: 10.1007/s00198-025-07685-w
Correction, July 22, 2026: This article was updated to correct the description of the comparison between pre- and postoperative REMS-BMD measurements. The study found that postoperative measurements were systematically lower by an average of 0.021 g/cm². A statement that REMS produced reproducible results across different clinical settings was also removed, as this was not assessed in the study.
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