Published in:
01-08-2008 | Scientific Article
Periprosthetic mineralization changes around femoral stems: a prospective 12-month study with DEXA
Published in: Skeletal Radiology | Issue 8/2008
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Objective
The objective was to evaluate bone mineral density (BMD) changes around the proximal femur after implantation of two different anatomical stems.
Materials and methods
Thirty-six patients (19 women and 17 men) who underwent total hip replacement were recruited. A Bihapro stem was implanted in 23 patients (with a mean age of 60.9 years) and a Citation stem in 13 patients (with a mean age of 59.7 years). All patients underwent serial radiography of the affected hip (follow-up time: 12 months). Baseline periprosthetic and overall BMD were measured with dual-energy X-ray absorptiometry (DEXA) 1 week and 12 months after hip replacement. Regions of interest (ROIs) were defined according to Gruen’s system (ROIs 1–7).
Results
All stems were classified as radiographically stable. Bone ongrowth (spot welds) was present in zones 1 and 2 in all patients with the Bihapro stem. The distribution of baseline densities was very similar in the two groups of patients. In Bihapro implants a significant increment of mineralisation was present in ROI 1 after 1 year; ROIs 2 to 7 showed no density variation. The following observations were made regarding the Citation implants: no increment in density was shown in ROI 1; the differences in densities among the ROIs were significant after 1 year in the global evaluation (p = 0.004); the comparison between the single ROIs showed decalcification in ROIs 2 and 7 and a density increment in ROI 5.
Conclusions
Bihapro stems appear to achieve adequate proximal fixation, avoiding the “stress shielding” phenomenon.