Periprosthetic Mineralization Around Cementless Total Hip Endoprosthesis: Longitudinal Study and Cross-Sectional Study on Titanium Threaded Acetabular Cup and Cementless Spotorno Stem with DEXA |
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| Authors: | D Sabo A Reiter H G Simank M Thomsen M Lukoschek V Ewerbeck |
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| Institution: | University of Heidelberg, Orthopedic Department I, Schlierbacher Landstra?e 200 a, D-69118 Heidelberg, Germany, DE
University of Heidelberg, Orthopedic Department II, Schlierbacher Landstra?e 200 a, D-69118 Heidelberg, Germany, DE
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| Abstract: | In a prospective longitudinal study over 2 years and a separate cross-sectional study more than 5 years after operation,
we analyzed periprosthetic bone mineral density (BMD) after cementless total hip arthroplasty (THA) (press-fit cementless
Spotorno stem, Mecron threaded acetabular cup) by dual-energy X-ray absorptiometry (DEXA). BMD was analyzed in a longitudinal
prospective study (n = 53 patients: 29 women, 24 men) and in a separate cross-sectional study (n = 23 patients: 13 women,
10 men) with good clinical outcome (Merle d' Aubigne score > 12). Regions of interest were defined according to Gruen (ROI
1–7) and as netto average ROI (NETAVG I) for the periprosthetic femur, and according to De Lee and Charnley (ROI I-III) and
as NETAVG II for the periprosthetic acetabulum. BMD during follow-up was compared with immediate postoperative values of the
affected limb. Mean precision error (CV%) was 2.6 ± 0.5% for ROI 1–7 and 1.3 ± 0.9% for ROI I–III. BMD significantly decreased
in the periprosthetic femur and acetabulum during the first 3 months after operation. At the femur, BMD (NETAVG I) for women
and men, respectively, was 92.4% and 87.5% at 6 months, then 89.4% and 96.2% at 2 years. ROIs around the proximal stem showed
the lowest absolute values and decreased most during follow-up (to 79.9% ROI 1 and 68.2% ROI 7, respectively). Mineralization
around the cup (NETAVG II), respectively, amounted to 81.1%, 82.6% at 6 months, then 80.1% and 93.8% at 2 years. The medially
placed ROI II demineralized most (respectively, 72.1% and 76.7%). More than 5 years after THA, BMD in the femur showed little
change, but decreased significantly to 76.4% and 79.1%, respectively, around the cup (NETAVG II). DEXA is a useful method
for analyzing changes of mineralization around cup and stem of cementless THA. The results reflect the different stress on
the periprosthetic bone after implantation of THA in defined ROIs, supporting earlier reported good clinical results of the
Spotorno stem and increased loosening rate of threaded acetabular cups after 5 years.
Received: 31 March 1997 / Accepted: 7 August 1997 |
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| Keywords: | : Bone mineral density (BMD) — Dual-energy X-ray Absorptiometry (DEXA) — Cementless total hip arthroplasty — Threaded acetabular cup |
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