PERIPROSTHETIC MINERALIZATION AROUND CEMENTLESS TOTAL HIP ENDOPROSTHESIS - LONGITUDINAL-STUDY AND CROSS-SECTIONAL STUDY ON TITANIUM THREADED ACETABULAR CUP AND CEMENTLESS SPOTORNO STEM WITH DEXA
D. Sabo et al., PERIPROSTHETIC MINERALIZATION AROUND CEMENTLESS TOTAL HIP ENDOPROSTHESIS - LONGITUDINAL-STUDY AND CROSS-SECTIONAL STUDY ON TITANIUM THREADED ACETABULAR CUP AND CEMENTLESS SPOTORNO STEM WITH DEXA, Calcified tissue international, 62(2), 1998, pp. 177-182
In a prospective longitudinal study over 2 years and a separate cross-
sectional study more than 5 years after operation, we analyzed peripro
sthetic bone mineral density (BMD) after cementless total hip arthropl
asty (THA) (press-fit cementless Spotorno stem, Mecron threaded acetab
ular cup) by dual-energy X-ray absorptiometry (DEXA). BMD was analyzed
in a longitudinal prospective study (n = 53 patients: 29 women, 24 me
n) and in a separate cross; sectional study (n = 23 patients: 13 women
, 10 men) with good clinical outcome (Merle d' Aubigne score > 12). Re
gions of interest were defined according to Gruen (ROI 1-7) and as net
to average ROI (NETAVG I) for the periprosthetic femur, and according
to De Lee and Charnley (ROI I-III) and as NETAVG II for the periprosth
etic acetabulum. BMD during follow-up was compared with immediate post
operative 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 significa
ntly decreased in the periprosthetic femur and acetabulum during the f
irst 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 abs
olute values and decreased most during follow-up (to 79.9% ROI 1 and 6
8.2% 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 (respecti
vely, 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 Il). 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 bo
ne after implantation of THA in defined ROIs, supporting earlier repor
ted good clinical results of the Spotorno stem and increased loosening
rate of threaded acetabular cups after 5 years.