Quantitative CT-assisted osteodensitometry of femoral adaptive bone remodelling after uncemented total hip arthroplasty

Abstract

The aim of this prospective study was to measure bone density changes and to assess adaptive bone remodelling after uncemented total hip arthroplasty with a taper-design femoral component using quantitative computer-tomographyassisted osteodensitometry. This method is able to differentiate cortical and cancellous bone structures. Twenty-seven consecutive patients (29 hips) with degenerative joint disease were enrolled in the study. Serial clinical, radiological and CTosteodensitometry assessments were performed after the index operation. At the 2-year follow-up, the clinical outcome was rated satisfactory in all hips. The radiological assessment showed signs of osteointegration and stable fixation of all cups and stems. We observed a −17% decrease of cortical bone density and −22% decrease of cancellous bone density in the greater trochanter and femoral neck region. Cortical and cancellous bone density decrease at the level of the lesser trochanter was −9% and respectively −4%. We observed small changes of cortical bone density in the diaphyseal regions; in contrast, cancellous bone density increased (range 6% to 27%) in the diaphyseal regions. Overall, a trend of bone density recovery was observed throughout the follow-up period. Periprosthetic bone density changes at the 2-year follow-up are suggestive of stable osteointegration with proximal femoral diaphysis load transfer and moderate metaphyseal stress-shielding.Résumé Le but de cette étude prospective est de mesurer par scanner et ostéodensitométrie la densité osseuse et le remodelage osseux après prothèse non cimentée. Cette méthode permet de différencier les structures osseuses corticales et spongieuses. 27 patients consécutifs (29 hanches) présentant une coxarthrose ont été inclus dans cette étude qui a comporté une analyse radiologique, scanographique et ostéo-densitométrie. Pour toutes les hanches à deux ans de suivi post-opératoire, le devenir clinique de ces patients était satisfaisant. La radiologie montrait des signes d'ostéointégra-tion et de fixation stables dans toutes les cupules et pour toutes les pièces fémorales. Nous avons observé une diminution de 17% de la densité corticale et de 22% de la densité de l'os spongieux au niveau du grand trochanter et au niveau du calcar. Il existe également une diminution de la densité osseuse au niveau du petit trochanter tant sur le plan cortical 9% qu'au niveau de l'os spongieux 4%. Nous avons égale-ment observé de petites modifications de la densité osseuse corticale au niveau de la région diaphysaire, a contrario nous avons également mis en évidence une augmentation de la densité osseuse de l'os spongieux à ce niveau (de 6 à 27%). Ces différentes modifications osseuses nous permettent, à deux ans de suivi post-opératoire, de penser que l'ostéointégration proximale des éléments prothétiques entraîne un transfert de charge et un stress-shielding métaphysaire modéré.

Changes in periprosthetic bone remodelling after redesigning an anatomic cementless stem

“…Second-generation cementless stems (anatomic design, metaphyseal press-fit, proximal coating) made of titanium still had a decrease of BMD at the end of the second year that ranged from 20% to 25% [9,17]. Tapered femoral components had a proximal loss between 10% to 30% [1,6,19]. Custommade implants reported the best results regarding the proximal loss of BMD, but with a fall of between 10% to 15% at the end of the third year [12,13].…”

Quantitative CT with finite element analysis: towards a predictive tool for bone remodelling around an uncemented tapered stem

“…Computed tomography scans were carried out on all patients postoperatively, one year, two and five years after the index operation. The method used for qCT assessment has been already described in the one and two-year follow-up reports [8,9].…”

“…We have used geometric and density information from qCT datasets of previous osteodensitometry studies [8][9][10] to create patient-specific finite element (FE) models. The hypothesis of this study is that the combination of these two modalities, qCT and FE, allows three dimensional patient specific imaging of cortical and cancellous bone changes over time as well as the consequences of stress shielding.…”

Five-year DEXA study of 88 hips with cemented femoral stem

“…The technical improvements in dual-energy X-ray absorptiometry (DEXA) have made it possible to accurately measure the quantity of bone near a metallic implant [11,12,14]. Recently quantitative computed tomography (QCT)-assisted osteodensitometry has also been shown to be useful in assessing the in vivo structural bone changes after total hip arthroplasty (THA) [20,21].…”