Changes of the bone mineral density in proximal femur following total hip resurfacing arthroplasty in osteonecrosis of femoral head

Abstract

Total hip resurfacing arthroplasty (THRA) is being performed with increasing frequency for osteonecrosis of femoral head (ONFH). To evaluate femoral bone remodeling in ONFH after THRA and determine the impact of stem-neck angle (SNA) of inserted femoral component on bone remodeling, we monitored the changes in BMD in proximal femur in 23 patients with ONFH after surgery. Patients were divided into group A (SNA ! 58) and group B (SNA < 58). The BMD was measured in seven Gruen zones and two neck zones using dual-energy X-ray absorptiometry preoperatively, then at 3, 6, 12, and 24 months after surgery. At all ROIs, the BMD decreased significantly by 3 months postoperatively. The BMD ceased to decrease and reversed by 6 months. The BMD in neck increased significantly in group A, compared with group B at 24 months. The BMD increased 2% at ROI1 at 24 months in both groups, and at ROI7, the BMD in group A reversed to baseline value by 6 months and increased 5.81% at 24 months. These findings implied that the bone stock of proximal femur in ONFH can be well reserved after total hip resurfacing arthroplasty with valgus positioning of the femoral component. ß

Activity intensity, assistive devices and joint replacement influence predicted remodelling in the proximal femur

“…All these changes are characteristic of most comparable hip resurfacing femoral components (Amstutz, Beaulé et al 2004;Spencer et al 2008), and were under-predicted by the model if the established control algorithm was used with the literature standard 75% threshold remodelling stimulus. More extensive resorption was predicted if a smaller threshold remodelling stimulus of 62.5% was used, but this is in disagreement with quantitative clinical data which shows a clear loss-recovery trend in the lateral neck and a progressive BMD increase in the medial neck (Lian et al 2008), especially distal to the head-neck junction (Kishida et al 2004;Häkkinen et al 2011;Penny et al 2012;Gerhardt et al 2014). Quantitative comparison of the predicted and clinically measured BMD changes remains difficult with hip resurfacing implants, owing to the variety of DXA zone definitions in these cited studies.…”

“…For some time there was limited quantitative clinical evidence of periprosthetic BMD changes (Cohen and Rushton 1995;Wilkinson et al 2001), and only more recently has the availability of DXA data become sufficient to enable more thorough spatiotemporal assessment of the validity of these predictions across the full periprosthetic region: for cemented THR (Jayasuriya et al 2013), cementless THR (Leichtle et al 2005;Kim et al 2007;Penny et al 2012), and for hip resurfacing (Kishida et al 2004;Lian et al 2008;Häkkinen et al 2011;Penny et al 2012;Huang et al 2013;Gerhardt et al 2014). This data demonstrated that past modelling studies have not reproduced clinically representative temporal trends of remodelling.…”

“…The cited clinical studies showed that BMD losses are often faster stabilising in the mid-stem zones (2 and 6), and that loss-recovery trends occur in more distal and lateral zones (3-5 and 1). The loss-recovery BMD change trend is also common in the bone supporting hip resurfacing implants, and is recorded distant from the implant (Lian et al 2008) and to some extent in the contralateral limb (Häkkinen et al 2011), suggesting that there is a contribution of extrinsic effects.…”

Cobalt, chromium and nickel affect hydroxyapatite crystal growth in vitro

“…Some of these patients also developed neck narrowing and, in a recent cohort of 377 patients, Little et al [8] reported that 4% of the patients had undergone femoral neck fracture. Although there is a growing body of evidence that the bone mineral density (BMD) is decreased around the implant in the first postoperative months, this could be attributed to the operation itself, as BMD seemed to increase after 3 months post-surgery [9][10][11]. Recent reports suggest that, besides bone density, other factors, often referred as ''bone quality", influence bone strength.…”

Is the increase in bone mineral density after hip resurfacing uniform across the femoral neck?

“…The whole femoral neck (R1) was analysed as one region and calculations were made. Several finiteelement analyses and original articles of case series in the literature reveal that bone remodelling is not uniform across the entire femoral neck [2][3][4]. The superolateral area adjacent to the implant has evinced a relative stress shielding [2].…”