Differences in stability and bone remodeling between a customized uncemented hydroxyapatite coated and a standard cemented femoral stem A randomized study with use of radiostereometry and bone densitometry

Abstract

The custom made Unique® stem is designed to fit closely to the metaphyseal region of the femur in order to obtain maximum mechanical stability and optimal load transfer. Thirty‐seven patients (38 hips) with non‐inflammatory arthritis were randomized to the uncemented custom made Unique® stem or the Elite Plus stem inserted with cement. The patients have been followed clinically as well as with radiostereometry (RSA) and Dual‐energy X‐ray Absorptiometry (DXA) for 2 years. After 2 years the RSA result showed minimal translation and rotation for the Unique® stem while the Elite Plus rotated slightly (mean 1.05°) into retroversion. Compared to previous studies the Elite Plus was as stable as the Charnley prosthesis. The DXA results showed a significantly higher proximal and total (10% for the Unique versus 5% for Elite) bone loss for the Unique® stem compared to the Elite Plus. Thus the optimal proximal press‐fit of the custom made stem did secure a stable fixation, but did not decrease the proximal bone loss. © 2005 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.

Immediate weight bearing after uncemented total hip arthroplasty with an anteverted stem: A prospective randomized comparison using radiostereometry

“…However, these stems showed almost no further subsidence at the 1-year follow-up, thus indicating that they had stabilized-as did the femoral stem of the patient in this study with femoral fracture. These findings are consistent with other observations (Grant et al 2005). Subsidence seems to be tolerated in some uncemented hydroxyapatite-coated stem designs up until 1 year.…”

Early migration characteristics of a hydroxyapatite-coated femoral stem: an RSA study

“…It is accurate to ±47 µm, with a precision of 30 µm when monitoring femoral stem distal migration [12]. The RSA technique has been used to evaluate mid to long-term outcome, compare cementless and cemented stems, or, more commonly, assess the wear of the acetabular component of hip prostheses [13][14][15]. However, there are comparatively few studies evaluating early migration characteristics of cementless stems using this technique.…”

Impact of trochanteric heterotopic ossification on measurement of femoral bone density following cemented total hip replacement

“…Arabmotlagh 40 suggested that preservation of BMD in zone 1 of some of their study group might have been due to the effects of HO, and a recent study examining femoral remodeling excluded a patient with ''extensive'' HO from analysis. 41 However, our study shows that merely excluding ''extensive'' HO is insufficient, as even mild HO produces a significant effect. The only BMD study comparing differences between patients with and without HO following THA is included in a study of biochemical markers of HO, 42 which showed no difference in BMD between the two groups.…”