Bone remodelling after total hip arthroplasty using an uncemented anatomic femoral stem: a three-year prospective study using bone densitometry.
ABSTRACT To evaluate the clinical, radiological, and densitometric changes in the bone-remodelling patterns of femoral stems aligned in neutral, valgus, or varus positions.
Between February and October 2000, 70 patients underwent unilateral total hip arthroplasty for primary osteoarthritis using an uncemented Anatomique Benoist Girard (ABG) II stem. 69 patients (30 males and 39 females) with a mean age of 59 years (range, 38-76 years) and a mean body weight of 79.3 kg (range, 29-110 kg) completed 3 years' follow-up on bone remodelling. The clinical, radiological, and densitometric changes of the neutral, valgus, and varus groups were evaluated, and the difference in bone-remodelling patterns between the 3 groups was analysed.
54 patients had neutrally placed stems, while varus and valgus malalignment occurred in 6 and 9 patients, respectively. Clinical and radiological evaluations were very similar among the 3 groups. Only densitometry could detect traceable changes resulting from the differing biomechanics of the neutral, varus, and valgus stem alignments.
The ABG II stem design made moderate errors in alignment biomechanically tolerable. Alignment defects had no clinical consequences and resulted in minimal differences in bone remodelling.
Full-textDOI: · Available from: Antonio Herrera, May 30, 2015
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ABSTRACT: Total joint replacement surgery is being performed on an increasingly large part of the population. Clinical longevity of implants depends on their osseointegration, which is influenced by the load, the characteristics of the implant and the bone-implant interface, as well as by the quality and quantity of the surrounding bone. Aseptic loosening due to periprosthetic osteolysis is the most frequent known cause of implant failure. Wear of prosthetic materials results in the formation of numerous particles of debris that cause a complex biological response. Dual-energy X-ray Absorptiometry (DXA) is regarded as an accurate method to evaluate Bone Mineral Density (BMD) around hip or knee prostheses. Further data may be provided by a new device, the Bone Microarchitecture Analysis (BMA), which combines bone microarchitecture quantification and ultra high resolution osteo-articular imaging. Pharmacological strategies have been developed to prevent bone mass loss and to extend implant survival. Numerous trials with bisphosphonates show a protective effect on periprosthetic bone mass, up to 72 months after arthroplasty. Strontium ranelate has been demonstrated to increase the osseointegration of titanium implants in treated animals with improvement of bone microarchitecture and bone biomaterial properties.01/2013; 2. DOI:10.12688/f1000research.2-266.v1
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ABSTRACT: Ti alloys are frequently used in the manufacture of femoral stems for total hip arthroplasty. Although low elastic modulus stems minimize bone stress shielding, they also may produce micromotions at the bone/implant interface, leading to excessive interfacial mechanical stress at the proximal region. This phenomenon may lead to the growth of fibrous tissues and, eventually, implant failure. To address both restrictions simultaneously, stems with adjustable rigidity may be used. Considering that the rigidity of β Ti alloys can be controlled by heat treatments, this paper introduces a new concept for a femoral stem with a graded elastic modulus using metastable β Ti alloy. The combination of solution heat treatment, water-quenching, and aging heat treatments allows the mechanical behavior of the metastable β Ti alloys to be tailored and, in particular, be used to construct a graded elastic modulus femoral hip stem. The results obtained revealed that it is feasible to design biomedical implants from metastable β Ti alloys with hybrid mechanical behavior. The specific mechanical behavior is obtained by focusing only on heat treatments. A stem with an elastic modulus varying from 65 GPa to 110 GPa was obtained.Materials and Design 03/2015; 69. DOI:10.1016/j.matdes.2014.11.040 · 3.17 Impact Factor