Neck fracture of a cementless forged titanium alloy femoral stem following total hip arthroplasty: a case report and review of the literature

<p>Abstract</p> <p>Introduction</p> <p>Fractures of the neck of the femoral component have been reported in uncemented total hip replacements, however, to our knowledge, no fractures of the neck of a cementless forged titanium alloy femoral stem coated in the proximal third with hydroxy-apatite have been reported in the medical literature.</p> <p>Case presentation</p> <p>This case report describes a fracture of the neck of a cementless forged titanium alloy stem coated in the proximal third with hydroxy-apatite.</p> <p>Conclusion</p> <p>The neck of the femoral stem failed from fatigue probably because of a combination of factors described analytically below.</p

Long-term behaviour of the Charnley offset-bore acetabular cup

We report the long-term radiological results of 58 total hip arthroplasties (THA) using the Charnley offset-bore acetabular socket. Wear was measured at four sites and radiolucent lines and possible migration were recorded. Four cups were retrieved at revision and were examined using light microscopy, SEM and X-ray microanalysis. At a mean follow-up of seven years the mean wear in the DeLee and Charnley zone I was 0.4 mm and in zone II 0.26 mm. The wear rate was 0.06 and 0.04 mm/year, respectively. Progression of radiolucent lines was seen in five cases (8.6%). Three sockets (5.2%) were revised because of aseptic migration at a mean follow-up of 9.8 years and one socket for infection at two years. The offset-bore acetabular cup had excellent wear behaviour and a low migration and revision rate. We recommend that it should be considered in THA since the use of small cups is increasing, particularly in revision cases

Fatigue Performance of Medical Ti6Al4V Alloy after Mechanical Surface Treatments

Mechanical surface treatments have a long history in traditional engineering disciplines, such as the automotive or aerospace industries. Today, they are widely applied to metal components to increase the mechanical performance of these. However, their application in the medical field is rather rare. The present study aims to compare the potential of relevant mechanical surface treatments on the high cycle fatigue (R = 0.1 for a maximum of 10 million cycles) performance of a Ti6Al4V standard alloy for orthopedic, spinal, dental and trauma surgical implants: shot peening, deep rolling, ultrasonic shot peening and laser shock peening. Hour-glass shaped Ti6Al4V specimens were treated and analyzed with regard to the material's microstructure, microhardness, residual stress depth profiles and the mechanical behavior during fatigue testing. All treatments introduced substantial compressive residual stresses and exhibited considerable potential for increasing fatigue performance from 10% to 17.2% after laser shock peening compared to non-treated samples. It is assumed that final mechanical surface treatments may also increase fretting wear resistance in the modular connection of total hip and knee replacements

Current evidence in designs and fixation surfaces in total hip arthroplasty

Since its introduction in the 1960s, total hip arthroplasty (THA) has proved to be an excellent and reliable mode of treatment for the end stages of hip pathology, with satisfactory clinical outcomes at 15-20 years [1-4]. Following the initial problems which the pioneers accounted in the 1960s and 1970s (such as surgical technique, structural design failures, and infection), in the 1980s, orthopaedic surgeons faced problems of choice of both acetabular and femoral components and the selection of cemented or cementless implant fixation. Soon afterwards, it was proved that the above dilemmas had been misleading since the long-term survival of a THA is a multifactorial issue, since, other than the implant, factors related to the diagnosis, the patient, the surgeon, and surgical technique are also important (Fig. 1.1). However, until now, the implant has been easy to blame for failures. A possible explanation is the fact that we do not have strong evidence supporting implant design and fixation principles. Instead, we have evidence of good and bad recipes, surgeons having learned from devastating clinical failures and patients having often been "fashion victims" [5]. © 2014 Springer-Verlag London. All rights are reserved