N°004 - January / February 2020
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Weight limits associated with commonly used femoral stems for total hip arthroplasty
By J. Griffiths(1), M. Quaye(2), S. Abouel-Enin(3), P.J. Yates(4), R. Carey-Smith(5), J. Latham(6) in category UPDATE
(1) Consultant Trauma and Orthopaedic Surgeon, Hampshire Hospitals NHS Foundation Trust (2) Specialist Registrar Trauma and Orthopaedic Surgery, University Hospital Southampton NHS Foundation Trust (3) Trauma and Orthopaedic Fellow, University Hospital Southampton NHS Foundation Trust (4) Professor Trauma and Orthopaedic Surgery, Freemantle Hospital, Perth, Australia (5) Professor Trauma and Orthopaedic Surgery, Sir Charles Gairdner Hospital, Perth, Australia (6) Consultant Trauma and Orthopaedic Surgeon, University Hospital Southampton NHS Foundation Trust / [email protected]
The World Health Organisation (WHO) suggests obesity to affect 200 million men and 300 million women worldwide (1). Obesity is defined per body mass index (BMI), with a patient being classified as overweight with a BMI of ≥25Kg/m2, obese with a BMI ≥30Kg/m2 and morbidly obese with a BMI ≥40Kg/m2 (2). Currently, in the UK, 26.1% of the adult population are thought to be obese(3). This figure is expected to rise to 60% of adult men and 50% of adult women by 2050(4). The NJR has reported an increase in the number of THR’s being performed in patients with a BMI between 25 Kg/m2-44 Kg/m2 from 69% in 2004 to 79% in 2012 (5). The rising incidence of obesity has led to an increase in the number of overweight/obese patients undergoing an elective THR surgery.
Failure of a THR due to fatigue fracture of the femoral stem is a rare complication. Its incidence varies between 0.23% and 10.7% (6). It was more commonly seen with the traditional forged stainless steel or cast cobalt chrome implants due to their relatively low fatigue strength and defects in their crystalline lattice microstructure (7) (8) (9) (10) (11) (12) (13). The introduction of the high strength ‘super alloys’ including forged cobalt chrome, high nitrogen stainless steel (HNSS) and...
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