Influence of clearance on the time-dependent performance of the hip following hemiarthroplasty: a finite element study with biphasic acetabular cartilage properties.
Bottom Line: Both a prolonged loading period of 4000 s and dynamic gait load of 10 cycles were considered.It was found that a larger clearance led to a higher stress level, a faster reduction in load supported by the fluid and a faster cartilage consolidation process.The results demonstrated that a larger clearance in hip hemiarthroplasty is more harmful to the acetabular cartilage and prosthesis heads with more available dimensions (i.e. smaller increments in diameter) could be manufactured for surgeons to achieve a lower clearance, and reduced contact stress in hemiarthroplasty surgeries.
Affiliation: Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, UK. Electronic address: firstname.lastname@example.org.Show MeSH
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Mentions: Results of the models under the static load over 4000 s period are summarised in Fig. 3. The hemiarthroplasty model with larger clearance had higher peak contact stress, higher peak fluid pressure, smaller contact area and greater changes in these results over the 4000 s. The peak contact stress decreased by 20.5% for the hemiarthroplasty model with 2 mm clearance, while there was almost no change (<1%) in the peak contact stress for the model with no clearance over the 4000 s period. The fluid support ratio was above 90% over the 4000 s period for all the models, and was slightly higher but decreased faster for models with larger clearances. The decrease in fluid support ratio was 6.9% and 4.5% for the model with a clearance of 2 mm and 0 mm, respectively. Comparable results were found between the natural hip model and the hemiarthroplasty model with no clearance.
Affiliation: Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, UK. Electronic address: email@example.com.