Resistance of a novel ceramic acetabular cup to critical impact loads

Abstract

<jats:p> A novel thin-walled direct-to-bone fixation ceramic cup was tested under critical impact loads simulating lateral fall and car crash scenarios. Three sizes of BIOLOX delta ceramic cups (total hip replacement cup with bearing diameter of 32 mm and two hip resurfacing cups with bearing diameters of 40 and 64mm) were implanted into reamed Sawbones blocks representing acetabulae. Three cups of each size were fully supported by the block and three were implanted with 15° of the cup’s outer diameter unsupported by the block. All testing was conducted with the corresponding bearing diameter heads lateralised by approximately 1 mm to represent worst case subluxed hips and all then subjected to test, replicating a lateral fall impact followed by a car crash impact. All cups passed lateral fall conditions without visible damage, although some movement of the cups was measured and damage to the blocks was observed. Five out of six of each cup size survived the car crash impacts with one fracture per size. In all cases, this was in the fully supported condition representing the highest cup inclination angle. The car crash impact force was equivalent to that reported to fracture the acetabulum and in all simulated cases, the Sawbones block showed signs of damage. Survival of five cups per size suggests the pelvis is much more likely to fracture before the cup. The ability of the cups to withstand these critical impact forces indicates they are unlikely to fracture in normal clinical use and should meet the more challenging demands of active patients likely to receive this device. </jats:p>

Hip Resurfacing Arthroplasty: Past, Present and Future

“…These include: resistance to chemical reactions in physiological conditions, bio-inertness, excellent wear properties and high fracture strength and toughness compared to previous generations. 45,59 Manufacturers have now incorporated lateral fall simulation impact tests to ensure the absence of fracture or visible damage, as well as high velocity car crash impaction test which have confirmed the suitability of modern ceramic materials for prosthesis design. 59,60 An additional advantage is the potential for reduced bacterial adhesion as demonstrated in in-vitro studies however, a reduction in periprosthetic joint infection remains controversial thought Pitto et al noted a lower risk of revision for deep infection in ceramic on ceramic THAs over a 15 year period in their registry based study.…”

“…45,59 Manufacturers have now incorporated lateral fall simulation impact tests to ensure the absence of fracture or visible damage, as well as high velocity car crash impaction test which have confirmed the suitability of modern ceramic materials for prosthesis design. 59,60 An additional advantage is the potential for reduced bacterial adhesion as demonstrated in in-vitro studies however, a reduction in periprosthetic joint infection remains controversial thought Pitto et al noted a lower risk of revision for deep infection in ceramic on ceramic THAs over a 15 year period in their registry based study. 61 Currently, there are two 'Medicines and Healthcare products Regulatory Agency' approved (MHRA) ceramic-on-ceramic HRA ongoing clinical trials.…”

“…61 Currently, there are two 'Medicines and Healthcare products Regulatory Agency' approved (MHRA) ceramic-on-ceramic HRA ongoing clinical trials. These are the H1 ® (Embody Ltd.) and the ReCerf ® (MatOrtho Ltd.) and their outcomes are yet to be published (59)(60)(61). Other groups have focused their efforts on developing metal-on-polyethylene HRAs though wear has been a concern.…”