Damage evolution in acetabular reconstructs under physiological testing in a saline environment

Damage development in cemented acetabular reconstructs has been studied under a combined cyclic loading block representative of routine activities in a saline environment. A custom-made environmental chamber was designed and installed on the Portsmouth hip simulator to allow testing of acetabular reconstructs in a wet condition for the first time. Damage was monitored and detected by scanning at selected loading intervals using micro-focus computed tomography (µCT). The preliminary results show that, although, as in dry cases, debonding at the bone-cement interface defined the failure of the cement fixation, the combination of mechanical loading and saline environment significantly affected the damage initiation and development, with drastically reduced survival lives of the reconstructs. Debonding was found to initiate at the bone-cement interface near the rim of the acetabular cup, or DeLee zone I, in wet condition, as opposed to initiation in DeLee zone II near the dome region in dry cases. The survival time of the reconstruct in wet condition is less than 10% of that in dry condition under a given applied hip contact force.