Abstract
Introduction
Revision total knee arthroplasty (TKA) has been often used with a metal block augmentation for patients with poor bone quality. However, bone defects are frequently detected in revision TKA used with metal block augmentation. This study focused on identification of a potential possibility of the bone defect occurrence through the evaluation of the strain distribution on the cortical bone of the tibia implanted revision TKA with metal block augmentation, during high deep flexion.
Materials and Methods
Composite tibia finite element (FE) model was developed and revision TKA FE model with a metal block augmentation (Baseplate size #5 44AP/67ML, Spacer size #5 44AP/67ML, Stem size Φ9, L30, Augment #5 44AP/67ML thickness 5mm) was integrated with the composite tibia FE model. 0°, 30° 60°, 90°, 120° and 140° flexion positions were then considered with femoral rollback phenomenon [Fig 1.A]. A compressive load of 1,600N through the femoral component was applied to the composite tibia FE model integrated with the tibia component, sharing by the medial and lateral condyles, simulating a stance phase before toe-off [Fig 1.B].
Results and Discussions
The strain distribution on the cortical bone of the tibia was shown in [Fig 2]. The results showed that the strains on the posterior region were gradually increased from extension to high deep of the knee joint and generally larger than the other regions. This fact was favorably corresponded to the femoral rollback phenomenon in the knee joint, showing a good accuracy of our FE model. In contrast to the results on the posterior region, the strains on the medial region were gradually decreased after 60° or 90° flexion position and relatively lower than the other regions. Particularly, the strains on the medial region were generally lower than 50–100 µstrain, which is known as critical value range able to inducing bone loss, during high deep flexion. This fact indicate that a potential possibility of bone defect occurrence in revision TKA used with a metal block augmentation may be relatively increased in patients who are frequently exposed to a personal lifestyle history with the loading conditions of the high flexion. This study may be valuable by identifying for the first time a potential possibility of the bone defect occurrence through evaluation of the strain distribution beneath metal block augmentation in revision TKA used with a metal block augmentation during high deep flexion.
Conclusions
A potential possibility of bone defect occurrence in revision TKA used with a metal block augmentation may be dependent on loading patterns applied on the knee joint related to personal lifestyle history. Particularly, it may be relatively increased in patients who are frequently exposed to a personal lifestyle history with the loading conditions of the high flexion.
Acknowledgements
This study was supported by a grant from the New Technology Product Evaluation Technical Research project, Ministry of Food and Drug Safety (MFDS), Republic of Korea.
