Strain measurements of proximal tibial following unicompartmental knee arthroplasty (UKA)

UKA stress fracture at medial tibial plateau has been observed clinically. However, the reasons for such occurrences have not been fully understood (Brumy et al, 2003) An experimental project involving strain gauge rosettes to study the principal strains in the tibia before and after Unicompartmental Knee Arthroplasty (UKA). The tibias are tested by applying various loadings on the knee joint. The experiment was conducted on six specimens of human cadaver knee joint. The strain measurements and failure loads were determined by the cadaver experiments. The changes in strain between intact and implanted were shown to be insignificant using paired sample t-Test. Various possible reasons contributing to these insignificancies are highlighted in the report. A preliminary hypothesis explaining reason for higher strain experienced at the edge of the medial tibia was proposed. Based on the available number of specimens tested, it was concluded that higher load distribution due to an increase in height has contributed to the aforementioned high strain experienced. The failure load of the implanted tibia at a loading rate of 0.05 mm/min ranged from approximately 5500 N to 6600 N. Bone has a property of an isoelastic material. Different loading rates will contribute to different failure rate; loading rate is inversely proportional to failure load. It is recommended that further testings are to be conducted to better determine the effect of the higher strain reading at the edge of the tibia.This problem could be addressed by redesigning the implants.Bachelor of Engineering (Mechanical Engineering