Evaluation of Bone Cutting Error of the Total Knee Arthroplasty with Computer-assisted Navigation

ABSTRACT

PURPOSE: To investigate the degree of bone cutting errors and its deviation and to evaluate the differences between a planned value before sawing and an achieved value after sawing in total knee arthroplasty (TKA) with computer-assisted navigation system. MATERIALS AND METHODS: 95 knees of 95 patients(81 females and 14 males) who underwent TKA with computer-assisted navigation (Orthopilot(R), AESCULAP) were studied. The planned value according to cutting block position and the achieved value according to achieved cutting planes were measured and compared. The bone cutting error which means a difference between the achieved value and the planned valued in each plane were statistically analysed. RESULTS: On each cutting planes, there were significant differences between planned values and measured values in coronal and sagittal plane of tibia and sagittal plane of femur (respectively p=0.0008, p=0.0002, p<0.0001), but coronal plane of femur showed insignificant difference (p=0.39). There was significant difference between bone cutting errors with valgus 0.05degrees (SD+/-0.66) in coronal plane and extension 0.47degrees (SD+/-0.91) in sagittal plane of femur and valgus 0.31degrees (SD=+/-0.80) in coronal plane band extension 0.21degrees (SD+/-2.09) in sagittal plane of tibial cutting (respectively p=0.0012, p<0.0001). CONCLUSION: Achieved values of bone cutting in coronal and sagittal plane of tibia and sagittal plane of femur on TKA were significantly different from planned values. The deviation of bone cutting errors showed valgus and extension in both femur and tibia. The bone cutting errors in sagittal plane were more significant than the coronal plane. Surgeons should take this bone cutting errors into consideration on operation.