Abstract
Purpose
Use of theguide angle method using intramedullary guide angle for distal femoral cutting in total knee arthroplasty may cause error when rotation of the femur occurs or the insertion point of the intramedullary guide is incorrectly positioned in preoperative radiography. On the other hand, use of the measured cutting method, in which resection of distal femoral condyles is performed according to predicted measured thickness in a preoperative radiograph can allow for correction of these errors intraoperatively. Therefore, we compared these two distal femoral bone cutting methods for restoration of accurate coronal alignment.
Methods
Between 2010 and 2012, 47 patients (70 knees) underwent total knee arthroplasty for treatment of osteoarthritis with varus deformity and flexion contracture less than 10 degrees. Bone resection depending on distal femur resection thickness measured before the operation was performed in 38 cases (Group I). Distal femoral cutting using the guide angle was performed in 32 cases (Group II). Radiographic evaluation, including mean value of lower leg mechanical axis angle and the frequency of errors of more than 3 degrees, was performed for comparison between the two groups.
Results
In Group I, mechanical axis was corrected from 8.4 ± 4.9 degrees (−7.2 to 16.9) on average before the operation to 0.1 ± 2.4 degrees (−5.87 to 2.98) after the operation, and, in Group II, from 6.7 ± 3.6 degrees (0.4 to 14.7) on average before the operation to 0.5 ± 2.8 degrees (−5.4 to 6.9) after the operation. No statistically significant difference in mechanical axis (p = 0.554) was observed between the two groups after the operation, and no difference in errors of more than 3 degrees was observed between the two groups, with four of 38 cases (11 %) in Group I and six of 32 cases (19%) in Group II (p = 0.495).
Conclusions
No significantly different results were observed between the measured resection technique and the existing guide angle technique. Therefore, predictive measurement of distal femoral cutting thickness is another useful method for restoration of accurate coronal alignment.
