Abstract
Purpose
the purpose of this study was to compare the rollback ratio in the bi-cruciate substituting BCS-TKA and the Oxford UKA.
Methods
20 subjects (28 knees) who were performed the BCS-TKA (Journey II: Smith and Nephew) and 24 subjects (29 knees) who were performed the Oxford UKA, were included in this study. Approximately 6 months after surgery, and when the subjects recovered their range of knee motion, following the Laidlow's method (The knee 2010), lateral radiographic imaging of the knee was performed with active full knee flexion. The most posterior tibiofemoral contact point was measured for evaluation of femoral rollback (Rollback ratio). Flexion angle was also measured using the same radiograph and the correlation of rollback and flexion angle was analyzed. As a control, radiographs of the contralateral knees of who were performed Oxford UKA were evaluated (29 knees).
Results
The rollback ratios of the BCS-TKA, Oxford UKA, and the control knees were 37.9±4.9%, 35.7±4.2%, and 35.3±4.8% respectively from the posterior edge of the tibia. No significant difference in rollback ratio was observed. The flexion angles of the BCS-TKA, Oxford UKA, and the control knees were 121.8±8.4°, 125.4±7.5°, and 127±10.3°, respectively. No significant difference in knee flexion angle was observed. Significant correlation between rollback ratio and knee flexion angle was observed (p=0.002: Pearson's correlation coefficient =−0.384).
Conclusion
In conclusion, BCS-TKA showed no significant difference of rollback ratio when compared with the control knees and the Oxford UKA knees. There is the possibility that the design of BCS-TKA could reproduce the native ACL and PCL function.
