Description
Objectives: The purpose of this study was to evaluate the accuracy of the bony resection in the robotic TKA for the treatment of knee OA in the Asian population. The hypothesis of this study was that the robotic TKA could resect the bone accurately with the pre-operative planning.
Methods: Twenty-one (21) subjects (17 female and 4 male: average age 78.7±9.1), were included in this study. All surgery were performed by a single surgeon (K.S.) with robotic assistance (CORI, Smith and Nephew, Co., Ltd, Boston MA, USA). Journey II BCS-TKA (Smith and Nephew, Co., Ltd, Boston MA, USA) was used for all subjects. Within 3 weeks after surgery, knee radiographic evaluation was performed. Both in accurate coronal and sagittal knee radiograph, tibial component of varus/valgus alignment, posterior tibial slope angle, and the lateral distal femoral angle (LDFA) were evaluated. Statistical analysis was performed to compare the varus/valgus angle, posterior slope tibial implant alignment, and LDFA between pre-operative planning and post- operative knee radiograph (Mann-Whitney’s U test).
Results: In the coronal plane, pre-operative planning of the tibial component’ varus angle was 1.8±1.2° (range: 0-3°), and post-operative radiographic component’ varus angle was1.9±1.1° (range: 0-4°). No significant difference was observed between pre-operative planning and post-operative radiographic evaluation. In the sagittal plane, pre-operative planning of the tibial component’ posterior slope angle was 4.5±1.3° (range: 3-6°), and post-operative radiographic component’ varus angle was 3±1.3° (range: 1-6°). Post-operative radiographic evaluation of tibial posterior slope angle was significantly smaller than pre-operative planning (p<0.001). Pre-operative planning of LDFA was 83.7±1.8° (range: 81-87°), and the post-operative radiographic measurement of LDFA was 81.5±1.7° (range: 77-85°). Post-operative radiographic evaluation of LDFA was significantly smaller than pre-operative planning (p<0.001). Considering that every standard deviation of data was approximately 1°, subjects under 1° difference between pre-operative planning and post- operative evaluation were regarded as accurate resection group and others were regarded as non-accurate resection group. In the coronal plane of tibial component, 20 subjects were included to the accurate resection group. On the other hands, in the sagittal plane of tibial component, only 9 subjects were included in the accurate resection group. For the femoral component, 6 subjects were included in the accurate resection group.
Conclusions: In conclusion, high accuracy was showed in the coronal plane of tibia component in the robotic assisted TKA, however, the accuracy in the sagittal plane of tibia component, and coronal plane of femoral component were relatively low. Surgeons should pay attention to perform careful joint surface mapping especially on the posterior part of tibia, and the existence of bone cement amount should be considered when they perform robotic TKA.
