Computer-Assisted TKR Vs Conventional TKR: Post-Operative Ankle Radiographic Finding and Ankle Clinical Assessment

Abstract

Background: Few previous studies showed that the conventional total knee replacement (TKR) has affection to the same side of talar tilt (TT). We expected to prevent this problem by the computer-assisted (CAS) TKR. Objective: The purpose of this study was to compare between pre and post-operative talar tilt and ankle clinical assessment on the CAS TKR and the Conventional TKR in 28 patients (56 knees) whom underwent bilateral TKR. Material and Method: 28 patients, 56 knees, whom underwent both CAS total knee replacement (TKR) and conventional total knee replacement (TKR), in both knees, with the combination of Gap Balance and Measurement Resection techniques performed by one surgeon (P. Sriphirom) at Rajavithi Hospital, Bangkok. The post-operative has a 12 months follow-up for ankle radiographic finding by tibiotalar angle (TTA), tibial articular surface angle (TAS), and talar tilt (TT) = (TAS-TTA) and for ankle clinical assessment by foot functional index (FFI) from pre-operation and post-operation from both groups. The study also compares the CAS TKR with the Conventional TKR for pre-operation and post-operation. Results: 56 knees, 28 patients, mean age = 67.79 years whom underwent bilateral TKR by the Conventional group and the CAS group had pre-operative TT (TT = TAS - TTA). The Conventional group = 1.5 (-5, 8), the CAS group = .5 (-5, 8), P value = .65. On post-operative TT the Conventional group = .0 (-5, 3), the CAS group = 1.0 (-3, 8), the P value = .4. The comparison of pre-operative TT and post-operative TT in the Conventional group, the P value = .01. On pre-operative TT and post-operative TT in the CAS group, the P value = .65. TT was significantly different in the Conventional group but was not significantly different in the CAS group. The ankle clinical assessment by foot functional index (FFI), which is (1) Pain, (2) Difficulty living, and (3) Daily life activity limitation. The pre-operative FFI in the Conventional group = 1.85 (.81, 6.88) and pre-operative FFI in the CAS group = 1.91 (.24, 66.5), the P value = .57. The post-operative FFI in the Conventional group = 1.68 (0.24, 7.0) and post-operative FFI in the CAS group = 1.65 (.24, 6.76), the P value = .04, which showed a significantly different between the post-operative FFI from both groups. In the Conventional group the post-operative FFI was not significantly different from pre-operative FFI, the P value = .2 but for the CAS group the post-operative FFI was not significantly different from pre-operative FFI, the P value = .04. Conclusion: This study has shown that the conventional TKR effected to post-operative talar tilt but the CAS TKR has less effect and was not significantly different to ankle joint. Finally, the study needs to be conducted on more patients and to be observed on a longer term follow-up.