Precision of the ultrasonography-integrated tibial extramedullary guide for total knee arthroplasty.

PURPOSE

Precise determination of the tibial mechanical axis in total knee arthroplasty (TKA) requires intraoperative identification of the talus center. We present the ultrasonography-integrated tibial extramedullary guide (USG) that enables real-time visualization of the talus. This study assesses the precision of USG compared to computer-assisted surgery (CAS) and validates the efficacy of USG.

METHODS

We evaluated 58 patients (62 knees) who underwent primary TKA retrospectively, categorizing them into USG and CAS groups (31 each). We statistically analyzed demographic data, the preoperative alignment of the tibial plateau to the mechanical axis, the postoperative alignment of the tibial component to planned alignment on 3D-CT, pain visual analog scale, and WOMAC scores. Additionally, the frequency of postoperative outlier from planned alignment over 2° was statistically compared.

RESULTS

No significant differences were observed in the preoperative data between the groups. The accuracy (mean deviation from the planned alignment) in both groups was not statistically different. However, in terms of the precision of coronal alignment, the USG group exhibited lower variance than the CAS group in the F-test (F value = 2.76, p = 0.023). Moreover, there were no postoperative deviations beyond 2 degrees in the USG group, in contrast to a 20% outlier frequency in the CAS group (p = 0.024). Concerning the precision of sagittal alignment (variance and deviations over 2°), no statistical differences were identified.

CONCLUSION

The USG demonstrated higher precision in the tibial coronal plane than CAS in coronal alignment. Direct identification of the individual talus may enhance precision.