The effect of C-arm fluoroscope on unicompartmental knee replacement arthroplasty

The aim of this study was to identify the effectiveness of C-arm fluoroscope in unicompartmental knee replacement arthroplasty through the clinical and radiologic results.

We investigated the 33 cases of unicompartmental knee replacement arthroplasty in 31 patients who diagnosed degenerative arthritis of knee between February 2011 and March 2014. We divided 2 groups, one is 15 cases using C-arm fluoroscope during operation (group A), the other is 18 cases not using that (group B). We measured femoro-tibial angle (FTA), medial proximal tibial angle (MPTA), posterior tibial slope angle (PTSA), femoral component coronal rotation angle (FCRA) by simple X-ray. We evaluated femur and tibia varus/valgus mismatch and posterior slope mismatch by above parameters after operation. And also we evaluated clinically by knee and functional score.

In group A, FTA average changes from -0.6° to 6.1°, MPTA changes from 84.5° to 87.6°, PTSA changes from 6.2° to 5.2° through operation. In group B, FTA changes from -0.4° to 5.8°, MPTA changes from 84.7° to 87.1°, PTSA changes from 6.3° to 5.5°, and FCRA is 0.6° in A group, 0.4° in B group after operation. The tibial varus/valgus mismatch cases after operation (nl.:87 ± 3°) was 1 in group A, 5 in group B. Post. slope mismatch cases after operation (nl.:7 ± 3°) was 1 in group A, 1 in group 31 B. All cases in both A and B group were not included in femoral varus/valgus mismatch (nl.:0 ± 3°) after operation. In group A, Knee score improved from 56.3 to 90.7, Functional score from 54.3 to 86.9 through operation. In group B, Knee score improved from 54.9 to 89.8, Functional score from 52.8 to 84.6.

There was no statistically significant difference in radiologic and clinical results between group A and B, but the number of tibial varus/valgus mismatch case were fewer in fluoroscope guided group. Sowe consider that thefluoroscope is helpful for tibial cuttingin unicompartmental knee replacement arthroplasty.