Does CT-based navigation improve the long-term survival in ceramic-on-ceramic THA?

Abstract

Background: Although navigated THA provides improved precision in implant positioning and alignment, it is unclear whether these translate into long-term implant survival.

Questions/purposes: We compared survivorship, dislocation rate, and incidence of radiographic failures such as loosening and bearing breakage after THA with and without navigation at a minimum 10-year followup.

Methods: We retrospectively reviewed 46 patients (60 hips) and 97 patients (120 hips) receiving THA with or without a CT-based navigation system, respectively, using cementless THA ceramic-on-ceramic bearing couples. There were no differences in age, sex, diagnosis, height, weight, BMI, or preoperative clinical score between groups. We evaluated survivorship, mode of acetabular and femoral component fixation, osteolysis, and implant wear or breakage at a minimum followup of 10 years (average, 11 years; range, 10-13 years).

Results: Survival at 13 years was 100% with navigation and 95.6% (95% CI, 88.4%-98.4%) without navigation. With navigation, all cups were placed within a zone of 40° (range, 30°-50°) of radiographic inclination and 15° (range, 5°-15°) of radiographic anteversion; without navigation, 31 cups (26%) were placed outside this zone. Hips treated without navigation had a higher rate of dislocation (8%) than the navigated cases (0%). Revision was performed in four nonnavigated cases, all of which showed evidence of neck impingement on the ceramic liner. Moreover, seven other cases without navigation showed posterior neck erosion on radiographs. These 11 impingement-related mechanical complications correlated with cup malorientation, and the incidence of impingement-related complications was higher in nonnavigated cases.

Conclusions: Navigation reduced the rates of dislocation and impingement-related mechanical complications leading to revision in cementless THA using ceramic-on-ceramic bearing couples over a minimum 10-year followup.

Level of evidence: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Figures

Fig. 1

A scattergram of cup orientation plots cup anteversion against cup inclination. All cups inserted with navigation are within the Lewinnek safe zone (outer rectangle). Dislocation occurred more frequently in the nonnavigation group (eight hips) than in the navigation group (no hips), but there was no difference in the dislocation rate between hips inside and outside the safe zone. The impingement-related mechanical complications comprised four revisions and seven neck erosions, all of which were seen in the nonnavigation group. The true safe zone without dislocation or mechanical complications seems to be 36° to 45° of inclination and 10° to 24° of anteversion (inner dotted rectangle).