Computer Navigated Total Hip Arthroplasty Via The Direct Superior Approach: A Retrospective Study of The First 30 Consecutive Cases

Abstract

Background The direct superior approach (DSA), which is one of the muscle-sparing approaches for total hip arthroplasty (THA), has been recently reported with positive outcomes. However, in minimally invasive THA, it has been reported that the visual intraoperative estimation of the cup position is not reliable. Therefore, those minimally invasive approaches are associated with the increased risk of acetabular cup malposition due to the limited exposure. Although the positive effects of computer navigation system on the accuracy of cup positioning have been reported in many studies, those are not unknown in THA via the DSA. In the current study, we investigated the accuracy of acetabular cup positioning in navigated THA via the DSA in the first 30 consecutive cases.Methods We have retroactively included the first 30 consecutive cases of navigated DSA, and the consecutive control cases using conventional posterior approach (PA) were included retroactively up to 30 cases. This retrospective study divided the cases of navigated DSA into 15 initial and 15 recent cases. The postoperative data were assessed on plain computed tomography to measure the radiographic inclination and anteversion of the acetabular component. Statistical analyses were performed using Mann-Whiteney U test for comparison of the mean, and Levene's tests for equality of standard deviations (SD). Results We found no significant differences in the means between navigated DSA and conventional PA for anteversion and inclination. For anteversion, the accuracy of acetabular cup positioning in navigated DSA (SD, 6.9°), including the recent 15 cases (SD, 4.1°), was significantly improved than in conventional PA (SD, 11.7°). For inclination, there were no significant differences in the accuracy of the acetabular cup positioning between navigated DSA (SD, 5.3°) and conventional PA (SD, 6.5°).Conclusions The increased variances of cup anteversion would be due to the frequency of pelvic malposition and the wide variation in pelvic orientation with the patient in the lateral decubitus position. Navigated THA via the DSA could be performed with good accuracy of cup placement in the first 30 cases. The results suggest that computer navigated THA via the DSA as a suitable option for hip replacement.

The Direct Superior Approach in Total Hip Arthroplasty

“…Most studies use the Lewinnek safe zone (5-25° anteversion, 30-50° inclination) to measure optimal implant positioning 31 . Five studies reported a mean cup inclination and mean cup anteversion within the Lewinnek safe zone 10,20-22,27 . The DSA showed cup inclination and anteversion comparable with the MPA and PLA 10,27 .…”

“…By contrast, no difference in dislocations or infection was reported. Four other observational studies did not find any difference in complication rates between the DSA and the PLA or mini posterior approach (MPA) [11][12][13]27 . Overall, while a RCT with a small sample size suggest a disadvantage for the DSA, larger realworld evidence studies present different outcomes.…”

“…The characteristics of included studies are presented in Table I. Seventeen studies including 3,551 patients met the inclusion criteria [10][11][12][13]17,[19][20][21][22][23][24][25][26][27][28][29][30] . The number of patients per study ranged from 20 to 1,341, with a mean age range of 51 to 74 years (Table I).…”

“…One hundred eighty-one studies were excluded after reviewing duplications using EndNote, and 207 articles were screened by title and abstract, of which 52 articles were eligible for full-text screening. Ultimately, 17 qualifying articles were selected [10][11][12][13]17,[19][20][21][22][23][24][25][26][27][28][29][30] (Fig. 1).…”

“…Five studies reported a mean cup inclination and mean cup anteversion within the Lewinnek safe zone 10,[20][21][22]27 . The DSA showed cup inclination and anteversion comparable with the MPA and PLA 10,27 . Ezzibdeh et al found that the mean cup anteversion was slightly higher for the MPA (16 6 4°) than for the DSA (12 6 3°) 21 .…”