Primary early clinical outcomes following MIS-ALA and DAA THA were similar in this study. These measures including the ability to climb stairs and walk, 6MWT, VAS pain, and JOA scores. Hospital stay postoperative was also similar for both groups. The similar clinical outcomes suggest that pain relief and functional recovery over the total hip were not significantly different for both groups, which may be owe to the reduced invasiveness of both surgical approaches. Although the overall similarity of the MIS-ALA and DAA outcomes, some significant differences were confirmed in other domains. Early postoperative data, 2 and 6 weeks postoperative FJS-12 score were significantly better for the MIS-ALA group, this shows that better patient-reported outcomes can be achieved by MIS-ALA THA. Nevertheless, the present study revealed that 12 weeks after surgery the FJS-12 score was similar between the MIS-ALA and DAA groups. Differences in favour of the MIS-ALA also included shorter operative times, less blood loss, lower Hb drop, fewer blood transfusions and LFCN neuropraxia.
The operation steps associated with the MIS-ALA, in part, explained the shorter surgical times with less blood loss, lower Hb drop, and fewer blood transfusions. The decreased blood loss was generally on the femoral side, related to an easier visualization of posterolateral capsular bleeders associated with the MIS-ALA. When THA was performed via the DAA, during elevation of the proximal femur release a portion of the posterolateral capsule and piriformis were at times necessary. Surgeon experience also played a great role, with over 100 MIS-ALA cases vs 200 DAA cases earlier to the study. However, the longer surgical time and more blood loss were not offset by better pain relief, faster function improved, and earlier discharge in the DAA group.
This study presented favorable implant alignments in THA with the both minimally invasive techniques. The MIS-ALA and DAA groups showed similar alignments both of cup and stem. Component positioning has a marked impact on the function and duration of THA19–21.The MIS-ALA and DAA surgical approaches can expose the hip joint intermuscular and internervous interval with the advantage of a lower chance of dislocation without higher revision risk 22, 23. Kawarai et al24 reported that cup anteversion in DAA nearly 4°larger than MIS-ALA in the supine position. Inconsistent with our results. The larger anteversion in DAA could be due to the difference in rotation and tilt angles of the pelvis in the supine position. This could lead to the flexor muscles and femoral weight. During the cup procedure, the ipsilateral pelvis posteriorly could be retracted. According to Kobayashi et al 25 research, it's a little difficult to insert the femoral stem in the position of neutral via DAA owing to the exposure of the proximal femur. Different with Kobayashi et al reports, the proximal femur could obtain adequate exposure to find the entry point in the DAA group and there was no statistically significant difference in stem implant alignment compared with the MIS-ALA group. The adequate exposure was obtained by longer surgical time to manage femur side.
The risk of minor surgical complications in our study favoured the MIS-ALA group due to the 14% incidence of LFCN neuropraxia in the DAA group. LFCN neuropraxia was a typical complication of DAA. Ozaki et al26, 27 demonstrated that LFCN neuropraxia mainly resolves spontaneously over time after THA. The study’s incidence was similar to previous reported range in the literature28–31. There were no connections between LFCN neuropraxia and 6MWT or JOA scores but had higher FJS-12 scores in MIS-ALA group. This was supported by Ozaki et al26.
This study has several limitations. First, it was an early evaluation of only 12 weeks after surgery. Longer follow-up was needed to compare the effects of the MIS-ALA and DAA methods on LFCN neuropraxia, FJS-12 scores, and implant alignment after THA. Second, the study could not be full blinded due to the visible difference in the surgical incisions. All radiographs review were blinded by two independent reviewers. In addition, only cementless stem was utilized. Generally, it was just needs narrower exposure of the proximal femur for a cementless stem to prepare the femur than did a cemented stem24, 32. In this manner, minimally invasive surgery becomes less technically demanding and generates an advantage for the cementless stem.