SuperPath® vs. direct anterior approach A retrospective comparison between two minimally invasive approaches in total hip arthroplasty

Objective: Minimally invasive approaches are subject to controversy in orthopedic surgery. The aim of the current study was to compare the radiographic parameters between two minimally invasive approaches in total hip arthroplasty. Material and methods: Between January 2018 and February 2019, the radiographic parameters of 80 patients undergoing total hip arthroplasty via minimally invasive approaches (DAA: n=40; SuperPath (R) SP: n=40) have been measured. The radiographic analysis was performed with digital software tool mediCad (R) (HECTEC (TM) GmbH, Landshut, Germany). Results: Patients treated with DAA showed significantly higher inclination (SP: 39.7 degrees +/- 7.3 degrees vs. DAA: 44.7 degrees +/- 5.3 degrees) and significantly lower cup anteversion values (SP: 31.2 degrees +/- 7.9 degrees vs. DAA: 27. 5 degrees +/- 5.3 degrees, p0.001) than patients undergoing THA via SP postoperatively. The horizontal femoral offset was neither preoperatively nor postoperatively higher in DAA than in SP cohort (preoperative: p=0.71, postoperative: p=0.25) (preoperative: SP:37.2mm +/- 7.3 vs. DAA 38.2mm +/- 7.5; postoperative: SP: 38.0mm +/- 7.2 vs. DAA: 40.5mm +/- 7.0). At both times, the acetabular offset was significantly higher in DAA cohort than in SP cohort (preoperative: SP: 32.9mm +/- 5.9 vs. DAA: 36.8mm +/- 4.9; postoperative: SP: 28.9mm +/- 4.2 vs. DAA: 33.4mm +/- 3.8) (preoperative: 0.001; postoperative: p0.001). The vertical height was preoperatively and postoperatively not significantly higher in SP cohort than in DAA cohort (preoperative: SP: 16.1mm +/- 4.1 vs. DAA: 15.5mm +/- 4.9; postoperative: SP: 16.6mm +/- 4.6 vs. DAA: 16.1mm +/- 4.6) (preoperative: p=0.77; postoperative: p=0.58). The preoperatively existing leg length discrepancy of the affected leg could be compensated via surgery without showing significant differences between the two cohorts (preoperative: SP: -3.2mm +/- 5.4 vs. DAA: 1.9mm +/- 4.9; postoperative: SP: 1.5mm +/- 5.4 vs. DAA: 4.8mm +/- 5.6) ( preoperative: p=0.34; postoperative: p=0.09). Conclusion: The current study demonstrates suitable cup positioning and stem alignment in the coronal plane using minimal-invasive approaches DAA and Superpath (R).