Comparative outcomes of the novel advanced minimally invasive gemelli-obturator (AMIGO) approach against three approaches to total hip arthroplasty: a propensity-matched study.

introductionThe advanced minimally invasive gemelli-obturator (AMIGO) approach is a novel, tissue-sparing variation of the posterior approach that aims to preserve the piriformis and quadratus femoris, while selectively detaching and repairing the gemelli and obturators , to preserve native anatomy . The aim of this study is to compare the clinical and radiological outcomes of four surgical approaches to total hip arthroplasty (THA) using a propensity-matched cohort: anterolateral, direct anterior (DAA), posterior, and AMIGO approaches.

methodsThis retrospective cohort study included 600 patients, with 150 per approach, undergoing elective THA between 2019 and 2022. Propensity score matching controlled for demographics, pre-operative score, radiological grade of osteoarthritis. Review of Patient Reported Outcomes Measures (PROMs), intra-operative and post-operative metrics and radiographic analysis was undertaken.

resultsThe AMIGO and DAA approaches achieved superior restoration of femoral offset (p < 0.001), with AMIGO showing the closest approximation to pre-operative offset. The AMIGO approach had the highest proportion of neutral stem alignment (p < 0.001). All approaches achieved acceptable cup version; the anterolateral group had a higher mean inclination (51.1°; p < 0.001). The AMIGO approach achieved the greatest absolute limb length correction due to larger preoperative discrepancies. There were no statistically significant differences in the PROMs across all approaches. Patients who underwent the AMIGO approach had a significantly shorter operative time and average hospital length of stay (1.3 days, p < 0.005). Two patients who underwent the THA through DAA experienced periprosthetic fractures (1.3%). No significant differences were observed in overall complication or 30-day readmission rates.

conclusionThe AMIGO approach demonstrated both radiological, intra- and post-operative and PROMs advantages when compared to other three approaches. Whilst statistical significance was not achieved for PROMs, the AMIGO approach demonstrated the highest Oxford Hip Score and EQ-5D-3L Scores. The AMIGO approach is a promising tissue-sparing alternative warranting further investigation in larger, long-term studies.