Peer review has expired on this program. It is the viewer’s responsibility to determine the educational value of this historical content.Peer review has expired on this program. It is the viewer’s responsibility to determine the educational value of this historical content.INTRODUCTION: Re-directional osteotomies have been a breakthrough in the treatment of residual hip dysplasia in adults and have demonstrated their ability to modify the progression to hip osteoarthritis. The periacetabular osteotomy (PAO), which is accepted worldwide, provides a powerful three-dimensional redirection of the acetabulum, maintaining hyaline to hyaline contact and congruency. Posterior column preservation allows patients to resume early postoperative assisted ambulation. Having followed from the beginning the classic technique described by the Bernese school, we have come to believe that the Söballe minimally invasive modification_as related to the approach and order of the cuts_prevents surgical aggressiveness, decreases detachments of major muscle groups, reduces intra- and extra-operative bleeding, and allows a faster postoperative recovery. This video shows the step-by-step details that we believe are crucial to the good practice of the Söballe procedure. At the end of the video, we present outcomes for our first consecutive 56 cases performed in the last 7 years. From 2003 to late 2008, 56 hips in 54 patients (42 female, 2 bilateral; 12 male) with a mean age of 27.2 years (16-45) were treated with PAO and followed up at mean 4.2 years (2-7). Since 2003, PAO was performed through a modified Smith-Petersen approach. In 2006, the ilioinguinal mini-open approach was introduced. Pre- and post-operative evaluated data included operating time, intraoperative bleeding, need for post-op blood transfusion, Wiberg's Center Edge Angle (CEA) in AP and lateral view on plain radiograph, Acetabular Index, WOMAC and Merle d'Aubigné scores, and complications. RESULTS: Mean operation time was 1h 43min (1h 15min-3h 35min). Intraoperative bleeding was reduced threefold in mini-open approaches when compared to Smith-Petersen approaches (mean 475cc; range 330-850cc to mean 1250cc; range 870-1480cc; p<0.001). The need for transfusion was reduced from 35% to 15.3% (p<0,001). Mean Wiberg's CEA improved to 19.5° (15°-38°) in the AP view and 22° (10°-45°) in the Lequesne view, with a mean final post-op CEA value of 32.5° and 35.10° coverage respectively. The mean Acetabular Index was 28° (22°-38°) with a mean value of 6° (2°-13°). The mean WOMAC score improved from a pre-op value of 47.3 to a post-op value of 92.7 (p<0.001), while the Merle d'Aubigné score improved from a pre-op value of 14.6 to a post-op value of 17.1 (p<0,001). We observed 19 instances of transient neurapraxia of the LCFN, one case of transient paresia of the sciatic nerve, and two cases of delayed bone union at the isquion cut. One case of post-operative anterior acetabular over-coverage required a mini-open anterior acetabuloplasty. One case required THR conversion. CONCLUSION: According to other published studies with similar follow-up, PAO provided promising results at short term and midterm. So far, the introduction of a mini-open technique for PAO has suggested a threefold reduction in intraoperative time and the need for transfusion. We have observed no major complications during this initial time, which could correspond to the learning curve.