Three-dimensional acetabular orientation during periacetabular osteotomy: a video analysis of acetabular rim position using an external fixator as navigation tool during reorientation procedure

Timo J Schwarz,Günther Maderbacher,Franziska Leiss,J Matussek,Joachim Grifka,G Heers

doi:10.1007/s00402-020-03632-y

Abstract

IntroductionBernese periacetabular osteotomy is an effective procedure for treating acetabular dysplasia. However, limited visual control of the acetabular position during surgery may result in under- or overcorrection with residual dysplasia or femoroacetabular impingement. Thus, we wanted to find a simple method to control the effect of correction in the sagittal and coronal plane.MethodThe acetabular coordinates are shown by two perpendicular tubes of an external fixator mounted onto a third tube that is fixed to the acetabular fragment with two Schanz screws. This method enables the isolated acetabular reorientation in the coronal, sagittal, and transverse plane. In a sawbone pelvis model, the acetabular rim is marked with a copper wire and a silicon adherent. To show the radiographic effect on acetabular parameters and the rim position, we visualized correction in the coronal and sagittal plane under fluoroscopic control.ResultsLateral rotation of the acetabular fragment had the highest impact on radiographic lateral coverage of the femoral head. But also ventral coverage increased during isolated lateral rotation. Anterior rotation showed almost no effect on lateral coverage and just a little effect on ventral coverage but caused severe total acetabular retroversion.ConclusionThree-dimensional control of the acetabular orientation during periacetabular osteotomy is important to avoid over- and under-correction. Isolated lateral rotation of the acetabular fragment should be the predominant direction of correction during periacetabular osteotomy. Ambitious anterior correction may be the main source for severe acetabular retroversion following periacetabular osteotomy.

Highlights

Bernese periacetabular osteotomy is an effective procedure for treating acetabular dysplasia
Bernese periacetabular osteotomy (PAO) for hip dysplasia—a method popularized by the work of Ganz et al [1]—has shown to be an effective procedure to improve acetabular coverage, reduce pain, and improve hip function in several mid- to long-term studies [2,3,4,5,6]
Three-dimensional control of the acetabular orientation during periacetabular osteotomy is important to avoid over- and under-correction as well as acetabular retroversion

Summary

Introduction

Bernese periacetabular osteotomy is an effective procedure for treating acetabular dysplasia. Bernese periacetabular osteotomy (PAO) for hip dysplasia—a method popularized by the work of Ganz et al [1]—has shown to be an effective procedure to improve acetabular coverage, reduce pain, and improve hip function in several mid- to long-term studies [2,3,4,5,6]. Acetabular reorientation is challenging, and even experienced surgeons have reported inadequate postoperative radiographic coverage (lateral CE angle) in approximately one fifth of the patients [14]. Malorientation such as total acetabular retroversion causes postoperative impingement, a restricted range of movement, and a positive Drehmann’s sign [15]. Some of these patients even required revision surgery, such as revision PAO or difficult total hip arthroplasty

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