Pelvic position, lying on a traction table, during THA by direct anterior approach. Comparison with the standing position and influence on the acetabular cup anteversion - 14/10/21

Doi : 10.1016/j.otsr.2021.103077

Guillaume Auberger ^a,⁎ , Erwan Pansard ^b,^c, Pierre-Alban Bouche ^b,^d, Jean-Luc Marmorat ^d, Thierry Judet ^d, Guillaume Lonjon ^e
^a Department of orthopaedic and trauma surgery, Croix Saint Simon Hospital, GH Diaconnesses Croix Saint Simon, Paris, France
^b Department of orthopaedic and trauma surgery, Ambroise Paré Hospital, 9, avenue Charles de Gaulle, 92100 Boulogne-Billancourt, France
^c Domont Clinic, RAMSAY Group, 85, route de Domont, 95460 Ezanville, France
^d Department of orthopaedic surgery, Raymond-Poincaré Hospital, 104, boulevard Raymond-Poincaré, 92380 Garches, France
^e Pasteur Polyclinic, 3, rue Pasteur, 34120 Pézenas, France

^⁎Corresponding author.

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Abstract

Introduction

The placement of prostheses for a total hip arthroplasty (THA) is essential to limit complications and optimize functional results. In a recent study of more than 100 THA placed through a direct anterior approach using a traction table, we found that the mean anteversion of the cup was greater (30°) than recommended (20°). To explain this phenomenon, we considered that the anterior pelvic plane (APP), defined by the plane passing through the anterior-superior iliac spines and the pubic symphysis, which serves as a landmark for the placement and calculation of the anteversion of the cup, was not horizontal when the patient was lying on the traction table. This concept has not been evaluated so we conducted a prospective study to: 1) measure the position of the pelvis on a traction table; 2) compare to the standing position, 3) assess its impact on the anteversion of the cup.

Hypothesis

The standing pelvic version is identical to the supine pelvic version on the traction table.

Material and methods

A prospective 3-month monocentric study was conducted. All patients operated on for a THA by a direct anterior approach, on a traction table, were included. The position of the pelvis was assessed by measuring the tilt of the APP on lateral pelvic X-rays, while on the traction table and while standing. The impact of the position of the pelvis on the positioning of the cup, as well as the anteversion, were measured using the EOS imaging system. The anatomic anteversion of the cup was measured in relation to the APP.

Results

Fifty-eight patients were included (32 women, 26 men) with an average age of 67 years. The tilt of the supine APP was 6°±8.3 [range of −10.5 to 31.0] (indicating a retroverted pelvis on the traction table). The difference between the tilt of the standing and lying APP (within 90°) was not significant (standing was on average 4.5° [range of −11.0 to 27.0] versus lying on the table, was on average 6° [range of −10.5 to 31.0] (p=0.75). A strong correlation was observed between the tilt of the supine APP and the anatomic anteversion of the cup (p<0.001). Thus, the more retroverted the pelvis was on the traction table, the lower the anatomic anteversion of the acetabular cup.

Conclusion

The supine pelvis on the traction table is not always horizontal and its position on the traction table is similar to its standing position, within 90 degrees. The analysis of the positioning of the preoperative pelvis appears to be essential in the planning of a THA through direct anterior approach using a traction table.