Digital templating for the implantation of a curved short hip stem with an anterolateral MIS approach shows gender differences in digital templating

Matthias Luger; Rainer Hochgatterer; Matthias C Klotz; Günter Hipmair; Tobias Gotterbarm; Bernhard Schauer

doi:10.1007/s00402-021-04005-9

Digital templating for the implantation of a curved short hip stem with an anterolateral MIS approach shows gender differences in digital templating

Arch Orthop Trauma Surg. 2022 Jul;142(7):1661-1668. doi: 10.1007/s00402-021-04005-9. Epub 2021 Jun 24.

Authors

Matthias Luger¹, Rainer Hochgatterer², Matthias C Klotz², Günter Hipmair², Tobias Gotterbarm², Bernhard Schauer²

Affiliations

¹ Department of Orthopaedics and Traumatology, Kepler University Hospital Linz, Krankenhausstrasse 9, 4020, Linz, Austria. Matthias.luger@kepleruniklinikum.at.
² Department of Orthopaedics and Traumatology, Kepler University Hospital Linz, Krankenhausstrasse 9, 4020, Linz, Austria.

Abstract

Purpose: Digital templating shows reliable accuracy for straight stem systems. In recent years, the implantation of short stems through minimally invasive approaches has gained more popularity. Minimally invasive approaches (MIS) show the risk of undersizing femoral components. Therefore, we questioned the planning adherence for a curved short stem and a bi-hemispherical acetabular cup implanted through an anterolateral MIS approach.

Methods: A consecutive series of 964 hips (index surgery between 2014 and 2019) with Fitmore^® curved short stem and Allofit/-S^® acetabular cup (both ZimmerBiomet Inc, Warsaw, IN) were included. Preoperative digital templating was conducted anterior-posterior (AP) digital radiographs of the hip using mediCAD^® version 5.1 (Hectec GmbH, Altdorf, Germany). The templates of acetabular and femoral components (offset option and stem size) were retrospectively evaluated for general adherence, and according to sex, BMI and planner's experience.

Results: Planning adherence for the exact offset option was 70.6 and 21.6% for exact offset option and stem size. Adherence for acetabular cup ± 1 size was 74.8%. A significant difference between male and female patients for the offset option could be found (p = 0.03, z = -2983). In 22.5% of male patients, an offset option one size higher and in 12.3% of female patients an offset option one size smaller than templated was used intraoperatively CONCLUSION: Digital templating for the Fitmore^® stem in cementless THA with a minimally invasive anterolateral approach shows comparable planning adherence to the existing literature for this cementless short stem. However, a lower planning adherence was detected compared to conventional straight stem systems. In male patients, the femoral offset is frequently undersized and in female patients frequently oversized compared to the preoperative plan. Surgeons should be aware of this difficulty in digital templating for Fitmore^® hip stem.

Keywords: Anterolateral approach; Digital templating; Fitmore; Minimally invasive; Short stem; Total hip arthroplasty.

MeSH terms

Arthroplasty, Replacement, Hip*
Female
Hip / surgery
Hip Joint / diagnostic imaging
Hip Joint / surgery
Hip Prosthesis*
Humans
Male
Retrospective Studies
Sex Factors