Subsidence analysis of a cementless short stem THA using EBRA-FCA - A seven-year prospective multicentre study

Hagen Mittelstaedt; Conrad Anderl; Reinhold Ortmaier; Carsten Johl; Thomas Krüger; Karsten Wallroth; Ulrich Weigert; Jan C Schagemann

doi:10.1016/j.jor.2023.06.009

Subsidence analysis of a cementless short stem THA using EBRA-FCA - A seven-year prospective multicentre study

J Orthop. 2023 Jul 23:43:93-100. doi: 10.1016/j.jor.2023.06.009. eCollection 2023 Sep.

Authors

Hagen Mittelstaedt¹, Conrad Anderl², Reinhold Ortmaier², Carsten Johl³, Thomas Krüger⁴, Karsten Wallroth⁵, Ulrich Weigert⁶, Jan C Schagemann^{1

7}

Affiliations

¹ UKSH Campus Lübeck, Klinik für Orthopädie und Unfallchirurgie Sektion Orthopädie, Ratzeburger Allee, Lübeck, Germany.
² Ordensklinikum Linz, Krankenhaus der Barmherzigen Schwestern Linz GmbH, Seilerstätte, Linz, Austria.
³ Klinikum Dahme-Spreewald GmbH, Lübben (Spreewald), Germany.
⁴ Helios Klinik Köthen, Hallesche Straße, Köthen (Anhalt), Germany.
⁵ Kreiskrankenhaus Stollberg GmbH, Jahnsdorfer Straße Stollberg, Stollberg, Germany.
⁶ Praxis für Orthopädie und Unfallchirurgie, Friedrichstraße, Erkner, Germany.
⁷ Christophorus Kliniken Coesfeld, Südring 41, 48653, Coesfeld, Germany.

PMID: 37575949
PMCID: PMC10415660 (available on 2024-09-01)
DOI: 10.1016/j.jor.2023.06.009

Abstract

Background: Metaphyseal fixation of short stem THA allows for minimally invasive surgery, less bone removal, improved bone load transfer and reduced stress shielding. Short stems facilitate the anatomic restoration i.a. of leg length, femoroacetabular offset, and center of rotation. However, metaphyseal fixation might cause impaired primary and/or secondary stability resulting in an inherent tendency for early axial migration and aseptic loosening eventually. The objective of this study was to investigate the long-term outcome and migration pattern of a calcar-guided short stem.

Methods: In a prospective multicenter study, 213 patients (224 THAs) were enrolled. Patients were followed for up to 84 months postoperatively. Clinical outcome was assessed using the Harris Hip Score and the VAS for pain and satisfaction. Standardized and calibrated radiographs were screened i.a. for stress shielding and loosening. Einzel-Bild-Roentgen-Analyse - femoral component analysis (EBRA-FCA) was used to detect longitudinal subsidence.

Results: At 7 year follow-up, n = 139/224 cases were available for analysis. All clinical parameters improved significantly (p < 0.001) and improvement persisted. There were no radiographic changes indicating stress shielding. EBRA-FCA revealed a mean subsidence of -1.44 mm followed by a stabilization. Weight >80 kg (p = 0.115), BMI <30 kg/m² (p = 0.282), male gender (p = 0.246), and age <65 years (p = 0.304) seemed to be associated with a higher risk for migration. The cumulative revision rate was 2.23%. Revisions due to stem migration (0.89%) occurred early (mean time between index surgery and revision: 3.3 months).

Conclusions: If at all, there appears to be a pronounced initial subsidence, which stabilizes thereafter. Stem migration was rarely a compelling reason for failure or revision. Demographics do not seem to have a significant effect on migration pattern. The absence of radioluce lines, resorption or hypertrophy of the proximal femora support the hypothesis of a reduced stress shielding for metaphyseal anchoring short stems.

Keywords: Bone preservation; EBRA-FCA; Hip prosthesis; Metaphyseal fixation; Migration; Short stem; Stress shielding; Subsidence; Total hip arthroplasty.