Influence of bone morphology and femur preparation method on the primary stability of hip revision stems

Aseptic loosening is one of the major reasons for re-revisions of cementless revision stems. Insufficient primary stability is associated with bone characteristics and the surgical process. This study aimed to investigate how femur morphology and preparation methods influence the primary stability of revision stems. The Femur morphology was described by the upper femoral curvature (UFC) and an individualized Dorr type classification based on the ratio between the canal-to-calcar ratio (CCR*) and the cortical index (CI*) introduced as the cortical-canal shape (CCS). Manual and powered reaming in combination with helical and straight reamers were used to prepare the bone cavity of 10 cadaveric human femur pairs. Forces during stem impaction were recorded (Reclaim, Depuy Synthes). Micromotion at the bone–implant interface during cyclic axial loading and torsional load to failure was determined. The CCS and impaction forces (R2 = 0.817, p < 0.001) or torsional strength (R2 = 0.577, p < 0.001) are inversely related. CCS did not correlate with micromotion during axial loading (R2 = 0.001, p > 0.999), but proximal femoral curvature did (R2 = 0.462, p = 0.015). Powered reaming and straight reamers led to an improved torsional strength (both: p = 0.043). The Individualized Dorr classification CCS and UFC allows a good estimation of the primary stability of revision stems. For severely curved Dorr type-C femurs, an alternative anchorage method should be considered clinically.

Schlagworte

bone morphology

canal reaming

Dorr type

femur curvature

primary stability

revision THA

DDC Class

570: Biowissenschaften, Biologie

610: Medizin

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Projekt DEAL

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The authors would like to thank Depuy Synthes for providing the prosthesis components, surgical tools, and financial support. All experimental studies were performed at the University Medical Center Hamburg‐Eppendorf (UKE) and the TUHH Hamburg University of Technology.

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https://creativecommons.org/licenses/by/4.0/

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Journal Orthopaedic Research - 2022 - Konow - Influence of bone morphology and femur preparation method on the primary.pdf

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Influence of bone morphology and femur preparation method on the primary stability of hip revision stems