Biomechanical and Clinical Validation of a Modulus-Graded Ti-Nb-Sn Femoral Stem for Suppressing Stress Shielding in Total Hip Arthroplasty

Stress shielding remains a major concern in cementless total hip arthroplasty (THA) due to the stiffness mismatch between femoral stems and surrounding bone. This study investigated the biomechanical and clinical performance of a novel Ti-33.6Nb-4Sn (Ti-Nb-Sn) alloy stem with a graded Young’s modulu...

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Main Authors: Yu Mori, Hidetatsu Tanaka, Hiroaki Kurishima, Ryuichi Kanabuchi, Naoko Mori, Keisuke Sasagawa, Toshimi Aizawa
Format: Article
Language:English
Published: MDPI AG 2025-04-01
Series:Applied Sciences
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Online Access:https://www.mdpi.com/2076-3417/15/9/4827
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author Yu Mori
Hidetatsu Tanaka
Hiroaki Kurishima
Ryuichi Kanabuchi
Naoko Mori
Keisuke Sasagawa
Toshimi Aizawa
author_facet Yu Mori
Hidetatsu Tanaka
Hiroaki Kurishima
Ryuichi Kanabuchi
Naoko Mori
Keisuke Sasagawa
Toshimi Aizawa
author_sort Yu Mori
collection DOAJ
description Stress shielding remains a major concern in cementless total hip arthroplasty (THA) due to the stiffness mismatch between femoral stems and surrounding bone. This study investigated the biomechanical and clinical performance of a novel Ti-33.6Nb-4Sn (Ti-Nb-Sn) alloy stem with a graded Young’s modulus achieved through localized heat treatment. A finite element model (FEM) of the Ti-Nb-Sn stem, incorporating experimentally validated Young’s modulus gradients, was constructed and implanted into a patient-specific femoral model. Stress distribution and micromotion were assessed under physiological loading conditions. Clinical validation was performed by evaluating radiographic outcomes at 1 and 3 years postoperatively in 40 patients who underwent THA using the Ti-Nb-Sn stem. FEM analysis showed low micromotion at the proximal press-fit region (4.89 μm rotational and 11.74 μm longitudinal), well below the threshold for osseointegration and loosening. Stress distribution was concentrated in the proximal region, effectively reducing stress shielding distally. Clinical results demonstrated minimal stress shielding, with no cases exceeding Grade 3 according to Engh’s classification. The Ti-Nb-Sn stem with a gradient Young’s modulus provided biomechanical behavior closely resembling in vivo conditions and showed promising clinical results in minimizing stress shielding. These findings support the clinical potential of modulus-graded Ti-Nb-Sn stems for improving implant stability in THA.
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spelling doaj-art-eb01ef8068ec4592bca060cdeb211b712025-08-20T02:30:45ZengMDPI AGApplied Sciences2076-34172025-04-01159482710.3390/app15094827Biomechanical and Clinical Validation of a Modulus-Graded Ti-Nb-Sn Femoral Stem for Suppressing Stress Shielding in Total Hip ArthroplastyYu Mori0Hidetatsu Tanaka1Hiroaki Kurishima2Ryuichi Kanabuchi3Naoko Mori4Keisuke Sasagawa5Toshimi Aizawa6Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, Sendai 980-8574, JapanDepartment of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, Sendai 980-8574, JapanDepartment of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, Sendai 980-8574, JapanDepartment of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, Sendai 980-8574, JapanDepartment of Radiology, Akita University Graduate School of Medicine, Akita 010-0041, JapanDepartment of Mechanical and System Engineering, Niigata Institute of Technology, Kashiwazaki 945-1103, JapanDepartment of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, Sendai 980-8574, JapanStress shielding remains a major concern in cementless total hip arthroplasty (THA) due to the stiffness mismatch between femoral stems and surrounding bone. This study investigated the biomechanical and clinical performance of a novel Ti-33.6Nb-4Sn (Ti-Nb-Sn) alloy stem with a graded Young’s modulus achieved through localized heat treatment. A finite element model (FEM) of the Ti-Nb-Sn stem, incorporating experimentally validated Young’s modulus gradients, was constructed and implanted into a patient-specific femoral model. Stress distribution and micromotion were assessed under physiological loading conditions. Clinical validation was performed by evaluating radiographic outcomes at 1 and 3 years postoperatively in 40 patients who underwent THA using the Ti-Nb-Sn stem. FEM analysis showed low micromotion at the proximal press-fit region (4.89 μm rotational and 11.74 μm longitudinal), well below the threshold for osseointegration and loosening. Stress distribution was concentrated in the proximal region, effectively reducing stress shielding distally. Clinical results demonstrated minimal stress shielding, with no cases exceeding Grade 3 according to Engh’s classification. The Ti-Nb-Sn stem with a gradient Young’s modulus provided biomechanical behavior closely resembling in vivo conditions and showed promising clinical results in minimizing stress shielding. These findings support the clinical potential of modulus-graded Ti-Nb-Sn stems for improving implant stability in THA.https://www.mdpi.com/2076-3417/15/9/4827Ti-Nb-Sn alloystress shieldingtotal hip arthroplastyfinite element modelYoung’s modulus gradient
spellingShingle Yu Mori
Hidetatsu Tanaka
Hiroaki Kurishima
Ryuichi Kanabuchi
Naoko Mori
Keisuke Sasagawa
Toshimi Aizawa
Biomechanical and Clinical Validation of a Modulus-Graded Ti-Nb-Sn Femoral Stem for Suppressing Stress Shielding in Total Hip Arthroplasty
Applied Sciences
Ti-Nb-Sn alloy
stress shielding
total hip arthroplasty
finite element model
Young’s modulus gradient
title Biomechanical and Clinical Validation of a Modulus-Graded Ti-Nb-Sn Femoral Stem for Suppressing Stress Shielding in Total Hip Arthroplasty
title_full Biomechanical and Clinical Validation of a Modulus-Graded Ti-Nb-Sn Femoral Stem for Suppressing Stress Shielding in Total Hip Arthroplasty
title_fullStr Biomechanical and Clinical Validation of a Modulus-Graded Ti-Nb-Sn Femoral Stem for Suppressing Stress Shielding in Total Hip Arthroplasty
title_full_unstemmed Biomechanical and Clinical Validation of a Modulus-Graded Ti-Nb-Sn Femoral Stem for Suppressing Stress Shielding in Total Hip Arthroplasty
title_short Biomechanical and Clinical Validation of a Modulus-Graded Ti-Nb-Sn Femoral Stem for Suppressing Stress Shielding in Total Hip Arthroplasty
title_sort biomechanical and clinical validation of a modulus graded ti nb sn femoral stem for suppressing stress shielding in total hip arthroplasty
topic Ti-Nb-Sn alloy
stress shielding
total hip arthroplasty
finite element model
Young’s modulus gradient
url https://www.mdpi.com/2076-3417/15/9/4827
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