{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,26]],"date-time":"2026-09-26T17:33:12Z","timestamp":1790443992226,"version":"4.1.0"},"reference-count":38,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2025,5,1]],"date-time":"2025-05-01T00:00:00Z","timestamp":1746057600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Mizuho Co., Ltd."}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Medical Sciences"],"abstract":"<jats:p>Background: Stress shielding (SS) after total hip arthroplasty (THA) leads to proximal femoral bone loss and increases the risk of complications such as implant loosening and periprosthetic fracture. While various low-stiffness stems have been developed to prevent SS, they often compromise mechanical stability. A novel femoral stem composed of Ti-33.6Nb-4Sn (TNS) alloy offers a gradually decreasing Young\u2019s modulus from proximal to distal regions, potentially improving load distribution and reducing SS. This study aimed to evaluate the mid-term clinical and radiographic outcomes of the TNS stem, with a particular focus on its effectiveness in suppressing SS. Methods: A prospective clinical study was conducted involving 35 patients who underwent THA using the TNS stem, with a minimum follow-up of 7 years. Twenty-one patients with Ti6Al4V metaphyseal-filling stems served as controls. Clinical outcomes were assessed using Japanese Orthopaedic Association (JOA) scores, and radiographic SS was graded using Engh\u2019s classification and analyzed in Gruen zones. Inter-examiner reliability and statistical comparisons between groups were performed using appropriate tests. Results: The TNS group showed significantly higher preoperative JOA scores than the control group, but no significant difference in final scores. Both groups demonstrated significant improvement postoperatively. Third-degree SS occurred in the TNS group, although the overall SS grade distribution was significantly lower than in the control group (p = 0.03). SS frequency was significantly reduced in Gruen Zones 2, 3, and 6 in the TNS group. Conclusions: The TNS stem demonstrated a significant reduction in SS progression compared to conventional titanium stems over a 7-year period, with comparable clinical outcomes. However, the occurrence of third-degree SS indicates that material optimization alone may be insufficient, highlighting the need for further design improvements.<\/jats:p>","DOI":"10.3390\/medsci13020051","type":"journal-article","created":{"date-parts":[[2025,5,2]],"date-time":"2025-05-02T07:44:23Z","timestamp":1746171863000},"page":"51","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Effectiveness of Stress Shielding Prevention Using a Low Young\u2019s Modulus Ti-33.6Nb-4Sn Stem: A 7-Year Follow-Up Study"],"prefix":"10.3390","volume":"13","author":[{"given":"Kazuyoshi","family":"Baba","sequence":"first","affiliation":[{"name":"Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8225-4690","authenticated-orcid":false,"given":"Yu","family":"Mori","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8679-9121","authenticated-orcid":false,"given":"Hidetatsu","family":"Tanaka","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0004-7975-6034","authenticated-orcid":false,"given":"Ryuichi","family":"Kanabuchi","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-8393-1056","authenticated-orcid":false,"given":"Yasuaki","family":"Kuriyama","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5023-4804","authenticated-orcid":false,"given":"Hiroaki","family":"Kurishima","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kentaro","family":"Ito","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4451-2967","authenticated-orcid":false,"given":"Masayuki","family":"Kamimura","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Daisuke","family":"Chiba","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1571-5618","authenticated-orcid":false,"given":"Toshimi","family":"Aizawa","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,5,1]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"519","DOI":"10.2106\/JBJS.19.00699","article-title":"Primary Total Hip Arthroplasty in Patients 20 Years Old and Younger","volume":"102","author":"Pallante","year":"2020","journal-title":"J. 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