{"title":"Long-term results of the metaphyseal-loading anterolaterally flared anatomic femoral stem for total hip arthroplasty.","authors":"Makoto Kitade, Tetsuro Tani, Akihiko Matsumine","doi":"10.1007/s00264-025-06624-y","DOIUrl":null,"url":null,"abstract":"<p><strong>Background: </strong>Patients with secondary hip osteoarthritis due to developmental dysplasia of the hip (DDH) often have abnormal femoral morphology, making stem design critical for long-term outcomes. The FMS-anatomic stem previously demonstrated favourable mid-term results. Its successor, the Anatomic Fit stem, was developed with a reduced hydroxyapatite-coated area to enhance proximal load transfer and a narrower lateral flare to facilitate insertion. This study aimed to analyze the long-term clinical and radiographic outcomes of these stems.</p><p><strong>Methods: </strong>The one-hundred seventy-eight hips underwent total hip arthroplasty using either the FMS-anatomic or Anatomic Fit stem. After applying exclusion criteria, 119 hips (36 FMS-anatomic and 83 Anatomic Fit) were analyzed. Clinical and radiographic outcomes were assessed, and stem survival was evaluated using Kaplan-Meier analysis with stem revision as the endpoint.</p><p><strong>Results: </strong>The 15- and 20-year survival rates were 97.2% and 94.4% for the FMS-anatomic stem, and 98.8% for the Anatomic Fit stem at both time points, with no significant difference. Spot welds were observed in nearly all cases, but their distribution differed significantly: zones 2 and 6 in the FMS-anatomic group and zones 1 and 7 in the Anatomic Fit group (P < 0.05). Stress shielding of Grade 3 or higher occurred in 16.5% of FMS-anatomic stems and 33.7% of Anatomic Fit stems (P < 0.05).</p><p><strong>Conclusions: </strong>Both stems showed excellent long-term survival and proximal fixation. However, the Anatomic Fit stem did not reduce stress shielding, despite its modified design intended to improve load transfer.</p>","PeriodicalId":14450,"journal":{"name":"International Orthopaedics","volume":" ","pages":"2509-2517"},"PeriodicalIF":2.6000,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12488776/pdf/","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"International Orthopaedics","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1007/s00264-025-06624-y","RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2025/9/6 0:00:00","PubModel":"Epub","JCR":"Q2","JCRName":"ORTHOPEDICS","Score":null,"Total":0}
引用次数: 0
Abstract
Background: Patients with secondary hip osteoarthritis due to developmental dysplasia of the hip (DDH) often have abnormal femoral morphology, making stem design critical for long-term outcomes. The FMS-anatomic stem previously demonstrated favourable mid-term results. Its successor, the Anatomic Fit stem, was developed with a reduced hydroxyapatite-coated area to enhance proximal load transfer and a narrower lateral flare to facilitate insertion. This study aimed to analyze the long-term clinical and radiographic outcomes of these stems.
Methods: The one-hundred seventy-eight hips underwent total hip arthroplasty using either the FMS-anatomic or Anatomic Fit stem. After applying exclusion criteria, 119 hips (36 FMS-anatomic and 83 Anatomic Fit) were analyzed. Clinical and radiographic outcomes were assessed, and stem survival was evaluated using Kaplan-Meier analysis with stem revision as the endpoint.
Results: The 15- and 20-year survival rates were 97.2% and 94.4% for the FMS-anatomic stem, and 98.8% for the Anatomic Fit stem at both time points, with no significant difference. Spot welds were observed in nearly all cases, but their distribution differed significantly: zones 2 and 6 in the FMS-anatomic group and zones 1 and 7 in the Anatomic Fit group (P < 0.05). Stress shielding of Grade 3 or higher occurred in 16.5% of FMS-anatomic stems and 33.7% of Anatomic Fit stems (P < 0.05).
Conclusions: Both stems showed excellent long-term survival and proximal fixation. However, the Anatomic Fit stem did not reduce stress shielding, despite its modified design intended to improve load transfer.
期刊介绍：
International Orthopaedics, the Official Journal of the Société Internationale de Chirurgie Orthopédique et de Traumatologie (SICOT) , publishes original papers from all over the world. The articles deal with clinical orthopaedic surgery or basic research directly connected with orthopaedic surgery. International Orthopaedics will also link all the members of SICOT by means of an insert that will be concerned with SICOT matters.
Finally, it is expected that news and information regarding all aspects of orthopaedic surgery, including meetings, panels, instructional courses, etc. will be brought to the attention of the readers.
Manuscripts submitted for publication must contain a statement to the effect that all human studies have been approved by the appropriate ethics committee and have therefore been performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki. It should also be stated clearly in the text that all persons gave their informed consent prior to their inclusion in the study. Details that might disclose the identity of the subjects under study should be omitted.
Reports of animal experiments must state that the "Principles of laboratory animal care" (NIH publication No. 85-23, revised 1985) were followed, as well as specific national laws (e.g. the current version of the German Law on the Protection of Animals) where applicable.
The editors reserve the right to reject manuscripts that do not comply with the above-mentioned requirements. The author will be held responsible for false statements or for failure to fulfil the above-mentioned requirements.
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