Kitade Makoto, Tani Tetsuro, Matsumine Akihiko
University of Fukui, Fukui, Japan.
Osaka University, Osaka, Japan.
Int Orthop. 2025 Sep 6. doi: 10.1007/s00264-025-06624-y.
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.
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.
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).
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.
因髋关节发育不良（DDH）导致继发性髋骨关节炎的患者，其股骨形态常常异常，这使得柄的设计对长期疗效至关重要。FMS解剖型柄先前已显示出良好的中期结果。其后续产品解剖适配柄在研发时减小了羟基磷灰石涂层面积以增强近端负荷传递，并缩小了外侧扩口以便于植入。本研究旨在分析这些柄的长期临床和影像学结果。
178例髋关节接受了使用FMS解剖型柄或解剖适配柄的全髋关节置换术。应用排除标准后，对119例髋关节（36例FMS解剖型和83例解剖适配型）进行了分析。评估了临床和影像学结果，并以柄翻修为终点，采用Kaplan-Meier分析评估柄的生存率。
FMS解剖型柄在15年和20年的生存率分别为97.2%和94.4%，解剖适配柄在这两个时间点的生存率均为98.8%，两者无显著差异。几乎在所有病例中均观察到点焊，但它们的分布有显著差异：FMS解剖型组为2区和6区，解剖适配型组为1区和7区（P<0.05）。3级或更高等级的应力遮挡在16.5%的FMS解剖型柄和33.7%的解剖适配型柄中出现（P<0.05）。
两种柄均显示出优异的长期生存率和近端固定效果。然而，解剖适配柄尽管其设计经过改良以改善负荷传递，但并未减少应力遮挡。
