Mid-term subsidence and periprosthetic radiolucency of the AMIStem: a 5-year EBRA-FCA analysis

Abstract

Background There has been an evolution in cementless total hip arthroplasty (THA) with newer short stem designs aimed to preserve metaphyseal bone stock and facilitate implantation through minimally invasive approaches. While early subsidence has been correlated to aseptic loosening in conventional stems, there is a paucity of data regarding short stems. The current study aims to report on stem subsidence and mid-term clinical outcomes of a cementless, metaphyseal-anchored short femoral stem, specifically designed for the direct anterior approach (DAA). Methods Ninety-four consecutive patients (100 hips) with a minimum follow-up of 5 years following cementless THA were included in this single-center retrospective study. Subsidence was evaluated using the “Ein-Bild-Roentgen-Analyse” (EBRA). Periprosthetic radiolucency allocated to the zones of Charnley and Gruen was assessed. Additionally, demographic and implant-related factors potentially associated with increased subsidence and clinical outcomes were evaluated. Results At the last follow-up, the average stem subsidence was 1.98 ± 1.20 mm, with 48% of the implants demonstrating subsidence of > 2 mm. Periprosthetic radiolucency of > 2 mm was found in 26% of the implants in zone 1 and in 9% in zone 7, respectively. Neither the amount of subsidence nor proximal periprosthetic radiolucency was associated with aseptic loosening or worse clinical outcomes. Conclusions Comparable to other proximally fixed short stem designs, the highest subsidence was observed within the first 3 months following implantation. No demographic or implant-related factors were found to have a statistically significant influence on stem subsidence. Periprosthetic radiolucency and subsidence of the AMISstem is not correlated with worse clinical outcomes at 5-year follow-up.

Subsidence rate and long-term outcome of a calcar-guided short stem: A prospective 10-year follow-up study

“…In our own cohort we also observed the highest subsidence within the rst 3 months but unlike as Kutzner et al we detected further subsidence thereafter up to the latest follow-up at 10 years, whereas notably the amount of additional subsidence was very little. In line with other studies the amount of subsidence did not correlate with clinical outcome at latest follow-up 10,[23][24][25] . Again, like other studies reporting on mid-term outcomes of calcar-guided short stems age, bodyweight and BMI did not in uence subsidence.…”

Demographic characteristics influencing the stem subsidence in total hip arthroplasty: an imaging study

“…Software and online platforms developed to assess subsidence are available. In this instance, “Ein Bild Roentgen Analyze—femoral component analysis” (EBRA-FCA) is an accurate tool to assess stem migration [ 39 ]. However, this software is not commonly used in clinical practice.…”

Contact states with femoral cortical bone and periprosthetic bone mineral density changes differ between traditional and newly introduced fully hydroxyapatite-coated stems

“…10,11 It has a triple-tapered design with a reduced lateral flare, a short length, and both the proximal and distal cross-sections are rectangular (Figure 2). 10,11 Three arthroplasty surgeons with 23, 26, and 26 years of experience, respectively, performed all the operations as part of the same surgical team. The modified Watson-Jones approach was used in the T-HA group, 12 and the direct anterior or modified Watson-Jones approach was used in the N-HA group.…”

“…7,8 The AMIStem (N-HA) is made of 5 µm sand-blasted TiAl 6 Nb 7 and plasma sprayed with an 80 µm layer of HA over its entire surface. 10,11 It has a triple-tapered design with a reduced lateral flare, a short length, and both the proximal and distal cross-sections are rectangular (Figure 2). 10,11 Three arthroplasty surgeons with 23, 26, and 26 years of experience, respectively, performed all the operations as part of the same surgical team.…”

“…In this study, we compared a newly introduced fully HA-coated (N-HA) stem whose design is based on the characteristics of a rectangular, tapered, straight uncemented stem (Khanuja's classification type 3 C), 9 with the T-HA stem. 10,11 While good clinical outcomes have been reported when using this N-HA stem, 10,11 to our knowledge, few authors have described its initial fixation pattern or periprosthetic changes in BMD. The hypothesis of this study was that different fully HA-coated stems would have different initial patterns of fixation and different local changes of BMD.…”