A shortened uncemented stem offers comparable positioning and increased metaphyseal fill compared to a standard uncemented stem

Alexandre Jacquel,Nicolas Bonin,Jeremy Valluy,Mo Saffarini,Augustin Le Viguelloux

doi:10.1186/s40634-019-0197-1

Alexandre Jacquel, Nicolas Bonin + Show 3 more

Open Access

https://doi.org/10.1186/s40634-019-0197-1

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Abstract

BackgroundShortened stems are increasingly used in uncemented total hip arthroplasty (THA) as they represent a compromise between the metaphyseal anchorage of short stems and the facilitated axial alignment of standard stems. The purpose of this study was to compare the metaphyseal canal-fill ratio (CFR) and axial alignment of a shortened double-tapered stem with those of a standard stem. The hypothesis was that the shortened stem would achieve greater metaphyseal fill and comparable axial alignment.MethodsThe authors reviewed routine follow-up anteroposterior radiographs taken 2 months after THA to evaluate metaphyseal fill and axial alignment of a shortened stem (n = 96) and a standard stem (n = 101). The CFR was calculated at the level of the tip and superior margin of the lesser trochanter. Stem alignment was defined as the angle between the stem axis and the proximal anatomic femoral axis. Stems were classified as being in varus or valgus alignment if they deviated by more than 3° from the anatomic axis of the femur.ResultsHips implanted with shortened and standard stems had comparable demographics and axial alignment (1.1° ± 1.7° vs 0.8° ± 1.2°; p = 0.331). However, varus alignment was observed in 5% of shortened stems compared to only 1% of standard stems, though this difference was not significant (p = 0.111). The femoral CFR was greater using shortened stems than using standard stems, both at the level of the tip of the lesser trochanter (0.91 ± 0.05 vs 0.85 ± 0.08; p < 0.001) and at its superior margin (0.76 ± 0.06 vs 0.72 ± 0.07; p < 0.001).ConclusionsCompared to the standard stem, the shortened stem had increased metaphyseal filling and equivalent alignment. These findings suggest that shortened stems could provide adequate metaphyseal fixation and correct alignment. Further studies remain necessary to evaluate how shortened stems perform in terms of osseointegration, clinical outcomes and survival.

Highlights

Shortened stems are increasingly used in uncemented total hip arthroplasty (THA) as they represent a compromise between the metaphyseal anchorage of short stems and the facilitated axial alignment of standard stems
Total hip arthroplasty (THA) using uncemented femoral stems demonstrated excellent long-term fixation (Khanuja et al, 2011) and clinical results (Tannast et al, 2009), though it remains associated with mid-thigh pain (Jo et al, 2016; Mihalko & Whiteside, 2015; Petis et al, 2015) likely related to inadequate load transfer (Fottner et al, 2018), and stress-shielding due to predominantly
There were no differences between patients who had collared and collarless standard stems in terms of canal-fill ratio (CFR) at the tip of the lesser trochanter (0.83 ± 0.09 vs 0.85 ± 0.07, p = 0.357) and at its superior margin (0.71 ± 0.07 vs 0.72 ± 0.07, p = 0.790), as well as stem mal-alignment (0% vs 1%, p = 0.202)

Summary

Introduction

Shortened stems are increasingly used in uncemented total hip arthroplasty (THA) as they represent a compromise between the metaphyseal anchorage of short stems and the facilitated axial alignment of standard stems. Shortened diaphyseal stems were developed as a compromise between the metaphyseal anchorage of short stems and the facilitated axial alignment of standard stems. This design rendered good clinical outcomes in smaller patients (Choy et al, 2013; Feyen & Shimmin, 2014) and is being increasingly used for the general population. There are no published studies investigating its metaphyseal fill and axial alignment

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