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. 2023 Mar;143(3):1651-1661.
doi: 10.1007/s00402-022-04393-6. Epub 2022 Mar 3.

Survival and performance of a dual tapered-wedge fully HA-coated press fit femoral stem

Ramakanth R Yakkanti  1 , Dylan N Greif  1 , Dennis J Vanden Berge  2   3 , Raymond P Robinson  1
Affiliations

Survival and performance of a dual tapered-wedge fully HA-coated press fit femoral stem

Ramakanth R Yakkanti et al. Arch Orthop Trauma Surg. 2023 Mar.

Abstract

Introduction: Fully hydroxyapatite-coated titanium alloy double-tapered stems have been successful implant designs for THA. The Novation Element Stem (Exactech, Gainesville, FL) is one of several of these implants following a modified Corail design philosophy. Although a great deal is known about the results of the Corail stem, little is known about the more recent Corail-inspired implants. The authors evaluated the clinical outcomes, radiographic findings and survival statistics of the collarless version of the Element Stem when used routinely in a diverse patient population.

Methods: A retrospective review was performed for all primary THR cases from 2010 to 2018. Patient demographics and HHS/OHS/patient satisfaction scores were obtained. Radiographs were evaluated for stem subsidence, radiolucencies, and bone responses to the implant.

Results: One hundred and fifty seven Element Stems were implanted with greater than 2 years of radiographic follow-up, while 105 Element Stems implanted during the study period had a survival of 5 years or more. Average HHS was 91.7 and average OHS was 44.0. 54 of 157 hips had radiolucencies, all of which included a proximal zonal radiolucency. Average subsidence was 3.33 mm; 18 hips had subsidence > 4 mm. There were 8 revisions for: aseptic loosening (4), trauma-related peri-prosthetic fractures, and early proximal-medial fractures. At 5 years, the all-cause survival rate is 92.4%, 96.2% based only on aseptic loosening and 98.1% based only on proximal medial fractures.

Conclusion: Clinical outcomes using the collarless Novation Element Stem are good, but early proximal medial fracture is still a factor in patients with poor-quality bone. Proximal radiolucencies progressing to aseptic loosening post-operatively are also a concern. The 11.5% rate of subsidence is comparable to other fully HA-coated collarless stems. This study provides a thorough critical analysis of outcomes and midterm survival data of this dual tapered-wedge fully HA-coated collarless stem used routinely in a diverse patient population.

Keywords: Aseptic loosening; Cementless collarless femoral stem; HA coating; Mid-term outcomes; Outcomes; Press fit femoral stem.

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Conflict of interest statement

One author is a paid consultant for Exactech., Inc, and Stryker, Inc (Athens Michigan) (R.P.R.).

Figures

Fig. 1
Fig. 1
Progressive radiolucencies leading to aseptic loosening in a 53-year-old female. A Post-operative recovery room film demonstrating appropriate fit. B Film at 10 months already demonstrates radiolucency in Zone 1. C Film at 24 months demonstrating progressive radiolucencies in Zones 1 and 2. D Film taken 60 months after surgery demonstrating progressive radiolucencies in Zones, 1,2,3 and 7 with the beginning of shelf formation
Fig. 2
Fig. 2
Kaplan–Meier survival curve
Fig. 3
Fig. 3
Proximal medial fracture in a 54-year-old female. A Post-operative recovery room films demonstrating stable fixation. B Proximal medial fracture necessitating revision less than 1 month after surgery
Fig. 4
Fig. 4
Retrieved element stem. A Element Stem prior to implantation. B Element stem retrieved after revision for aseptic loosening. Demonstrated is the uniform loss of hydroxyapatite coating, likely secondary to resorption and abrasion
See this image and copyright information in PMC

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