Migration behaviour of 2 clinically excellent cementless stems with different design rationales: 5-year follow-up of a randomised RSA-study

Hip International, vol. 32, pp. 747–758

Abstract

INTRODUCTION: Excellent long-term survival has been reported for both the Taperloc and the Mallory-Head cementless stems. However, little is known about the migration behaviour of these stems which have different design rationales. The purpose of this randomised clinical trial was to compare the migration and clinical outcomes of these stems during 5 years of follow-up. METHODS: 42 consecutive hips in 38 patients scheduled to receive cementless THA were randomised to either a Taperloc or a Mallory-Head stem. Evaluation took place preoperatively and postoperatively on the second day, at 6, 12, 26, and 52 weeks, and annually thereafter. Primary outcome was stem migration measured using roentgen stereophotogrammetric analysis (RSA) and secondary outcomes were the Harris Hip Score (HHS) and 36-Item Short-Form Health Survey (SF-36). No patients were lost to follow-up; in 1 patient the THA was removed due to deep infection 3 months postoperatively. In 6 hips migration measurements were not possible due to insufficient marker configuration. RESULTS: = 0.04). Initial subsidence and retroversion were respectively as large as 6.8 mm and 3.6° for the Taperloc stem and 5 mm and 3.6° for the Mallory-Head stem. After the first postoperative year, both implants had stabilised. The mean increment of HHS, as well as the SF-36 scores during the 5-year follow-up, were comparable between the 2 stems. CONCLUSIONS: The excellent long-term survival of both designs was confirmed in this study showing comparable initial migration with subsequent stabilisation. However, the Taperloc design with a flat, wedged geometry showed better rotational stability.

Authors 6

1. Paul van der Voort corresponding Aachen Department of Orthopaedics, Biomechanics and Imaging Group

   Leiden University Medical Center

   Affiliation as printed

   Department of Orthopaedics, Biomechanics and Imaging Group, Leiden University Medical Center, Leiden, The Netherlands

2. Danny van Delft Aachen Department of Orthopaedics, Biomechanics and Imaging Group

   Leiden University Medical Center

   Affiliation as printed

   Department of Orthopaedics, Biomechanics and Imaging Group, Leiden University Medical Center, Leiden, The Netherlands

3. Edward R. Valstar Aachen Department of Orthopaedics, Biomechanics and Imaging Group

   Leiden University Medical Center · Delft University of Technology

   Affiliation as printed

   Department of Biomechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology Delft, The Netherlands

   Department of Orthopaedics, Biomechanics and Imaging Group, Leiden University Medical Center, Leiden, The Netherlands

4. Bart L. Kaptein Aachen Department of Orthopaedics, Biomechanics and Imaging Group

   Leiden University Medical Center

   Affiliation as printed

   Department of Orthopaedics, Biomechanics and Imaging Group, Leiden University Medical Center, Leiden, The Netherlands

5. Marta F. Fiocco Aachen Department of Medical Statistics and Bioinformatics Mathematical Institute

   Leiden University · Leiden University Medical Center

   Affiliation as printed

   Department of Medical Statistics and Bioinformatics, Leiden University Medical Center, Leiden, The Netherlands

   Mathematical Institute, Leiden University, Leiden, The Netherlands

6. Rob G. H. H. Nelissen Aachen Department of Orthopaedics, Biomechanics and Imaging Group

   Leiden University Medical Center

   Affiliation as printed

   Department of Orthopaedics, Biomechanics and Imaging Group, Leiden University Medical Center, Leiden, The Netherlands