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Stable migration pattern of an ultra-short anatomical uncemented hip stem: a prospective study with 2 years radiostereometric analysis follow-up

Abstract

Introduction

Shorter, anatomically shaped and proximally loading stems have been developed to achieve better stress distribution and be more bone preserving. The purpose of this prospective study was to evaluate the migration pattern of the Proxima™ ultra-short uncemented stem using radiostereometric analysis (RSA), and to review the literature regarding the migration of short stemmed hip arthroplasty.

Methods

25 patients (28 hips) with hip osteoarthritis received a Proxima stem during total hip arthroplasty (THA). To measure stem migration, repeated RSA examinations were done during a 2 year follow up period. The patients were evaluated with the hip specific (HOOS) and the generic health (EQ5D) scores up to 1 year, and clinically for 6 years postoperatively.

Results

Almost all migration occurred within the first 3 months, with mean subsidence of 0.22 mm and varus rotation of 1.04°, being the primary effect variables. After the third postoperative month and up to the 2 year RSA follow up no further significant migration occurred. The outcome scores showed substantial improvement after 1 year. No revisions were performed or indicated for any stem after a mean clinical follow up of 72.1 months.

Conclusions

Like many other uncemented stems, the Proxima showed early migration up to 3 months hereafter osseointegration seems to have occurred. The achieved stability and clinical outcomes indicate favorable early results for this stem in younger patients who have good bone quality and average BMI. We found, however, the surgical technique to be slightly more demanding compared to conventional stems owing to the unique implant design that necessitates specific adjusted femoral cutting and broaching procedures.

Hip Int 2017; 27(3): 259 - 266

Article Type: ORIGINAL RESEARCH ARTICLE

DOI:10.5301/hipint.5000458

Authors

Ahmed Nageeb Mahmoud, Uldis Kesteris, Gunnar Flivik

Article History

Disclosures

Financial support: Depuy-Synthes has unconditionally sponsored part of the RSA examinations and tantalum bead marking of the stems but no other benefits have been received or will be received from a commercial party related directly or indirectly to the subject of this article.
Conflict of interest: We have no conflicts of interest to report in regards to preparation of this manuscript. However, Gunnar Flivik is in the speaking bureau for Depuy-Synthes and also for Zimmer-Biomet, Stryker, Link, Materealise and JRI.

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Authors

Affiliations

  • Department of Orthopaedics, Skåne University Hospital, Clinical Sciences, Lund University, Lund - Sweden

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