Elsevier

The Journal of Arthroplasty

Volume 29, Issue 9, September 2014, Pages 1768-1773
The Journal of Arthroplasty

Midterm Results of a Femoral Stem With a Modular Neck Design: Clinical Outcomes and Metal Ion Analysis

https://doi.org/10.1016/j.arth.2014.04.039Get rights and content

Abstract

Modular neck femoral stems have a higher-than-anticipated rate of failure in registry results, but large single-center cohort studies are lacking. This is a retrospective cohort of 152 hips implanted with a single titanium stem with a modular titanium neck, presenting clinical, radiographic, and metal ion results at a mean 4.5-year follow-up. Five hips were revised during the study period, for an overall Kaplan–Meier survival of 0.894 at 8 years. There was one modular neck fracture (0.66%), but others demonstrated corrosion or adverse tissue reaction. Serum metal levels demonstrated wide variability. Despite good clinical results in the majority of patients, we confirmed an increased rate of femoral revision at mid-term follow-up, and therefore urge caution in the use of this particular stem design.

Section snippets

Materials and Methods

Between May 2003 and March 2010, 195 total hip arthroplasties (THA) were performed in 176 patients by the lead author (author initials blinded) using the Profemur Z uncemented stem. This stem was used in all 193 primary THA procedures and two revision THA procedures performed by the senior author over this time period.

The Profemur Z stem is a dual-tapered titanium alloy stem (Ti-6Al-4 V) with a rectangular cross-section that is implanted via a broach-only technique (Fig. 1), and comes in 9 sizes

Results

Mean Harris Hip scores were 85.8 points at latest follow-up (range, 30 to 100 points). Radiographic analysis demonstrated radiolucent lines consistent with loosening around the femoral component in 8 of 152 hips (5.3%), while progressive proximal osteolysis was seen in two patients (Fig. 3). The mean acetabular abduction angle was calculated to be 43.6° (range, 25° to 69°).

Five hips have been revised to date (Table 3). One was revised for modular neck fracture, one was revised for squeaking of

Discussion

This is the first large cohort study to report clinical outcomes of the Profemur Z modular neck femoral stem. There have been numerous case reports of failure in this specific stem design, which have generally related to corrosion and modular neck fracture 5., 6., 7., 8., 10., 12., however the clinical performance of this stem had not previously been described. The present study has strengths of being a single surgeon, consecutive cohort series of all patients implanted with this stem design

Grants and Acknowledgments

Metal ion testing was funded by the (hospital name blinded) Division of Adult Reconstruction’s research fund. The authors also thank (blinded name) for her invaluable and tireless effort in tracking our patients and managing our database.

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    The Conflict of Interest statement associated with this article can be found at http://dx.doi.org/10.1016/j.arth.2014.04.039.

    1

    Investigation performed in the Division of Adult Reconstruction, Henry Ford Hospital, Detroit, MI.

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