Trunnion Corrosion and Early Failure in Monolithic Metal-on-Polyethylene TMZF Femoral Components: A Case Series

Abstract

We describe four patients who were treated with primary total hip arthroplasty (THA) at two tertiary academic Australian teaching hospitals that experienced premature failure of head-neck trunnions through dissociation of the head-neck taper junction. This retrospective case series has similar clinical presentations and macroscopic pathology with severe head-neck taper junction loss of material, corrosion and early catastrophic failure. It is proposed that the accelerated wear is related to use of varus offset neck in a proprietary beta titanium alloy (Ti-12Mo-6Zr-2Fe or TMZF� Stryker Osteonics, Mahwah NJ, USA) TMZF femoral stem, longer head-neck combination in a relatively active, older, male patient population. In this limited case series presentation was on average 80 months (range 53-92) following index procedure. In three of the four patients, a prodromal period of groin or buttock pain was reported for between 1 week and 2 months prior to acute presentation. Significant metallosis and local tissue damage including gluteal muscle insufficiency was evident. Each stem revised was well fixed. An extended trochanteric osteotomy was required in two of the four cases for stem extraction. We recommend caution and further evaluation on the relationship between TMZF metal alloy and its longevity in higher demand patients with high neck offset, varus stem geometry and large CoCr bearing heads.

Femoral Head-Trunnion Dissociation in Metal-on-Polyethylene Total Hip Arthroplasty – A Unique Case Report

“…Walker et al noted time to gross failure ranging from 4.4 to 7.6 years in a case series consisting of four patients [11]. Similarly, the time to trunnion failure observed in the presented case was nearly nine years after initial implantation.…”

Head Taper Corrosion Causing Head Bottoming Out and Consecutive Gross Stem Taper Failure in Total Hip Arthroplasty

“…A further contributing factor is the accelerated corrosion of TMZF in simulated body fluid in comparison to Ti6Al4V, which might further precipitate the process [30]. It is surprising that the catastrophic GTF cases did apparently not exhibit clinical symptoms due to raised Co and Cr metal ions, which must have been caused by the amount of CoCr lost from the female head taper (above 15mm³, Figure 6, Figure 7), and/or the large amounts of taper, even so the extend is much larger [9][10][11][12][13][14][15][16][17][18].…”

“…Several studies on elevated metal ion levels or even catastrophic gross taper failures (GTF) after hip joint replacement highlight one particular stem design with a small V-40 taper made from a less stiff Ti-12Mo-6Zr-2Fe titanium-alloy (TMZF; Accolade I, Stryker, Mahwah, NJ) in combination with head sizes of mostly 36mm and above ( Figure 1) [9][10][11][12][13][14][15][16][17][18]. This proprietary beta titanium alloy was introduced in 2002 based on the potential benefits of more closely mimicking the modulus of elasticity of cortical bone than standard Ti-6Al-4V alloys [19].…”

Taper corrosion: a complication of total hip arthroplasty

“… 26 Such failures are reported mostly for one particular stem design with a small V-40 taper made from a less stiff Ti-12Mo-6Zr-2Fe titanium-alloy (TMZF; Accolade I, Stryker, Mahwah, New Jersey, USA) in combination with heads made of Cobald-Chromium-Alloy (CoCr) of sizes of mostly 36 mm and above. 27 – 31 …”