Aims. To present a surgically relevant update of trunnionosis. . Materials and Methods. Systematic review performed April 2017. Results. Trunnionosis accounts for approximately 2% of the revision total hip arthroplasty (THA) burden. Thinner (reduced flexural rigidity) and shorter trunnions (reduced contact area at the taper junction) may contribute to mechanically assisted corrosion, exacerbated by high offset implants. The contribution of large heads and mixed metallurgy is discussed. Conclusion. Identifying causative risk factors is challenging due to the multifactorial nature of this problem. Cite this article: Bone Joint J 2018;100-B(1 Supple A):44–9

Background

There has been a trend in the evolution of total hip arthroplasty towards increased modularity, with this increase in modularity come some potentially harmful consequences. Modularity at the neck shaft junction has been linked to corrosion, adverse reaction to metal debris and pseudotumor formation.

The aim of this retrieval study is to assess whether the surface integrity of the polyethylene (PE) liner is affected by metal wear debris in a single implant design series of THA revised for trunnionosis.

Aims

We have previously demonstrated raised cobalt and chromium levels in patients with larger diameter femoral heads, following metal-on-polyethylene uncemented total hip arthroplasty. Further data have been collected, to see whether these associations have altered with time and to determine the long-term implications for these patients and our practice.

Trunnionosis, due to mechanical wear and/or corrosion at the head stem taper junction, can occur in metal on polyethylene (MOP) hip implants. In some patients this results in severe soft tissue destruction or Adverse Reaction to Metal Debris (ARMD). The amount of material required to cause ARMD is unknown but analyses of retrieved hips may provide the answer to this clinically important question. We collected implants from 20 patients with failed hips with MOP bearings, revised due to ARMD. We collected clinical, imaging and blood test data. We graded the severity of taper corrosion (1 to 4), and quantified the volume of material loss from this junction. We compared our results with previous data collected for metal-on-metal (MOM) hips. The median time to revision of the MOP hips was 51.3 (23.1–56.4) months. All head tapers were moderately to severely corroded with a median corrosion score of 4. The median (range) of total material loss at the taper of the MOP hips was 3.9 mm. 3. (2.96 – 7.85 mm. 3. ) and the material loss rate was 1.4 mm. 3. / year (0.56 – 1.82). Comparison with MOM hips revealed no significant difference in taper material loss (p=0.7344) with a median rate of 0.81 mm. 3. / year (0.01–3.45). We are the first to quantify the volume of material loss at the head taper of hip implants with MOP bearings that were revised due to trunnionosis. This data indicates that a clinically significant dose of cobalt and chromium to induce ARMD is approximately 1.4 mm. 3. / year. We have identified a clinically significant volume of taper material loss in MOP hips

Trunnionosis is an important failure mechanism of total hip arthroplasties as has recently been reported by the England and Wales national joint registry. Adverse local tissue reaction has also recently been associated with total hip arthroplasty (THA) with metal on polyethylene and ceramic on polyethylene articulations. The contributing factors in the mechanism of this failure pattern have not been elucidated, however they are likely multifactorial to include corrosion, fretting, taper design, implantation time, metal particulate debris, and wear at the metal on metal interface. Furthermore, dissimilar metallic combinations have been shown to exacerbate tribocorrosion. Authors have also reported on the use of ceramic heads to reduce trunniononis, however, tribocorrosion is still present. The majority of the literature regarding modular head neck taper fretting and corrosion involves cobalt chrome (CoCr) alloy. Little is known about head neck fretting corrosion with Oxinium femoral heads. To measure fretting, corrosion, and wear on the female tapers of retrieved Oxinium femoral heads and to determine how demographic and device factors affect these measurements. Ninety-two (92) retrieved 12/14 Oxinium heads were graded using the modified Goldberg score for subjectively grading corrosion and fretting on the taper surface. A novel silicone molding technique was validated, then applied to the female tapers of the retrievals and of two pristine Oxinium femoral heads, sizes 32+0 and 32+4. The molds were scanned using a Konica Minolta 3D laser scanner for reconstruction of the topography, dimensions, and surface features of the tapers. Geomagic software was used to align the retrieved to the pristine 3D models, allowing measurement of surface deviations (from wear) that had occurred while the heads were implanted. Patient demographic and implant data were correlated with Goldberg scores and wear deviations. The mean Goldberg score was 1.6. Goldberg scores of 1 (minimal), 2 (mild), and 3 (moderate) were present in 41 of the 92 heads (45%), 43 heads (47%), and 8 heads (8%) respectively. No implants received a score of 4 (severe). A positive significant correlation was found between length of implantation and increased female taper fretting (R = 0.436, p < 0.01). Wear deviations were significantly greater with 36mm heads compared to 32mm heads (p < 0.01) and with +4 offsets compared to 0 offsets (p = 0.013). Similar to previous work analyzing ceramic heads, Oxinium heads demonstrated predominately mild tribocorrosion grades, however do not eliminate tribocorrosion. Tribocorrosion was increased with large heads and increased offsets. This finding is consistent perhaps with greater mechanical burden that larger implants with increased offsets experience. Further investigation is needed to elucidate if Oxinium femoral heads reduce fretting and corrosion when compared to CoCr femoral heads

Aims

Modular dual-mobility constructs reduce the risk of dislocation after revision total hip arthroplasty (THA). However, questions about metal ions from the cobalt-chromium (CoCr) liner persist, and are particularly germane to patients being revised for adverse local tissue reactions (ALTR) to metal. We determined the early- to mid-term serum Co and Cr levels after modular dual-mobility components were used in revision and complex primary THAs, and specifically included patients revised for ALTR.