The poor outcome of large head metal on metal total hip replacements (LHMOMTHR) in the absence of abnormal articulating surface wear has focussed attention on the trunnion / taper interface. The RedLux ultra-precision 3D form profiler provides a novel indirect optical method to detect small changes in form and surface finish of the head taper as well as quantitative assessment of wear volume. This study aimed to assess and compare qualitatively tapers from small and large diameter MOMTHR's. Tapers from 3 retrieval groups were analysed. Group 1: 28mm CoCr heads from MOMTHRs (n=5); Group 2: Large diameter CoCr heads from LHMOMTHRs (n=5); Gp 3 (control): 28mm heads from metal on polyethylene (MOP) THRs; n=3). Clinical data on the retrievals was collated. RedLux profiling of tapers produced a taper angle and 3D surface maps. The taper angles were compared to those obtained using CMM measurements. There was no difference between groups in mean 12/14 taper angles or bearing surface volumetric and linear wear. Only LHMOMs showed transfer of pattern from stem trunnion to head taper, with clear demarcation of contact and damaged areas.3D surface mapping demonstrated wear patterns compatible with motion or deformations between taper and trunnion in the LHMOM group. These appearances were not seen in tapers from small diameter MOM and MOP THRs. Differences in appearance of the taper surface between poorly functioning LHMOMTHRs and well functioning MOP or MOM small diameter devices highlight an area of concern and potential contributor to the mode of early failure

The disadvantage of removing a well-fixed femoral stem are multiple (operating time, risk of fracture, bone and blood loss, recovery time and post-op complications. Ceramic heads with titanium adapter sleeves (e.g. BIOLOX®OPTION, Ceramtec) are a possibility for putting a new ceramic head on slightly damaged used tapers. ‘Intolerable’ taper damages even for this solution are qualitatively specified by the manufacturers. The aim of this study was to determine the fracture strength of ceramic heads with adapter sleeves on stem tapers with such defined damage patterns.

Pristine stem tapers (Ti-6Al-4V, 12/14) were damaged to represent the four major stem taper damage patterns specified by the manufacturers: -

‘Truncated’: Removal of 12.5% of the circumference along the entire length of the stem taper at a uniform depth of 0.5mm parallel to the taper slope.

BIOLOX®OPTION heads (Ø 32mm, length M) with Ti adapter sleeves were assembled to the damaged stem tapers and subjected to ISO7206-10 ultimate compression strength testing.

The forces required to fracture the head were high and caused complete destruction of the ceramic heads in all cases. The ‘Truncated’ group showed the lowest values (136kN ± 4.37kN; Fig. 3). Forces were higher and similar for the ‘Cut’ (170kN ± 8.89kN), ‘Control’ (171.8 ± 16.5kN) and ‘Slanted’ (173kN ± 21.9kN) groups, the ‘Scratched’ group showed slightly higher values (193kN ± 11.9kN). The Ti adapter sleeves were plastically deformed but did not fail catastrophically.

The present study suggests that manufacturer's recommendations for removal of a well fixed femoral stem could be narrowed down to the ‘Truncated’ condition. Even this might not be necessary since the fracture load is still substantially higher than the ASTM standard requires. Surgeons should consider to keep stems with larger taper damages as previously thought and spare the patient from stem revision. The greatest reservation regarding adapter sleeves is the introduction of the new metal-on-metal interface between stem and sleeve, which could possibly facilitate fretting-corrosion, which is presently one of the major concerns for modular junctions (3). Clinically such problems have not been reported yet. Ongoing FE-simulations are performed to investigate whether micromotions between stem and head taper are altered by the investigated damages.

Introduction

Modular junctions in total hip replacement (THR) have been a primary source of fretting and corrosion which can lead to implant failure. Fretting is a result of unintended micromotion between the femoral head and stem tapers and is suspected to result after improper taper seating during assembly. Two design factors known to influence in-vitro taper assembly mechanics are relative taper alignment—mismatch angle—and the surface finish—micro-grooves. However, these factors have not been systematically evaluated together.

Introduction

Since the introduction of modular hip taper junctions, corrosion has been studied yet the clinical effect remains unclear. Mechanically assisted corrosion and crevice corrosion are thought to be the primary clinical processes driving taper corrosion. Like all corrosion reactions, these processes require the taper junction to be in contact with an electrolyte. This study investigates the effect of sealing the taper junction from the environment on the mechanically-induced corrosion of a modular hip taper junction.

Background

Fretting corrosion at the junction of the modular head neck interface in total hip arthroplasty is an area of substantial clinical interest. This fretting corrosion has been associated with adverse patient outcomes, including soft tissue damage around the hip joint. A number of implant characteristics have been identified as risk factors. However, much of the literature has been based on metal on metal total hip arthroplasty or subjective scoring of retrieved implants. The purpose of this study was to isolate specific implant variables and assess for material loss in retrieved implants with a metal on polyethylene bearing surface.

Introduction

There is much current debate concerning wear and corrosion at the taper junctions of large head total hip replacements, particularly metal-on-metal hips. Is such damage a modern concern or has it always occurred in total hip replacement but not previously noted. To investigate this five explanted V40 Exeter femoral stems (Stryker Howmedica) were obtained following revision surgery at a single centre. In all cases, the 24–26 mm femoral heads were still attached.

Metallic contacts in hip replacements are susceptible to wear and corrosion processes which lead to the release of particles and metal ions. Adverse local tissue reactions (ALTRs) and systemic manifestations to solid and soluble debris can be debilitating for the patients. It is believed that particles originating from CoCrMo taper junctions trigger more severe body reactions compared to debris from MoM hip bearings. The body's reaction is highly dependent on particle characteristics, such as size, morphology, composition and aggregation state, which can reflect the specific wear and corrosion conditions at the site of release.

Here we proposed to investigate wear and corrosion flakes collected from around CoCrMo tapers at the time of revision. The particles were initially characterised with scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). This revealed the microstructure of the corrosion products, which appeared to be made of smaller metallic aggregates, entrapped in a biological matrix. The in depth characterisation of the particles released from the organo-metallic composite, was performed with transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM), both fitted with EDX. The investigation revealed clusters and individual nanoparticles, as small as 3 nm, which represent the building blocks of the large corrosion flakes, reported and characterised in the past mainly with low resolution microscopy techniques. The majority of the particles consisted of Cr and O, potentially in the form of chromium oxides, with little evidence of Co and Mo. Particles size distribution (PSD) provided by STEM and TEM characterisation showed statistically different results. The STEM technique was able to resolve tiny particles found in close proximity and provided a PSD shift towards the smaller end of the size range.

The study is the first to show microscopy evidence of Cr rich nanoparticles (3–60 nm) released in vivo from the modular taper interface, which can have important health implications caused by their increased potential to disseminate and corrode within the body.

Introduction: To investigate the head/neck interface of total hip replacements and to see whether the use of small spigots (minispigots) results in enhanced wear and corrosion of tapers compared to standard spigots and the influence of the surface finish on this.

Methods: In the total hip replacement combinations the heads were made of cobalt-chrome (CoCr) and the stems of titanium alloy (Ti). Firstly wear and corrosion of minisigots were compared with standard spigots (Test 1) and secondly, these minispigots were compared with another minispigot with a smoother taper surface finish (Test 2). The samples were immersed in aerated Ringers solution (37°C) and loaded for 10 million cycles. The specimens surface parameters and profiles were measured before & after the test. Electrochemical static corrosion tests were carried out on the rough & smooth minispigots from Test 2 where the current was measured with constant potential under loaded and non-loaded conditions. A cyclical sinusoidal load of 1500-200 Newtons for 1000 cycles at ~1 Hz was used. Pitting tests measured the current while increasing and then decreasing the potential of non-loaded and loaded specimens. Two newly manufactured rough and smooth minispigots were subjected to the same electrochemical corrosion tests.

Results: In Test 1 the results demonstrated that pre-test the surfaces of the female tapers were similar for all heads. Post-testing the Ra values on the female tapers had become greater for the minispigots compared with standard spigots. An abrupt change was noted on the surface profile of the female taper where it was in contact with the male Ti taper, indicating the the CoCr head had corroded. The Ti male tapers were unchanged. Scanning electron microscopy showed that the coarser profile in the corroded region of the CoCr was similar to the profile on the Ti male taper. Pitting corrosion was evident in the grooves on the CoCr. In Test 2 the smooth spigots were not affected, but in the rough minispigots, Ra values had increased in the female tapers. Static corrosion tests showed evidence of fretting in the rough but not the smooth minispigots. When comparing new rough & smooth minispigots, static corrosion testing with clyclical loading showed that for minispigots with a rough finish the current fluctuated with each cycle. Pitting scans showed a greater hysteresis with the rough minispigot compared with the smooth minispigot indicating potentially greater corrosion in the former.

Conclusion: The cobalt-chrome/titanium alloy combinations where the surface finish on the male taper was coarse, corrosion was increased in minispigots compared with standard spigots. This was due to the smaller area of contact of the minispigot at the interface. This corrosion appears to be mediated through the mechanism of fretting corrosion. Surface finish was crucial and corrosion of the minispigot was reduced if the surface finish was smooth. Manufacturers should investigate the effect of surface finish on the corrosion of their tapers particularly where cobalt-chrome/titanium alloy combinations are used.

Introduction

Numerous factors have been hypothesized as contributing to mechanically-assisted corrosion at the head-neck junction of total hip prostheses. While variables attributable to the implant and the patient are amenable to investigation, parameters describing assembly of the component parts can be difficult to determine. Nonetheless, increasing evidence suggests that the manner of intraoperative assembly of modular components plays a critical role in the fretting and corrosion of modular implants. This study was undertaken to measure the magnitude and direction of the impaction forces applied by surgeons in assembling modular head-neck junctions under operative conditions where both the access and visibility of the prosthesis may potentially compromise component fixation.

The poor outcome of large head metal on metal total hip replacements (LHMOMTHR) in the absence of abnormal wear at the articulating surfaces has focussed attention on the trunnion / taper interface. The RedLux ultra-precision 3D form profiler provides a novel indirect optical method to detect small changes in the form and surface finish of the head taper as well as a quantitative assessment of wear volume. This study aimed to assess and compare qualitatively the tapers from well functioning small diameter, with poorly functioning LHMOMTHR's using the above technique.

Aims: To investigate whether the use of mini-spigots result in enhanced wear and corrosion of tapers compared to standard spigots and the influence of the surface finish on this. Methods: The heads were cobalt chrome and the stems titanium alloy. Firstly wear and corrosion of standard spigots were compared with mini-spigots and secondly, these mini-spigots with another mini-spigot with a smoother surface finish. The samples were immersed in aerated Ringers solution (37°C) and loaded for 10 million cycles. Then samples were sectioned and the surface parameters measured and interfaces investigated using scanning electron microscopy. Static corrosion tests were used under loaded and non-loaded conditions and pitting tests for non-loaded samples. Results: Pre-experimentation the surfaces of the female tapers were similar for all heads. At the end of the first test the surface parameters on the female tapers had become significantly greater (p=0.034) for the mini-spigots compared with standard spigots and an abrupt change noted on the surface profile of the female taper where it contacted the male taper, indicating that the cobalt chrome head had corroded. Scanning electron microscopy showed that the coarser profile in the corroded region of the cobalt chrome head was similar to the profile on the titanium stem taper. Pitting corrosion was evident in the grooves on the cobalt chrome. The smooth mini-spigots were less affected. Conclusions: In cobalt chrome- titanium alloy combinations where the surface finish on the taper is coarse, corrosion is increased on a mini spigot compared with standard spigot. Surface finish is crucial and corrosion of the mini spigot is reduced if the surface finish is smooth.

Aims

The aim of this study was to develop a novel computational model for estimating head/stem taper mechanics during different simulated assembly conditions.

Introduction

The National Joint Registry has recently identified failure of large head metal on metal hip replacements. This failure is associated with the high torque at the interface of standard modular taper junction leading to fretting and corrosion. A number of manufacturers produce mini spigots, which in theory, provide a greater range of motion as the neck head junction is reduced. However, the relative torque to interface ratio at this junction is also increased. In this study we investigated hypothesis that the use of small spigots (minispigots) will increase wear and corrosion on modular tapers.

Revision hip surgery is increasing each year. We describe a case of revision hip surgery of a fully ingrown modular stem in which the supplied manufactures replacement modular head did not fit the original taper. This resulted from a change in the manufacturing process and taper dimensions between the primary index hip replacement and the revision operation. The manufacturing company was not aware of this change in their manufacturing process. This caused problems during surgery.

A thirty-nine year old male patient had a Mittel-meier uncemented hip prosthesis performed for avascular necrosis of the femoral head in 1988. Twelve years following the index primary hip replacement the cup was loose and migrating so revision of the acetabular component was planned.

A selection of Mittelmeier heads was obtained from the company. The ceramic head was removed and the acetabular component revised for a cemented cup. It was then discovered, during the operation, that the supplied heads did not fit the taper on the stem. The manufacturers had changed the dimensions of the taper since the original prosthesis had been implanted in 1988. Several companies had marketed this prosthesis since 1988 and the current supplier was unaware of a change in the taper. With the cup already cemented in place there were limited options. By chance the Exeter heads fitted the taper on the femoral component and were used. The patient recovered uneventfully.

The Mittlemier is not the only prosthesis to change its taper during its lifetime. If as in this case the manufacturers are unaware of a change in the manufacturing process the surgeon has no way of confirming the information provided prior to the surgery. This case highlights the potential problems when trying to partially revise a modular component.

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 mm³ (2.96 – 7.85 mm³) and the material loss rate was 1.4 mm³ / 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 mm³ / 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 mm³ / year.

We have identified a clinically significant volume of taper material loss in MOP hips.

Taper corrosion and fretting have been associated with oxide layer abrasion and fluid ingress that contributes to adverse local tissue reactions with potential failure of the hip joint replacement. [1,2]. Both mechanisms are considered to be affected by the precise nature of the taper design. [3]. Indeed relative motion at the taper interface that causes fretting damage and wear effects, such as pistoning and rocking, have been described following analysis of implants at retrieval. [4,5]. However, there is much less reported about the mechanisms that allow the fluid ingress/egress at the taper interface which would drive corrosion. Thus the aim of the present study was to investigate the effect of trunnion design on the gap opening and taper relative motions under different load scenarios and taper designs. A 3-D finite element model of a 40mm CoCr modular femoral head and a Ti6Al4V trunnion was established in Abaqus CAE/2018. Femoral head and trunnion geometries were meshed with an element (C3D8) size of 0.17mm. Tapers were assembled by simulating a range of impact forces (AF); taper interface behaviour was evaluated under physiological forces and frictional moments simulated during walking activity. [6]. , assuming different coefficients of friction (CF), Figure 1. The output involved the total and normal relative motion of the surfaces at the taper interface. The model predicted for a taper mismatch of 0.36° which, when combined with an assembly force of 2kN, generated the largest taper gap opening (59.2mm) during walking, Figure 2. In all trunnion designs the largest normal relative motion coincided with heel strike in the gait cycle (0–5%). The taper gap and normal relative motions were related to the initial taper lock area. Furthermore, the direction of the total motion was different in all three taper mismatches, with a shift in the direction towards the normal of the surface as the taper mismatch increased, Figure 3. By contrast, the direction of the normal relative motions did not change with different trunnion designs. Contact patterns were asymmetrical and contact areas varied throughout the walking activity; contact pressure and the largest taper gap were located on the same side of the taper, suggesting toggling of the trunnion. The relationship between taper gap opening and initial taper lock contact area suggests that the taper contact area functions as a fulcrum in a lever mechanism. Large taper mismatches create larger relative motions that will not only create more wear and fretting damage but also larger normal relative motions. This may allow fluid ingress into the taper interface and/or the egress of fluid along with any metal wear particles into the body. This increased understanding of the taper motion will result in improved designs and ultimately taper performance. For any figures or tables, please contact the authors directly

Introduction. Frictional behavior and, therefore, the coefficient of friction (CoF) play an important role in the evolution of fretting wear. Several studies investigated fretting at the ball head-taper junction with a remarkable variation in the CoF (0.15 to 0.55). This may be due to different material couplings, surface topographies or macro-geometries. Since the results of Finite Element (FE) models are strongly dependent on the choice of CoF it is crucial to determine the correct CoF for a speci?c system. Therefore, this study aimed to determine the CoF for the interface between ceramic ball heads and metal tapers. Materials and Methods. Three groups of taper-ball head couplings were investigated (n=18 titanium (Ti), n=18 cobalt chromium (CoCr), n=18 steel tapers (SS)). Line profiles of the taper surfaces were measured and tapers and ball heads were assembled using different loads (2, 4, 6 kN). Tapers were disassembled from ball heads by using liquid nitrogen, surface topography was remeasured and the effective contact area was determined. Another set of measurements was conducted (n=5 tapers per taper material) to measure the contact pressure. Here, pressure sensitive films were placed between tapers and ball heads during assembly. Using the effective contact area and contact pressure the CoF was calculated. Results. Effective contact area increased logarithmically with increasing assembly load with maximum values around 100 mm² for SS and Ti tapers at 6 kN. Contact pressure also increased with increasing load. Maximum contact pressures were found at the proximal end of the tapers and decreased linearly towards the distal end. Highest values were found for SS and CoCr (138 and 126 MPa). CoF increased with increasing load and varied from 0.44 to 0.68, while a decrease of the CoF between 4 and 6 kN for SS tapers was found. Largest values were found for Ti and CoCr tapers. Discussion. Since contact pressure increases with increasing load it seems plausible that the CoF also increases. Absolute pressure values are within the range of literature data (25–280 MPa). At first sight, the CoF seem to be independent from the material coupling, but looking at taper subsidence there are distinct differences between materials with SS showing the lowest and Ti the highest subsidence. Therefore, the different deformation behavior of the materials and, thus, the different evolution of effective contact area have also an effect on CoF. Ti shows largest deformation and SS shows lowest deformation. This effect seems plausible since Ti has the lowest Young's Modulus of the three taper materials examined. Some of the CoF determined here are larger than literature values. This may be due to different surface specifications and geometrical parameters (e.g. angular mismatch), different material couplings and loading conditions. Here surface roughness and angular mismatch was kept constant for all couplings tested. The results of this study will be used to develop friction laws to be implemented in FE models examining fretting and wear processes

Introduction. There are increasing reports of total hip replacement (THR) failure due to corrosion within modular taper junctions, and subsequent adverse local tissue reactions (ALTRs) to corrosion products. Modular junction corrosion is a multifactorial problem that depends on material, design, patient and surgical factors. However, the influence of alloy microstructure on corrosion has not been studied sufficiently. Especially for cast CoCrMo, there are concerns regarding microstructure variability with respect to grain size and hard-phase volume fraction. Therefore, it was the goal of this study to (1) identify different types of microstructures in contemporary implants, and (2) determine implications of alloy microstructure on the occurring corrosion modes. Methods. Fifteen surgically retrieved femoral stems made from cast CoCrMo alloy were analyzed for this study. Damage on the taper surfaces was investigated by scanning electron microscopy (SEM) and damage was assessed with the Goldberg Score. The alloy microstructure was evaluated by standard metallographic techniques. Alloy samples were sectioned off the femoral stem, and microstructural features were visualized by chemical etching. Cyclic potentio-dynamic polarization tests were carried out with alloy samples from two implants with different commonly occurring types of microstructures. Both had a similar grain size, but type 1 had no hard-phases, where as type 2 exhibited hard-phases along the grain boundaries, as well as intra-granular hard-phase clusters. Tests were performed in bovine serum at 37°C with a saturate calomel reference electrode and a graphite counter electrode. In vitro generated corrosion damage was then compared to in vivo generated damage features on the taper surfaces of the corresponding implants. Results. Tapers with high damage scores exhibited varying degrees of grain and phase boundary corrosion, along with fretting and pitting corrosion. In several cases thick chromium oxide films were observed. The metallographic analysis showed that nominally identical alloys (ASTM F75) exhibited a broad variability in grain size (250 micrometers to several millimeters), hard-phase volume fraction (0–6%), and hard-phase type (carbides and intermetallic phases). The corrosion tests revealed that the alloy without hard-phases (type 1) had a significantly higher pitting potential (p=0.001) than type 2 alloy without hard-phases. After testing, both alloys exhibited grain boundary corrosion. However, type 2 had a higher degree of material loss due to hard-phase detachment. Additionally, type 2 exhibited pitting within the grains around hard-phases, along with the formation of thick oxide films which was consistent with the lower pitting potential. The results also corresponded with the damage features on the corresponding tapers, where type 1 exhibited only mild damage features, and type 2 underwent severe grain and phase boundary corrosion along with thick oxide films (Figure 3). Discussion. It appears that the alloy microstructure drives local modes of corrosion. Additional phase boundaries due to hard-phase content promote corrosion. The fact that the same alloy can differ broadly even within the same design shows that material standards are currently not sufficient. Optimizing implant alloys will help to reduce in vivo corrosion processes, and subsequently the risk of implant failure due to ALTRs. For figures/tables, please contact authors directly.

Introduction:. Large diameter metal on metal total hip arthroplasty (MOM THA) have shorter lengths of implantation due to increased failure caused by wear either at the articulating surface as well as the taper-trunnion interface. Taper-trunnion wear may be worse in large diameter MOM THA due the increased torque at the taper-trunnion interface. However little has been done to understand how differences in taper-trunnion geometry and trunnion engagement effects wear. The purpose of this study was to (1) measure the differences in taper geometry and trunnion engagement on the head-taper of 11/13, 12/14, and Type 1 taper designs and (2) to determine if taper geometry affects fretting, corrosion, and wear at the taper interface. Methods:. We identified 54 MOM THA primary revision implants with head diameters greater than 36 mm from our retrieval archive. Patients' charts were queried for demographic information and pre-revision radiographs were measured for cup inclination and cup anteversion. To measure taper geometry and wear the head tapers were imaged using Redlux©. The point clouds obtained from this were analyzed in Geomagic©. Taper angles and contact length where the trunnion engaged with the female taper of the head-tapers were measured. The diameter of the taper at the most distal visual area of trunnion engagement was also measured. Best fit cones were fit to the unworn regions to approximate the pristine surface. Differences between the raw data and the unworn surface were measured and volumetric wear rates were calculated. Fretting and corrosion of the head-taper was graded using the Goldberg Scoring. Results:. Geometric differences were found between the three designs with the Type 1 being the narrowest with an average taper angle of 3.97 ± 0.09° and an average distal diameter of 12.42 ± 0.35 mm; 11/13 was the second narrowest with a taper angle of 5.97 ± 0.03° and a distal diameter of 13.13 ± 0.27 mm. The widest taper was 12/14 with a taper angle of 5.58 ± 0.21° and a distal diameter of 13.91 ± 0.35 mm. Contact lengths were greatest for 11/13 tapers, 18.96 ± 1.51 mm, then 12/14, 13.31 ± 3.46 mm and least for Type 1, 11.98 ± 4.44 mm (Table 1). Differences in geometry did not significantly affect volumetric wear rate or corrosion but did affect fretting. Type 1 tapers had significantly lower fretting scores (2.9 ± 1.5, p < 0.05) than 12/14 tapers (5.0 ± 1.6) and 11/13 tapers (6.4 ± 2.1). Discussion:. We were able to measure determine geometric differences between three common taper designs which may affect taper damage. Tapers which are narrower and have less contact length (i.e. Type 1) had less head-taper fretting than those which are wider and have longer contact lengths. This may be a function of less surface of the trunnion contacting the head taper interface. While we could not demonstrate any differneces in trunnion wear rates among taper types, volumetric wear and corrosion may be independent of taper geometries

Aims

Head-taper corrosion is a cause of failure in total hip arthroplasty (THA). Recent reports have described an increasing number of V40 taper failures with adverse local tissue reaction (ALTR). However, the real incidence of V40 taper damage and its cause remain unknown. The aim of this study was to evaluate the long-term incidence of ALTR in a consecutive series of THAs using a V40 taper and identify potentially related factors.