Titanium-Titanium Junctions in the Knee Corrode, Generating Damage Similar to the Hip.

BACKGROUND: Previous studies identified corrosion between the modular tibial components of total knee arthroplasty devices. However, gaps persist. Compared to the hip, damage modes that occur within taper junctions in the knee remain poorly understood. In this study, we investigated corrosion on total knee arthroplasty components with titanium-titanium junctions. We asked the following question: under typical in vivo cyclic loading conditions, will the same alloy damage modes from total knee arthroplasty devices resemble those documented in the hip? METHODS: A total of 50 paired titanium alloy tibial baseplates and stems were collected and semiquantitatively analyzed using Goldberg corrosion scoring. To characterize damage, a subsection of moderately and severely corroded components was sectioned and imaged using scanning electron and digital optical microscopy. RESULTS: Of the 100 device components, 95% showed visual evidence of corrosion. The initial contact area between the stem and bore generally occurred 3 mm from the stem taper base. Scanning electron microscopy revealed 4 damage modes, including oxide film formation, crevice corrosion, selective dissolution, and pitting. CONCLUSIONS: Each of the damage modes identified in modular titanium-titanium tibial junctions was previously reported by total hip arthroplasty retrieval studies. Cumulatively, our results suggest that mechanically assisted crevice corrosion promoted this damage in vivo.

Gross Taper Failure and Fracture of the True Neck in Total Hip Arthroplasty: Retrieval Scanning Electron Microscope Analysis.

Background and objectives: wear and corrosion can lead to the gross failure of the Morse taper junction with the consequent fracture of the true neck of the prosthetic stem in hip arthroplasty. Materials and Methods: 58-year-old male patient, with a BMI of 38 kg/m2. Because of avascular necrosis, in 2007, a metal-on-metal total hip arthroplasty was implanted in him, with a TMZF stem and a Co-Cr head. In December 2020, he complained of acute left hip pain associated with the deterioration of his left leg and total functional impairment, preceded by the crunching of the hip. X-rays and CT scan showed a fracture of the prosthetic neck that necessitated prosthetic revision surgery. A Scanning Electron Microscope (SEM) analysis of the retrieved prosthetic components was conducted. Results: Macroscopically, the trunnion showed a typical bird beak appearance, due to a massive material loss of about half of its volume. The gross material loss apparently due to abrasion extended beyond the trunnion to the point of failure on the true neck about half a centimeter distal from the taper. SEM analysis demonstrated fatigue rupture modes, and the crack began close to the neck's surface. On the lateral surface, several scratches were found, suggesting an intense wear that could be due to abrasion. Conclusions: The analysis we conducted on the explanted THA showed a ductile rupture, began close to the upper surface of the prosthetic neck where the presence of many scratches had concentrated stresses and led to a fatigue fracture.

Quantification of trunnion damage in a series of intact total hip arthroplasty femoral stems previously identified to be at risk of catastrophic failure.

BACKGROUND: Corrosion at the head-neck junction of femoral stems is a rare complication of total hip arthroplasty (THA) with manifestations ranging from subclinical wear to failure. Prior studies have identified a single femoral component design with an increased propensity for catastrophic trunnion failure. The purpose of the present study was to quantify trunnion damage of this femoral component retrieved from patients undergoing revision THA for non-trunnionosis indications. METHODS: 24 femoral components from a single manufacturer were identified for study inclusion. Each prosthesis underwent stereomicroscopic inspection. Corrosion and fretting scores were assigned per the Goldberg criteria to quadrants of the trunnion. Material loss was calculated based on cone angles across trunnion quadrants. This was carried out using a coordinate measuring machine that digitised each trunnion surface. Stems were compared to a series of femoral stems with the same trunnion design. RESULTS: 20 of the 24 (83%) trunnions demonstrated corrosion, all 24 trunnions demonstrated fretting. Corrosion scores did not statistically differ with respect to trunnion zone (p = 0.53), while fretting scores were higher in the inferior compared to the superior zones (p < 0.001). There was no significant difference in cone angles assessing material loss between stems (p = 0.25). CONCLUSIONS: Evidence of trunnion damage was observed in each stem retrieved for non-trunnionosis revision. Fretting occurred more frequently about the inferior quadrants. However, digitised trunnion shapes were similar between compared stems exhibiting no material loss. Therefore, it is possible that previous reports of trunnion failures for this implant are not a systemic issue, and that further investigation is required.

Evaluation of Mechanically-Assisted Crevice Corrosion of Different Modular Dual Mobility Constructs.

BACKGROUND: Modular dual mobility (MDM) acetabular component use is rising in total hip arthroplasty. However, concern of mechanically assisted crevice corrosion (MACC) at the shell-liner interface remains. We investigated shell-liner corrosion using retrieval analyses and corrosion chamber testing. METHODS: We analyzed fretting and corrosion on 10 matched pairs of 2 commercial MDM constructs (MDM1 and MDM2). Also, pristine pairs of Ti6Al4V shells and CoCrMo liners from 3 commercial dual mobility systems (MDM1, MDM2, and MDM3) were tested in vitro to model MACC performance. Three pairs of each were placed into an electrochemical chamber with stepwise increasing cyclic compression loads while measuring currents generated at the shell-liner taper. Onset fretting loads and fretting currents were calculated. RESULTS: Corrosion damage scores on retrieved components were low but higher in the MDM2 to MDM1 liners (P = .006), specifically outside the taper region (P = .00003). Fretting currents were higher in the MDM2 than in MDM1 or MDM3 (P = .011). Onset loads were also higher in the MDM2 (P = .001). CONCLUSION: Among retrieved liners, MDM2 tapers seem prone to non-mechanical corrosion modes. Higher onset loads and fretting currents in MDM2 tapers indicate greater MACC resistance but higher severity once corrosion begins. Differences among the devices were likely due to taper design and surface finish. Currents in all 3 were <5 µA, much lower than those observed with head-neck tapers. Our findings suggest that, among the types of corrosion observed in these MDM designs, mechanically driven corrosion may not be the most significant.

Late Hematogenous Total Hip Infection After Revision for Mechanically Assisted Crevice Corrosion With Adverse Local Tissue Reaction.

Mechanically assisted crevice corrosion (MACC) at the trunnion-bore junction of a total hip arthroplasty may cause adverse local tissue reaction (ALTR) with inflammatory reaction and tissue necrosis. Complications, including acute infection, continued pain, and instability, are therefore common after a revision surgery for MACC. We now present 2 cases of late hematogenous bacterial infection years after revision for MACC and ALTR, a previously unreported outcome in this population. We hypothesize that MACC-induced tissue necrosis does not heal over time, and some patients with metal-on-polyethylene total hip arthroplasty treated for ALTR are at long-term risk of hematogenous bacterial infection.

Neurologic Dysfunction Associated With Mechanically Assisted Crevice Corrosion and Elevated Cobalt Ion Levels After Total Hip Arthroplasty.

Adverse local tissue reactions secondary to mechanically assisted crevice corrosion (MACC) at the trunnion is a complication of total hip arthroplasty known to cause local soft-tissue damage. However, what is not as well appreciated is that MACC in metal-on-polyethylene (MOP) articulations can lead to cobalt ion serum elevations with associated neurological dysfunction just as in metal-on-metal articulations. We report a compelling case for the association of neurologic dysfunction tied to metal ion elevations secondary to MACC at two distinct MOP tapers in a 58-year-old intensive care unit nurse with two hips implanted 3 years apart. This report further raises awareness about the potential of MACC-generated elevated ion levels to produce neurological symptoms that might otherwise be overlooked in patients with MOP articulations.

Outcomes Following Revision for Mechanically Assisted Crevice Corrosion in a Single Femoral Design.

BACKGROUND: Mechanically assisted crevice corrosion (MACC) is a described complication following metal-on-polyethylene (MoP) total hip arthroplasty (THA). The literature regarding outcomes following revision for MACC suggests that complication rates are high. The purpose of this investigation is to add to this literature with the largest reported series to date. METHODS: This is a retrospective cohort study of 552 consecutive patients who underwent 621 MoP primary THAs. We identified patients who subsequently underwent revision THA for a diagnosis of MACC. All patients were implanted with the same implant combination (Accolade I stem/cobalt-chromium low friction ion treatment femoral head). Patient demographic, surgical, and laboratory data were collected. Follow-up was calculated from the revision surgery and Hip Disability and Osteoarthritis Outcome Score Joint Replacement and hip subjective values (HSV) were examined at final follow-up. Descriptive statistics were performed. RESULTS: The revision rate for MACC was 11.6% and mean time to revision was 6.6 (±2.4) years. Revised patients (n = 69) had a mean preoperative serum cobalt-chromium ratio of 3.5 (±2.4). There were 8 cases of gross trunnion failure. At mean 3.2 (±1.9) years following revision, the overall major complication rate was 11.6% with a 5.8% reoperation rate. At final follow-up, mean Hip Disability and Osteoarthritis Outcome Score Joint Replacement scores were 83.2 (±15.6) and mean hip subjective value was 77.6 (±17.4). Revision resulted in significant increases in both parameters (P < .001). CONCLUSION: The incidence of MACC in MoP THA is likely higher than previously reported, particularly for certain implant combinations. Revision surgery for MACC can achieve good outcomes but a high clinical suspicion with early detection and revision is likely key to success.

"Off-label" Usage of an Oxidized Zirconium Femoral Head in Revision of a Total Hip Arthroplasty with Mechanically Assisted Crevice Corrosion and a Legacy Taper.

We present a case of a 72-year-old male with a history of a late 1980s metal-on-polyethylene total hip arthroplasty who presented with unilateral leg vascular compromise, joint pain, and stiffness and subsequently underwent revision for adverse local tissue reaction secondary to mechanically assisted crevice corrosion. His stable and extensively porous coated femoral implant had a legacy taper with no currently manufactured option for a non-Co-alloy femoral head. After shared decision-making with the patient, we opted to use an oxidized zirconium femoral head from another manufacturer with a similar taper during his revision surgery and documented that his vascular compromise resolved and his serum Co was undetectable 3 years after the revision.

Mechanically Assisted Crevice Corrosion in a Metal-on-Polyethylene Total Hip Presenting With Lower Extremity Vascular Compromise.

Mechanically assisted crevice corrosion in modular total hip replacements may lead to an adverse local tissue reaction (ALTR) with a variety of sequelae. Although an ALTR is most commonly recognized with metal-on-metal modular hip constructs, tribocorrosion at the head-neck junction of metal-on-polyethylene (MoP) total hip arthroplasties may also lead to an ALTR. We present a case of a 79-year-old woman with a history of MoP total hip arthroplasty who presented with unilateral leg swelling, joint pain, and stiffness and subsequently underwent revision for an ALTR secondary to mechanically assisted crevice corrosion. This unique case of lower extremity vascular compromise resulting from an ALTR is important because clinicians should consider corrosion-related ALTRs when treating patients with an MoP hip prosthesis presenting with new-onset lower extremity swelling.

Standardizing terms for tribocorrosion-associated adverse local tissue reaction in total hip arthroplasty.

Recognizing and adopting standardized terms for adverse local tissue reaction associated with tribocorrosion in total hip arthroplasty are essential for clear scientific discourse and clinical communication. Our goal was to develop terms that can be broadly applied to characterize the local tissue response to tribocorrosion debris, based on current evidence regarding the etiology of this failure mode and its consequences. The proposed standardized terms will improve the understanding and interpretation of analytical tests, advance diagnostic and treatment algorithms, and reduce confusion in research by maintaining consistent nomenclature.

Adverse Local Tissue Reaction due to Mechanically Assisted Crevice Corrosion Presenting as Late Instability Following Metal-on-Polyethylene Total Hip Arthroplasty.

BACKGROUND: Mechanically assisted crevice corrosion (MACC) at modular junctions can cause a spectrum of adverse local tissue reactions (ALTRs) in patients who have undergone total hip arthroplasty (THA). The purpose of this study is to describe the presentation, treatments, and related complications of a cohort of patients presenting with late instability following metal-on-polyethylene THA due to underlying MACC and ALTR. METHODS: This multicenter retrospective case series presents 17 patients (12 women, mean age 62.6, range 42-73) presenting with late instability secondary to ALTR and MACC. All patients had a metal (Cobalt Chrome)-on-polyethylene bearing surface. Patients experienced a mean 2.7 dislocations (range 1-6) at mean 4.3 years (range 0.4-17.0) following their index surgery. Serum metal levels (n = 12) demonstrated a greater elevation of cobalt (mean 6.9, range 0.13-20.88 ng/mL) than chromium (mean 1.9, range 0.13-3.23 ng/mL). RESULTS: Patients were revised for instability at a mean of 6.8 years (range 2.1-19.4) following their index surgery. ALTR was encountered in every case and the modular head-neck junction demonstrated visible corrosion. An exchange of the CoCr head to a ceramic head with a titanium sleeve and placement of a constrained liner was performed for a majority of patients (n = 15, 88.2%). Five patients (29.4%) had complications postoperatively including peroneal palsy (n = 2), periprosthetic joint infection (n = 2), and ALTR recurrence (n = 1). CONCLUSION: Recurrent instability in the setting of otherwise well-positioned THA components and without another obvious cause should raise concern for ALTR as a potential underlying etiology.

What the Surgeon Can Do to Reduce the Risk of Trunnionosis in Hip Arthroplasty: Recommendations from the Literature.

Trunnionosis, defined as wear and corrosion at the head-neck taper connection, is a cause of failure in hip arthroplasty. Trunnionosis is linked to a synergistic combination of factors related to the prosthesis, the patient, and the surgeon. This review presents analytical models that allow for the quantification of the impact of these factors, with the aim of providing practical recommendations to help surgeons minimize the occurrence of this failure mode. A tighter fit reduces micromotion and, consequently, fretting of the taper connection. The paramount parameters controlling the fixation force are the coefficient of friction and the impaction force. The influence of the head diameter, as well as of the diameter and angle of the taper, is comparatively small, but varus alignment of the taper and heads with longer necks are unfavourable under physiologic loads. The trunnion should be rinsed, cleaned, and dried carefully, while avoiding any contamination of the bore-the female counterpart within the head-prior to assembly. Biological debris, and even residual water, might critically reduce the fixation of the taper connection between the head and the neck. The impaction force applied to the components should correspond to at least two strong blows with a 500 g hammer, striking the head with an ad hoc impactor aligned with the axis of the taper. These strong blows should correspond to a minimum impaction force of 4000 N.

How to Interpret Metal Ions in THA.

BACKGROUND: Modern total hip arthroplasty has seen an unfortunate increase in proportional implant failures secondary to adverse local tissue reactions (ALTRs) secondary to wear of metal-on-metal (MoM) bearings and mechanically assisted crevice corrosion (MACC) related to corrosion at implant junctions and tapers. The purpose of this study is to describe the appropriate choice of metal ion testing and evaluation of those levels to identify failed total hip arthroplasty implants containing cobalt and chromium. METHODS: When presented with an arthroplasty of concern, the surgeon must determine what metal ion levels to obtain and then incorporate those levels into a treatment algorithm. Patients with painful hip arthroplasties are evaluated for chromium and cobalt by obtaining whole blood and synovial metal levels. RESULTS: Synovial fluid cobalt had the highest correlation with ALTR compared with the other tests, with a threshold of 19.75 ng/ml, with a specificity of 89%, if the cobalt-to-chromium ratio is greater than 1.4 ng/ml in a metal on polyethylene hip, with a sensitivity of 95%. CONCLUSION: The interpretation of whole blood metal ions is a key component of the algorithm in treating the symptomatic hip arthroplasty but is not to be used in a vacuum.

Taper Design, Head Material, and Manufacturer Affect the Onset of Fretting Under Simulated Corrosion Conditions.

BACKGROUND: We investigated the effect of taper design, head material, and manufacturer on simulated mechanically assisted crevice corrosion (MACC). METHODS: Six pristine C-taper stems coupled with alumina-zirconia or cobalt-chromium (CoCr) heads were tested in a mechanical/electrochemical setup to measure average fretting currents and fretting current onset loads. Outcomes were compared with previous data from V40 tapers from the same manufacturer and 12/14 tapers from another manufacturer. RESULTS: Within a single manufacturer, differences in average fretting current between V40 and C-taper designs were dependent on head material. Only with V40 tapers did CoCr heads show higher average fretting currents than ceramic heads. Between manufacturers, differences were found between similar taper designs, as 12/14 taper couples showed higher average fretting currents than C-taper couples, regardless of head material. CONCLUSION: Taper design, head material, and factors inherent to different manufacturers influence fretting current in simulated MACC. Unlike clinical and retrieval studies, this experimental design allows for investigations of factors affecting MACC in a controlled environment. Taper design, independent of manufacturer, contributes to the observed differences in average fretting current between head materials. In some taper designs, head composition, specifically ceramic, should not be considered alone to reduce risk of corrosion.

Metal-on-metal total hip arthroplasty adverse local tissue reaction with intermittent unilateral vascular claudication.

Osteolysis and adverse local soft-tissue reactions are well-documented complications of metal-on-metal prosthetic implants. This case report describes a 68-year-old man who presented to the clinic 10 years after staged bilateral metal-on-metal total hip arthroplasty revisions with the primary complaint of groin pain, intermittent right leg pain, swelling, and muscle cramping while ambulating that resolved with rest. A complete workup was negative for deep venous thrombosis and infection. His symptoms were found to be secondary to an iliopsoas bursal mass externally compressing the femoral vasculature resulting in vascular claudication. He was treated with revision arthroplasty and drainage of the fluid within the iliopsoas bursal effusion with symptomatic resolution.

Gross trunnion failure after a metal-on-polyethylene total hip arthroplasty leading to dissociation at the femoral head-trunnion interface.

Gross trunnion failure (GTF) leading to dissociation at the femoral head-trunnion interface is an uncommon complication after total hip arthroplasty (THA). The incidence of this complication is currently unknown due to the limited number of reported cases but it is significantly more common in the context of a recalled femoral head. This report details the case of a gross trunnion failure and secondary polyethylene failure of a non-recalled metal-on-polyethylene primary THA from a taper type previously reported to be associated with an increased prevalence of mechanically assisted crevice corrosion (MACC). This case describes a 77-year-old man who was 10 years status post right THA presenting with acute-onset right hip pain after trying to rise from a seated position. Radiographs showed that the right femoral head was dissociated from the femoral component. At the time of surgical revision, there was extensive dark metallic debris in the hip joint. A revision THA was performed using a modular revision system. Clinicians must be aware that MACC can eventually lead to GTF, which can result in dissociation at the femoral head-trunnion interface in metal-on-polyethylene primary THA. Further research is needed to determine patient and implant factors that make patients susceptible to MACC/GTF so that adequate screening and patient counseling can be performed.

Taper-Trunnion Interface Stress Varies Significantly With Head Size and Activity.

BACKGROUND: Total hip arthroplasty is performed with modular parts. Either a metal or ceramic ball is fastened to the trunnion of a femoral stem via a Morse taper. This implant scenario has been successful. However, recently larger (36 mm or greater) metal heads have become more popular as a means to reduce the incidence of hip joint dislocation. Today, a number of clinical failures have occurred due to mechanically assisted crevice corrosion at the head (taper) stem (trunnion) interface necessitating revision surgery. The objective of this research is to investigate how trunnion stress varies with head size, and how taper-trunnion geometric parameters including horizontal lever arm (HLA), taper engagement level, and a new parameter called trunnion load offset affect trunnion stresses. We hypothesized that trunnion stress may increase with increasing head size and HLA. METHODS: This hypothesis was tested by conducting finite element analysis of a titanium hip stem and 4 commercially available cobalt-chromium femoral heads subjected to 4 different moderate to severe physiological loading conditions. RESULTS: Results showed that trunnion stress increases with increasing head size, increased HLA, and trunnion load offset. It was also found that under certain load cases the trunnion stresses get exceptionally high, especially for the larger head sizes. CONCLUSION: This study suggests trying to avoid larger femoral head sizes that may result in higher implant stresses under certain loading conditions.

Effects of seating load magnitude and load orientation on seating mechanics in 5°40' mixed-alloy modular taper junctions.

BACKGROUND: Mechanically-assisted crevice corrosion of modular tapers continues to be a concern in total joint replacements. Surgical factors that may affect taper seating mechanics include seating load magnitude and load orientation. Seating mechanics is defined as the seating load versus displacement behavior. In this study, mixed-alloy (CoCrMo/Ti-6Al-4V) modular head-neck 5°40' taper junctions were seated over a range of axially-oriented loads and off-axis orientations, capturing load-displacement during seating. The goals of the study were to assess the effects of seating load magnitude and load orientation on seating mechanics and correlate those findings with the taper pull-off load. METHODS: A testing fixture measured head-neck seating displacement as the load was quasistatically applied. Motion was captured using two non-contact differential variable reluctance transducers which were mounted to the neck targeting the head. Seating experiments ranged from 1000 N to 8000 N. Load orientation ranged from 0° to 20° at 4000 N. RESULTS: Seating load-displacement behavior at different seating loads showed a consistent characteristic behavior. Testing demonstrated increased seating displacement with seating load. Pull-off loads increased with seating load and were approximately 44% of the seating load across the range of seating loads investigated. Seating load orientation up to 20° had no significant effect on seating displacement and taper pull-off load. CONCLUSION: Increased seating load magnitude increased seating displacement, work of seating and pull-off loads in mixed-alloy 5°40' head-neck tapers. Altering load orientation up to 20° off-axis had no significant effect. Direct measurements of seating mechanics provides insights into the locking of taper junctions.

A case of bilateral hip mechanically assisted crevice corrosion after staged total hip arthroplasty.

Mechanically assisted crevice corrosion (MACC), also known as trunnionosis, and adverse local tissue reaction (ALTR) are entities that can lead to pain and necessitate revision in total hip arthroplasty (THA). We present a case of a 75-year-old female who received a bilateral staged primary THA with metal on cross-linked polyethylene implants and had subsequent bilateral revisions for MACC and ALTR. In both instances, she presented with anterior thigh pain, weakness, and difficulty ambulating, and she was revised to ceramic on cross-linked polyethylene implants. This case may suggest a biologic predisposition or systemic immunogenic reaction to metal debris in some patients with ALTR or represent an implant-specific complication. To our knowledge, this is the first case reported of a patient having bilateral MACC from staged THA performed by 2 different surgeons using the same brand implant.

Effects of Seating Load Magnitude on Incremental Cyclic Fretting Corrosion in 5°40' Mixed Alloy Modular Taper Junctions.

BACKGROUND: Mechanically assisted crevice corrosion of modular tapers continues to be a concern in total joint arthroplasties. A surgical factor that may affect taper fretting corrosion during cyclic loading is seating load magnitude. In this study, modular head-neck taper junctions were seated, capturing load-displacement, over a range of axially oriented loads, and electrochemical and micromotion data were captured during short-term incremental cyclic fretting corrosion (ICFC) tests. The hypothesis is low seating loads result in greater motion and fretting corrosion in ICFC tests. The effect of assembly load on pull-off force post-ICFC testing was also evaluated. METHODS: The study employed custom-built test fixtures which measured head-neck micromotion and an electrochemical chamber to monitor electrochemical reactions. Head-neck motion measurements were captured using 2 noncontact differential variable reluctance transducers mounted to the head. Seating experiments ranged from 1000 to 8000 N. RESULTS: Significant differences due to seating loads were reported in seating displacement, ICFC subsidence, and fretting current at 4000 N cyclic load. Seating load decreased but did not eliminate currents. Fretting onset load remained fixed (approximately 1200 N) for tapers seated above 2000 N. Fretting subsidence was negligible for seating loads of 4000 N or higher, and increased subsidence was observed below 4000 N. CONCLUSION: This short-term test method evaluated the acute performance of modular implants which were assembled under various loads and demonstrated the link between seating loads, fretting motions, and electrochemical reactions. While increased seating loads reduced fretting corrosion and taper subsidence, it did not prevent fretting corrosion even at 8 kN seating.