Metallosis following hip arthroplasty: two case reports

Osteoarthritic Human Synovial Fluid Alters CoCrMo Electrochemical Properties on a Patient-Specific Basis

Cobalt-chromium-molybdenum (CoCrMo) femoral components are widely used in total knee arthroplasty (TKA). However, recent retrospective clinical trials associate moderate adverse local tissue reactions with CoCrMo release in the knee. Additionally, gaps persist in our understanding of the fundamental corrosion processes that occur at the CoCrMo-synovial fluid interface. In this study, we investigated the electrochemical behavior of CoCrMo in human synovial fluid obtained at the time of primary TKA, using CoCrMo in phosphate-buffered saline (PBS) as a comparison. Synovial fluid was collected from 118 patients immediately before arthroplasty, then transferred to a three-electrode electrochemical cell with a wrought CoCrMo alloy working electrode. To quantify electrochemical properties, open circuit potential (OCP), electrochemical impedance spectroscopy, and linear polarization tests were run. Generally, the properties varied on a patient-by-patient basis and significantly differed (p < 0.05) from comparison tests performed in PBS. In human synovial fluid, we measured OCPs between a range of -0.38 and 0.15 V and corrosion potentials (Ecorr) between -0.95 and -0.2 V. Additionally, we reported instantaneous corrosion rates (1/Rp) spanning nearly four orders of magnitude. The variability we documented suggested that the electrochemical properties of CoCrMo implants may depend on the patient's local physiological environment, influenced by the biological and chemical components of synovial fluid. Statement of Clinical Significance: This study shows that human synovial fluid affects the electrochemical behavior of CoCrMo, evidenced by the variation on a patient-by-patient basis. This study may have implications for long-term biological response to orthopaedic implants, including total knee arthroplasty.

Are We Ready for Pseudotumors in Total Ankle Arthroplasty? A Case Report

Background: Pseudotumors are defined as exuberant non-neoplastic inflammatory masses. This condition can be associated with hip and knee arthroplasty but has not been reported in Total Ankle Arthroplasty (TAA). This paper reports a pseudotumor that formed following TAA, highlighting its clinical presentation, management, and histopathology. Methods: A 55-year-old male with end-stage post-traumatic ankle osteoarthritis underwent TAA using a mobile-bearing prosthesis. The procedure was reported to be successful, with no immediate complications. Results: Three years postoperatively, following a period of symptom resolution, the patient presented with progressively worsening ankle pain, swelling, and limited weight-bearing ability. Imaging revealed indirect signs of a periarticular mass and loosening components. Revision surgery involved prosthesis explantation and mass excision for histological and microbiological analysis, followed by concomitant tibio-talo-calcaneal fusion with a retrograde nail. The histopathology identified a pseudotumor characterized by chronic inflammation, fibrous tissue, and necrotic debris, with no evidence of infection. The postoperative recovery was uneventful, with pain resolution and successful fusion confirmed at a one-year follow-up. Conclusions: In patients experiencing unexplained pain or symptoms following TAA, the possibility of a pseudotumor, although rare, should be considered. Prompt and comprehensive clinical and radiographic evaluation is crucial to raise suspicion and prevent this condition from being overlooked.

Association between metallic implants and stroke in US adults from NHANES 2015-2023 a cross-sectional study

Objective

Metal implants play a vital role in orthopedic treatment and are widely used in fracture repair, joint replacement and spinal surgery. Although these implants often contain key elements such as chromium (Cr), their potential health effects, particularly their association with stroke risk, have not been fully elucidated. This study aimed to evaluate the association between metallic implants and stroke.

Methods

Using data from the 2015 to 2023 National Health and Nutrition Examination Survey (NHANES), we conducted a cross-sectional analysis of 12,337 US adults, in which 3,699 participants reported having metal implants and 8,638 without. Implant-like.

Results

Through logistic regression analysis, we revealed a significant positive association between metallic implants and stroke risk (adjusted OR = 1.458, 95%CI (1.130, 1.881), p = 0.004). Further stratified analysis found that this positive association was more significant among older and less physically active participants.

Conclusion

Findings suggest that metallic implants may be associated with an increased risk of stroke, but given the inherent limitations of cross-sectional studies, this study cannot establish causality.

Blood Metal Ion Levels After Hip Resurfacing: A Comparison of 2 Different Implants

Background

While hip resurfacing arthroplasty has been shown to be an effective prosthetic solution for end-stage osteoarthritis, prior studies have also reported an increasing concern regarding blood metal ion levels following the use of metal-on-metal articulations. The purpose of this study was to compare early and midterm blood metal ion levels to functional outcomes and implant survivorship for patients treated with the Birmingham Hip Resurfacing (BHR) implant system and the ReCap Magnum.

Methods

A retrospective review identified 104 patients who underwent 134 hip resurfacing arthroplasties using BHR (n = 67) and ReCap (n = 67) at a single institution between 2006 and 2018. ReCap and BHR patients were matched 1:1 by sex, femoral head and acetabular cup sizes, age, and year of surgery. The primary outcome of interest was cobalt (Co) and chromium (Cr) ion levels.

Results

The ReCap cohort had lower median metal ion levels compared to the BHR cohort at 1-2 y (Co: 1.5 vs 1.9 parts per billion [ppb], P = .018; Cr: 1.3 vs 2.8 ppb, P = .008) and 3-5 y (Co: 1.1 vs 1.9 ppb, P = .001; Cr: 1.2 vs 2.2 ppb, P = .003) after surgery. Correlation analysis showed no significant associations between Co and Cr ion levels and pre- and postoperative patient-reported outcomes. Indications for revision differed between groups. Three BHR hips were revised due to adverse reactions to metal debris, whereas 2 ReCap hips required revisions: one for instability and another for periprosthetic fracture.

Conclusions

BHR patients had higher metal ion levels than ReCap patients at 1-2 and 3-5 y after surgery, though these metal levels are still low and in line with prior studies. Indications for revision differed between patients treated with BHR and ReCap. Surgeons should be aware of these outcomes when counseling patients regarding these metal-on-metal articulations.

The role of femoral head size in metal-on-metal hip arthroplasty: analysis of a cohort of 3813 patients with long term follow-up

Metal-on-metal (MoM) large headed arthroplasties were suggested to decrease failure rates by means of reduced volumetric wear and enhanced implant stability. However, they caused high rates of revisions due to adverse reaction to metal debris, osteolysis, pseudotumor growth, and other issues. The study aims to present the long-term outcomes of MoM arthroplasties on a large cohort of patients, evaluating the impact of head sizes on survival rate. All data were retrieved from the regional joint register (Registro dell'Implantologia Protesica Ortopedica, RIPO, Italy). We include in the study all patient who underwent cementless MoM total hip arthroplasties (THAs) between 2000 and 2020, dividing them in two subgroups according to head size (<36 mm, ≥36 mm). Failures were recorded up to December 31, 2020. Patients lost to follow-up were excluded. A total of 3813 THAs met the inclusion/exclusion criteria. The average follow-up period is 12.4 years (0-21 years). 178/1625 (or 11.0%) small head MoM THAs and 265/2188 large head ones failed by the end of follow up. Large diameter heads reported lower survival rate (p-value < 0.001), with unexpected higher dislocation rate (1.0 vs. 0.4%). Moreover, large head size was found to increases the risk of metallosis (p-value < 0.0001). Gender, patient's age and the use of modular neck were not correlated with higher failure rates. MoM implants implants do not have the same reliability as other couplings, considering the significantly greater failure/complication rates. However, the knowledge of risks linked to head size is fundamental for establishing the right type of follow-up to the patient and recognize any complications early.

Severe metallosis following catastrophic failure of total shoulder arthroplasty - a case report

Metallosis is an unusual but consequential complication arising from orthopedic hardware implantation, characterized by the deposition of metallic particles in the periprosthetic soft tissues. The incidence of metallosis associated with shoulder arthroplasties is exceptionally rare since the shoulder is not a weight-bearing joint, making it less susceptible to mechanical wear and, consequently, to conditions like particle disease and metallosis. Nevertheless, anomalous metal-on-metal interactions can develop in total shoulder arthroplasties if the polyethylene component fails due to wear, fracture, or dissociation. If left unaddressed, metallosis can incite an adverse immune-mediated local tissue response, culminating in joint destruction and adjacent soft tissues and muscle necrosis. In this case report, the diagnosis of metallosis was made in a patient with an anatomic total shoulder arthroplasty using a state-of-the-art photon counting detector CT supplemented by post-processing metal artifact reduction algorithms. This advanced imaging approach was effective in discerning the source of implant failure and in identifying manifestations of severe metallosis including osteolysis and pseudotumor formation. Advanced imaging methods can accurately characterize the severity and extent of metallosis, thereby helping guide surgical planning to mitigate serious complications associated with this condition.

Metallosis Following Non-Metal-on-Metal Hip Arthroplasty: A Case Report and Review

Introduction

Metallosis which is traditionally associated with Metal-on-Metal (MoM) hip arthroplasty can occur with other bearing surfaces too, posing diagnostic challenges. They can be asymptomatic or present with local and systemic symptoms. This article reports a case of metallosis in a total hip replacement (THR) with metal on polyethylene (PE) articulation who presented with dislocation. It also reviews the pathology and various presentations of metallosis following hip arthroplasty.

Case Report

A 35-year-old female patient presented 4 years after a left THR with recurrent dislocation. It was an uncemented prosthesis with metal on PE articulation. Serology and radiological investigations were done to evaluate for infection, implant loosening, implant malposition, etc. The femoral stem appeared to be in varus malposition. She was posted for revision surgery with a pre-operative plan to change the femoral stem and head if necessary. Intraoperative signs of local metallosis were noticed. Debridement was done along with the change of the femoral stem and bearing surface to ceramic on PE. Metallosis was also later confirmed by the histopathological report. The patient has been symptom-free during the 2-year follow-up period.

Conclusion

Metallosis can occur even in non-MoM articulations and a high degree of clinical suspicion is required to detect the same preoperatively. Classical signs of metallosis can often be absent in the early disease and subtle signs of instability must be looked out for even in the absence of obvious misalignment in radiographic assessment. Metallosis when combined with malposition or malalignment can be more detrimental. If detected early before osteolysis and periarticular soft tissue damage sets in, a complete revision of all the implant components and abductor damage can be avoided. In suspected cases, a lower threshold should be adopted for sending blood and joint aspirates for cobalt-chromium levels.

ACR Appropriateness Criteria® Imaging After Total Hip Arthroplasty

This article reviews evidence for performing various imaging studies in patients with total hip prostheses. Routine follow-up is generally performed with radiography. Radiographs are also usually the initial imaging modality for patients with symptoms related to the prosthesis. Following acute injury with pain, noncontrast CT may add information to radiographic examination regarding the presence and location of a fracture, component stability, and bone stock. Image-guided joint aspiration, noncontrast MRI, and white blood cell scan and sulfur colloid scan of the hip, are usually appropriate studies for patients suspected of having periprosthetic infection. For evaluation of component loosening, wear, and/or osteolysis, noncontrast CT or MRI are usually appropriate studies. Noncontrast MRI is usually appropriate for identifying adverse reaction to metal debris related to metal-on-metal articulations. For assessing patients after hip arthroplasty, who have trochanteric pain and nondiagnostic radiographs, ultrasound, or MRI are usually appropriate studies. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.