Severe metallosis after unicompartmental knee arthroplasty

Wear and corrosion of titanium alloy spinal implants in vivo

To investigate the wear and corrosion of titanium alloy spinal implants in vivo, we evaluated removed implants and their surrounding scar tissues from 27 patients between May 2019 and April 2021. We performed scanning electron microscopy, energy-dispersive X-ray spectroscopy, and histological analysis. The results revealed metal-like particles in the soft tissues of seven patients, without any considerable increase in inflammatory cell infiltration. Patients with fractures showed lower percentages of wear and corrosion compared with other patients (42% and 17% vs. 59% and 26%). Polyaxial screws exhibited higher wear and corrosion percentages (53% and 23%) compared with uniaxial screws (39% and 3%), although in patients with fracture, the reverse was observed (20% and 0% vs. 39% and 3%). We found that titanium alloy spinal implants experience some degree of wear and corrosion in vivo. The titanium alloy particles formed by wear exhibited good histocompatibility, not causing inflammation, foreign body reactions, or osteolysis. Therefore, spinal implants should be removed cautiously when treating titanium alloy spinal metallosis. The wear and corrosion of the implants increase with the increase in implantation time, although the screw structure does not significantly affect these changes.

Unicompartimental knee arthroplasty metallosis treated with uni-on-uni revision: A case report

BACKGROUND

Metallosis is the result of metallic wear debris in the soft tissues and is associated to both local and systemic inflammatory response. Metallosis has been reported after total hip and total knee arthroplasty (TKA), but rarely after a unicompartimental knee arthroplasty (UKA). In the context of UKA metallosis, surgeons often opt for revision using a TKA. However, in this paper, the authors successfully treated UKA revising the metal back only.

CASE SUMMARY

Prior to treat our patient we conducted a literature research through which we identified eleven cases of metallosis after UKA, ten (90.9%) were treated revising using though a TKA. Only one case was managed through a uni-on-uni revision, reporting high knee function. Our patient complained worsening pain and function after a snap occurred at 16 mo after UKA implantation. At 18 mo following surgical debridment and uni-on-uni revision surgery, our patient exhibited a relevant improvement in Oxford Knee Score and a reduction of metal ion levels in the blood.

CONCLUSION

Our study highlights that in case of metallosis after UKA, the treatment may be based on surgical debridement and just revising the mobilized components.

Metallosis and Nonunion: A Case Series and Literature Review

Metallosis, defined as the presence of free metal particles in the tissue, including bone and soft tissue, is a rare phenomenon seen in orthopedic practice. It is more commonly seen in arthroplasty surgeries, but its occurrence in the presence of other metal implants is also well recognized. Multiple hypotheses are suggested to explain the genesis of metallosis, but it is traditionally believed that abnormal contact between the metal surfaces leads to abrasive wear causing the release of metal particles into the surrounding tissue eliciting foreign body reactions from the body's immune system. The consequences can be local effects, which can be asymptomatic soft tissue lesions, or lead to significant osteolysis, tissue necrosis, joint effusion, and large soft tissue masses, causing secondary pathological effects. The systemic distribution of these metal particles can also contribute to the clinical picture. The literature contains multiple case reports of metallosis following arthroplasty surgeries, but there is limited information on metallosis resulting from osteosynthesis of fractures. In this review, we are presenting our experience with a few patients who developed nonunion following the index surgeries and on revision were found to have metallosis as well. It is difficult to postulate whether metallosis was contributory to the nonunion or the other way around or whether the occurrence of nonunion in face of metallosis was a pure coincidence. Additionally, one of our patients had a positive intraoperative culture, further complicating the picture. In addition to the case series, we present a succinct review of the literature on metallosis found in previous studies.

Chronic Wear-Induced Bearing Dislocation in a Fixed-Bearing Unicompartmental Knee Arthroplasty: A Case Report

Case

We present a case of late onset, bearing wear-induced failure of locking mechanism, resulting in bearing dislocation and rapidly progressive severe metallosis in a medial fixed-bearing (FB) unicompartmental knee arthroplasty (UKA).

Conclusion

Bearing dislocation is a rare complication of chronic wear in FB UKA, and early recognition is essential to prevent metallic component articulation-induced metallosis and catastrophic failure.

Fatal vascular complication due to metallosis

Metallosis is a well-known complication at the site of total hip and knee arthroplasty. Vascular involvement of this complication is rare and generally results from vascular compression by a mass or pseudotumor. In the present report, we have described a case of lower limb acute arterial ischemia due to arterial injury as a complication of metallosis with a fatal outcome.

Metallosis after knee replacement: a review

INTRODUCTION

Although metallosis is a well-known complication after total hip arthroplasty, little is known about this phenomenon after total (TKA) or unicompartmental knee arthroplasty (UKA). The aim of the present work was to review the current knowledge about the reasons and the diagnostic as well as therapeutic management of metallosis after knee arthroplasty.

MATERIALS AND METHODS

A literature search was performed through PubMed until April 2019. Search terms were "metallosis" in combination with "knee", "knee prosthesis", "knee arthroplasty" and "knee replacement", respectively. All publications were analyzed regarding publication year, level of evidence, number of knees/patients treated, type of prosthesis, metallosis cause, time period between primary implantation and metallosis emergence, laboratory examination, treatment, complications and follow up.

RESULTS

A total of 38 studies reporting on a total of 97 knees were identified. 29 studies reported on metallosis after TKA, 8 after UKA, and one study after both procedures. The time period between the primary implantation and metallosis emergence ranged between 6 weeks and 26 years. The most common reason was the failure of a metal-backed patellar component in 40%, followed by implant/structural- and PE failure (wear/dislocation) in 27% and 18% of the cases, respectively. Complete blood cell count, serum chemistry, erythrocyte sedimentation rate or C-reactive protein serum values were not indicative to diagnose metallosis. The diagnosis was confirmed by histopathological analyses and macroscopic evaluation during surgery. Depending on the particular cause various surgical procedures have been performed. Complete prosthesis exchange was the most common one showing no complications in 89.4% of the cases.

CONCLUSIONS

Metallosis after knee arthroplasty is a rare and perhaps underestimated or under published complication. A systematic diagnostic approach is necessary for the timely and correct diagnosis. A thorough debridement as well as a (sub)total synovectomy should be always performed. In cases with a damaged component, a partial/complete prosthesis exchange leads to the best results. Should a malalignment be the cause of the metallosis, then it should be corrected within the revision surgery.

Severe metallosis-related osteolysis as a cause of failure after total knee replacement

BACKGROUND

Metallosis is a syndrome of metal-induced synovitis caused by friction between two metal surfaces. In contrast to the hip joint after resurfacing arthroplasty or metal-on-metal (MoM) total hip replacement, metallosis of the knee is extremely rare.

MATERIALS

We describe 4 patients who underwent revision total knee replacement because of disabling pain and implant loosening after a mean time of 21 (range: 13-30) years of knee replacement surgery. They were all females with a mean age of 79 (range: 75-82) years. Septic loosening was excluded through microbiological examination and synovial fluid analysis.

RESULTS

Direct metal-on-metal contact at the tibiofemoral interface was confirmed intraoperatively in all cases. All knees showed severe metallosis with advanced osteolysis and pseudotumor formation. In one knee there was a complete fracture of the tibial tray. All patients had a one-stage revision surgery with implant removal, profound synovectomy and implantation of a constrained modular revision knee system. Long modular stems with offset adapters, wedges and/or blocks were used in all cases.

CONCLUSION

Metallosis-associated osteolysis should be suspected in cases with radiologically evident polyethylene wear after knee replacement. Recognizing that revision arthroplasty is very technically demanding in such cases, surgeons should have a back-up with modular revision components and a ready access to reconstructive options at this revision setting.

Rupture of the femoral component and severe metallosis of the knee 10 years after unicompartmental knee arthroplasty (UKA): a case report

A case of a 71-year-old man with femoral and tibial osteolysis and severe metallosis of the knee, resulting from abrasive wears of the metal components of a unicompartmental knee arthroplasty, that leaded to the rupture of the femoral component of the prosthesis is reported. An unicompartmental prosthesis, in a varus knee, was implanted in 2007. In March 2017, the patient felt that his knee was becoming increasingly unstable with pain and increasing disability. At clinical evaluation there was an effusion, 110° of flexion and – 10° of extension and a slight instability at the varus/valgus stress tests. BMI was 35. In a CT scan performed in June 2017 no signs of alteration were evident, but an X-Ray performed in January 2018 showed a rupture of the femoral component. A revision surgery was performed in February 2018. At the time of revision surgery, the synovitis and the metallosis were evident. A cemented total knee arthroplasty was performed. Samples of the fluid and surface did not show any bacterial growth. Histological examination confirmed the presence of a massive metallosis. The patient had a satisfactory rehabilitation. According to the literature, metallosis and rupture of the prosthetic components due to polyethylene wear after UKA is a common complication. In our case report the elevated BMI and varus knee accelerated the wear of the polyethylene. The aim of this case report is to enhance how an appropriate diagnosis (clinical and radiographic) and early treatment can lead to a successful result. (www.actabiomedica.it)

Metallosis in cemented titanium alloy total knee arthroplasty without apparent metal-on-metal articulation

BACKGROUND

Metallosis is an uncommon phenomenon observed in late failures of cemented total knee arthroplasty (TKA), and it is rarely seen in the absence of metal-on-metal articulation.

METHODS

We report the case of a TKA patient with cemented titanium-alloy components and a polyethylene patella that was revised for early loosening with intra-operative severe metallosis.

RESULTS

We found that loosening and severe metallosis were associated with methacrylate particle abrasion on titanium alloy surfaces.

CONCLUSION

Serum titanium ion level measurement may be helpful in the workup of a painful TKA with titanium-alloy components in order to establish a diagnosis.

Early failure with massive metallosis and posteromedial wear following atraumatic anterior cruciate ligament rupture after medial unicompartmental knee arthroplasty

Severe metallosis following medial unicompartmental knee arthroplasty (UKA) is relatively rare. It is usually due to long-standing wear of the polyethylene component, resulting in frictional wear between the femoral and tibial metallic components. Biomechanical and cadaveric studies have shown the effects of anterior cruciate ligament (ACL) transection following medial UKA. We describe a case of a 58-year-old male who developed attritional rupture of the ACL 16 months following medial UKA leading on to early accelerated failure over the next 8 months. The patient underwent revision to total knee arthroplasty with good outcome. The clinical effect of spontaneous ACL transection on medial UKA causing abnormal posteromedial wear of polyethylene component and tibial tray, massive metallosis, and worsening of mechanical axis can be demonstrated in this case report.

Metallosis with pseudotumour formation: Long-term complication following cementless total hip replacement in a dog

CASE DESCRIPTION

A 10-year-old female Belgian Teruven dog was presented to our clinic for total hip revision following a diagnosis of implant (cup) failure with metallosis and abdominal pseudotumour formation. The patient had a cementless metal-on-polyethylene total hip replacement performed nine years prior to presentation.

CLINICAL FINDINGS

The clinical findings, including pseudotumour formation locally and at sites distant from the implant and pain associated with the joint replacement, were similar to those described in human patients with this condition. Histopathological, surgical, and radiographic findings additionally supported the diagnosis of metallosis and pseudotumour formation.

TREATMENT AND OUTCOME

Distant site pseudotumours were surgically removed and the total hip replacement was explanted due to poor bone quality. The patient recovered uneventfully and has since resumed normal activity.

CONCLUSION

In veterinary patients with metal-on-polyethylene total hip implants, cup failure leading to metallosis and pseudotumour formation should be considered as a potential cause of ipsilateral hindlimb lameness, intra-pelvic abdominal tumours, or a combination of both. These clinical findings may occur years after total hip replacement surgery.

Metallosis: CT findings in a total hip arthroplasty

We report a case of a 50-year-old man with extensive metallosis 20 years after right total hip arthroplasty. CT demonstrated osteolysis and radiodense debris surrounding the right hip joint. Although the radiographic appearance of metallosis has been well documented in the literature, the CT appearance of metallosis after total hip arthroplasty has been only sparsely described.

Serum metal ion concentrations in paediatric patients following total knee arthroplasty using megaprostheses

The purpose of this study was to determine the concentrations of cobalt, chromium, and molybdenum in the serum of paediatric tumour patients after fixed hinge total knee arthroplasty. Further, these metal ion levels were compared with serum metal ion levels of patients with other orthopaedic devices such as hip and knee prostheses with metal-on-metal or metal-on-polyethylene articulation to find differences between anatomical locations, abrasion characteristics, and bearing surfaces. After an average follow-up of 108 months (range: 67 to 163) of 11 paediatric patients with fixed hinge total knee arthroplasty, the mean concentrations for Co and Cr were significantly increased while Mo was within the limits compared to the upper values from the reference laboratory. Furthermore, these serum concentrations were significantly higher compared to patients with a standard rotating hinge device (P = 0.002 and P < 0.001) and preoperative controls (P < 0.001). On the other hand, the serum levels of patients following MoM THA or rotating hinge arthroplasty using megaprostheses were higher. Therefore, periodic long-term follow-ups are recommended due to the rising concerns about systemic metal ion exposure in the literature. Upon the occurrence of adverse reactions to metal debris the revision of the fixed hinge implant should be considered.

Severe metallosis following total knee arthroplasty: a case report and review of radiographic signs

Metallosis is an uncommon complication following total knee arthroplasty that leads to osteolysis and implant loosening due to chronic inflammatory reaction. Abrasion between the metallic surfaces of the implant releases metallic debris that interacts with the periprosthetic soft tissues and causes chronic synovitis. Here we present a case of a 65-year-old man who had undergone total knee arthroplasty 10 years ago and developed implant loosening associated with severe metallosis and varus instability. Radiographs show the three typical signs of metallosis: metal-line sign, bubble sign, and cloud sign. This patient was subjected to revision surgery consisting of debridement and primary implant replacement by a hinged endoprosthesis. Knowledge of the typical radiographic and clinical findings of metallosis is important to rapidly diagnose this complication and avoid progressive joint destruction.

Metallosis following Knee Arthroplasty: A Histological and Immunohistochemical Study

Metallosis represents a rare and severe complication of knee replacement surgery. It is caused by the infiltration and accumulation of metallic debris into the peri-prosthetic structures, deriving from friction between metallic prosthetic components. In knee arthroplasty, this event generally occurs as a result of polyethylene wear of the tibial or metal-back patellar component. The real incidence of metallosis is still unknown, although it seems to be more frequent in hip than in knee arthroplasty. The metallic debris induces a massive release of cytokines from inflammatory cells, making a revision necessary whenever osteolysis and loosening of the prosthesis occur. We report four patients who underwent revision of their knee arthroplasty because of severe metallosis. In one of these patients, polyethylene wear had determined friction between the metal-back patellar component and the anterior portion of the femoral component. In the remaining three cases, metallosis was caused by friction between the femoral and tibial prosthetic metal surfaces, resulting from full-thickness wear of the tibial polyethylene. T lymphocytes were activated by metal particles present in periprosthetic membranes. In all patients, one-stage revision was necessary, with rapid pain disappearance and a complete functional recovery of the knee joint.

Scientific evidence for the use of modern unicompartmental knee arthroplasty

Unicompartmental knee arthroplasty as a surgical treatment for monocompartmental knee arthritis remains a controversial procedure with questions surrounding the benefits and survivorship of the procedure versus osteotomies or total knee arthroplasties. The authors, by examining the complete body of literature for scientific evidence concerning the procedure, will describe the history of usage of these prostheses, their rationale for usage, modern devices and their results, and why they may have advantages as a treatment modality for monocompartmental knee arthritis. Outcomes of current unicompartmental designs will be presented and evaluated to determine which aspects of the design and patient selection technique are associated with success or failure. Commonly asked questions regarding the use of these devices will be addressed. The authors will also describe some potential modifications that might affect the use of these components in the future, including minimally invasive procedures and robotics, and how these devices may change over the next 5 years.

The immediate effect of navigation on implant accuracy in primary mini-invasive unicompartmental knee arthroplasty

The success of unicompartmental knee arthroplasty (UKA) is highly dependent on the accuracy of the component alignment. Objective of the present study was to evaluate the immediate effect of image-free computer navigation technology on implant accuracy in primary mini-invasive UKA. This study reviews 40 patients with primary isolated arthritis of the medial compartment of the knee that underwent unicompartmental knee arthroplasty through a minimally invasive approach. A cohort of the 20 most recent consecutive UKA's implanted with standard instrumentation was followed by a cohort of the very first 20 consecutive cases after conversion to the navigated technique. There was no variability regarding implant (Oxford meniscal unicompartmental knee system--Biomet Orthopedics, Inc., Warsaw, Indiana 46580, USA), surgeons and surgical technique, except for the use of the navigation system (Treon plus--Medtronic Inc., Minnesota, MI, USA). The axis alignment and accuracy of implant positioning was measured on postoperative long-leg standing radiographs and standard lateral X-rays with regard to the valgus angle and the coronal and sagittal component angle. In addition, preoperative deformities of the mechanical leg axis, tourniquet time, age, gender, and body mass index were correlated. Statistical analyses were performed using the SPSS 14.0 (SPSS Inc., Chicago, IL, USA) software package. Optimal implant alignment including all measurements in the desired angular range was significantly (P=0.041) higher in the navigated cohort. Navigation eliminated outliers in the frontal mechanical alignment and coronal orientation of the femoral component totally and significantly (P<0.02). Furthermore, navigation narrowed the range of outliers in all other planes of component orientation. There were no statistically significant differences in the mean numerical values between the cohorts, except for the frontal mechanical alignment (P<0.009) and coronal tibial alignment (P<0.037). The average tourniquet time was increased by 10.95 min in the navigated cohort. Our results indicate that navigation immediately improves accuracy of bone cuts and reduces the number of outliers with implementation in UKA.

The imaging appearances of metallosis

Metallosis is an uncommon condition in which there is infiltration of periprosthetic soft tissues and bone by metallic debris resulting from wear of joint arthroplasties. It is often associated with significant osteolysis; therefore the identification of metallosis is an indication for revision arthroplasty. The radiographic, CT and MRI features of metallosis in a 63-year-old man who presented 16 years post-arthroplasty are described in this case report.