Pseudotumor Formation Research Articles

Pseudotumor formation following large-diameter metal-on-metal total hip arthroplasty—Report of two cases and literature review

Pseudotumor after metal-on-metal total hip arthroplasty is an increasingly frequent complication in Taiwan. Orthopedic surgeons should be aware of this complication and follow up their patients regularly so that the disease can be detected early and properly managed. We report two cases of this complication. Case 1 exhibited cystic change with fluid accumulation, and in Case 2 a semisolid mass was found. In Case 1, a high inclination angle of the cup (at 65°) was noted. In Case 2, the cup was placed at a normal inclination angle, but it was too anteverted (31°). The histopathological studies revealed that the cystic pseudotumor had more diffuse lymphocyte infiltration and perivascular lymphocyte cuffing with eosinophil and plasma cells. The semisolid mass of Case 2 had less lymphocyte infiltration. Both cases had metal debris with foreign body granuloma. In patients with residual groin pain and a palpable mass after surgery, the possibility of pseudotumor formation should be considered. Various imaging techniques, such as ultrasound, computed tomography scan, and magnetic resonance imaging, can be used to confirm the presence of such lesions. Revision with nonmetal-on-metal articulation is suggested to relieve the symptoms.

Viral Gastritis in Granulomatosis with Polyangiitis

Purpose: A 62-year-old Hispanic female with past medical history of granulomatosis with polyangiitis (Wegener's) was evaluated for chronic anemia. Review of symptoms was negative for diarrhea, nausea, vomiting, abdominal pain, melena or hematochezia. Her medications included prednisone 20 mg and cyclophosphamide 50 mg. Physical exam was remarkable for pallor, normal oropharynx and negative for lymphadenopathy. Abdomen was soft, non-tender, non-distended, with normal bowel sounds. Pertinent laboratory data included hemoglobin (7.9 g/dL), and serum albumin 3.1 gm/dL. Iron studies were consistent with anemia of chronic disease. Colonoscopy was significant only for diverticulosis. Esophagogastroduodenoscopy (EGD) revealed multiple erosions in the gastric antrum along with small non-bleeding clean based ulcer (Forrest class III). Biopsy of the gastric antrum showed intra-nuclear inclusions bodies (“owl's eye”) with positive immune staining for Cytomegalovirus (CMV) antigen, pathognomonic for CMV gastritis. Patient received intravenous ganciclovir treatment for one week followed by one week of oral valganciclovir, which was curative as confirmed by negative CMV serology. There have been reported cases of symptomatic CMV gastritis. However, we present a rare case of CMV gastritis in an asymptomatic patient with history of granulomatosis with polyangiitis. Symptoms usually include nausea, vomiting, dysphagia, odynophagia, abdominal pain, tenesmus and hematochezia. It frequently affects immune-compromised patients with Human Immunodeficiency Virus, malignancy, organ transplant recipients, those on immunosuppressive medications or long standing steroid therapy. CMV infection of the gastrointestinal tract commonly involves the esophagus, stomach and colon. The endoscopic findings of CMV infection are variable from simple erosion, ulceration to pseudo-tumor formation. In patients with persistent immune deficiency such as granulomatosis with polyangiitis, endoscopic evaluation is a reasonable approach to prevent potential serious complications such as gastrointestinal hemorrhage, progressive intestinal disease and death.Figure

High Prevalence of Pseudotumors in Patients with a Birmingham Hip Resurfacing Prosthesis

Recently, concern has emerged about pseudotumors (lesions that are neither malignant nor infective in the soft tissues surrounding total hip arthroplasty components) after hip arthroplasties with metal-on-metal bearings. Patients treated in our hospital for degenerative arthritis of the hip with a Birmingham Hip Resurfacing (BHR) prosthesis were invited to return for follow-up evaluation. The prevalence and clinical relevance of pseudotumors were investigated. Risk factors for pseudotumor formation were sought. A single-center cross-sectional prospective cohort study was conducted and included all patients who received a BHR from 2005 to 2010 in Martini Hospital, Groningen, The Netherlands. Data were collected on patient and surgical characteristics, clinical hip outcome scores (Harris hip score and Oxford score), serum metal ion levels (cobalt and chromium), and radiographs. A computed tomographic scan (without metal suppression) was made. In patients who had a revision, tissue samples were histologically examined. Originally, there were 129 patients with 149 BHRs. Four patients (six hips; 4%) were lost to follow-up. Our final cohort consisted of 125 patients (143 hips). From this final cohort, eleven patients (twelve hips) had a revision, and three of them (three hips) had the revision before the present study was conducted. Seven patients (eight hips; 5.6%) had a revision because of a symptomatic pseudotumor. Survival analysis showed an implant survival rate of 87.5% at five years (failure was defined as a revision for any reason). A pseudotumor was found on computed tomography in thirty-nine patients (forty hips; 28%). Of those patients, ten (eleven hips; 28%) had complaints involving groin pain and discomfort, a noticeable mass, or paresthesia. Symptomatic pseudotumors were significantly larger than asymptomatic pseudotumors (a mean volume of 53.3 cm3 compared with 16.3 cm3; p = 0.05). A serum cobalt level of >85 nmol/L was a predictor for pseudotumor formation (odds ratio, 4.9). Pseudotumor formation occurred in 28% of hips after an average follow-up of forty-one months. Most pseudotumors (72.5%) were asymptomatic. Larger pseudotumors were associated with more complaints. Survival analysis showed an implant survival of 87.5% at five years. Failure occurred in 5.6% (eight) of 143 hips because of a symptomatic pseudotumor.

Treatment of Pseudotumors After Metal-on-Metal Hip Resurfacing Based on Magnetic Resonance Imaging, Metal Ion Levels and Symptoms

Peri-prosthetic pseudotumor formation can be a severe complication following Metal-on-Metal hip resurfacing arthroplasty (MoMHRA), with limited data on the optimal management of this complication. The aims of this study were (1) to evaluate the prevalence and severity of pseudotumors in a consecutive cohort of 248 MoMHRA (214 patients, mean follow-up 4.6 years, range: 1 - 8.2), and (2) to present a clinical guideline for their treatment based on severity grading with Metal Artefact Reduction Sequence Magnetic Resonance Imaging, metal ion levels and symptoms. Pseudotumor prevalence was 36.3%: 61 mild, 25 moderate and four were graded severe. Five revisions followed, all in symptomatic patients with elevated metal ion levels. Pseudotumor severity grading allowed us to be conservative with revision surgery for mild and moderate MoM disease.

Adverse Local Tissue Reaction Associated With a Modular Hip Hemiarthroplasty

The local and systemic effects of wear debris and corrosion products remain a concern in arthroplasty and reaction to corrosion or wear products from modular junctions has been reported in primary and revision total joint arthroplasties. These effects have not been reported previously for unipolar hemiarthroplasties where there is no prosthetic bearing surface to contribute to the phenomenon. This may have implications for clinical surveillance and implant design. We report the case of a 72-year-old man who had symptomatic pseudotumor formation, confirmed by pathologic examination of the excised pseudotumor, with a large-head modular hip hemiarthroplasty. Metallosis and corrosion of the modular head/neck taper junction were noted at the time of revision surgery. To our knowledge, this is the first report of pseudotumor formation where the corrosion or wear products arose from the modular junction of the implant with no bearing couple present to contribute wear debris that may influence the formation of the pseudotumor. Adverse tissue reactions to wear debris generated at prosthetic articulating surfaces and corrosion and wear products from nonarticulating prosthetic junctions have been reported. The problem has been reported to be higher in metal-on-metal bearing couples and in large-diameter hip arthroplasties. Mixed-alloy junctions appear to be more susceptible to corrosion. We believe that corrosion should be considered a possible diagnostic entity when investigating persistent symptoms after hemiarthroplasty and may be avoided with the use of monoblock components.

Bearing exchange in the management of pseudotumours

Soft tissue reactions following metal-on-metal (MoM) arthroplasty of the hip have been under considerable discussion. These reactions are seen following both hip resurfacing and MoM total hip arthroplasty (THA). The phenomenon may arise owing to shedding of metal particles in high wear states, hypersensitivity with normal metal wear rates or a combination of the two. Three patients were identified who had developed a soft tissue reaction (pseudotumour) following MoM hip resurfacing procedures. The prostheses were revised to ceramic-on-ceramic (CoC) THA with only minimal debridement of the pseudotumour. Pre and postoperative magnetic resonance imaging was performed to assess the size of the lesions. Progressive and satisfactory resolution of the associated pseudotumours was identified following revision of the prostheses to CoC THA. In the early stages of pseudotumour formation following MoM hip resurfacing, this potentially devastating condition can be managed adequately with revision to a CoC bearing THA with minimal soft tissue excision.

Pseudotumor formation caused by delayed hypersensitivity to metal release from metal-on-polyethylene hip replacement

Pseudotumor formation caused by delayed hypersensitivity to metal release from metal-on-polyethylene hip replacement

Pseudotumour Formation Due to Tribocorrosion at the Taper Interface of Large Diameter Metal on Polymer Modular Total Hip Replacements

We present an in-depth failure analysis of two large diameter bearing metal-on-polymer (MoP) modular total hip replacements, which have required revision surgery due to pseudotumour formation. The failure analysis showed a discrete pattern of material loss from the distal end of the head taper/stem trunnion interface. We postulate that the use of a proximal contacting taper design had provided insufficient mechanical locking between the head and the stem, enabling the head to toggle on the trunnion. In addition, the difference in angle between the taper and the trunnion formed a crevice between the two components. Through a combination of crevice environment, mechanically assisted corrosion, mechanical wear and erosion; debris and metal-ions have been released resulting in the adverse local tissue reactions (ALTR).

Pseudotumor in Metal-on-Polyethylene Total Hip Arthroplasty - A Case Report

Pseudotumor formation is a rare, but severe potential complication of total hip arthroplasty. Focus has been on metal on metal articular surfaces as the primary cause. Also known as Adverse Local Tissue Reactions (ALTR’s), previous reported cases have presented as infections. Prior ALTR’s of non-metal on metal articulations have been reported and of cases in which modularity of the neck may have been a factor. We report on a case of a non-modular neck with a metal on polyethylene articulation which presented as an infection, but in which ALTR was the causative factor.

Pulsed electron beam surface melting of CoCrMo alloy for biomedical applications

The use of CoCrMo alloys in biomedical applications has come under scrutiny recently due to unacceptable revision rates of certain hip resurfacing and total hip arthroplasty designs. Failure analysis has demonstrated that solid and soluble wear debris and corrosion products, released from the joints have resulted in adverse local tissue reactions (ALTR), pseudo-tumour formation and ultimately implant retrieval and replacement. In order to improve the surface properties of a wrought CoCrMo alloy, a low energy high current pulsed electron beam surface treatment process was investigated. Samples were irradiated at two cathode voltages of 15 and 35kV at pulse numbers of 1, 15 and 25. At low beam energies a polishing effect was observed as a result of surface melting. At higher beam energies a higher Ra value was the result of the formation of surface craters. Nano-indentation and scratch testing of the treated surface were carried out using a nano-indenter. Depth profiling nano-indentation was performed using a Berkovich tip in load control. Loading was performed in 8mN increments up to 160mN at a rate of 3.5mN/s, with a 60s dwell period and 40% unloading. The results demonstrated that the surface treatment process reduced both the modulus and the hardness of the surface in comparison to the control. Scratching was performed with a 20μm radius spherical diamond and loading rate of 2mN/s up to a maximum of 100mN, over a 1mm scratch length. Similar scratch depths for both control and treated surfaces were observed. However, an improvement in the dynamic friction coefficient was observed at certain beam energies. These results are discussed in the light of XRD evidence that suggested rapid cooling of the surface induced preferential formation of an ε-martensite HCP phase which may be beneficial for biomedical applications.

Postradiofrequency ablation inflammatory pseudotumor associated with pulmonary venoocclusive disease: case report and review of the literature

Radiofrequency ablation of pulmonary veins is a common therapeutic intervention for atrial fibrillation. Pulmonary vein stenosis and venoocclusive disease are recognized complications, but the spectrum of pathologies postablation have not been previously reviewed. A recent case at our hospital showed a left hilar soft tissue mass in association with superior pulmonary vein stenosis in a patient 4 years postablation. On resection, this proved to be an inflammatory pseudotumor composed of myofibroblasts in an organizing pneumonia-type pattern with adjacent dendriform ossifications. Pulmonary venoocclusive change was a prominent feature. Literature on the histopathology of postradiofrequency ablation complications is limited. The severity of vascular pathology appears to increase with the postablation interval. Although pulmonary vascular changes are the most common late finding, fibroinflammatory changes including pulmonary pseudotumor formation, attributable to thermal injury, should be considered in the differential diagnosis of these cases.

High Incidence of Pseudotumours after Hip Resurfacing Even in Low Risk Patients; Results from an Intensified MRI Screening Protocol

We intensified our screening protocol for the presence of pseudotumours in a consecutive series of patients with a hip resurfacing arthroplasty (HRA), to establish whether we should be alert to the presence of 'silent' pseudotumours. Patients categorised with high risk (11 hips) and low risk (10 hips) for pseudotumour development and a control group (23 hips) were screened with metal artefact reduction sequence (MARS) magnetic resonance imaging (MRI). The Anderson classification to grade any metal-on-metal (MoM) disease present on MARS-MRI images was used. In 15 out of 44 MRI scans pseudotumours were observed (34.1%), of which six were graded with mild (13.6%), eight with moderate (18.2%) and one with severe MoM disease (2.3%). Twelve pseudotumours were present in asymptomatic patients (27.3%). Metal ion levels were normal in 80% of the MARS-MRI screened patients. As a consequence of our intensified screening protocol, one patient was revised for pseudotumour formation and another patient was scheduled for revision. Silent pseudotumours were observed in all three groups. Before our intensified screening protocol was initiated, no pseudotumours were encountered in our cohort of 289 HRAs. We concluded that clinical outcomes and plain radiographs for screening MoM patients underestimates the presence of pseudotumours in MoM patients. The true clinical relevance of these pseudotumours is still unclear.

Metal-on-Metal Total Hip Arthroplasty: Causes and High Incidence of Early Failure

Early failures of metal-on-metal total hip arthroplasty (THA) occur due to aseptic loosening, metal hypersensitivity reactions, pseudotumor formation, and component seizing. The purpose of this study was to investigate the timing, common modes of failure, clinical outcomes, and incidence of metal-on-metal THA revisions. A review was performed of 80 patients who underwent revision of a failed metal-on-metal THA for any reason. The most common reason for metal-on-metal failure was aseptic acetabular loosening, with a rate of 56.25% (45/80 patients). Early failure of metal-on-metal THAs was noted, with 78% of these revisions being performed within 2 years of the index operation and 92.5% within 3 years. Furthermore, 13% of patients experienced significant localized soft tissue reactions. Mean preoperative Harris Hip Score was 42.35 ± 14.24 and mean postoperative Harris Hip Score was 66.5 ± 23.2 (range, 9.55-95.4), with an average follow-up of 438 ± 492 days (range, 40-2141), or 1.2 years.It is imperative that clinicians be cognizant of the fact that the proposed advantages of metal-on-metal THA are not without potential detrimental sequelae. This article proposes an algorithm to aid in diagnosing the etiology of a painful metal-on-metal THA, as well as 2 classification schemes regarding metal-on-metal THA complications to help direct treatment.

Corrosion at the neck-stem junction as a cause of metal ion release and pseudotumour formation

We present a series of 35 patients (19 men and 16 women) with a mean age of 64 years (36.7 to 75.9), who underwent total hip replacement using the ESKA dual-modular short stem with metal on-polyethylene bearing surfaces. This implant has a modular neck section in addition to the modular head. Of these patients, three presented with increasing post-operative pain due to pseudotumour formation that resulted from corrosion at the modular neck-stem junction. These patients underwent further surgery and aseptic lymphocytic vaculitis associated lesions were demonstrated on histological analysis. Retrieval analysis of two modular necks showed corrosion at the neck-stem taper. Blood cobalt and chromium levels were measured at a mean of nine months (3 to 28) following surgery. These were compared with the levels in seven control patients (three men and fourwomen) with a mean age of 53.4 years (32.1 to 64.1), who had an identical prosthesis and articulation but with a prosthesis that had no modularity at neck-stem junction. The mean blood levels of cobalt in the study group were raised at 50.75 nmol/l (5 to 145) compared with 5.6 nmol/l (2 to 13) in control patients. Corrosion at neck-stem tapers has been identified as an important source of metal ion release and pseudotumour formation requiring revision surgery. Finite element modelling of the dual modular stem demonstrated high stresses at the modular stem-neck junction. Dual modular cobalt-chrome hip prostheses should be used with caution due to these concerns.

High incidence of pseudotumour formation after large-diameter metal-on-metal total hip replacement

Peri-articular soft-tissue masses or ‘pseudotumours’ can occur after large-diameter metal-on-metal (MoM) resurfacing of the hip and conventional total hip replacement (THR). Our aim was to assess the incidence of pseudotumour formation and to identify risk factors for their formation in a prospective cohort study. A total of 119 patients who underwent 120 MoM THRs with large-diameter femoral heads between January 2005 and November 2007 were included in the study. Outcome scores, serum metal ion levels, radiographs and CT scans were obtained. Patients with symptoms or an identified pseudotumour were offered MRI and an ultrasound-guided biopsy. There were 108 patients (109 hips) eligible for evaluation by CT scan at a mean follow-up of 3.6 years (2.5 to 4.5); 42 patients (39%) were diagnosed with a pseudotumour. The hips of 13 patients (12%) were revised to a polyethylene acetabular component with small-diameter metal head. Patients with elevated serum metal ion levels had a four times increased risk of developing a pseudotumour. This study shows a substantially higher incidence of pseudotumour formation and subsequent revisions in patients with MoM THRs than previously reported. Because most revision cases were identified only after an intensive screening protocol, we recommend close monitoring of patients with MoM THR.

Edge Loading Has a Paradoxical Effect on Wear in Metal-on-Polyethylene Total Hip Arthroplasties

Edge wear is an adverse factor that can negatively impact certain THAs. In some metal-on-metal THAs, it can lead to adverse tissue reactions including aseptic lymphocytic vasculitis-associated lesions and even to pseudotumor formation. In some ceramic-on-ceramic THAs, it can lead to squeaking and/or stripe wear. Edge wear in metal-on-metal and ceramic-on-ceramic THAs can also be associated with accelerated wear across the articulation of these joints. I asked: Does edge wear occur in metal-on-polyethylene (MOP) articulations? And if so, does it increase joint wear? I examined the evidence in the literature for edge wear occurring in MOP THA and then assessed the evidence in the literature for data supporting the concept that edge wear in MOP hips could accelerate wear across the articulation over time. Extensive data in the literature confirm edge wear is common in MOP THA. Surprisingly, the evidence does not support that it accelerates wear across the articulation. In fact, substantial data support the concept that it does not. These observations suggest, in terms of edge wear accelerating overall wear, MOP articulation may have a privileged position compared to hard-on-hard THA articulations.

Metal-On-Metal Bearings, Inflammatory Pseudotumours and Their Neurological Manifestations

Metal-on-metal bearings have become more popular for hip arthroplasty in younger patients in the last 15 years. We present a review of the neurological consequences relating to such bearing surfaces illustrated by an appropriate case report. The mechanisms of increased metal ion production and pseudotumour formation are discussed. If unexplained neurology, hip/groin pain or a localised mass around the hip are present with a metal bearing hip then urgent referral to a specialist orthopaedic surgeon is warranted for consideration of exchange arthroplasty.

Mixing and matching causing taper wear

We report a case of a male patient presenting with bilateral painful but apparently well-positioned and -fixed large-diameter metal-on-metal hip replacements four years post-operatively. Multiple imaging modes revealed a thick-walled, cystic expansile mass in communication with the hip joint (a pseudotumour). Implant retrieval analysis and tissue culture eliminated high bearing wear or infection as causes for the soft-tissue reaction, but noted marked corrosion of the modular neck taper adaptor and corrosion products in the tissues. Therefore, we believe corrosion products from the taper caused by mismatch of the implant components led to pseudotumour formation requiring revision.

Pseudotumors Are Common in Well-positioned Low-wearing Metal-on-Metal Hips

Pseudotumors are sterile inflammatory lesions found in the soft tissues surrounding metal-on-metal (MOM) and metal-on-polyethylene hip arthroplasties. In patients with MOM hip arthroplasties, pseudotumors are thought to represent an adverse reaction to metal wear debris. However, the pathogenesis of these lesions remains unclear. Currently, there is inconsistent evidence regarding the influence of adverse cup position and increased wear in the formation of pseudotumors. We therefore determined whether pseudotumor formation was associated with (1) adverse cup position, (2) raised metal ion levels, and (3) increased wear rates of the retrieved components. We retrospectively reviewed all 352 patients for whom we had retrieved specimens from revisions of a current-generation MOM hip prosthesis between February 2008 and September 2010; of these, 105 met our inclusion criteria. We used multivariate logistic regression analysis to compare acetabular orientation, metal ion levels before revision, and component wear rates between patients with (n = 72) and without (n = 33) pseudotumors, according to findings on metal artifact reduction sequence MRI. The proportion of patients demonstrating evidence of a pseudotumor in well-positioned hips was similar to those with adverse cup positions (67% and 66%, respectively). Patients revised with pseudotumors had similar whole-blood metal ion levels and component wear rates to those who were not revised. Pseudotumors were not associated with increased wear or metal ion levels, suggesting patient susceptibility is likely to be more important.

Prevalence of Pseudotumor in Asymptomatic Patients After Metal-on-Metal Hip Arthroplasty

The cause of recently reported pseudotumor formation in patients with metal-on-metal hip replacements is unknown. It has been postulated that there is an association between elevated levels of serum metal ions and pseudotumor formation. The primary purpose of this study was to assess the prevalence of pseudotumor formation in asymptomatic patients with a metal-on-metal total hip replacement after a minimum duration of follow-up of two years. A secondary purpose was to assess whether a correlation exists between elevated serum metal ion levels and pseudotumor formation. In the present study, the prevalence of pseudotumor formation, as detected with ultrasound, was evaluated for thirty-one asymptomatic patients with a metal-on-metal total hip arthroplasty, twenty-four asymptomatic patients with a metal-on-polyethylene total hip arthroplasty, and twenty asymptomatic patients with a metal-on-metal hip resurfacing arthroplasty. Serum levels of cobalt and chromium were measured in the metal-on-metal total hip arthroplasty and hip resurfacing arthroplasty groups. Ten patients (32%) in the metal-on-metal total hip arthroplasty group had a solid or cystic mass, with another three patients (10%) having a substantial fluid collection. Five patients (25%) in the hip resurfacing arthroplasty group had a solid or cystic mass, with another patient (5%) having a fluid collection. Pseudotumor formation was significantly more frequent in the metal-on-metal total hip arthroplasty group compared with the metal-on-polyethylene total hip arthroplasty group (p = 0.015). We did not detect a significant correlation between the serum metal ion levels and the size of pseudotumor abnormality. The median serum metal ion level was greater in patients with pseudotumor formation than it was in those without pseudotumor formation, but the difference was not significant. We recommend high-resolution ultrasound surveillance of all asymptomatic patients with a metal-on-metal implant that is known to result in high serum metal ion levels. Once a metal-on-metal implant is known to be associated with high serum metal ions, the measurement of ion levels does not helpfully contribute to surveillance.