Pseudotumors associated with total hip arthroplasty

Pseudotumor following total hip arthroplasty: experience of a tertiary referral center and proposal of the new "PCS" classification system

INTRODUCTION

This study summarizes outcomes in treating pseudotumors of the hip at a tertiary referral center and introduces a classification system to aid treatment decisions and enhance communication among providers.

MATERIALS AND METHODS

We collected data from 39 patients who underwent surgery for hip pseudotumor, analyzing implant failures based on patient history, revision reasons, bearing surface type, mass location and size, bone loss, revision type, and whether it was single- or two-stage. We introduce the PCS classification: 'P' for Pseudotumor (with 's' for symptomatic, 'e/I' for intra/extrapelvic location, and 'm' for high Chromium/Cobalt levels), 'C' for implant status, and 'S' for bone loss extent. In 37 patients, we evaluated Cohen's kappa coefficient to evaluate interobserver reliability.

RESULTS

Twenty (51.2%) patients were female, with a mean age of 71 years (range 36-89; σ 12.11); the mean follow-up duration was 54.43 months (range 12.2-128.3). The average size of the pseudotumor was 13.10 cm (range 3.3-37.2; σ 7.11) with 61.5% exhibiting extra-pelvic localization only. Bearing surfaces were MoM in 27 patients (69.2%). Single-stage revision surgery was performed in 87.1% of patients. There were 7 (17.9%) implant failures. No significant differences in failure rates were observed based on considered parameters. The agreement following Cohen's coefficient for the combined PCS classification was k = 0.43. Moderate to almost perfect agreement was obtained for parameter P and S, with k = 0.48 for parameter C.

CONCLUSION

No correlation was found between failures and analyzed characteristics. Our classification assesses clinical scenarios and stratifies surgical complexity for indication purposes. While interobserver agreement varies with parameter C, it is consistent with parameters P and S.

Foreign Body Entrapment on the Bearing Surface in Total Hip Arthroplasty: A Report of Three Cases

Total hip arthroplasty (THA) is a highly effective surgical intervention for end-stage hip joint disorders. While common complications such as infection, dislocation, and prosthetic loosening are well-documented, rarer complications remain underreported. One such complication is foreign body interposition on the bearing surface, which can compromise joint mechanics and adversely affect outcomes. This study presents three cases of foreign body interposition involving soft tissue, bone fragments, and cement debris, observed postoperatively in patients undergoing THA. In the first case, a 79-year-old woman presented with soft tissue interposition, which resolved spontaneously through joint motion without surgical intervention. The second case involved a 71-year-old woman with a bone fragment interposed between the femoral head and liner, necessitating reoperation for removal. The third case, a 32-year-old man, required immediate reoperation to remove a 1 cm cement fragment causing a gap on the bearing surface. In all cases, postoperative outcomes were favorable, with patients resuming independent ambulation and reporting no persistent symptoms. These cases underscore the potential for foreign body interposition to occur during or after THA due to residual debris or displaced tissues. This rare complication has an estimated incidence of 0.2% based on 1,340 procedures at three affiliated hospitals over two years. Key preventive strategies include meticulous removal of debris before reduction, thorough irrigation, and intraoperative imaging to confirm proper alignment. For management, immediate mobilization may resolve soft tissue interpositions, but solid foreign bodies typically require reoperation to prevent long-term damage to the bearing surfaces and subsequent complications, such as osteolysis, implant loosening, or catastrophic ceramic fracture. This report emphasizes the importance of heightened awareness, careful intraoperative techniques, and prompt postoperative imaging to identify and address this preventable complication. By sharing these insights, we aim to enhance perioperative safety and improve long-term outcomes for patients undergoing THA.

Aggressive granulomatous pseudotumor following total hip prosthesis: Diagnostic and therapeutic strategies from a single institution experience

Introduction

Granuloma formation following total hip arthroplasty (THA) can occur regardless of the bearing surface. In very rare cases, extensive granulomas mimicking tumors may develop which are known as pseudotumors. The aim of this study is to report on these rare yet complex situations to stimulate reflection in diagnostic and therapeutic approaches.

Methods

A retrospective case series study of 5 patients (2 females, 3 males) of aggressive granulomatous lesions on primary prostheses and 4 revision prostheses for aseptic loosening, implanted at a mean age of 74.8 years (range 64-83). A clinical, functional, radiographic, and anatomopathological analysis were conducted.

Results

Four patients underwent revision surgery, while one died before intervention. Functional impairment was significant with a mean pre-reintervention Postel-Merle d'Aubigné (PMA) score of 8.2 (range 4-11). Femoral involvement was constant, associated with acetabular involvement in only one case. bony involvement was major, with a minimum of 5 Gruen zones affected, showing complete cortical lysis. Histopathological analysis consistently revealed multinucleated giant cells and macrophages, predominantly with metallic wear particles. In 2 cases, vascular involvement was suspected without a clearly delineated tumor. Two cases required femoral resection prostheses, one necessitated inter-ilio-abdominal amputation due to extensive soft tissue involvement, one underwent implant removal which failed to prevent progression, and one patient died before reoperation.

Conclusion

The volume of lesions in these 5 cases appears markedly larger than reported cases.Extensive pseudo-tumoral granulomatous lesions following THA are rare but carry poor functional prognosis. Evaluation to rule out infection and neoplastic pathology is imperative. Surgical management often resembling tumor treatment should be considered. Early diagnosis is crucial to allow intervention before reaching the stage of massive prosthetic replacement.

Level of evidence

IV retrospective study.

Correlation and diagnostic performance of metal ions in patients with pseudotumor after MoM hip arthroplasty: a systematic review and meta-analysis

BACKGROUND

The persistently rising complication, pseudotumor, after hip arthroplasty required surgeons' vigilance. Although the remaining controversial relationship between metal ions and pseudotumor, metal ion detection had been widely employed in clinic. The aim of this study is to evaluate the correlation between metal ions and pseudotumor, as well as the effectiveness of metal ion analysis in the screening and diagnosis of pseudotumor through systematic review and meta-analysis.

METHODS

The Medline and Embase databases were searched for studies evaluating metal ions and patients with pseudotumors after hip arthroplasty. A systematic review of risk ratio and diagnostic performance for metal ions was conducted.

RESULTS

Seven studies were included in the systematic review. The mean Methodological Index for Non-Randomized Studies (MINORS) score of the included studies was 19 (range, 14 to 22). Pooled risk ratio (RR) value was 2.01(95% CI: 1.25-3.24; P = 0.004) for cobalt ions level and 1.44 (95% CI: 1.10-1.88; P = 0.008) for chromium ions level. The pooled sensitivity, specificity and the area under the curve (AUC) for cobalt and chromium ions were determined to be 0.59, 0.82, 0.73 and 0.34, 0.82, 0.56, respectively.

CONCLUSIONS

The metal ions level has a low diagnostic value. It is of certain value for confirmation, but should not be used as a routine screening indicator. The diagnostic value of cobalt ions is higher than that of chromium.

LEVEL OF EVIDENCE

Diagnostic Level IV.

Cobalt Toxicity Induces Retinopathy and Optic Neuropathy in Mice

Purpose

To explore the effect of cobalt toxicity on vision.

Methods

A total of 103 wild-type (WT) mice were injected with cobalt chloride by two routes in different concentrations: single intravenous (IV) high or low doses (total, n = 43); or daily repeated intraperitoneal (IP) high (three days) or low (28 days, 56 days) dose, and low-dose cobalt with added minocycline (56 days) (total, n = 60); 10 WT mice served as a control group. An additional group of 17 immunodeficient NOD scid gamma (NSG) mice were injected IV or IP with cobalt, and 10 NSG mice served as control. Cobalt levels were measured in blood, urine, and tears by particle-induced X-ray emission (PIXE). Macroscopic, immunohistochemical, electroretinography (ERG), and molecular studies were done.

Results

PIXE revealed cobalt elimination from the blood by two hours, with increased levels in urine but under the detection limit in tears. In the retina, ERG recordings showed decreased b-wave amplitude. Apoptosis mainly involved the inner retina, with inner retinal inflammatory reaction in both WT and less in the NSG mice. In the optic nerves, an increased microglial and astrocytic activation was noted.

Conclusions

This study demonstrated functional visual impairment with extensive inflammatory reaction secondary to cobalt toxicity in mice.

Blood metal concentrations and cardiac structure and function in total joint arthroplasty patients

BACKGROUND

There is concern regarding potential long-term cardiotoxicity with systemic distribution of metals in total joint arthroplasty (TJA) patients.

AIM

To determine the association of commonly used implant metals with echocardiographic measures in TJA patients.

METHODS

The study comprised 110 TJA patients who had a recent history of high chromium, cobalt or titanium concentrations. Patients underwent two-dimensional, three-dimensional, Doppler and speckle-strain transthoracic echocardiography and a blood draw to measure metal concentrations. Age and sex-adjusted linear and logistic regression models were used to examine the association of metal concentrations (exposure) with echocardiographic measures (outcome).

RESULTS

Higher cobalt concentrations were associated with increased left ventricular end-diastolic volume (estimate 5.09; 95%CI: 0.02-10.17) as well as left atrial and right ventricular dilation, particularly in men but no changes in cardiac function. Higher titanium concentrations were associated with a reduction in left ventricle global longitudinal strain (estimate 0.38; 95%CI: 0.70 to 0.06) and cardiac index (estimate 0.08; 95%CI, -0.15 to -0.01).

CONCLUSION

Elevated cobalt and titanium concentrations may be associated with structural and functional cardiac changes in some patients. Longitudinal studies are warranted to better understand the systemic effects of metals in TJA patients.

The contribution of metal allergy to the failure of metal alloy implants, with special reference to titanium: Current knowledge and controversies

After almost three-quarters of a century during which contact dermatologists have often struggled to comprehend the relationship between metal allergy and failure of metal-alloy containing implant, it is possible to say that a relationship does exist, particularly for cobalt and chromium, but also for nickel. There is still debate as to whether allergy develops as a consequent of failure but thenceforth contributes to it, or whether sensitisation starts first and induces failure secondarily-opinion probably favours the first. Metal-on-polypropylene articulations were associated with few metal allergic problems but now are less favoured by orthopaedists due to plastic wear products causing osteolysis and pseudotumour formation through local inflammation. New metal alloys are regularly being introduced such that interested dermatologists need to stay on top of the situation. The jury is still out as to whether the recent favouring of titanium-containing alloys will confirm them to be more inert allergenically. Case reports do show some clinical reactions to titanium-containing implants and patch test series have inferred sometimes quite a high background rate of allergy, but interpretation must be tempered by the awareness that titanium salts on patch testing have a tendency to cause irritant reactions. Blood monitoring of metal ion values is now recommended in certain situations after joint replacement and increasing levels may be an indication that allergy with joint failure can develop, in which case patch testing is indicated, and suggested series are available. Predictive patch testing, whilst generally not recommended in the past, has been introduced into some protocols often by non-dermatologists, such that it is now needed for temporo-mandibular joint and Nuss bar insertion, and it can be anticipated that this may become more commonplace in the future. One of the major current deficits for patch testers is standardised guidance on which preparation or preparations to use for suspected titanium allergy. One suggestion is 0.5% titanium sulphate in petrolatum, though experience in at least one centre suggests the use of a battery of titanium salts might be desirable.

A Sarcoma Masquerading as a Pseudotumor After Total Hip Arthroplasty: A Case Report

CASE

There is an increasing emphasis on adverse reactions to metal debris around prosthetic hip implants. We present a case report of a patient with increasing pain around a previous total hip arthroplasty and magnetic resonance imaging findings consistent with a pseudotumor. Serum metal ion levels were not elevated and initial biopsy findings inconclusive. The patient was diagnosed with an extraskeletal chondrosarcoma after revision total hip arthroplasty and subsequently underwent external hemipelvectomy with negative margins.

CONCLUSION

This report highlights the importance of remaining vigilant for malignant sarcomas presenting as pseudotumors around hip replacements, particularly in the absence of abnormal metal ion levels or definitive biopsy results.

An Atypical Adverse Local Tissue Reaction Seen With Metal-On-Metal Total Hip Arthroplasty Utilizing Polyethylene Liners With Metal Inlays

Adverse local tissue reaction (ALTR) is a frequently described, although uncommon, complication of metal-on-metal total hip arthroplasty. Here in we report on 2 patients with unique metal-inlay polyethylene liners who suffered from ALTR that required revision arthroplasty. In 2 of 3 cases the femoral trunnion was noted to have minimal corrosion and the stem was salvaged with a titanium adapter. In one case there was catastrophic femoral stem failure and an extended trochanteric osteotomy was required to remove the unique lateral flare stem. The surgeon must pay special attention when scrutinizing radiographs to identify a metal inlay polyethylene liner and when performing revision arthroplasty to prevent greater trochanter fracture in a patient who likely already has compromised abductor function due to ALTR.

A "Congenitally Adapted" TFCC Tear in Radial Longitudinal Deficiency: Case Report and Review of Literature

We present a case of chronic wrist pain in a 14-year-old child with mild radial longitudinal deficiency and radiographic carpal collapse due to the absence of the scaphoid. Wrist arthroscopy demonstrated synovitis and a tear to the TFCC, which would be called "degenerative," according to the Palmer classification. This was debrided, and the patient is still asymptomatic at long-term follow-up. Review of the literature found one paper with a similar observation in a 17-year-old adolescent. We propose that paediatric "degenerative" tears ought to be called "congenitally adapted" tears.

Pseudotumor after Total Wrist Arthroplasty Mimicking a Neoplasm

Background  Total wrist arthroplasty can lead to a variation of complications. One of these is the formation of a pseudotumor. Although this complication is well known after total hip arthroplasty, it is rare in patients with wrist implants. Case Description  A 55-year-old man with a Universal 2 (Integra, Plainsboro, NJ) wrist prosthesis was seen with a progressive mass on the radial side of his wrist since 1 year, initially suspicious for a neoplasm. However, after exploration, histopathology confirmed a particle-induced foreign body reaction. Literature Review  There is little literature on pseudotumor formation after total wrist arthroplasty. Currently, there is no clear consensus about the etiology of pseudotumors but possible causes may include foreign body reaction, hypersensitivity, and wear debris. Clinical Relevance  This case report shows that particle debris-induced pseudotumors should be considered when a patient with a wrist prosthesis presents with a mass suspicious for a neoplasm. In addition, treatment options of pseudotumors after wrist arthroplasty in literature is discussed.

Adverse Local Tissue Reaction Associated With Ceramic-On-Metal Bearing Surface in Primary Total Hip Arthroplasty: Report of Two Cases

Total hip arthroplasty (THA) is one of the most common and successful surgical procedures worldwide. At the same time, it is constantly evolving, and as a consequence, advances in implant technology have led to significant improvements in the different materials of the acetabular and femoral components. The selection of bearing surfaces and their tribology are critical to achieving a successful outcome. Pseudotumors are important, and usually misdiagnosed, complications associated with hard bearing surfaces such as metal-on-metal couples. They belong to a group of reactions called adverse local tissue reaction, which can occur in the vicinity of any THA. We present 2 cases of adverse local tissue reaction associated with the use of ceramic-on-metal bearings surfaces in 2 primary THAs that were treated with modular component exchange during single-stage revision surgery.

Level of Evidence

IV.

Involvement of NF-κB/NLRP3 axis in the progression of aseptic loosening of total joint arthroplasties: a review of molecular mechanisms

Particulate wear debris can trigger pro-inflammatory bone resorption and result in aseptic loosening. This complication remains major postoperative discomforts and complications for patients who underwent total joint arthroplasty. Recent studies have indicated that wear debris-induced aseptic loosening is associated with the overproduction of pro-inflammatory cytokines. The activation of osteoclasts as a result of inflammatory responses is associated with osteolysis. Moreover, stimulation of inflammatory signaling pathways such as the NF-κB/NLRP3 axis results in the production of pro-inflammatory cytokines. In this review, we first summarized the potential inflammatory mechanisms of wear particle-induced peri-implant osteolysis. Then, the therapeutic approaches, e.g., biological inhibitors, herbal products, and stem cells or their derivatives, with the ability to suppress the inflammatory responses, mainly NF-κB/NLRP3 signaling pathways, were discussed. Based on the results, activation of macrophages following inflammatory stimuli, overproduction of pro-inflammatory cytokines, and subsequent differentiation of osteoclasts in the presence of wear particles lead to bone resorption. The activation of NF-κB/NLRP3 signaling pathways within the macrophages stimulates the production of pro-inflammatory cytokines, e.g., IL-1β, IL-6, and TNF-α. According to in vitro and in vivo studies, novel therapeutics significantly promoted osteogenesis, suppressed osteoclastogenesis, and diminished particle-mediated bone resorption. Conclusively, these findings offer that suppressing pro-inflammatory cytokines by regulating both NF-κB and NLRP3 inflammasome represents a novel approach to attenuate wear-particle-related osteolytic diseases.

Compression of the Rectum, Bladder, and External Iliac Vein Due to Hip Arthroplasty-Related Pseudotumor

A 58-year-old male who underwent left total hip arthroplasty in 1988 for post-traumatic arthritis after an operatively-treated acetabular fracture presented with progressive left hip pain, lower extremity swelling, urinary urgency, constipation, and tenesmus (the feeling of needing to pass stool despite having an empty colon). Imaging demonstrated massive pseudotumor causing iliac vein compression and significant displacement of the rectum and bladder requiring decompression in combination with general surgery followed by revision hip arthroplasty four months later. This case highlights a unique constellation of symptoms due to pseudotumor after total hip arthroplasty, as well as the severity to which pseudotumor can progress, requiring staged decompression with general surgery before revision.

Metals and Metal-Nanoparticles in Human Pathologies: From Exposure to Therapy

An increasing number of pathologies correlates with both toxic and essential metal ions dyshomeostasis. Next to known genetic disorders (e.g., Wilson's Disease and β-Thalassemia) other pathological states such as neurodegeneration and diabetes are characterized by an imbalance of essential metal ions. Metal ions can enter the human body from the surrounding environment in the form of free metal ions or metal-nanoparticles, and successively translocate to different tissues, where they are accumulated and develop distinct pathologies. There are no characteristic symptoms of metal intoxication, and the exact diagnosis is still difficult. In this review, we present metal-related pathologies with the most common onsets, biomarkers of metal intoxication, and proper techniques of metal qualitative and quantitative analysis. We discuss the possible role of drugs with metal-chelating ability in metal dyshomeostasis, and present recent advances in therapies of metal-related diseases.

Incidence of Pseudotumors in a Dual Modular Stem Construct With and Without Metal-on-Metal Bearing Surface

BACKGROUND

The purpose of this study was to compare the incidence of pseudotumors in metal-on-metal (MoM) titanium modular neck hip arthroplasties to non-MoM modular neck hip arthroplasties. A secondary goal was to determine whether a correlation exists between elevated metal concentrations and pseudotumor incidence.

METHODS

The data were collected and evaluated from 49 MoM joints and 26 non-MoM joints between the years 2012 and 2017. Hip ultrasonography was done after a minimum of 5 years postimplantation. Whole serum metal (titanium, cobalt, and chromium) concentrations were measured at the hip ultrasonography study.

RESULTS

The average time elapsed between surgery and ultrasonography visit was 7.6 years. In the 49 patients with MoM joints, 22.4% (n = 11) had a pseudotumor. In the 26 patients with non-MoM joints, 9.1% of metal-on-polyethylene hips (n = 1) and 0% of ceramic-on-ceramic/polyethylene hips developed a pseudotumor. No significant statistical correlation was observed between serum metal concentrations and pseudotumor formation (P > 0.05). A significant correlation was observed of serum titanium concentration to pseudotumor size (P = 0.024).

CONCLUSION

The incidence of pseudotumor formation in MoM total hip arthroplasties was more than five times the incidence associated with non-MoM bearings. The correlation between serum titanium concentration and pseudotumor size suggests that titanium levels may be a useful indicator for pseudotumor formation in patients with this particular titanium modular neck femoral implant. No notable correlation was observed between serum cobalt and chromium concentration and pseudotumor formation or size.

Echocardiographic Changes in the Context of Metal-on-Metal Versus Nonmetal-on-Metal Total Hip Arthroplasty

BACKGROUND

The purpose of this study is to determine if there is a difference in echocardiographic results between patients with metal-on-metal (MoM) vs non-MoM total hip arthroplasty (THA) and to determine if a correlation exists between serum metal levels and echocardiographic outcomes.

METHODS

Seventy-five patients with the same modular THA enrolled in this prospective cohort study, and 49 had MoM bearings. All patients had serum cobalt, chromium, and titanium levels drawn at 2 study visits with a transthoracic echocardiogram at the second visit. Serum metal concentrations and echocardiographic parameters were compared with 2-way t-tests. Multiple linear regression analyses identified any significant predictors of echocardiographic outcomes.

RESULTS

Mean serum cobalt and chromium levels were significantly greater in the MoM group at both time-points (P < .001 and P < .05, respectively). Titanium levels were similar between groups (P > .05). MoM patients had significantly lower global longitudinal strain compared with the non-MoM group (18.4% vs 20.2%; P = .026). Serum cobalt concentration was found to be an independent predictor of tricuspid annular plane systolic excursion (P = .02).

CONCLUSION

MoM THA bearings are associated with increased serum cobalt and chromium levels. Patients with MoM THAs had decreased global longitudinal strain, a measure of left ventricular function, but both groups remained within normal range. The clinical impact of the positive association between serum cobalt concentration and tricuspid annular plane systolic excursion, a marker of right ventricular function, deserves further study. These findings can reassure physicians and patients that metal-induced cardiomyopathy is not typical in the setting of MoM THA.

LEVEL OF EVIDENCE

Level II, Prospective Cohort Study.

Giant cell tumor formation due to metallosis after open latarjet and partial shoulder resurfacing

Shoulder metallosis with giant cell tumor formation is rarely seen in shoulder surgery. With an increase in shoulder arthroplasty and complex revision shoulder surgeries, clinicians should have an index of suspicion for possible metallosis in patients that presents with unexplained persistent pain with metal components on both the glenoid and humeral side. This case describes a 43-yearold female with a history of six prior shoulder surgeries who presented with shoulder metallosis and giant cell tumor formation after a screw from her open Latarjet procedure began rubbing against her Hemicap implant. She successfully underwent a revision total shoulder arthroplasty for post traumatic arthritis with pectoralis major transfer for her chronic subscapularis rupture and had complete symptom resolution.

Do Polyethylene Supra-Macroparticles Lead to Pseudotumor Formation in Metal-on-Polyethylene Total Hip Arthroplasty?

We describe 2 cases of pseudotumors induced by an unusual size of polyethylene wear particle after metal-on-polyethylene total hip arthroplasty (MoP THA). The supra-macroparticles of size >100 μm originated from a polyethylene liner with relatively small cup anteversion, potentially leading to excessive loading and increased wear of the anterior edge of the polyethylene liner. Histopathology showed a foreign-body reaction to the polyethylene particles without an adverse reaction to metal debris and with no severe signs of corrosion at the head-neck junction, which have been noted in past reports of pseudotumors in MoP THA. It has been suggested that the large polyethylene wear particles might be the cause of pseudotumor formation in MoP THA.

Challenges in the Measurement and Interpretation of Serum Titanium Concentrations

The measurement of circulating metal ion levels in total hip arthroplasty patients continues to be an area of clinical interest. National regulatory agencies have recommended measurement of circulating cobalt and chromium concentrations in metal-on-metal bearing symptomatic total hip arthroplasty patients. However, the clinical utility of serum titanium (Ti) measurements is less understood due to wide variations in reported values and methodology. Fine-scale instrumentation for detecting in situ Ti levels continues to improve and has transitioned from graphite furnace atomic absorption spectroscopy to inductively coupled plasma optical emission spectrometry or inductively coupled plasma mass spectrometry. Additionally, analytical interferences, variable sample types, and non-standardized sample collection methods complicate Ti measurement and underlie the wide variation in reported levels. Normal reference ranges and pathologic ranges for Ti levels remain to be established quantitatively. However, before these ranges can be recognized and implemented, methodological standardization is necessary. This paper aims to provide background and recommendations regarding the complexities of measurement and interpretation of circulating Ti levels in total hip arthroplasty patients.

Cobalt hip prosthesis intoxication mimicking an autoimmune disease

Cobalt-containing hip prosthesis may cause systemic toxicity due to the release of cobalt from metal-on-metal (MoM) joint arthroplasty into the bloodstream. High cobalt blood levels can lead to a variety of clinical manifestations, mimicking other disorders, especially autoimmune, hematologic, and infectious diseases. Our purpose is to describe a clinical case of cobalt hip prosthesis intoxication mimicking an autoimmune disease, with systemic inflammation signs, arthro-myalgias unrelated to overt synovitis, and multiple autoantibody positivity. A 69-years-old woman presented with a 1-year history of right coxalgia, recurrent fever, arthro-myalgias, mediastinal and right iliac reactive lymphadenopathy. She underwent hip replacement surgery seven years earlier. The physical examination was unremarkable except for right hip pain. Laboratory tests showed markedly increased inflammatory indices and microbiological tests were all negative. Ultrasound-guided arthrocentesis of right hip yielded limpid fluid with negative cultures. Increased cobalt levels in plasma and urine showed metal intoxication. Magnetic resonance imaging with metal artifact reduction sequence (MARS) confirmed a periprosthetic mass as usually seen in reaction to metal debris. Prosthesis substitution was performed with a resolution of the clinical picture and normalization of cobalt levels.

Comparison of Harris Hip Scores and Revision Rates in Metal-on-Metal Versus Non-Metal-on-Metal Total Hip Arthroplasty

INTRODUCTION

This study compares functional outcome scores and revision rates between metal-on-metal (MoM) and non-MoM total hip arthroplasty patients.

METHODS

A cohort of 75 patients who underwent implantation of the same dual modular hip arthroplasty between the years of 2004 and 2010 was enrolled. Patients were subsequently evaluated in 2015 to 2017 for joint revision history and functionality, as measured by the Harris hip score (HHS). Patients requiring a revision arthroplasty were not included in the HHS analysis.

RESULTS

A total of 49 patients had MoM implants (65.3%), and 26 patients had non-MoM implants (34.8%). At a mean follow-up of 7.6 years, 10.2% (5/49) of MoM prostheses required revision, whereas 3.8% (1/26) of non-MoM prostheses required revision (P = 0.334). The mean HHS in the MoM cohort was 89.8, compared with 88.1 in the non-MoM cohort (P = 0.69).

CONCLUSION

HHSs were not notably different between cohorts. The MoM cohort had three times as many revisions as the non-MoM cohort, but given the numbers available, this difference did not reach significance. Given the clinical importance of these revision data, further study is warranted to determine survivorship of the MoM versus non-MoM total hip arthroplasty at long-term follow-up.

Pseudotumor Caused by a Retained Intra-articular Bullet: A Case Report

CASE

A 54-year-old man presented with systemic lead poisoning due to a gunshot wound to the hip suffered 35 years prior to presentation. He urgently underwent removal of the bullet with total hip arthroplasty and was found to have a pseudotumor. This case highlights the team-based approach to manage systemic lead poisoning caused by an intra-articular bullet.

CONCLUSION

We report on the first documented case of systemic lead toxicity and a pseudotumor caused by an intra-articular bullet. An expeditious, team-based approach is necessary for appropriate treatment. Our treatment algorithm can guide future teams on the management of this reversible disorder.

Pseudotumor recurrence in a post-revision total hip arthroplasty with stem neck modularity: A case report

BACKGROUND

This unique presentation of hip swelling is only the seventh reported case of pseudotumor recurrence in a non-metal-on-metal total hip arthroplasty (THA) construct. The constellation of patient symptoms and laboratory findings contradict the expected elevated serum metal ion levels associated with the formation of pseudotumor. The presentation, lab trends, and imaging findings contribute to the growing base of knowledge surrounding the effects of corrosion in arthroplasty constructs with stem-neck modularity.

CASE SUMMARY

A 74-year-old man status post primary THA presented with left hip swelling and elevated serum metal ions five years after implantation of a modular stem-neck prosthesis. The swelling was diagnosed as pseudotumor based on laboratory trends and imaging findings and was treated with revision arthroplasty that completely resolved the initial hip swelling. The patient presented with recurrent hip swelling and recurrent pseudotumor findings on imaging in the same hip four months later. Non-operative management with ultrasound-guided hip aspiration resulted in symptom relief and resolution of the recurrent swelling. After one year of follow-up, the patient had no further recurrences of hip swelling.

CONCLUSION

This case of post-revision pseudotumor recurrence elucidates attributable patient, surgical, and implant factors with a discussion of diagnostics, management, and prognosis for patients with pseudotumor in non-metal-on-metal arthroplasty constructs.

Revision Total Wrist Arthroplasty Due to Polyethylene Wear, Metallosis-Induced Carpal Tunnel Syndrome, Distal Ulnar Impingement, and Fourth Carpometacarpal Joint Pain: Case Report and Pitfalls to Avoid

Background: Total wrist arthroplasty (TWA) is indicated to alleviate pain secondary to arthritis while preserving wrist motion. Despite vigilant measures, TWAs are susceptible to complications. The current case illustrates an array of preventable complications which are addressed through operative technique in a revision setting. Case presentation: The patient was a 72-year-old man who presented with chronic pain at the fourth carpometacarpal joint (CMCJ) and distal radioulnar joint with paresthesias in the median nerve distribution. Surgery was undertaken to address the following complications secondary to a previous TWA: impingement of the native distal ulna on the prosthesis, carpal tunnel due to metallosis and polyethylene synovitis, loose carpal component, and prominent screw at the fourth CMCJ. Surgical correction included open carpal tunnel release with extensive flexor tenosynovectomy, distal ulna resection and implant arthroplasty with shortening, revision of carpal component with bone grafting, and shortening of the ulnar screw to avoid crossing the fourth CMCJ. Within 6 months of the procedure, the patient reported resolution of neuropathic symptoms and pain-free motion of the wrist. Discussion: Preventable complications associated with TWA are individually highlighted. In addition, we compare and contrast our approach and surgical technique to current reported literature. Overall, we provide education and guidance to avoid possible TWA pitfalls. Conclusion: With this case report, we hope to increase TWA knowledge with emphasis on the requirements of judicious patient selection, preoperative planning, meticulous surgical technique, and complication awareness for subsequent optimization of wrist function, stability, and durability.

Metal Ion Release after Hip and Knee Arthroplasty - Causes, Biological Effects and Diagnostics

All metal implants in human bodies corrode which results in metal ions release. This is not necessarily a problem and represents for most patients no hazard. However, if a critical metal ion concentration is exceeded, local or rarely systemic problems can occur. This article summarizes the mechanisms of metal ion release and its clinical consequences. Several situations can result in increased metal ion release: metal-on-metal hip arthroplasties with increased wear, increased micromotion at taper interfaces, direct metal-metal contact (polyethylene wear, impingement), erroneously used metal heads after ceramic head fracture. Possible problems are in most cases located close to the concerned joint. Furthermore, there are reports about toxic damage to several organs. Most of these reports refer to erroneously used metal heads in revisions after a broken ceramic head. There is currently no evidence of carcinogenic or teratogenic effects of implants but data is not sufficient to exclude possible effects. Cobalt and chromium blood levels (favorably in whole blood) should be measured in patients with suspected elevated metal ions. According to current knowledge levels below 2 µg/l seem to be uncritical, levels between 2 and 7 µg/l are considered borderline with unknown biological consequences and levels above 7 µg/l indicate a local problem which should be further diagnosed. Metal ion levels always need to be interpreted together with clinical symptoms and imaging results.

Laser Resonance Frequency Analysis: A Novel Measurement Approach to Evaluate Acetabular Cup Stability During Surgery

Artificial joint acetabular cup stability is essential for successful total hip arthroplasty. However, a quantitative evaluation approach for clinical use is lacking. We developed a resonance frequency analysis (RFA) system involving a laser system that is fully contactless. This study aimed to investigate the usefulness of laser RFA for evaluating acetabular cup stability. First, the finite element method was performed to determine the vibration mode for analysis. Second, the acetabular cup was press-fitted into a reamed polyurethane cavity that replicated the human acetabular roof. The implanted acetabular cup was vibrated with pulse laser irradiation and the induced vibration was detected with a laser Doppler vibrometer. The time domain signal from the vibrometer was analyzed by fast Fourier transform to obtain the vibration frequency spectrum. After laser RFA, the pull-down force of the acetabular cup was measured as conventional implant fixation strength. The frequency of the first highest amplitude between 2 kHz and 6 kHz was considered as the resonance peak frequency, and its relationship with the pull-down force was assessed. The peak frequency could predict the pull-down force (R² = 0.859, p < 0.000). Our findings suggest that laser RFA might be useful to measure acetabular cup stability during surgery.

The influence of bearing surfaces on periprosthetic hip infections: analysis of thirty nine thousand, two hundred and six cementless total hip arthroplasties

PURPOSE

Periprosthetic hip infection (PHI) is a devastating complication. The association between PHI and bearing surfaces as well as patient-related factors has been recently investigated, with contradictive outcomes. The dataset of Emilia-Romagna region Registry for Orthopaedic Prosthetic Implants (RIPO) has been assessed to investigate, if the bearing choice influenced the risk of septic loosening occurrence.

METHODS

RIPO data about 39,206 cementless total hip arthroplasties (THA), collected since 2003, were analysed. Age, gender, BMI, diabetes and bearing surfaces were evaluated. The end point of the study was the revision of at least a single component due to sepsis.

RESULTS

Adjusted and unadjusted survival rates showed that ceramic-on-ceramic (COC) implants had the lower incidence of PHIs, whereas metal-on-metal (MOM) THAs were significantly more prone to infection. In MOM cohort, stemmed implants were involved in 28 out of 30 cases. Among the demographical features and comorbid conditions, only diabetes statistically influenced the rate of sepsis.

CONCLUSIONS

Bearing surfaces influenced the rate of PHI; in particular, stemmed MOM implants were at higher risk, probably due to metal debris consequent to taperosis. Despite the preliminary results, stemmed MOM THAs should be used with care, and diabetic patients should be warned about increased septic risks.

Aggressive granulomatosis of the hip: a forgotten mode of aseptic failure

PURPOSE

It has been acknowledged that implant wear correlates with the risk for periprosthetic osteolysis, being aggressive granulomatosis the worst expression of bone resorption. We sought to determine the clinical, radiological, and histological features of aggressive granulomatosis after primary total hip arthroplasty (THA).

METHODS

We included nine cases with aggressive granulomatosis of the hip around cemented stems. Indications for revision THA consisted of progressive signs of extensive bone resorption or implant loosening. Mean follow-up since revision THA was 143 months (SD ± 59.4). We analysed clinical outcomes, component loosening and gross as well as histological characteristics of the granulomatous lesions.

RESULTS

Overall mean time between primary THA and revision surgery was 81 months (SD ± 20.8). All of the cases evidenced multiple ovoid tumour-like lesions around the stem with extensive bone loss. Only one case reported thigh pain before revision surgery, with radiological evidence of stem loosening; the remaining cases were asymptomatic with well-fixed implants. Gross anatomy findings revealed metallosis in the femoral canal and inside the cystic lesions. Pathology analysis showed monocyte-macrophage-dominated adverse foreign-body-type tissue reaction with fibroblastic reactive zones and granulomatous inflammation.

CONCLUSIONS

We found a prevalence of 1% of this aseptic mode of implant failure. Since most of the retrieved stems were not loose, we did not find any alarming clinical symptoms anticipating implant failure. In this scenario, surgeons should be aware of the rapidly progressive nature of this entity and propose a revision THA in a timely fashion.

Pseudotumor and Subsequent Implant Loosening as a Complication of Revision Total Hip Arthroplasty with Ceramic-on-Metal Bearing: A Case Report

Pseudotumors are not uncommon complications after total hip arthroplasty (THA) and may occur due to differences in bearing surfaces of the head and the liner ranging from soft to hard articulation. The most common causes of pseudotumors are foreign-body reaction, hypersensitivity and wear debris. The spectrum of pseudotumor presentation following THA varies greatly-from completely asymptomatic to clear implant failure. We report a case of pseudo-tumor formation with acetabular cup aseptic loosening after revision ceramic-on-metal hip arthroplasty. The patient described herein underwent pseudotumor excision and re-revision complex arthroplasty using a trabecular metal shell and buttress with ceramic-on-polyethylene THA. Surgeons should be aware of the possibility of a pseudotumor when dealing with revisions to help prevent rapid progression of cup loosening and implant failure, and should intervene early to avoid complex arthroplasty procedures.

Adverse reaction to metal debris after small-head diameter metal-on-metal total hip arthroplasty: an increasing concern

INTRODUCTION:

Failures due to adverse reaction to metal debris (ARMD) have become an area of common focus among surgeons performing hip replacements. Several authors have reported data on the prevalence of these masses, in both symptomatic and asymptomatic patients after either large-diameter head metal-on-metal (MoM) total hip arthroplasty (THA) or hip resurfacing arthroplasty, with a large variability of rate. To our knowledge, few data are reported on the association of this lesion with the use of small-head diameter MoM.

METHODS:

15 hips that were revised for ARMD in small-head MoM THA were included in this study. We focused our attention on the difficulties of diagnosis and treatment and also on the histologic aspects of the harvested pathologic tissue.

RESULTS:

The histological examination of our cases showed a presence of lymphocytic infiltrate suggesting a delayed hypersensitivity reaction to the metal of type IV (ALVAL), but different from each other in term of the prevalence of the cellular component. Osteolysis and severe soft tissue damage were also observed. Revision resulted in remission of the lesion and successful implant.

CONCLUSIONS:

Our observation suggests that the evidence of ARMD should be considered even in case of small-head MoM arthroplasty and therefore these patients should be followed scrupulously with 2nd level diagnostic tools such as magnetic resonance imaging with metal artifact reduction sequence (MARS-MRI) and metal ion levels at least once. Further investigations are necessary to establish the real prevalence of this phenomenon in the whole population of small-head MoM THAs.

Metal ion trend in patients with metal-on-metal total hip arthroplasty: a 10-year prospective study

INTRODUCTION:

There have been reported adverse reactions in patients with large head metal-on-metal hip arthroplasty, therefore metal particle debris are a cause for concern. The aim of this study was to evaluate the release trend of metal ions and the correlated variables.

METHODS:

54 patients were prospectively enrolled into the study from 2004 to 2006. All patients had 36-mm metal head, Pinnacle acetabular component, Summit stem and Ultamet CoCr alloy liner (Depuy Inc.), and underwent clinical and radiological management. The haematic concentration of Cr-Co at 0, 6, 12, 24, 60 and 120 months after the implantation was analysed in a sub-cohort of 34 patients.

RESULTS:

10-year revision rate for each case was 8.9%. The average concentration of Co at 120 months was 3.12 μg/L (median 2.20) with 53% values >2 μg/L and 1 >7 μg/L. After 6 months the median levels of Cr and Co were higher than time 0 ( p < 0.0001); no significant differences were found between 6 and 24 months; while Co had significant increase between 60 and 120 months ( p = 0.002). Overweight, University of California at Los Angeles (UCLA) >9 and <50 years old patients have significantly higher circulating metal ions.

DISCUSSION:

This is 1 of the few prospective studies on the argument. The revision rate is conforming to records. Our data shows ionic concentration is not predictive of revision or adverse reaction to metals. We described a 3-phase trend for Co probably due to the loss of integrity of the surfaces.

Assessment of material loss of retrieved magnetically controlled implants for limb lengthening

Purpose: We aimed to understand wear from the telescopic component of PRECICE nails, which are used for distraction osteogenesis of the femur or tibia. We also aimed to identify any correlation between implant performance and patient factors. Methods: This retrieval study involved 11 magnetically controlled intramedullary nails from nine patients who had achieved the targeted leg length. All the nails were assessed macroscopically and microscopically for wear. All implants were radiographed to assess the internal mechanism. A Talyrond 365 (Taylor Hobson, Leicester, UK) roundness measuring machine was used to generate three-dimensional surface maps of the telescopic components to allow for measurement of wear. Results: Visual assessment of all the nails showed evidence of wear from the telescopic component. The radiographs revealed that all the nails had intact internal mechanism and no evidence of fractured pins. The roundness measuring machine showed that the quantity of wear was lowest in the latest design of the PRECICE nail. There was no significant correlation between wear and the two patient factors (duration of the lengthening phase, the time of implantation) included in this study. Conclusion: This study is the first to investigate the performance of the three different designs of the PRECICE system with a focus on wear. We found that the latest design had the best implant performance. We are confident of the continued success of the PRECICE system and reassure surgeons and patients that they are unlikely to encounter problems with the implant related to wear.

A six-year observational study of 31 children with early-onset scoliosis treated using magnetically controlled growing rods with a minimum follow-up of two years

Aims

Magnetically controlled growing rod (MCGR) systems use non-invasive spinal lengthening for the surgical treatment of early-onset scoliosis (EOS). The primary aim of this study was to evaluate the performance of these devices in the prevention of progression of the deformity. A secondary aim was to record the rate of complications.

Patients and Methods

An observational study of 31 consecutive children with EOS, of whom 15 were male, who were treated between December 2011 and October 2017 was undertaken. Their mean age was 7.7 years (2 to 14). The mean follow-up was 47 months (24 to 69). Distractions were completed using the tailgating technique. The primary outcome measure was correction of the radiographic deformity. Secondary outcomes were growth, functional outcomes and complication rates.

Results

The mean Cobb angle was 54° (14° to 91°) preoperatively and 37° (11° to 69°) at the latest follow-up (p < 0.001). The mean thoracic kyphosis (TK) was 45° (10° to 89°) preoperatively and 42° (9° to 84°) at the latest follow-up. The mean T1-S1 height increased from 287 mm (209 to 378) to 338 mm (240 to 427) (p < 0.001) and the mean sagittal balance reduced from 68 mm (-76 to 1470) preoperatively to 18 mm (-32 to 166) at the latest follow-up. The mean coronal balance was 3 mm (-336 to 64) preoperatively and 8 mm (-144 to 64) at the latest follow-up. The mean increase in weight and sitting and standing height at the latest follow-up was 45%, 10% and 15%, respectively. The mean Activity Scale for Kids (ASKp) scores increased in all domains, with only personal care and standing skills being significant at the latest follow-up (p = 0.02, p = 0.03). The improvements in Cobb angle, TK and T1-S1 heights were not related to gender, the aetiology of the EOS, or whether the procedure was primary or conversion from a conventional growing rod system. A total of 21 children developed 23 complications at a rate of 0.23 per patient per year. Seven developed MCGR-specific complications. Complications developed at a mean of 38 months (3 to 67) after the initial surgery and required 22 further procedures. Children who developed a complication were more likely to be younger, have syndromic EOS, and have a single-rod construct (6.9 versus 9.3 years, p = 0.034).

Conclusion

The progression of EOS can be controlled using MCGRs allowing growth and improved function. Younger and syndromic children are more likely to develop complications following surgery. Cite this article: Bone Joint J 2018;100-B:1187-1200.

Silva M, Coelho R, Cardoso P, Oliveira V. Pseudotumor complicating a well-fixed ceramic-on-polyethylene total hip arthroplasty

A suspicious area surrounding hardware components, usually following arthroplasty, should raise awareness to a possible particle related disease. Even in the presence of confusing or less typical symptoms, clinicians and surgeons must join efforts to diagnose and treat the patient effectively and in the appropriate time.

Is There a Cardiotoxicity Associated With Metallic Head Hip Prostheses? A Cohort Study in the French National Health Insurance Databases

BACKGROUND

There are four distinguishable types of THA devices in wide use, as defined by the femoral and acetabular bearing surfaces: metal-on-polyethylene (MoP), ceramic-on-polyethylene (CoP), metal-on-metal (MoM), and ceramic-on-ceramic (CoC). Metallic head THAs (MoP and MoM) can potentially induce cardiac toxicity because cobalt species, generated at the head-neck trunnion, and in the case of MoM devices, at the articular surface as well, can be absorbed systemically. However, studies have provided inconsistent results.

QUESTIONS/PURPOSES

The purpose of this study was to assess the risk of dilated cardiomyopathy (DCM) or heart failure (HF) associated with metallic head THAs using data from the French national health insurance databases.

METHODS

Between 2008 and 2011 in France, 399,968 patients ≥ 55 years had a first THA. A total of 127,481 were excluded after we applied the exclusion criteria regarding arthroplasty and 17,137 as a result of a history of DCM/HF, recorded in the French national health insurance reimbursement databases, between January 1, 2006, and the date of inclusion. The final cohort included 255,350 individuals (43% men; mean age 72 ± 9 years). Of them, 93,581 (37%) had been implanted with MoP, 58,095 (23%) with CoP, 11,298 (4%) with MoM, and 92,376 (36%) with CoC THAs. Patients were followed until December 2015. Patients with incident DCM/HF were identified by a new entitlement to the long-term disease scheme or a first hospitalization with a diagnosis of DCM or HF. MoP and CoP THAs are generally implanted in old patients, whereas MoM and CoC are mostly indicated in young, active male patients. Thus, to consider the specific indications of the bearing couples, analyses were separately performed in two distinct subcohorts, one comprising patients with MoP or CoP and one comprising patients with MoM or CoC THA. In each subcohort, the DCM/HF risk was compared between patients with metallic head versus nonmetallic head THAs (MoP versus CoP, MoM versus CoC). Hazard ratios (adjusted HRs) of incident DCM/HF were estimated using Cox models adjusted for baseline sex, age, THA characteristics (fixation technique with cement, use of a modular femoral neck), and comorbidities at baseline. Cox models were stratified by sex and age.

RESULTS

The crude incidence of DCM/HF per 100 person-years was 2.4 in patients with MoP, 1.8 with CoP, 1.2 with MoM, and 1.1 with CoC THAs. Overall, metallic head THAs were associated with a slight increase in DCM/HF risk (MoP versus CoP: adjusted HR, 1.08; 95% confidence interval [CI], 1.05-1.12; p < 0.001; MoM versus CoC: adjusted HR, 1.11; 95% CI, 1.03-1.19; p = 0.007). In the MoM-CoC subcohort, the risk tended to be more pronounced with MoM versus CoC THAs in women (MoM versus CoC: adjusted HR, 1.20; 95% CI, 1.07-1.35; p = 0.002) and patients aged ≥ 75 years (MoM versus CoC: adjusted HR, 1.16; 95% CI, 1.04-1.29; p = 0.009).

CONCLUSIONS

Metallic head THAs were associated with a slightly increased DCM/HF risk, especially with MoM in women and older patients. Some caveats should be mentioned: severity of DCM or HF was not available and residual confounding cannot be ruled out despite considering many covariates. Our findings suggest that cardiac function should be regularly monitored in patients with metallic head THAs. Further investigations should be planned on large international cohorts.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Differential proteomic analysis of synovial fluid from hip arthroplasty patients with a pseudotumor vs. Periprosthetic osteolysis

Adverse tissue reactions to metal implants, including pseudotumors, can compromise implant functionality and survivorship. The identification of specific proteins in the synovial fluid (SF) of hip arthroplasty patients with a pseudotumor may lead to a better understanding of the underlying pathomechanisms. The objective of the present study was to compare the protein content of SF from patients with a short-term metal-on-metal hip implant associated with a pseudotumor and patients with a long-term metal-on-polyethylene hip implant associated with periprosthetic osteolysis. Discovery proteomics was used to identify differentially abundant proteins in albumin-depleted SF. In toto, 452 distinct proteins (present in at least half of the patients in one or both groups) were identified. Thirty of these 452 proteins were differentially abundant between the two groups, including two potential biomarkers: 6-phosphogluconate dehydrogenase (which plays a major protective role against oxidative stress) for the pseudotumor group, and scavenger receptor cysteine-rich type 1 protein M130 (which is involved in low-grade inflammation) for the periprosthetic osteolysis group. Other differentially abundant proteins identified suggest the presence of an adaptive immune response (particularly a type-IV hypersensitivity reaction), necrosis, and greater oxidative stress in patients with a pseudotumor. They also suggest the presence of an innate immune response, oxidative stress, tissue remodeling, and apoptosis in both patient groups, although differences in the specific proteins identified in each group point to differences in the pathomechanisms. Overall, results provide insights into the molecular mechanisms underlying metal-related pseudotumors and periprosthetic osteolysis, and may ultimately help elucidate pseudotumor etiology and assess the risk that asymptomatic pseudotumors will develop into an aggressive lesion. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1849-1859, 2018.

Periosteal pseudotumor in complex total knee arthroplasty resembling a neoplastic process

This case report describes in detail an erosive distal diaphyseal pseudotumor that occurred 6 years after a complex endoprosthetic hinge total knee arthroplasty (TKA). A female patient had conversion of a knee fusion to an endoprosthetic hinge TKA at the age of 62. At her scheduled 6-year follow-up, she presented with mild distal thigh pain and radiographs showing a 6-7 cm erosive lytic diaphyseal lesion that looked very suspicious for a neoplastic process. An en bloc resection of the distal femur and femoral endoprosthesis was performed. Histologic review showed the mass to be a pseudotumor with the wear debris emanating from within the femoral canal due to distal stem loosening. We deduce that mechanized stem abrasion created microscopic titanium alloy particles that escaped via a small diaphyseal crack and stimulated an inflammatory response resulting in a periosteal erosive pseudotumor. The main lesson of this report is that, in the face of a joint replacement surgery of the knee, pseudotumor formation is a more likely diagnosis than a neoplastic process when encountering an expanding bony mass. Thus, a biopsy prior to en bloc resection, would be our recommended course of action any time a suspicious mass is encountered close to a TKA.

[Mid-term effectiveness of large-head metal-on-metal total hip arthroplasty]

Objective

To explore the mid-term effectiveness of large-head metal-on-metal total hip arthroplasty (THA).

Methods

A retrospective analysis was made on the clinical date of 40 patients (43 hips) who were treated with the large-head metal-on-metal THA between April 2009 and June 2010. There were 18 males (20 hips) and 22 females (23 hips) with an average age of 55.1 years (range, 20-85 years). Unilateral hip was involved in 37 cases and bilateral hips in 3 cases. The disease causes included osteonecrosis of the femoral head in 14 cases (15 hips), osteoarthritis in 6 cases (7 hips), rheumatoid arthritis in 4 cases (4 hips), femoral neck fracture in 4 cases (4 hips), and developmental dysplasia of the hip in 12 cases (13 hips). Before operation, the Harris score and University of California Los Angeles (UCLA) score were 38.51±5.62 and 4.21±1.43, respectively. The visual analogue scale (VAS) score was 6.78±0.95.

Results

All patients were followed up 6.7-8.3 years (mean 7.5 years). All incisions healed primarily and no neurovascular injury, infection, and hip dislocation occurred. At last follow-up, the Harris score and UCLA score were 93.33±3.21 and 7.32±1.45, respectively, showing significant differences when compared with preoperative scores ( t=51.753, P=0.000; t=23.232, P=0.000). The thigh pain occurred in 3 cases (3 hips) in whom the inflammatory pseudotumor of soft tissues was found in 1 case (1 hip). Postoperative X-ray films showed that the acetabular abduction angle and anteversion angle were (46.5±3.2)° and (14.8±3.6) °, respectively. The initial stability of femoral stem prosthesis was excellent in 39 hips and good in 4 hips according to Mulliken standard. Osteolysis occurred in 2 hips and revision was performed in 1 hip of secondary loosening of prosthesis. The rest patients had no prosthesis loosening or sinking.

Conclusion

The mid-term effectiveness of large-head mental-on-mental THA in treatment of the terminal diseases of hips are good.

PET/CT to detect adverse reactions to metal debris in patients with metal-on-metal hip arthroplasty: an exploratory prospective study

Metal-on-metal (MoM) bearings in total hip arthroplasties and hip resurfacing arthroplasties have recently shown a new type of complication: adverse reactions to metal debris (ARMD). ARMD is characterized by local severe inflammation and tissue necrosis leading to implant failures. The gluteal muscle region is important for the patient outcome after revision surgery. This prospective positron emission tomography/computed tomography (PET/CT) study was undertaken to evaluate the characteristics of 2-deoxy-2-[¹⁸ F]fluoro-d-glucose ([¹⁸ F]FDG) and [⁶⁸ Ga]Gallium citrate ([⁶⁸ Ga]Citrate) PET/CT in ARMD patients. [¹⁸ F]FDG and [⁶⁸ Ga]Citrate PET/CT were performed in 18 hip arthroplasty patients: 12 ARMD patients (with 16 MoM hips) and six arthroplasty controls without ARMD. Tracer uptake was evaluated visually, and maximum standardized uptake (SUV_max ) was measured in the gluteal muscle region. ARMD severity was graded by metal artefact reduction sequence-magnetic resonance imaging (MARS-MRI). Periprosthetic [¹⁸ F]FDG uptake was observed in 15 of 16 hips, [⁶⁸ Ga]Citrate uptake in three of 16 hips, respectively. The distribution of tracer uptake resembled infection in three hips. In the gluteal muscle region, the SUV_max of [¹⁸ F]FDG was significantly greater in hips with moderate and severe ARMD compared with the controls (P = 0·009 for [¹⁸ F]FDG and P = 0·217 for [⁶⁸ Ga]Citrate). In patients who needed revision surgery, an intraoperative finding of gluteal muscle necrosis was associated with increased local SUV_max as detected by preoperative [¹⁸ F]FDG (P = 0·039), but not by [⁶⁸ Ga]Citrate (P = 0·301). In conclusion, the inflammatory reaction to metal debris in hip arthroplasty patients is best visualized with [¹⁸ F]FDG.

Ultrasound findings in asymptomatic patients with modular metal on metal total hip arthroplasty

OBJECTIVE

The use of metal-on-metal and modular total hip arthroplasty is associated with potentially serious local and systemic complications. The primary aim of this study was to identify the prevalence of a pseudotumor in asymptomatic patients with a particular metal-on-metal hip prosthesis after a minimum follow-up of 5 years using ultrasound evaluation. A secondary purpose was to identify associations between the presence of pseudotumor and serum metal ion levels following implantation.

METHODS

We prospectively evaluated data collected from 36 asymptomatic patients who underwent implantation of a Profemur Z metal-on-metal total hip arthroplasty from January 2004 to January 2010. Serum metal ion levels were collected in 2012 and 2015. Hip ultrasounds were performed in 2015.

RESULTS

Pseudotumors were found in 7/36 patients (19.4%). The average pseudotumor size measured 38.2 cm³ (range 7.35 cm³-130.81 cm³). Elevated metal ion levels were found in all patients at all time points. No statistical correlation was found between the presence of pseudotumor and patient age, age of the implant, component design, and any of the serum metal ion levels or ratios.

CONCLUSIONS

One in every five asymptomatic patients with metal-on-metal implants was found to have a periarticular pseudotumor. There was no dose-dependent relationship found between elevated serum metal ion levels and the development of a pseudotumor. Our findings suggest that in patients with known elevated metal ion levels, continued monitoring of ion levels may not be a reliable predictor of pseudotumor formation, and ultrasound surveillance can and should be routinely used to document the presence and progression of pseudotumor.

Metallosis following implantation of magnetically controlled growing rods in the treatment of scoliosis: a case series

AIMS

We present a case series of five patients who had revision surgery following magnetic controlled growing rods (MGCR) for early onset scoliosis. Metallosis was found during revision in four out of five patients and we postulated a mechanism for rod failure based on retrieval analysis.

PATIENTS AND METHODS

Retrieval analysis was performed on the seven explanted rods. The mean duration of MCGR from implantation to revision was 35 months (17 to 46). The mean age at revision was 12 years (7 to 15; four boys, one girl).

RESULTS

A total of six out of seven rods had tissue metallosis and pseudo-capsule surrounding the actuator. A total of four out of seven rods were pistoning. There were two rods which were broken. All rods had abrasive circumferential markings. A significant amount of metal debris was found when the actuators were carefully cut open. Analytical electron microscopy demonstrated metal fragments of predominantly titanium with a mean particle size of 3.36 microns (1.31 to 6.61).

CONCLUSION

This study highlights concerns with tissue metallosis in MCGR. We recommend careful follow-up of patients who have received this implant. Cite this article: Bone Joint J 2016;98-B:1662-7.

A 5-year survival analysis of 160 Biomet Magnum M2 metal-on-metal total hip prostheses

BACKGROUND

Large-head metal-on-metal (MoM) total hip arthroplasties (THA) are associated with high failure rates and possible pseudotumour formation. This study reports the first results of 160 Biomet Magnum M2 large-head MoM total hip articulations.

PATIENTS AND METHODS

From 2006 to 2010 the Reinier de Graaf Hospital implanted 160 large-head Magnum M2 MoM THAs (Biomet Inc. Warsaw, Indiana, USA) in 150 patients. These patients were recalled after a warning from the Dutch Orthopaedic Association. Patients were offered a clinical and radiographic assessment of the hip prosthesis, serum control on cobalt and chromium ions, and an ultrasound of the hip. If indicated, additional MARS-MRI or CT scan was performed. Descriptive statistical analysis, correlations, t-tests, non-parametric tests and implant survival were calculated.

RESULTS

The mean follow-up was 6.1 years (4.8-8.4). A cumulative survival rate of 93.1% (95% CI: 88.3-98%) was found after 5 years. Reasons for revision were loosening, pain, infection and pseudotumour formation. The prevalence of pseudotumour formation around the prostheses was 8.75%.

CONCLUSIONS

This study reports the first results of 160 MoM THAs implanted in our clinic from 2006-2010. In total, 13 (8.1%) of the THAs were eligible for revision after the recall. In most patients the reason for revision was pseudotumour formation. A total of 14 (8.75%) pseudotumours were diagnosed at the first recall. These results show that a comprehensive follow-up strategy is essential for MoM THAs to promptly identify and manage early complications.

Metal wear-induced pseudotumour following an endoprosthetic knee replacement for Ewing sarcoma

Pseudotumours are well recognised as a complication of metal-on-metal hip arthroplasties and are thought to develop on the basis of an innate and adaptive immune response to cobalt-chrome (Co-Cr) wear particles. We report a case of a large pseudotumour that developed following a knee endoprosthetic replacement (EPR) undertaken for Ewing sarcoma. The lesion contained necrotic and degenerate connective tissue in which there were numerous scattered metal wear-containing macrophages, eosinophil polymorphs, lymphocytes, plasma cells and aseptic lymphocyte-dominated vascular-associated lesion-like lymphoid aggregates. Metal ion levels were elevated. No evidence of infection or tumour was noted and it was concluded that the lesion was most likely an inflammatory pseudotumour developing on the basis of an innate and adaptive immune response to components of Co-Cr metal wear derived from the knee EPR.

Longitudinal Followup of Incidentally Detected Pseudotumors in Patients with Metal on Metal Implants: A Retrospective Study

BACKGROUND

This study describes the significance and temporal evolution of incidentally detected, presumed, metal-induced reactive periprosthetic masses in patients with metal on metal (MoM) hip arthroplasty and its management. The literature concerning the temporal evolution of these lesions is meagre and so it is still unclear, whether asymptomatic patients with periprosthetic collections should undergo revision.

MATERIALS AND METHODS

Patients with MoM hip replacements fitted with a recalled implant (ASR, DuPuy) often undergo magnetic resonance imaging with metal artifact reduction sequences to look for complications. From a cohort of 136 asymptomatic patients, with 181 MoM hips, hips with a mention of periprosthetic masses in their reports at first presentation, and a repeat scan within 6 months to 3 years were selected for this retrospective study. Patients with complications such as loosening, osteomyelitis, and muscle/tendon tears were excluded from the study, and the final study cohort consisted of 55 MoM hips and 61 periprosthetic masses. Ethics committee approval is not required in our institution for retrospective studies. The followup scans of each patient were compared, and the periprosthetic masses were described to have progressed, regressed, or remained unchanged.

RESULTS

Comparison revealed that 29 of the 61 reactive masses remained unchanged, 20 regressed, while only 12 showed progression. The study, therefore, has maximum power as the outcome of interest, i.e., regression or unchanged status of the pseudotumors, was seen in approximately 80% (more than half) of the study group. The P value of the study was < 0.005.

CONCLUSION

Periprosthetic soft tissue masses are not uncommon in patients with MoM hips. The majority of them in asymptomatic individuals remain stable or regress in the short to medium term, and close followup or decisions on revision surgery may not be warranted in asymptomatic patients.

Targeting Toll-like receptor 4 prevents cobalt-mediated inflammation

Cobalt-chrome alloy is a widely used biomaterial in joint replacements, dental implants and spinal rods. Although it is an effective and biocompatible material, adverse reactions to metal debris (ARMD) have arisen in a minority of patients, particularly in those with metal-on-metal bearing hip replacements. There is currently no treatment for ARMD and once progressive, early revision surgery of the implant is necessary. Therapeutic agents to prevent, halt or reverse ARMD would therefore be advantageous.

Cobalt ions activate Toll-like receptor 4 (TLR4), an innate immune receptor responsible for inflammatory responses to bacterial lipopolysaccharide (LPS) resulting in the production of pro-inflammatory cytokines and chemokines. We hypothesised that anti-TLR4 neutralising antibodies, reported to inhibit TLR4-mediated inflammation, could prevent the inflammatory response to cobalt ions in an in vitro macrophagecell culture model.

This study shows that a monoclonal anti-TLR4 antibody inhibited cobalt-mediated increases in pro-inflammatory IL8, CCL20 and IL1A expression, as well as IL-8 secretion. In contrast, a polyclonal antibody did not prevent the effect of cobalt ions on either IL-8 or IL1A expression, although it did have a small effect on the CCL20 response. Interestingly, both antibodies inhibited cobalt-mediated neutrophil migration although the greater effect was observed with the monoclonal antibody.

In summary our data shows that a monoclonal anti-TLR4 antibody can inhibit cobalt-mediated inflammatory responses while a polyclonal antibody only inhibits the effect of specific cytokines. Anti-TLR4 antibodies have therapeutic potential in ARMD although careful antibody design is required to ensure that the LPS response is preserved.