Trunnion Failure of the Recalled Low Friction Ion Treatment Cobalt Chromium Alloy Femoral Head

Do Intra-articular Metal Ion Levels Predict Adverse Local Tissue Reaction in Revision Total Hip Arthroplasty for Mechanically Assisted Crevice Corrosion?

BACKGROUND

Mechanically assisted crevice corrosion is a complication that may occur in vivo at modular metal interfaces following metal-on-polyethylene total hip arthroplasty (THA). Metal ions released in vivo may be associated with adverse local tissue reactions (ALTRs). While there is no definitive value, high serum ion levels are implicated as contributors to ALTR, and various screening levels have been recommended. The purpose of this investigation was to evaluate the relationship between synovial fluid (SF) cobalt and chromium ion levels and the risk of developing ALTR.

METHODS

This was a retrospective cohort study of 552 patients who underwent 621 metal-on-polyethylene primary THAs. A total of 69 patients underwent revision THA due to symptomatic primary failure with elevated serum metal ions levels. There were 28 who had preoperative serum and intraoperative SF chromium and cobalt samples. Patient demographics, surgical, and laboratory data were collected. Descriptive statistics, Mann-Whitney U, analysis of variance tests, and linear regression analyses were performed.

RESULTS

There were 40.6% of revisions that had preoperative serum and intraoperative SF samples. The mean time to revision was 5.7 (range, 3.8 to 7.6) years. Mean SF cobalt and chromium levels were 870.9mcg/L (range, 1.1 to 8,300.0) and 573.5mcg/L (range, 1.3 to 10,000.0). Mean serum and SF cobalt-chromium ratios were 4.0 (range, 0.9 to 7.1) and 6.4 (range, 0 to 15.1), respectively. Elevated serum cobalt levels were predictive of ALTR (P = 0.002), SF levels were not. Analysis of preoperative serum to SF cobalt-chromium ratios showed poor correlation (R2 = 0.05).

CONCLUSIONS

There was no correlation between SF ion levels and ALTR. Also, serum and intra-articular ion levels did not correlate. The SF levels did not provide additional value over serum levels for diagnosis or prognosis of mechanically assisted crevice corrosion. Further studies are needed to better understand the relationship between serum and SF ion levels and its relationship to ALTR.

Failure Following Revision Total Hip Arthroplasty After Cobalt-Chrome Femoral Heads are Placed on a Retained Femoral Stem

BACKGROUND

Failure due to trunnionosis with adverse local tissue reaction (ALTR) has been reported with cobalt-chrome (CoCr) heads in total hip arthroplasty (THA); however, there are limited data on the use of these heads in the revision setting. The purpose of this study was to analyze the outcomes of patients who underwent revision THA with a retained femoral component and received a CoCr femoral head on a used trunnion.

METHODS

In this retrospective review, we identified all patients who underwent revision THA with a retained femoral component and received a CoCr femoral head between February 2006 and March 2014. Demographic factors, implant details, and postoperative complications, including the need for repeat revisions, were recorded. In total, 107 patients were included (mean age 67 years, 74.0% women). Of the 107 patients, 24 (22.4%) required repeat revisions.

RESULTS

Patients who required repeat revision were younger than those who did not (mean age: 62.9 versus 69, P = .03). The most common indications for repeat revision were instability (8 of 24, 33.3%), ALTR (5 of 24, 20.8%), and infection (4 of 18, 16.7%). Evidence of ALTR or metallosis was identified at the time of reoperation in 10 of the 24 patients who underwent re-revision (41.7%).

CONCLUSIONS

The placement of a new CoCr femoral head on a used trunnion during revision THA with a retained femoral component carries a significant risk of complication (22.4%) and should be avoided when possible.

Removal of uncemented components: hope for the best, prepare for the worst-technical tips and tricks

Removing well-fixed uncemented components can be challenging. With thoughtful surgical planning, appropriate surgical instruments, and proper surgical techniques, most implants can be removed expeditiously with little bone loss and minimal impact on the subsequent reconstruction. Preoperative planning is one of the most essential steps to remove uncemented implants. Obtaining previous surgical records, although tedious, should always be attempted preoperatively to determine if specific instruments will be required and to help anticipate which steps may need special attention. These include the presence of ceramic or metal bearings and the presence of acetabular screws or stem collars. Without proper preparation and available tools, the removal of implants can negatively impact the subsequent reconstruction and patient outcomes. We will describe techniques and practical tips for removing uncemented stems from the top (intramedullary) or transfemoral using an extended trochanteric osteotomy. We will also describe techniques and tools to remove uncemented acetabular shells efficiently. Case examples will highlight these clinical situations where careful planning is necessary and potential problems that may be encountered with the recurring theme of preparing for the worst but hoping for the best. We have also included cases such as removing well-fixed cementless collared stems, broken stems, and fully coated stems.

Gross trunnion failure in an elderly obese patient presenting 10 years after total hip arthroplasty with a cobalt chromium femoral head: A case report

INTRODUCTION

Trunnionosis of total hip prosthesis is defined as corrosion at the head-neck taper junction combined with local tissue reaction. Trunnionosis is a rare complication of total hip arthroplasty (THA) that is often missed in diagnosis. Severe trunnionosis can result in head-neck dissociation, which is called gross trunnion failure (GTF).

CASE PRESENTATION

We describe a case of GTF in a 70-year-old male patient 10 years after right total hip arthroplasty with a cobalt chromium (CoCr) femoral head and a titanium alloy stem. A revision of the stem, cup and femoral head was performed. Six months after surgery, the patient is recovering well and walking.

DISCUSSION

Trunnionosis is associated with hip prostheses with a CoCr femoral head and a titanium alloy stem. Metal Artefact Reduction Sequence (MARS) and serum cobalt and chromium levels are diagnostic tools that can be useful when trunnionosis is suspected.

CONCLUSION

Trunnionosis remains hard to diagnose in an early stage when gross trunnion failure is not present. This case of a 70-year-old patient with gross trunnion failure 10 years after right total hip arthroplasty supports the literature suggesting that a CoCr femoral head, a high body mass index (BMI), and a longer implantation time are risk factors for developing trunnionosis. When conventional X ray and C-reactive protein are inconclusive, serum cobalt and chromium levels should be determined. When serum cobalt and chromium levels are elevated, a MARS MRI should be performed to confirm trunnionosis.

Trunnionosis in Metal-on-Polyethylene Total Hip Arthroplasty With Periprosthetic Infection: A Case Report

A 67-year-old man who underwent right hemiarthroplasty and left total hip arthroplasty (THA) experienced left hip pain two years previously. No previous diagnosis was made at other hospitals. Radiography revealed left hip trunnionosis because of stem-neck shortening, with periprosthetic joint infection (PJI) spreading to both hips. Bilateral revision THA was performed, but the treatment was difficult due to the delayed diagnosis, necessitating the extraction of the well-fixed stem for PJI. Trunnionosis is caused by implant-related, surgical, and patient factors, and early diagnosis is important because of its association with PJI. Furthermore, even implants with few reports of trunnionosis can lead to this complication. Surgeons should always consider that performing THA using a large-diameter head predisposes the patient to trunnionosis.

Can severity of trunnion damage be estimated by visual inspection alone?

Taper corrosion has been widely reported to be problematic for modular total hip arthroplasty implants. A simple and systematic method to evaluate taper damage with sufficient resolution is needed. We introduce a semiquantitative grading system for modular femoral tapers to characterize taper corrosion damage. After examining a unique collection of retrieved cobalt-chromium (CoCr) taper sleeves (n = 465) using the widely-used Goldberg system, we developed an expanded six-point visual grading system intended to characterize the severity, visible material loss, and absence of direct component contact due to corrosion. Female taper sleeve damage was evaluated by three blinded observers using the Goldberg scoring system and the expanded system. A subset (n = 85) was then re-evaluated following destructive cleaning, using both scoring systems. Material loss for this subset was quantified using metrology and correlated with both scoring systems. There was substantial agreement in grading among all three observers with uncleaned (n = 465) and with the subset of cleaned (n = 85) implants. The expanded scoring criteria provided a wider distribution of scores which ultimately correlated well with corrosion material loss. Cleaning changed the average scores marginally using the Goldberg criteria (p = 0.290); however, using the VGS, approximately 40% of the scores for all observers changed, increasing the average score from 4.24 to 4.35 (p = 0.002). There was a strong correlation between measured material loss and new grading scores. The expanded scoring criteria provided a wider distribution of scores which ultimately correlated well with corrosion material loss. This system provides potential advantages for assessing taper damage without requiring specialized imaging devices.

Do polyethylene wear particles affect the development of pseudotumor in total hip arthroplasty? A minimum 15-year follow-up

BACKGROUND

Adverse local tissue reactions have been problematic as an implant-related complication in total hip arthroplasty (THA). Despite the absence of significant metal wear and corrosion, granulomatous pseudotumor has been reported to be caused by polyethylene wear. We performed a long-term follow-up study investigating the relationship between polyethylene wear and pseudotumor formation in THA.

METHODS

This study included 57 patients (64 hips) that underwent primary THA with metal-on-polyethylene or ceramic-on-polyethylene bearing over a minimum follow-up of 15 years. They were stratified into pseudotumor and non-pseudotumor groups and their linear wear rates of polyethylene liner and serum cobalt (Co) and chromium (Cr) ion levels were compared. Pseudotumor was diagnosed on metal artifact reduction sequence-MRI according to its composition and wall thickness using the Hauptfleisch classification.

RESULTS

The incidence of pseudotumor was 34% (22/64 hips) at the mean follow-up of 16.9 years. Metal ion levels did not differ between the pseudotumor and non-pseudotumor groups, and none of the patients exceeded the Co/Cr ratio of 2.0 μg/L. Moreover, the wear rate in the pseudotumor group was 1.8 times greater than in the non-pseudotumor group (0.14 vs. 0.08 mm/year, P < 0.001). According to an analysis of the receiver operating characteristic curves, the cutoff level of the wear rate to discriminate between pseudotumor and non-pseudotumor patients at 15 years was 0.11 mm/year (area under the curve = 91%; sensitivity = 95%; specificity = 78%; accuracy = 87%).

CONCLUSIONS

Our results might provide new insights into excessive polyethylene wear potentially leading to the future development of both pseudotumor and osteolysis. Further studies are needed to clarify the direct relationship between polyethylene wear and pseudotumor and the mutual effects of osteolysis and pseudotumor in particle reactions.

Trunnions and Modularity in Total Hip Arthroplasty: A Historical Review With Current Clinical Implications

Trunnion in total hip arthroplasty refers to the interface between the neck of a femoral stem and the femoral head. Clinical complications arising from damage to this junction, whether it be due to mechanical wear, corrosion, or a combination, are referred to as mechanically assisted crevice corrosion (MACC), also commonly known as trunnionosis. With the use of modular hip prostheses, which help customize offset and leg length to an individual patient's anatomy, the incidence of MACC and revision due to MACC has increased in recent years. Although the cause of MACC is multifactorial, with patient factors and technique factors contributing to this condition, taper design and geometry, metallurgical properties of implants, and size mismatch of the bearing couple are some of the implant factors that have also been implicated in this clinical phenomenon. Understanding the history of taper design and geometry, the track record of older implants, and the rationale behind the development of current prostheses can help surgeons choose the right implants for their patients and accurately assess the pros and cons of new implants being introduced to the market each year.

Application of 3D-printed prosthesis in revision surgery with large inflammatory pseudotumour and extensive bone defect: A case report

BACKGROUND

Hip revision surgery is the final treatment option for the failure of artificial hip joints, but it is more difficult than the initial operation. For patients with hip joint loosening around the prosthesis combined with large inflammatory pseudotumours and large segment bone defects, hip revision is even more difficult, and clinical reports are rare.

CASE SUMMARY

Male, 59 years old. The patient underwent left hip replacement 35 years ago and was now admitted to hospital due to massive masses in the left thigh, shortening of the left lower extremity, and pain and lameness of the left hip joint. X-ray, computed tomography and magnetic resonance imaging revealed prosthesis loosening, left acetabular bone defect (Parprosky IIIB type), and a bone defect of the left proximal femur (Parprosky IIIA type). Inflammatory pseudotumours were seen in the left hip and left thigh. Hip revision surgery was performed using a 3D-printed custom acetabular prosthesis was used for hip revision surgery, which was produced by Arcam Electron Beam Melting system with Electron Beam Melting technology. The operation was successful, and the patient was followed up regularly after the operation. The custom-made acetabular prosthesis was well matched, the inflammatory pseudotumour was completely removed, the postoperative hip prosthesis was stable, and the old greater trochanter fracture was well reduced and fixed. The patient was partially weight-bearing with crutches 3 mo after the operation and walked with full weight-bearing after 6 mo. The hip prosthesis was stable, and there was no recurrence of inflammatory pseudotumours at the last follow-up. The Visual Analogue Scale was 3, and the Harris hip score was 90.

CONCLUSION

The use of 3D-printed personalized custom prostheses for complex hip revision surgery has satisfactory surgical results and has great clinical application value.

Unusual Case of a Trunnion Fracture Following a Revision Hip Arthroplasty Surgery: A Brief Review of the Literature and Discussion About Causes of Failure

Trunnion fracture is an incredibly rare complication of total hip arthroplasty. Of the few reported cases, all involve implants with faulty designs, a small neck taper, or an extended neck length or offset. Most also report corrosion and an adverse soft-tissue reaction. We present a review of the literature and report on the first case, to our knowledge, of trunnion fracture in a well-fixed, cemented cobalt-chromium femoral component with a standard neck length and offset with no evidence of corrosion. This failure was likely related to scratching of the metal during previous procedures which led to crack propagation and catastrophic failure. The patient was treated with revision hip arthroplasty to an uncemented, distal-fit femoral component and insertion of new bearing surfaces.

Selecting a Press-fit Stem for Total Hip Arthroplasty: The Rationale and Evolution of the Modern Femoral Prosthesis

Noncemented press-fit femoral stems predominate in total hip arthroplasty for all age groups with generally excellent long-term survivorship. The 2021 American Joint Replacement Registry reports that 96% of all elective primary total hip arthroplasties used noncemented femoral implant fixation. 1 Today, there are many styles of press-fit stems, each with supposed benefits, based on a range of design philosophies. Design aspects to consider when selecting a stem are numerous, including stem geometry, stem length, collared or collarless, material properties, and surface structure. Although most stem designs demonstrate excellent results, the differences in stem designs are intimately linked to additional factors such as ease of use/implantation, percentage of surface osseointegration, overall bone removal versus bone stock preservation, subsequent femoral stress shielding, and consideration of complexity of later revision. A surgeon with a broad understanding and appreciation of femoral stem designs should be prepared to select between the multitude of options to best serve individual patients.

Blood cobalt ion level in patients with different sizes of cobalt/chrome femoral head with the Accolade TMZF stem

BACKGROUND

Corrosion of stem-cobalt/chromium (Co/Cr) head interface and subsequent systemic Co ion complication have been a clinical concern after total hip arthroplasty (THA). The aim of this study is to investigate correlation between type of femoral head and blood Co ion level.

METHODS

One hundred four patients with THA using accolade TMZF and Co/Cr femoral head (32-mm; 55 cases, 36-mm; 20 cases, dual mobility system (DM) with 22.2 or 28-mm inner head; 29 cases) participated in this study, and blood Co ion concentration test was performed in patients a minimum of four years after THA.

RESULTS

DM group was significantly older than 32-mm and 36-mm group (DM: 73.9 ± 4.6, 32-mm: 63.3 ± 8.5, 36-mm: 66.8 ± 10.5). The median (interquartile range) blood Co concentration of each group was 32-mm group 0.26 µg/L (0.69), 36-mm group; 0.21 µg/L (0.30); and DM group 0.21 µg/L (0.13). There was a significant difference of Co concentration between DM and 32-mm group (p = 0.023). Abnormal values of the blood Co concentration (> 1 µg/L) were observed in the 32-mm group; 12 cases (21.8%), 36-mm group; 2 cases (10.0%); and DM group; 0 case (0%) (p = 0.018).

CONCLUSIONS

Co blood concentration differed among the different sizes of Co/Cr femoral head. THA using DM is a safe option with low risk of complication from cobalt ion if it is used for elderly patients.

High Incidence of Mechanically Assisted Crevice Corrosion at 10 Years in Non-Cemented, Non-Recalled, Contemporary Total Hip Arthroplasties

BACKGROUND

One percent to 3% of contemporary non-cemented total hip arthroplasties (THAs) present with symptomatic mechanically assisted crevice corrosion (MACC). The incidence of this problem, however, as well as the rate of asymptomatic elevations in serum cobalt, is unknown.

METHODS

Cobalt and chromium levels were obtained in conjunction with radiographs at routine 10-year surveillance follow-up of THAs from a single manufacturer with a titanium stem, cobalt alloy femoral head, and cross-linked polyethylene countersurface.

RESULTS

Ten-year follow-up of patients with 162 consecutive THAs revealed that 17 patients with 18 hips had died of unrelated causes prior to metal ion testing. Two hips were revised for other reasons, and of the remaining 142 hips, 33 were in patients who were lost, leaving 109 hips (77% of those in alive patients and unrevised for other reasons and 67% of the entire cohort) for investigation. Sixty-three patients (58%) had a serum cobalt less than 1 ppb, and 35 (32%) a cobalt of ≥1 ppb, a cutoff consistent with MACC. Of the 32 hips with definite MACC, 15 of 32 (47%) patients were symptomatic, 16 of 30 (53%) patients had adverse local tissue reaction on magnetic resonance imaging, and 19 of 32 (59%) patients have undergone revision surgery for MACC to date.

CONCLUSION

At 10-year follow-up, a minimum of 22% (35/162) of hips had a cobalt level more than 1 ppb, consistent with MACC. Symptoms and adverse local tissue reactions are each present about one-half of the time, and 59% of those with documented MACC have undergone revision.

The incidence of adverse local tissue reaction due to head taper corrosion after total hip arthroplasty using V40 taper and 36 mm CoCr head

AIMS

Head-taper corrosion is a cause of failure in total hip arthroplasty (THA). Recent reports have described an increasing number of V40 taper failures with adverse local tissue reaction (ALTR). However, the real incidence of V40 taper damage and its cause remain unknown. The aim of this study was to evaluate the long-term incidence of ALTR in a consecutive series of THAs using a V40 taper and identify potentially related factors.

METHODS

Between January 2006 and June 2007, a total of 121 patients underwent THA using either an uncemented (Accolade I, made of Ti₁₂Mo₆Zr₂Fe; Stryker, USA) or a cemented (ABG II, made of cobalt-chrome-molybdenum (CoCrMo); Stryker) femoral component, both with a V40 taper (Stryker). Uncemented acetabular components (Trident; Stryker) with crosslinked polyethylene liners and CoCr femoral heads of 36 mm diameter were used in all patients. At a mean folllow-up of 10.8 years (SD 1.1), 94 patients (79%) were eligible for follow-up (six patients had already undergone a revision, 15 had died, and six were lost to follow-up). A total of 85 THAs in 80 patients (mean age 61 years (24 to 75); 47 (56%) were female) underwent clinical and radiological evaluation, including the measurement of whole blood levels of cobalt and chrome. Metal artifact reduction sequence MRI scans of the hip were performed in 71 patients.

RESULTS

A total of 20 ALTRs were identified on MRI, with an incidence of 26%. Patients with ALTR had significantly higher median Co levels compared with those without ALTR (2.96 μg/l (interquartile range (IQR) 1.35 to 4.98) vs 1.44 μg/l (IQR 0.79 to 2.5); p = 0.019). Radiological evidence of osteolysis was also significantly associated with ALTR (p = 0.014). Median Cr levels were not significantly higher in those with ALTR compared with those without one (0.97 μg/l (IQR 0.72 to 1.9) v 0.67 μg/l (IQR 0.5 to 1.19; p = 0.080). BMI, sex, age, type of femoral component, head length, the inclination of the acetabular component, and heterotopic ossification formation showed no significant relationship with ALTR.

CONCLUSION

Due to the high incidence of local ALTR in our cohort after more than ten years postoperatively, we recommend regular follow-up investigation even in asymptomatic patients with V40 taper and metal heads. As cobalt levels correlate with ALTR occurrence, routine metal ion screening and consecutive MRI investigation upon elevation could be discussed. Cite this article: Bone Joint J 2022;104-B(7):852-858.

Association of the Psoas Muscle Index and Sagittal Spinal Alignment With Patient-Reported Outcomes After Total Hip Arthroplasty: A Minimum 5-Year Follow-Up

BACKGROUND

The aim of this study is to assess the association between a spinopelvic malalignment and patient-reported perception of the hip as being "artificial" after total hip arthroplasty (THA). This is a critical issue as an age-related spinopelvic mismatch has been postulated to be associated with the risk of poor outcomes after THA.

METHODS

This is a retrospective case-control study of 274 THAs (244 of whom were women), with a mean follow-up of 6.2 (range 5.0-8.2) years. Hip perception was assessed by asking subjects whether their joint felt "natural" or "artificial." The association between an artificial perception and the following factors was evaluated: age, gender, psoas muscle index (PMI, cross-sectional area of bilateral psoas at L3 divided by height squared), and spinopelvic measures using logistic regression analysis.

RESULTS

An artificial hip perception (130 hips, 47.4%) was associated with a lower PMI (P = .016), Hip Disability and Osteoarthritis Outcome Score Joint Replacement score (P = .035), EuroQol 5-Dimension score (P = .041), and a higher incidence of a pelvic incidence-minus-lumbar lordosis (PI-LL) mismatch >10° (P < .001). A flatback deformity (odds ratio 2.24, 95% confidence interval 1.22-6.31, P = .001) and PMI (odds ratio 0.61, 95% confidence interval 0.34-0.82, P = .012) were predictive of an artificial perception. With the threshold of PI-LL set to 10°, PMI (P = .034), Hip Disability and Osteoarthritis Outcome Score Joint Replacement score (P < .001), joint perception (P = .020), EuroQol 5-Dimension score (P = .028), pain (P = .031), and satisfaction (P < .001) differed between the 2 groups.

CONCLUSION

A flatback deformity is associated with the risk of an artificial perception post-THA, especially in patients with sarcopenia. PMI and PI-LL measurements may help predict THA outcomes.

Intermediate to Long-Term Outcomes and Causes of Aseptic Failure of an At-Risk Femoral Stem

BACKGROUND

The Accolade TMZF is a tapered-wedge cementless metaphyseal-coated femoral stem that was widely utilized from 2002 to 2012. In recent years, there have been reports of early catastrophic failure of this implant. The purposes of the present study were to establish the long-term survival of this stem and to analyze patients who underwent aseptic revision to understand the causes and risk factors for failure.

METHODS

We retrospectively reviewed the records of all patients who had undergone primary total hip arthroplasty with use of an Accolade TMZF stem at a high-volume arthroplasty center. The causes and timing of revision surgery were documented. Survivorship analysis was performed with use of Kaplan-Meier curves to determine the overall and aseptic survival rates at the time of the latest follow-up. Patient and implant factors commonly associated with aseptic failure were extracted, and a Cox proportional hazards model was used.

RESULTS

A consecutive series of 2,609 patients who had undergone unilateral primary total hip arthroplasty with use of an Accolade TMZF femoral stem were included. The mean time from the primary procedure was 11.3 years (range, 0 days to 19.4 years). The cumulative survival rate was 95.5% ± 0.1% at the time of the latest follow-up. One hundred and seven patients underwent revision surgery, with aseptic loosening of the femoral component being the most common cause of aseptic failure in this cohort (33 of 2,609; 1.3%). Smaller femoral size and larger femoral head offset were independent risk factors for aseptic failure.

CONCLUSIONS

To our knowledge, this is the largest series representing the longest follow-up of this tapered-wedge cementless femoral implant. Despite early concerns, the Accolade TMZF stem had excellent survivorship in this cohort. Trunnionosis as the cause for revision surgery was rare.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Fracture of a triple-polished tapered cemented femoral stem at the Morse taper after metal-on-metal primary total hip arthroplasty

Total hip arthroplasty, one of the most successful orthopaedic procedures, is influenced by several variables. Corrosion at the modular junction is known as trunnionosis. Despite being reported infrequently, corrosion between the femoral head and the Morse taper can result in severe complications. Fracture of the femoral component in primary metal-on-metal (MoM) total hip arthroplasty at the Morse taper is an extremely rare event and can be associated with several risk factors. We report a case of corrosion at the Morse taper in a hybrid primary MoM total hip arthroplasty, resulting in Morse taper fracture with consequent femoral head entrapment inside the acetabular component. We hypothesise that some risk factors, such as age over 60years, active male patients, body mass index above 30kg/m², large femoral heads, high-offset stems, 9/10 Morse taper and MoM-bearing surfaces, are associated with this mode of failure.

Parametric analysis of the effect of impaction load on the stability of head-neck junction in total hip arthroplasty

BACKGROUND

Tribocorrosion at head-neck interface is one of the main causes leading to the failure of hip implants in total hip arthroplasty. Impaction load has been acknowledged as one of the key factors influencing the stability of the taper junction. It is understood that the magnitude of impaction force differs from the surgeon to surgeon in primary total hip arthroplasty or revision. Clinically, it is sufficient enough to keep the male and female tapers inseparable utilizing a low impaction, which seems to contradict previous researches. The objective of this study was to investigate the effect of impaction loads on the stability of taper junction during assembly and gaits.

METHODS

A finite element model with 12/14 taper and the taper mismatch of 4' was developed for investigation. The impaction force profiles were collected from surgeon as the inputs, and then the contact mechanics over one or multiple gaits was further analyzed and validated utilizing hip simulator test.

FINDINGS

Impaction force ranging from 200 to 2000 N could provide the same taper connection effect after the first gait due to the secondary seating. As for impaction loads of 3000 N and above, an increased impaction force would lead to the tighter taper connection.

INTERPRETATION

The effect of impaction load on the stability of head-neck junction is a piecewise function, indicating that the stability of taper junction is not affected by different impaction loads and tends to be consistent while its magnitude is below the threshold. Instead, the stability of taper junction is positively correlated with impaction force.

Predictors of Adverse Local Tissue Reaction in a High-Risk Population

Background

Adverse local tissue reaction (ALTR) is a recognized complication of total hip arthroplasty (THA) with metal-on-polyethylene (MoP) bearing surface implants. Specific models of THA implants have been identified as having a higher incidence of ALTR. The purpose of this study is to determine if serum metal levels, patient symptoms, implant factors, and imaging findings can be predictive of ALTR within this high-risk population.

Methods

We retrospectively reviewed an observational cohort of 474 patients who underwent MoP THA and were at increased risk of having ALTR. Patients were stratified based on the presence or absence of ALTR. Patient symptoms, serum metal ions, implant head offset, and imaging findings were compared.

Results

Patients with ALTR were more likely to be symptomatic (52.9% vs 9.9%, P < .0001). The presence of ALTR was associated with significantly higher serum cobalt and chromium levels (6.2 ppb vs 3.6 ppb, P < .0001; 2.3 ppb vs 1.2 ppb, P < .0001). Head offsets greater than 4 mm were associated with a higher prevalence of ALTR (53% vs 38%, P = .05). On metal artifact reduction sequence magnetic resonance imaging, patients with ALTR had larger effusions (4.7 cm vs 2.1 cm, P < .001) and a higher incidence of trochanteric bursitis (47% vs 16%, P < .001).

Conclusions

In high-risk MoP implants, serum cobalt and chromium levels are elevated, even in patients without ALTR. A larger femoral head offset is a risk factor for the development of ALTR. Our study suggests that patients presenting with painful THA and elevated metal ions require risk stratification based on patient symptoms, metal artifact reduction sequence magnetic resonance imaging findings, and implant factors.

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

BACKGROUND

Mechanically assisted crevice corrosion (MACC) is a described complication following metal-on-polyethylene (MoP) total hip arthroplasty (THA). The literature regarding outcomes following revision for MACC suggests that complication rates are high. The purpose of this investigation is to add to this literature with the largest reported series to date.

METHODS

This is a retrospective cohort study of 552 consecutive patients who underwent 621 MoP primary THAs. We identified patients who subsequently underwent revision THA for a diagnosis of MACC. All patients were implanted with the same implant combination (Accolade I stem/cobalt-chromium low friction ion treatment femoral head). Patient demographic, surgical, and laboratory data were collected. Follow-up was calculated from the revision surgery and Hip Disability and Osteoarthritis Outcome Score Joint Replacement and hip subjective values (HSV) were examined at final follow-up. Descriptive statistics were performed.

RESULTS

The revision rate for MACC was 11.6% and mean time to revision was 6.6 (±2.4) years. Revised patients (n = 69) had a mean preoperative serum cobalt-chromium ratio of 3.5 (±2.4). There were 8 cases of gross trunnion failure. At mean 3.2 (±1.9) years following revision, the overall major complication rate was 11.6% with a 5.8% reoperation rate. At final follow-up, mean Hip Disability and Osteoarthritis Outcome Score Joint Replacement scores were 83.2 (±15.6) and mean hip subjective value was 77.6 (±17.4). Revision resulted in significant increases in both parameters (P < .001).

CONCLUSION

The incidence of MACC in MoP THA is likely higher than previously reported, particularly for certain implant combinations. Revision surgery for MACC can achieve good outcomes but a high clinical suspicion with early detection and revision is likely key to success.

Experimental validation of the abrasive wear stage of the gross taper failure mechanism in total hip arthroplasty

BACKGROUND

Gross taper failure (GTF) is a rare but catastrophic failure mode of the head-stem-taper junction of hip prostheses, facilitated by massive material loss. GTF is a two stage process initiated by corrosion leading to head bottoming out, followed by abrasive wear due to the head rotating on the stem. The purpose of this study was to reproduce the clinical failure patterns and to determine the material loss during simulated gait.

METHODS

Six cobalt-chromium alloy heads (36 mm, 12/14 taper) with three different head lengths (short / medium / extra long) were combined with stem taper replicas made from titanium alloy sized to achieve bottoming out. A hip simulator was used to simulate gait loading after (ISO 14242-1 for 2 million cycles).

RESULTS

Wear patterns from in-vitro testing match the clinical failure patterns. Stem taper wear increased linearly with time (p< 0.001). After two million cycles the material loss of short / medium / extra long heads was (M+-STD) 1168±242 mg / 400±23 mg / 94±12 mg on the stem side and 46±36 mg / 46±24 mg / 70±8 mg on the head side. Stem taper wear decreased with increasing head length (p=0.01), whereas clinical failures are mostly seen for long and extra long heads.

Comparison of Asymptomatic and Symptomatic Adverse Local Tissue Reaction in Patients With Head-Neck Taper Corrosion

BACKGROUND

Diagnosis of adverse local tissue reaction (ALTR) in metal-on-polyethylene (MoP) total hip arthroplasty (THA) secondary to head-neck taper corrosion is challenging. The purpose of this study is to compare differences between asymptomatic and symptomatic ALTR in an observational cohort, including presentation, metal ion differences, and metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) findings.

METHODS

We performed a retrospective review of an observational cohort of 492 MoP THA patients at increased risk of developing ALTR. Ninety-four patients underwent revision arthroplasty for ALTR. Patients were stratified into symptomatic and asymptomatic ALTR groups. Presentation, metal ion levels, and imaging findings were compared.

RESULTS

For patients with confirmed ALTR, 41% were asymptomatic. There was a statistically significant difference in the serum chromium levels between symptomatic and asymptomatic ALTR patients (2.2 μg/L vs 3.1 μg/L, P = .05). There was no statistically significant difference between the serum cobalt levels or MRI findings in these 2 groups. We observed that extracapsular disease associated with ALTR could be misinterpreted as trochanteric bursitis.

CONCLUSION

Almost half of the MoP THA ALTR cases identified were asymptomatic. Cobalt levels could not differentiate between symptomatic and asymptomatic pseudotumor formation. Symptomatic and asymptomatic MoP ALTRs have similar MARS MRI characteristics. Our findings suggest that it is essential to risk stratify patients who could potentially have ALTR based on implant type, symptoms, ion levels, and MARS MRI.

Pseudotumors in Total Joint Arthroplasty

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The true incidence of pseudotumors in association with total joint arthroplasty is underestimated.

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Pseudotumors occur with metal-on-metal, metal-on-polyethylene, and metal-on-ceramic articulations.

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Metal ion levels should not be the only factor in decision-making regarding revision surgery.

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Revision surgery is only indicated in symptomatic patients with clinical and radiographic findings and elevated metal ion levels.

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Revision to a non-metal articulation is strongly suggested.

Bilateral Mechanically-Assisted Crevice Corrosion Resulting in Femoral Stem-Head Dissociation in Metal-on-Polyethylene Total Hip Arthroplasty

There are emerging reports of complications related to corrosion in modular femoral components. We report a unique case describing an 83-year-old man with bilateral mechanically-assisted crevice corrosion in hip replacements performed 10 years previously, by the same surgeon using the same size 3 Accolade TMZF stem and same 44-mm CoCr LFIT V40 head (Stryker Orthopedics, Mahwah NJ). Our patient presented with complete femoral stem-head complex dissociation of his right hip and elevated serum cobalt and chromium levels. He subsequently underwent right hip revision arthroplasty while his contralateral hip is monitored closely as an outpatient. This case helps to define the poorly understood mechanisms and component design factors implicated in this emerging issue. We also hope to provoke discussions about guidelines for monitoring and revising failing metal-on-polyethylene arthroplasty systems.

Impending Trunnion Failure: An Uncommon Radiographic Presentation of Total Hip Arthroplasty Failure

Trunnionosis is emerging as an early mode of failure in conventional metal-on-polyethylene total hip arthroplasty. It is defined as wear or corrosion at the trunnion, the taper at the femoral head-neck interface. Trunnion wear can result in a variety of negative sequelae and, in severe cases, necessitate revision arthroplasty. We describe a 64-year-old man with a metal-on-polyethylene total hip arthroplasty who presented with a sensation of clunking in the hip. Initial imaging and laboratory studies were inconclusive, and the decision was made to monitor. Two years later, trunnion wear was detected on radiographs, presenting as an abnormal alignment of the femoral neck relative to the femoral head. Several case reports and series describe catastrophic total hip arthroplasty failure due to trunnionosis. However, few describe the radiographic signs of wear at the trunnion before gross failure. This early presentation is important to recognize to minimize patient morbidity and aid surgical planning.

Taper junctions in modular hip joint replacements: What affects their stability?

BACKGROUND

Although taper junctions are beneficial in the reconstruction of hip joints, some clinical concerns like the formation of adverse local tissue reactions have recently emerged. These reactions are associated with wear and corrosion products from the interface of insufficient taper connections regarding strength. Commonly used tapers vary in their geometric and topographical design parameter. Therefore, this study aims to evaluate interactions between design and surgical related parameters to the taper connection strength.

METHODS

In this study, the effect of the taper contact situation, surface roughness and head material in combination with assembly force on the taper connection strength were assessed using torque-off tests. Furthermore, the type of use in terms of single-use or re-use of the stem taper was investigated.

RESULTS

The study showed that the impaction force is the predominant factor that determines the taper strength followed by the type of use and the head material. The contact situation seems to slightly influence the determined torque-off moment, whereas the surface topography of the stem taper obviously plays a minor role for the taper connection strength.

CONCLUSION

Clinical users should be aware that an increased assembly force will strengthen the stability of the taper junction, whereas care should be taken when reusing hip stems with metal heads as this may decrease their connection strength.

Impending spontaneous head neck dissociation caused by anteverted cup: A case report on reverse bottle opener effect and review of literature

Modularity in total hip arthroplasty (THA) not only allows adjustments of leg length and offset but also simplifies the revision. It allows limited revision of various components and decreases surgical morbidity of complete revision. Despite benefits, modularity is associated with risks like corrosion and component dissociation. Dissociation between head and neck taper is rare and the cause is attributed to taper corrosion, revision, stem subsidence, pumping phenomenon, injury and closed reduction of dislocated THA. We report a case of late-onset impending head-neck dissociation in a THA caused by a well-fixed anteverted cup with polyethylene liner wear by "reverse bottle opener effect." To our knowledge, this is the most late-onset reported case of head-neck dissociation, occurring after 13yrs of index surgery.

Three Femoral Stem Designs Without Corrosion: A Review of 2095 Stems

Introduction

Corrosion at the head-neck interface of modular components in total hip arthroplasty (THA) has been reported as a cause of failure of modern total hip replacement implants. While this method of failure has been well described, it remains poorly understood. The purpose of this study is to review the three most commonly used uncemented femoral stems at our institution over the last fifteen years and to correlate any established risk factors with rates of revision, particularly corrosion.

Methods

We reviewed 2095 patients from March 2000 to September 2015 who underwent total hip arthroplasty with one of three uncemented femoral stem designs. All stems were made of a Ti6Al4V alloy with a 12/14 taper design. We included only those stems coupled with a CoCr head and a highly crosslinked polyethylene liner. We evaluated age, gender, body mass index (BMI), femoral head size, head length, neck angle and offset and correlated these to the incidence of all cause revision, as well as revision excluding infection.

Results

There were no recognized corrosion-related revisions identified. There was no association between age, BMI, gender, head length, neck angle and offset to all cause revision or revision with infection excluded (p>0.05). Femoral head size less than 32mm was associated with higher all cause revision rates (OR 4.60 (95% CI 1.8, 11.8)) and when excluding infection as a reason for revision (OR 4.94 (95% CI 1.7, 14.41)).

Conclusion

Over the last fifteen years, we have not identified any cases of corrosion with the three most commonly used femoral stems used at out institution. While we acknowledge that no femoral stem is immune to corrosion, certain femoral stem designs may be uniquely resistant to this mode of failure.

Level of Evidence

III.

New materials for hip and knee joint replacement: What's hip and what's in kneed?

Over the last three decades there have been significant advancements in the knee and hip replacement technology that has been driven by an issue in the past concerning adverse local tissue reactions, aseptic and septic loosening. The implants and the materials we utilize have improved over the last two decades and in knee and hip replacement there has been a decrease in the failures attributed to wear and osteolysis. Despite these advancements there are still issues with patient satisfaction and early revisions due to septic and aseptic loosening in knee replacement patients. This article reviews the state of current implant material technology in hip and knee replacement surgery, discusses some of the unmet needs we have in biomaterials, and reviews some of the current biomaterials and technology that may be able to solve the most common issues in the knee and hip replacement surgery.

What Is the Risk of THA Revision for ARMD in Patients with Non-metal-on-metal Bearings? A Study from the Australian National Joint Replacement Registry

BACKGROUND

There are increasing reports of corrosion between the femoral head and trunnion in primary conventional THA, resulting in metal particulate release often termed trunnionosis. There may be heightened awareness of this condition because of severe soft-tissue reactions initially thought to be solely attributable to prostheses with a metal-on-metal (MoM) bearing surface. It is unclear what percentage of revisions for THA with non-MoM bearing surfaces can be attributed to trunnionosis and to what extent adverse reaction to metal debris (ARMD) seen with MoM bearings may also be seen with other bearing surfaces in THA.

QUESTIONS/PURPOSES

We analyzed data from a large national registry to ask: (1) What is the revision risk for the indication of ARMD in patients with conventional THA and modern non-MoM bearing surfaces such as metal or ceramic-on-cross-linked polyethylene (XLPE) or ceramic-on-ceramic? (2) What prosthesis factors are associated with an increased risk of such revision? (3) What is the relative revision risk for ARMD in THAs with large-head MoM bearings, small-head MoM bearings, and non-MoM modern bearing surfaces?

METHODS

The Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) longitudinally maintains data on all primary and revision joint arthroplasties, with nearly 100% capture. The study population included all THAs using modern bearing surfaces (defined as metal or ceramic heads-on-XLPE and ceramic-on-ceramic bearing couples) revised because of ARMD between September 1999 and December 2018. Prostheses with modular necks were excluded. The cumulative percent revision (CPR) because of ARMD was determined. The study group consisted of 350,027 THAs with a modern bearing surface, 15,184 THAs with a large-head MoM bearing (≥ 36 mm), and 5474 THAs with a small head MoM bearing (≤ 32 mm). The patients in the group who received the modern bearing surfaces were slightly older than the patients in the groups who received the large- and small-head bearing surfaces, with a mean age 68 years (SD 12) versus a mean age 63 years (SD 12), and a mean age 62 years (SD 11), respectively. There was a higher proportion of women in the modern bearing surface group; 55% (193,312 of 350,027), compared with 43% (6497 of 15,184) in the large-head MoM group and 50% (2716 of 5474) in the small-head MoM group. The outcome measure was the CPR, which was defined using Kaplan-Meier estimates of survivorship to describe the time to the first revision for ARMD at 17 years. Hazard ratios (HR) from Cox proportional hazards models, adjusting for age and sex, were performed to compare the revision rates among groups. The registry defines a revision as a reoperation of a previous hip arthroplasty in which one or more of the prosthetic components is replaced or removed, or one or more components is added.

RESULTS

The CPR for ARMD for patients with a modern bearing surface at 17 years was 0.1% (95% confidence interval 0.0 to 0.1). After controlling for age and sex, we found that cobalt chrome heads, two specific prostheses (Accolade® I and M/L Taper), and head sizes ≥ 36 mm were associated with an increased risk of revision for ARMD. Metal-on-XLPE had a higher risk of revision for ARMD than ceramic-on-ceramic or ceramic-on-XLPE (HR 3.4 [95% CI 1.9 to 6.0]; p < 0.001). The Accolade 1 and the M/L Taper stems had a higher risk of revision than all other stems (HR, 8.3 [95% CI 4.7 to 14.7]; p < 0.001 and HR 14.4 [95% CI 6.0 to 34.6]; p < 0.001, respectively). Femoral stems with head sizes ≥ 36 mm had a higher rate of revision for ARMD than stems with head sizes ≤ 32 mm (HR 3.2 [95% CI 1.9 to 5.3]; p < 0.001).Large-head MoM bearings had a greater increase in revision for ARMD compared with modern bearing surfaces. The CPR for patients with a large-head MoM bearing at 17 years for ARMD was 15.5% (95% CI 14.5 to 16.6) and it was 0.1% for modern bearing surfaces (HR 340 [95% CI 264.2 to 438.0]; p < 0.001). Modern bearing surfaces likewise had a lower HR for revision for ARMD than did THAs with small-head MoM bearings, which had a 0.9% (95% CI 0.7 to 1.4) CPR compared with modern bearings from 0 to 9 years (HR 10.5 [95% CI 6.2 to 17.7]; p < 0.001).

CONCLUSIONS

The revision risk for ARMD with modern bearing surfaces in THA is low. The Accolade 1 and the M/L Taper stem have a higher risk of revision for ARMD and cobalt-chrome heads, and head sizes ≥ 36 mm have a higher rate of revision than ≤ 32 mm head sizes. ARMD is a rare failure mode for THA with non-MoM bearings, but in patients presenting with unexplained pain with no other obvious cause, this diagnosis should be considered and investigated further.

LEVEL OF EVIDENCE

Level III, therapeutic study.

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

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

Gross trunnion failure in metal on polyethylene total hip arthroplasty-a systematic review of literature

BACKGROUND

Multiple cases of dissociation of the head from the neck termed as gross trunnion failure (GTF) in total hip replacement have been described. Very little quantitative data is available for patient and implant factors associated and predisposing to this complication.

STUDY PURPOSE

To systematically review and analyze all studies which have gross trunnion failure in case of metal on polyethylene (MoP) total hip replacement.

METHODS

PubMed database was searched. We also performed a secondary search by pearling bibliography of all full text articles obtained. Predefined inclusion and exclusion criteria were used for abstract screening by two independent observers. A total 46 cases met our inclusion criteria. These were included in the final analysis and data was pooled.

RESULTS

Till date, 46 cases of GTF in MoP THR have been reported. The mean age at time of revision was 70.13 years (range 50 to 89 years). The mean time to revision surgery was 8.24 years (range 4.7 to 14 years). 91.4% cases were male. BMI was ≥ 25 in 38/41 cases and ≥ 30 in 21/41 cases. Pain (95.5%) and difficulty or inability to walk (97.7%) were the most common symptoms. A total of 19/44 cases described varying sounds like click, clunk, and pop before dislocation. Accolade TMZF/TMZF plus was the most common stem used in 34/46 cases. The stem neck angle was 127 degrees in 97% cases (32/33 cases). A positive neck offset of 4 mm or more was used in 91.1% cases (40/44 cases). The head size ≥ 36 mm in approximately 90% cases. The head material was cobalt chromium in all 45 cases, where data was available. Among the intra-operative findings, the most common findings were metallosis (41/44), black or brow coloured synovial fluid (21/44), pseudotumour (19/44), synovial hypertrophy (18/44), damage to the abductor musculature (17/44), proximal femoral osteolysis (5/44 cases), and heterotrophic ossification (2/44 cases). Histopathological analysis was available in 11 cases and was suggestive of fibrous tissue with chronic cellular infiltrate in all cases. The serum cobalt and chromium concentrations were raised above normal in 86.4% (19/22) and 21.7% cases (5/23) respectively.

CONCLUSIONS

Gross trunnion failure may not be as uncommon as was previously thought. A number potential associations and predisposing factors of this complication have been highlighted in this review. But due to small sample size and weak level of evidence, further studies are needed in this field.

Catastrophic femoral head trunnion dissociation: a case series with surface wear analysis

INTRODUCTION

Modular designs enhance accuracy of limb length and offset during total hip arthroplasty. However, such interfaces can be the site of corrosion and implant failure. The purpose of this study was to review 5 cases of catastrophic femoral head trunnion dissociation to better understand clinical and implant related risk factors for this complication.

METHODS

We describe 5 cases of femoral head dissociation following significant trunnion wear. Patient and implant related factors are reviewed. Surface wear patterns were assessed using electron microscopy and wear patterns were described qualitatively.

RESULTS

Commonalties among 5 presented cases include male, age over 65 and increased BMI. All femoral heads were cobalt chromium with a head size of at least 36 mm or greater. 4 out of 5 had high offset. All stems were the same design. Surface wear analysis showed material removed initially on the inferomedial aspect of the trunnion where the femoral head contacted the stem.

CONCLUSIONS

Femoral head dissociation secondary to failure of the trunnion is a rare complication. We show associations with older age, increased BMI and male patients with increased femoral head size and offset. Material is removed initially inferomedially and progresses to fracturing the superior aspect of the trunnion.

Diagnosis and Management of Adverse Reactions to Metal Debris

Modern total hip arthroplasty implants have incorporated modularity into their designs, providing the benefits of intraoperative flexibility and the ability to exchange the femoral heads in the future if necessary. However, this feature has unfortunately predisposed patients to the effects of corrosion, potentially resulting in adverse local tissue reactions (ALTR) and even systemic effects. A thorough understanding of the science of corrosion is important for the treating surgeon so that they can understand the underlying pathology, quickly diagnose the condition of ALTR, and risk stratify their patients to determine the best method of treatment. Revision surgery is not always necessary in cases of trunnionosis or ALTR, but the results of revision surgery are generally favorable.

Trunnion Corrosion in Total Hip Arthroplasty-Basic Concepts

There has been increased interest in the role of corrosion in early implant failures and adverse local tissue reaction in total hip arthroplasty. We review the relationship between the different types of corrosion in orthopaedic surgery including uniform, pitting, crevice, and fretting or mechanically assisted crevice corrosion (MACC). Passive layer dynamics serves a critical role in each of these processes. The femoral head-neck trunnion creates an optimal environment for corrosion to occur because of the limited fluid diffusion, acidic environment, and increased bending moment.

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

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

Role of corrosion in taper failure and head disassociation in total hip arthroplasty of a single design

Modular junctions have been associated with corrosion in total hip arthroplasty. In a small number of cases, disassociation of the femoral head from the stem following gross wear of the taper has been reported. The purpose of this study was to investigate the role of corrosion in the development of mechanical changes leading to disassociation. Twenty-one retrieved stems and heads of one design previously reported with head disassociation were identified in an IRB-approved database. Components were scored for corrosion and measured for material loss. Stem alloy hardness was measured. Parametric and non-parametric statistics were performed (α < 0.05). Seven of twenty-one stems demonstrated gross material loss of the stem taper and head disassociation. The maximum linear depth (MLD) of material loss on stem tapers without dissociation and all head bores was 7.63 ± 6.04 and 63.76 ± 60.83 μm, respectively. Hardness of the stem material was statistically distinct, but similar to other stem materials. Results suggest material loss via corrosion at the head bore loosens the taper lock, allowing relative motion leading to abrasive wear of the stem taper. All cases of disassociation occurred at greater than 65 months with a minimum of 50 μm of loss at on the head bore. It may be warranted to survey patients with systems reporting head disassociation; for this system, including recalled heads, risk appears to begin after 6 years in vivo. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2996-3003, 2018.

Head Taper Corrosion Causing Head Bottoming Out and Consecutive Gross Stem Taper Failure in Total Hip Arthroplasty

BACKGROUND

Taper corrosion in total hip arthroplasty for bearings with metal heads against polyethylene has developed from an anecdotal observation to a clinical problem. Increased taper wear and even gross taper failure have been reported for one particular design. It is hypothesized that corrosion of the female head taper results in taper widening, allowing the cobalt-chromium head to turn on the stem and wear down the softer titanium alloy by abrasive wear, ultimately causing failure. The purpose of this study is to investigate the time course of this process and the general role of taper dimensions and material in this problem.

METHODS

Retrieved cobalt-chromium alloy heads (n = 30, LFIT; Stryker, Mahwah, NJ) and Ti-12Mo-6Zr-2Fe (TMZF) stems (n = 10, Accolade I; Stryker) were available for analysis. Taper material loss was determined using three-dimensional coordinate measurements and scanning. The pristine tip clearance between head and stem was analytically determined. The influence of taper material and taper size on taper deformation and micromotion was investigated using a finite element model.

RESULTS

Material loss at the head taper increased with time in situ up to a volume of 20.8 mm³ (P < .001). A mean linear material loss above 76 μm at the head taper was analytically confirmed to result in bottoming out, which was observed in 12 heads. The finite element calculations showed significantly larger deformations and micromotions for a small 11/13 TMZF taper combined with a distinctly different micromotion pattern compared to other materials and taper designs.

CONCLUSION

A 11/13 TMZF taper design with 36-mm head diameters bears a higher risk for corrosion than larger tapers made from stiffer materials. Failures of this combination are not restricted to the head sizes included in the recall. Patients with this implant combination should be closely monitored.

Evidence-Based Management of Trunnionosis in Metal-on-Polyethylene Total Hip Arthroplasty: A Systematic Review

Multiple recent reports have indicated a rising awareness of trunnionosis-related implant failures, accounting for up to 3% of all total hip arthroplasty revisions. Moreover, aseptic loosening and osteolysis from local release of metal debris can be the presenting manifestations, and thus the true incidence of trunnionosis is thought to be underreported. Furthermore, the relatively unclear and multifactorial pathogenesis and the widely variable clinical presentations pose a diagnostic challenge. A consensus regarding the ideal intervention and its timing is also lacking. Because of the relative paucity of reports regarding the diagnosis and management of trunnionosis, we conducted this evidence-based review to evaluate the (1) incidence, (2) pathogenesis, (3) diagnosis, and (4) treatment of trunnionosis in metal-on-polyethylene total hip arthroplasty. We then propose an algorithm for the diagnostic work-up and management of this condition.

Do Well-functioning THAs Retrieved at Autopsy Exhibit Evidence of Fretting and Corrosion?

BACKGROUND

Our understanding of fretting and corrosion at head-neck junctions in modular THAs in vivo is based largely on the analysis of retrieved implants removed for various diagnoses. Little is known about the condition of head-neck tapers in well-functioning THAs.

QUESTIONS/PURPOSES

Regarding a cohort of well-functioning autopsy-retrieved modular THAs, we asked: (1) Does trunnion geometry or femoral head material affect the pull-off force of the femoral head? (2) Is there a relationship between trunnion damage and length of implantation time, head diameter, and neck length? (3) Does visual damage scoring accurately determine the presence or absence of corrosion on cobalt-chrome trunnions?

METHODS

Sixty-six femoral stems and engaged femoral heads were retrieved at autopsy from 53 patients at Anderson Orthopaedic Research Institute from 1998 to 2014. Ten stems were excluded for low stem design group size or insufficient head-stem clearance for pull-off testing, leaving a cohort of 56 THAs with a median implantation time of 10 years (range, 1-24 years). The femoral stems included three cobalt-chrome (CoCr) designs from a single manufacturer with either a 12/14 or 14/16 trunnion design (N = 36 and 20, respectively) mated with alumina or CoCr heads (N = 13 and 43, respectively). The force required to pull off the femoral heads was measured using a uniaxial load frame according to ASTM F2009-00. Mating surfaces were visually examined to assess the presence and severity of fretting and corrosion using a modified Goldberg scoring system. Three 12/14 trunnions of similar implantation lengths and varied damage scores were selected for imaging with a scanning electron microscope (SEM) and energy dispersive x-ray analysis (EDAX) to confirm the absence or presence of corrosion damage.

RESULTS

No difference was seen in pull-off force between groups based on trunnion geometry and head material (median [range], alumina-12/14: 3127 [2320-6992] N, alumina-14/16: 2670 [1095-7919] N, CoCr-12/14: 2255 [1332-5939] N, CoCr-14/16: 2812 [1655-4246] N; p = 0.132). A positive correlation was found between damage score and length of implantation (ρ = 0.543, p < 0.001). However, no correlation between damage score and either head diameter or neck length was found (ρ = -0.012, p = 0.930 and ρ < 0.001, p = 0.995, respectively). In all, 39 of 56 specimens demonstrated no fretting or corrosion, and 16 specimens had mild damage scores. One specimen demonstrated severe corrosion without visual evidence of fretting. The presence of intergranular corrosion on this trunnion was determined by SEM imaging and EDAX. The absence of corrosion products on two trunnions with no observed damage was confirmed.

CONCLUSIONS

This study found little evidence of fretting and corrosion in a cohort of well-functioning CoCr-CoCr and alumina-CoCr head-neck couples. Further studies are necessary to characterize fretting and corrosion at head-neck junctions of well-functioning implants of other designs and manufacturers.

CLINICAL RELEVANCE

The results from this study suggest that patients with well-functioning THAs using polyethylene bearing surfaces with alumina or CoCr heads appear to be at low risk for trunnion corrosion for the specific CoCr alloy stems and trunnion geometries analyzed here.

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

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

Impaction Force Influences Taper-Trunnion Stability in Total Hip Arthroplasty

BACKGROUND

This study investigated the influence of femoral head impaction force, number of head strikes, the energy sequence of head strikes, and head offset on the strength of the taper-trunnion junction.

METHODS

Thirty titanium-alloy trunnions were mated with 36-mm zero-offset cobalt-chromium femoral heads of corresponding taper angle. A drop tower impacted the head with 2.5J or 8.25J, resulting in 6 kN or 14 kN impaction force, respectively, in a single strike or combinations of 6 kN + 14 kN or 14 kN + 14 kN. In addition, ten 36-mm heads with -5 and +5 offset were impacted with sequential 14 kN + 14 kN strikes. Heads were subsequently disassembled using a screw-driven mechanical testing frame, and peak distraction force was recorded.

RESULTS

Femoral head pull-off force was 45% the strike force, and heads struck with a single 14 kN impact showed a pull-off force twice that of the 6 kN group. Two head strikes with the same force did not improve pull-off force for either 6 kN (P = .90) or 14 kN (P = .90). If the forces of the 2 impactions varied, but either impact measured 14 kN, a 51% higher pull-off force was found compared to impactions of either 6 kN or 6 kN + 6 kN. Femoral head offset did not significantly change the pull-off force among -5, 0, and +5 heads (P = .37).

CONCLUSION

Femoral head impaction force influenced femoral head trunnion-taper stability, whereas offset did not affect pull-off force. Multiple head strikes did not add additional stability, as long as a single strike achieved 14 kN force at the mallet-head impactor interface. Insufficient impaction force may lead to inadequate engagement of the trunnion-taper junction.

Association Between Pseudotumor Formation and Patient Factors in Metal-on-Metal Total Hip Arthroplasty Population

BACKGROUND

Pseudotumor formation from metal-on-metal (MoM) hip implants is associated with implant revision. The relationship between pseudotumor type and patient outcomes is unknown.

METHODS

We retrospectively reviewed patients with a MoM total hip arthroplasty and metal artifact reduction sequence magnetic resonance imaging. Pseudotumors were graded using a validated classification system by a fellowship-trained radiologist. Patient demographics, metal ion levels, and implant survival were analyzed.

RESULTS

Pseudotumors were present in 49 hips (53%). Thirty-two (65%) pseudotumors were cystic thin walled, 8 (16%) were cystic thick walled, and 9 (18%) were solid masses. Patients with pseudotumors had high offset stems (P = .030) but not higher metal ion levels. Patients with thick-walled cystic or solid masses were more likely to be symptomatic (P = .025) and were at increased risk for revision (P = .004) compared to patients with cystic lesions.

CONCLUSION

Pseudotumor formation is present in 53% of patients with a MoM total hip arthroplasty, of which 40% were asymptomatic. Patients with thick-walled cystic and solid lesions were more likely to be symptomatic and undergo revision.

The onset of fretting at the head-stem connection in hip arthroplasty is affected by head material and trunnion design under simulated corrosion conditions

Mechanically assisted crevice corrosion (MACC) is a mechanism for trunnion damage in total hip arthroplasties (THAs). Retrieval studies have shown reduced MACC-related damage for ceramic heads compared with cobalt-chromium (CoCr) heads. We propose that ceramic heads demonstrate fretting at higher cyclic compressive loads than CoCr heads on titanium alloy trunnions in a simulated corrosion model. A closed electrochemical chamber was used to measure fretting current onset loads for two modern titanium alloy trunnions (Zimmer 12/14 and Stryker V-40) in which trunnion failure has been reported. Ceramic and CoCr alloy 36 + 0 mm heads were impacted on each trunnion and cyclically loaded at 3 Hz with increasing magnitude from 100 to 3,400 N for 540 cycles. Onset load was the cyclic compressive load at which the slope of the average fretting current increased significantly. A CoCr head with V40 trunnion demonstrated the lowest onset load (1,400 N), while the V40 trunnion with a ceramic head showed the highest onset load (2,200 N). Significant differences occurred in average fretting current between head materials for V40 trunnions (p < 0.001) at loads over 2,000 N. CoCr-12/14 and ceramic-12/14 couples demonstrated similar onset loads (2,000 N). All head-trunnion combinations showed cyclical fretting response to loading at 100 N. Head material composition was observed to increase fretting at the taper junction but the effect was taper geometry dependent. Using ceramic heads may reduce the phenomena of trunnion fretting and corrosion but the effect of both trunnion geometry and metallurgy warrants further investigation. Statement of clinical significance: Trunnion corrosion may occur with titanium alloy stems regardless of the head material used. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1630-1636, 2018.

No Consensus for Femoral Head Impaction Technique in Surgeon Education Materials From Orthopedic Implant Manufacturers

BACKGROUND

Prior studies indicate that one factor that may contribute to total hip arthroplasty failure due to mechanically assisted crevice corrosion at the femoral head-trunnion junction is the method of femoral head fixation.

METHODS

Up-to-date on-line surgical technique guides describing fixation of the prosthetic femoral head of common implants of the 4 largest manufacturers as well as 2 minor manufacturers were identified. The information given regarding preparation and fixation of the femoral head was evaluated and compared.

RESULTS

A total of 24 surgical technique guides were evaluated. Most guides (22/24) addressed fixation technique; of these, 19 of 22 suggested cleaning and 20 of 22 suggested drying the trunnion prior to affixing the femoral head. The manner of fixation, however, varied widely and there was no single technique advocated.

CONCLUSION

The majority of surgeon education materials do not specify a single technique for assembly of the head femoral component in total hip arthroplasty. If the method of fixation is indeed important, efforts should be made to identify the best technique, and improve and unify the surgical technique instructions.

High Early Major Complication Rate After Revision for Mechanically Assisted Crevice Corrosion in Metal-on-Polyethylene Total Hip Arthroplasty

BACKGROUND

Failed total hip arthroplasty caused by mechanically assisted crevice corrosion (MACC) has serious consequences such as adverse local tissue reaction. Revision is currently indicated for significant hip pain, stiffness, and dysfunction; hip instability; progressive bone loss; and soft tissue destruction. Outcomes of this revision surgery are not yet completely understood.

METHODS

We examined the surgical outcomes at a minimum of 6 months (average, 25; range, 7-68 months) in a cohort of 27 consecutive patients who underwent revision total hip arthroplasty for MACC associated with a single implant vendor and taper type.

RESULTS

Major orthopedic complications occurred in 7 of 27 patients (25.9%), each after the original revision surgery. Five additional major complications occurred in subsequent surgeries. Postoperative hip dislocation occurred in 6 of 27 (22.2%), deep infection occurred in 3 of 27 (11.1%), and aseptic acetabular loosening, seroma requiring irrigation and debridement, pulmonary embolism, periprosthetic fracture, and reintubation each occurred in 1 of 27 (3.7%). Harris hip scores improved significantly with surgery (P = .0002), but overall, scores were lower for those who had major complications (70.9 vs 89.2), and only 20 of 27 patients (74.1%) had good or excellent outcomes.

CONCLUSION

Symptomatic MACC is a potentially devastating diagnosis, because of decreased soft tissue and bone viability associated with adverse local tissue reaction. This leads to a high early major complication rate.