What are the predictors and prevalence of pseudotumor and elevated metal ions after large-diameter metal-on-metal THA?

Metal-on-Metal Hip Arthroplasty: A Comprehensive Review of the Current Literature

Metal-on-metal (MoM) total hip arthroplasty has been widely used since the end of the 20th century, although rates have now decreased due to concerns regarding adverse reactions and failure rates. The MoM implant has been replaced with other materials, such as ceramic-on-ceramic (CoC) and metal-on-polyethylene (MoP). This literature review looks at the past and present use of MoM prostheses to assess whether the turn away from MoM use is justified. Online literature searches were performed on PubMed, Ovid Medical Literature Analysis and Retrieval System Online (MEDLINE), and Web of Science online databases using the search terms "MoM and (ARMD and ALVAL)" (ARMD: adverse reaction to metal debris; ALVAL: aseptic lymphocyte-dominant vasculitis-associated lesion). A total of 64 relevant titles were included in the review. Although risk factors for adverse reactions and the causes of ARMD are generally agreed upon, more work is required to further understand the specific thresholds of blood metal ion levels that can be used to consistently identify ARMD and excessive metal wear-debris in patients who have not had their MoM implants revised. Metal-on-metal devices are not an acceptable option for total hip arthroplasties (THAs) in their current formulation due to the high rate and risk of ARMD. Some MoM hip resurfacing operations are appropriate for very carefully selected patients who are fully aware of the risks posed by the implant. It is recommended that device-specific thresholds for metal ion levels be developed to identify patients at risk of ARMD locally and systemically while using auxiliary tools to assist diagnosis, such as metal artefact reduction sequences (MARS)-MRI and hip scoring tools. Further work should investigate device-specific blood metal ion levels, the systemic effects of raised metal ion concentrations secondary to MoM arthroprosthetic wear, and the potential risks of ARMD caused by wear from tapered stems (including the implications this has for patients with CoC and MoP prostheses).

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.

Minimum 10-Year Results of Modular Metal-On-Metal Total Hip Arthroplasty

Background: this study aimed to assess the long-term outcomes of (a minimum of 10-years) total hip arthroplasty with a metal-on-metal acetabular prosthesis. Methods: Eighty-nine primary total hip arthroplasties (82 patients) were performed using a Pinnacle modular metal-on-metal acetabular prosthesis. Clinical hip function outcomes were evaluated using the Japanese Orthopaedic Association hip score preoperatively and at the final follow-up. Radiological analysis was performed at the final follow-up and magnetic resonance imaging in all hips postoperatively. Results: Out of 82 patients, 17 were excluded who were followed up for <10 years. Of the remaining 65 patients (70 hips), 19 (20 hips) developed pseudotumors during 2−10 years postoperatively. After 10 and 13 years, the survival rates of revision endpoint were 93.6% and 90.4%, respectively. Clinical hip function outcomes had improved significantly at the final follow-up. In the radiological analysis, the mean cup angle of inclination and mean ratio of femoral offset on the operated hip to the contralateral hip was highest in patients with revision surgery for adverse reactions to metal debris. Conclusions: This study showed a 29.0% prevalence of pseudotumors. Some cases required revisions even after 10 years following surgery. Regular clinical surveillance is recommended for the early detection of adverse reactions to metal debris.

Adverse Tissue Reactions and Metal Ion Behavior After Small-Head Metasul Hip Arthroplasty: A Long-Term Follow-Up Study

Objective

To investigate the long‐term survivorship, incidence of adverse reactions to metal debris (ARMD), and metal ion behavior in patients who underwent small‐head Metasul metal‐on‐metal (MoM) total hip arthroplasty (THA).

Methods

Between February 1998 and September 2003, a retrospective study was performed on 43 consecutive patients (43 hips) who underwent unilateral cementless Metasul MoM THAs at our institution. Of them, 35 patients (nine males and 26 females) who were available for follow‐up more than 15 years after THA were enrolled in this study and underwent metal artifact reduction sequence magnetic resonance imaging (MARS‐MRI) to identify ARMD. The mean age at surgery of the patients was 59.7 years old (range, 31–83). Clinical and radiographic outcomes were evaluated retrospectively. Clinical examinations were conducted using the Harris Hip Score (HHS). Serum cobalt (Co) and chromium (Cr) ion levels and Co/Cr ratio were assessed at different postoperative periods of <5, 5–10, 11–14, and ≥15 years.

Results

The mean follow‐up period for the 35 patients included was 18.1 years (range, 15–22). The mean HHS significantly improved from 44.6 ± 11.3 points preoperatively to 89.4 ± 7.9 points at the final follow‐up (P < 0.0001). ARMD was found in 20% of the patients using MARS‐MRI. No signs of stem loosening were found clinically or radiographically, whereas cup loosening and ARMD were observed in three patients (9%), for whom revision THAs were performed. The Kaplan–Meier survival rates with revision for any reason as the endpoint were 90.9% at 5 years, 84.8% at 10 years, 84.8% at 15 years (95% CI, 67.1–93.6), and 70.3% at 20 years (95% CI, 43.6–87.0). The survival rates with revision for ARMD as the endpoint were 100% at 5 years, 96.6% at 10 years, 96.6% at 15 years (95% CI, 77.2–99.7), and 80.1% at 20 years (95% CI, 45.3–95.2). Serum Co ion level peaked at 5–10 years after THA, which was significantly higher than that <5 years; however, it decreased to the initial level after 15 years. In contrast, serum Cr ion level significantly increased at 5–10 years and then remained almost constant. Significant differences in Cr ion levels (1.0 vs 2.0 μg/L, P = 0.024) and Co/Cr ratio (1.3 vs 0.9, P = 0.037) were found between non‐ARMD and ARMD patients at >11 years postoperatively.

Conclusion

Our results suggest that increased Cr ion levels and decreased Co/Cr ratio may be signs of ARMD in patients who underwent small‐head Metasul MoM THA.

Adverse Local Tissue Reactions are Common in Asymptomatic Individuals After Hip Resurfacing Arthroplasty: Interim Report from a Prospective Longitudinal Study

BACKGROUND

The evaluation of the natural history prevalence of adverse local tissue reactions (ALTRs) using MRI has focused only on metal-on-metal (MoM) bearing surfaces without comparison to nonMoM bearing surfaces.

QUESTIONS/PURPOSES

To determine (1) the longitudinal changes and differences in blood metal ion levels in patients with hip resurfacing arthroplasty (HRA), ceramic-on-ceramic (CoC) THA, and metal-on-polyethylene (MoP) THA compared with those undergoing ceramic-on-polyethylene (CoP) THA; (2) how the longitudinal change of synovial reaction classification in patients with HRA, CoC THA, and MoP THA compares with those undergoing CoP THA, and whether there is an association between the presence of an ALTR or metallosis on MRI with corresponding patient-reported outcomes, or the presence of capsular dehiscence; and (3) differences in blood metal ion levels between patients undergoing HRA with an ALTR or metallosis on MRI and those with HRA without these conditions.

METHODS

Between March 2014 and February 2019, 22,723 patients underwent primary HRA and THA at one center. Patients received an HRA based on their desired athletic level after surgery and the presence of normal acetabular and proximal femoral bone morphology without osteopenia or osteoporosis. Two percent (342 of 22,723) of patients were contacted to participate, and 71% (243 of 342 hips in 206 patients) were enrolled for analysis at baseline. The patients underwent arthroplasty for degenerative joint disease, and 25 patients withdrew over the course of the study. We included patients who were more than 1 year postarthroplasty. All participants had an MRI examination and blood serum ion testing and completed a Hip Disability and Osteoarthritis Outcome Score survey annually for four years (baseline, year 1, year 2, year 3). Morphologic and susceptibility-reduced MR images were evaluated by a single radiologist not involved in the care of patients for the presence and classification of synovitis (Gwet AC1: 0.65 to 0.97), synovial thickness, and volume (coefficient of repeatability: 1.8 cm3). Linear mixed-effects models were used to compare the mean synovial thickness, synovial volume, and Hip Disability and Osteoarthritis Outcome Score subscales between bearing surfaces at each timepoint and within each bearing surface over time. Marginal Cox proportional hazards models were used to compare the time to and the risk of developing ALTR only, metallosis only, and ALTR or metallosis between bearing surfaces. All models were adjusted for age, sex, BMI, and length of implantation based on known confounders for hip arthroplasty. Adjustment for multiple comparisons was performed using the Dunnett-Hsu method.

RESULTS

Patients with unilateral HRA had higher cobalt and chromium serum ion levels (baseline: 1.8 ± 0.8 ppb, year 1: 2.0 ± 1.5 ppb, year 2: 2.1 ± 1.2 ppb, year 3: 1.6 ± 0.7 ppb) than those with unilateral CoP bearings (baseline: 0.0 ± 0.1 ppb, year 1: 0.1 ± 0.3 ppb, year 2: 0.0 ± 0.2 ppb, year 3: 0.0 ± 0.0 ppb) at all timepoints (p < 0.001 for each time point). More patients who received an HRA developed ALTR or metallosis on MRI than did patients with CoP bearings (hazard ratio 4.8 [95% confidence interval 1.2 to 18.4]; p = 0.02). There was no association between the longitudinal change of synovial reaction to ALTR or metallosis on MRI with patient-reported outcomes. In addition, there was no association between the presence of dehiscence at baseline and the subsequent development of ALTR or metallosis, as seen on MRI. There were elevated cobalt (4.7 ± 3.5 ppb) and chromium (4.7 ± 2.6 ppb) serum levels in patients with unilateral HRA who had an ALTR or metallosis present on MRI at year 1 compared with patients without an ALTR or metallosis on MRI (cobalt: 1.8 ± 1.0 ppb, mean difference 4.7 ppb [95% CI 3.3 to 6.0]; p < 0.001; chromium: 2.3 ± 0.5 ppb, mean difference 3.6 ppb [95% CI 2.2 to 5.0]; p < 0.001) as well as for chromium at year 3 (3.9 ± 2.4 ppb versus 2.2 ± 1.1 ppb, mean difference 1.3 ppb [95% CI 0.3 to 2.4]; p = 0.01).

CONCLUSION

We found a higher proportion of ALTR or metallosis on MRI in patients with HRA compared with patients with CoP, even when patient self-assessed symptomatology of those with an ALTR or metallosis on MRI was not different than the absence of these features. MRI detected ALTRs in high-function patients, emphasizing that an annual clinical assessment dependent on survey or blood ion testing alone may not detect soft tissue complications. The results of this study are in line with prior consensus recommendations of using MRI as part of a routine follow-up protocol for this patient population.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Predictive Factors for Revision and Survivorship Analysis of a Prevalent 36-mm Metal-on-Metal Total Hip Replacement System: A Large Single-Center Retrospective Cohort Study

BACKGROUND

To our knowledge, this is the largest single-center cohort of the 36-mm Corail-Pinnacle metal-on-metal total hip replacements system, aiming to determine 10-year survivorship and identify predictors of revision. We further assessed year of implantation given reports of manufacturing variations affecting shells made after 2006 predisposing these components to increasing wear.

METHODS

All Corail-Pinnacle 36-mm metal-on-metal hips implanted in a single center (2005-2012). The effect of patient and implant-related variables, and year of implantation on revision risk was assessed using Kaplan-Meier, Cox regression, and interrupted time series analysis.

RESULTS

In total, 1212 metal-on-metal total hip replacements were implanted with a 10-year survival rate of 83.4% (95% confidence interval [CI] = 81.3-85.5). Mean follow-up duration was 7.3 years with 61% of patients reaching a minimum of 7 years of follow-up. One hundred nineteen patients required revision surgery (9.8%). Univariate analysis identified female gender (hazard ratio [HR] = 1.608, CI = 1.093-2.364, P = .016), age at implantation (HR = 0.982, CI = 0.968-0.997, P = .019), smaller 50-mm to 54-mm cup diameter (HR = 1.527, CI = 1.026-2.274, P = .037), and high-offset stems (HR = 2.573, CI = 1.619-4.089, P < .001) as predictors of revision. Multivariate modeling confirmed female gender and high-offset stems as significant predictors of revision. For components implanted after 2007, the number of revisions showed no statistically significant step increase compared to pre-2007 implantation.

CONCLUSION

We observed a high 10-year failure rate (16.6%) with this implant, mostly due to adverse reaction to metal debris. Female gender and high femoral offset stems were significant predictors for all-cause revision. Year of implantation was not significantly associated with an increasing number of revisions from 2007 onwards, although further studies to validate the impact of manufacturing discrepancies are recommended.

Metal Ion Release, Clinical and Radiological Outcomes in Large Diameter Metal-on-Metal Total Hip Arthroplasty at Long-Term Follow-Up

Total hip arthroplasty (THA) with metal-on-metal (MoM) bearings have shown problems of biocompatibility linked to metal ion release at the local level causing an adverse reaction to metal debris (ARMD) and at a systemic level. The aim of this study was to evaluate clinical and radiological outcomes, and metal ion concentrations in the blood and urine of patients who underwent THA with the LIMA Met-Met hip system. Patients with ceramic-on-ceramic (CoC) bearings were included as a control group. In this study, 68 patients were enrolled: 34 with MoM THAs and 34 with CoC THAs. Patients were evaluated clinically (Harris Hip Score, SF-36) and radiologically at a median of 7.4 years after surgery. Whole blood and urinary cobalt and chromium levels were also assessed. Both types of implants were comparable in terms of clinical and functional results. Ion levels were significantly higher in the MoM group compared with CoC group 7 years after surgery. No correlations were found between metal ion levels and patient demographics, functional and radiological outcomes, and prosthesis features. Patient monitoring is thus advised to establish if prosthesis revision is necessary, especially in the case of MoM THA.

MARS MRI Characteristics of Adverse Local Tissue Reactions in Taper Corrosion of Metal-On-Polyethylene THA Differ From Metal-On-Metal THA

BACKGROUND

Metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) has been recommended as a cross-sectional imaging modality in clinical evaluation of adverse local tissue reactions (ALTRs) in metal-on-metal (MoM) patients and metal-on-polyethylene (MoP) patients with taper corrosion. The aim of the study was to compare MARS MRI characteristics of ALTR in MoM total hip arthroplasty (THA) with ALTR in MoP THA with modular taper corrosion.

METHODS

A total of 197 patients with ALTR were evaluated: 86 patients with MoM THA; 37 MoP patients with head-neck taper corrosion; and 74 MoP patients with neck-stem dual taper corrosion. MARS MRI scans were evaluated to identify location, size, type of ALTR (I-III), and associated ALTR synovitis (cystic, solid, and mixed).

RESULTS

MARS MRI characteristics of ALTR were significantly different between the MoM and MoP groups (P = .017). The MoP group demonstrated the highest proportion of thick-walled cystic masses type II (56.7% in head-neck taper corrosion MoP and 46.5% in dual taper corrosion MoP vs 28.7% in MoM), whereas the MoM group had the highest proportion of thin-walled cystic masses type I. MoM implants (96.8%) were significantly more likely to have ALTR in multiple locations compared with both MoP groups (P = .001).

CONCLUSION

This study demonstrates that MARS MRI characteristics of ALTR differ by bearing type with a significantly higher percentage of mixed type and solid type ALTR in the taper corrosion MoP THA compared with MoM THA. This information provides clinically useful information in evaluation of symptomatic MoP and MoM THA patients for ALTRs.

Sex-based differences in the outcomes of total hip and knee arthroplasty: a narrative review

Total joint arthroplasty (TJA) is an effective treatment for end-stage osteoarthritis, which aims to alleviate pain and improve function and mobility. Despite the remarkable success of TJA, complications can arise, leading to unplanned hospital readmission, implant failure, morbidity and mortality. Recently, there has been a growing interest in analysing sex-based differences in diseases and response to medical interventions. This review summaries evidence pertaining to the widening gap between men and women regarding the utilization and outcome of TJA surgery. Interactions between sex and patient-reported outcome, implant failure and medical complication are complex and often demonstrate conflicting results. Significantly, there is a global consensus that men are at a higher risk of developing prosthetic joint infection following joint arthroplasty. Guided by the literature, there is a clear need for standardized methods of collecting, analysing and reporting sex-specific data to improve outcomes for both men and women who undergo TJA.

Outcome of Ceramic-on-Ceramic Total Hip Arthroplasty with 4th Generation 36 mm Head Compared to that with 3rd Generation 28 mm Head by Propensity Score Matching

BACKGROUND

With the development of 4th generation ceramic bearing, the large ceramic head is available for ceramic-on-ceramic total hip arthroplasty (THA). This retrospective study aimed to compare the outcomes of ceramic-on-ceramic THA with 4th generation 36 mm head to those with 3rd generation 28 mm head using propensity score matching.

METHODS

We retrospectively reviewed the results of 133 ceramic-on-ceramic THAs with 4th generation 36 mm ceramic head in 129 patients and 133 ceramic-on-ceramic THAs identified from 405 ceramic-on-ceramic THAs with 3rd generation 28 mm head by propensity score matching. There were 83 males and 50 females in both groups with a mean age of 55 years. There was no significant difference in other demographic features except for follow-up period (4.2 years in the 36 mm group and 6.4 years in the 28 mm group, p < 0.001). Clinical and radiological results and occurrence of complication were compared between the two groups.

RESULTS

Harris Hip Score was increased significantly from 46.4 to 92.1 in the 36 mm group and from 46.7 to 93.6 in the 28 mm group. No loosening or osteolysis was observed in the 36 mm group. However, one hip showed radiologic sign of loosening in the 28 mm group. As for complication, postoperative dislocation was more frequent in the 28 mm group (6 in the 28 mm group vs. 0 in the 36 mm group, p = 0.03). Otherwise, there was no significant difference in other results including inguinal pain, squeaking or ceramic fracture.

CONCLUSION

Ceramic-on-ceramic THA with 4th generation 36 mm head significantly reduced postoperative dislocation rate without increasing the rate of inguinal pain, squeaking, or ceramic fracture compared to that with 3rd generation 28 mm head.

A Mid- to Long-Term Follow-Up Experience with a Specific Metal-on-Metal Total Hip Arthroplasty Design

Purrpose  Metal-on-metal (MoM) total hip arthroplasty (THA) has been a subject of recent discussion and concern due to the early failures caused by local and systemic adverse reactions related to specific designs. The aim of this study is to analyze the outcomes and survival rates of a single brand of MoM implants implanted in a consecutive series of patients at a single institution.

Methods  Between 2007 and 2012, 116 (118 hips) patients were evaluated at a mean follow-up of 6.6 years after primary THA. The diagnosis leading to surgery was osteoarthritis (80 patients) and proximal femoral fracture (36 patients). A single design of THA was implanted. All patients were evaluated before surgery and postoperatively at 1, 3, 6, and 12 months by clinical scores and radiographic studies. The data analysis was made using Student's t -test.

Results  The minimum follow-up was of 4 years, with a mean follow-up of 6.6 years. Two aseptic loosenings of the acetabular component were recorded (one per group), which were not associated with local or systemic complications related to metal ion release. Both were revised by an isolated acetabular cup substitution with metal-on-polyethylene couplings. Nonprogressive radiolucency lines < 2 mm in zone 2 were observed in other six patients around the acetabular component without clinical manifestation (four in the arthritis group and two in the fracture group). Postoperative Harris Hip Score and SF-36 (36-Item Short Form Survey) score improved in both groups.

Conclusion  Despite several MoM implants showing early complications and failures, a specific MoM design may be associated with good clinical results at a mid- to long-term follow-up.

Level of Evidence  This is a therapeutic case series, Level 4 study.

Ultrasound-based decision making following metal-on-metal hip arthroplasty

BACKGROUND

Metal-on-Metal (MoM) total hip arthroplasty (THA) represents a very controversial procedure because of the possibility of postoperative adverse local tissue reaction (ALTR). This study investigates the reliability of the ultrasound scan as a diagnostic tool to quantify a clinically useful threshold in the level of periprosthetic fluid collection to suggest implant revision.

METHODS

This study includes 116 patients (123 implants) who received an Articular Surface Replacement XL (ASRTMXL, De Puy Synthes, USA) MoM THA. The study group included 56 males and 60 females with a mean age of 66.6 years (range, 15-86 years). All patients were clinically and radiologically annually evaluated (according to the Harris Hip Score) up to a mean follow-up of 7.5 years (min. 1.4 - max. 10.3 years) from the primary surgery: all patients underwent standard ultrasound evaluation of the affected hip and Cobalt/Chromium blood detection testing according to a custom-made diagnostic algorithm for MoM THA revision.

RESULTS

At final follow-up, 51 (43.1%) of 117 implants underwent revision after a mean of 6 years (1.79-9.26) from the primary ASR implant. The authors found a statistically significant correlation between Cr (p = 0.015) and Co (p = 0.009) blood values and different ultrasound grades. Statistical analysis showed a significant association between periprosthetic fluid collection and revision surgery (p < 0.0001) and the final revision risk was estimated to be 7 times greater in patients with ultrasound grade ≥ 2 (peri-prosthetic collection ≥ 20 mm).

CONCLUSIONS

This study confirms the reliability of ultrasound evaluation in detecting clinically significant peri-prosthetic joint effusions: a new diagnostic algorithm for MoM THA revision is here presented. Longer follow up studies are mandatory to better understand the potential advantages of this diagnostic protocol.

The 10-year outcomes of the ASR XL Acetabular System: a single-center experience from China

Background

The revision rate of articular surface replacement (ASR) implants continues to rise in China because of metal debris. However, there are few reports on the clinical results of ASR implants with prolonged follow-up time in China. This study investigated the clinical outcomes and the risk factors of revision surgery in patients with ASR implants.

Methods

In total, 74 patients (74 hips) who underwent primary total hip arthroplasty (THA) with ASR implants over the past 4 to 10 years were retrospectively analyzed. Relevant clinical, radiographic, and biochemical data were examined.

Results

The average follow-up time was 88.46 (range 23–114) months, and the ASR implants of 18 hips (24.3%) were revised. Patients who received revision surgery had worse joint function with significantly lower Harris Hip Score and Western Ontario and McMaster Universities index than non-revision patients (61.11 ± 6.68 vs 85.30 ± 9.16, p < 0.001; 61.00 ± 3.83 vs 79.04 ± 14.49, p < 0.001; respectively). Higher acetabular abduction angle and serum Co and Cr concentration were significantly relevant to worse joint function as measured by HSS (p = 0.018, 0.009, 0.043, respectively). ROC curve analysis was applied to categorize the optimal cutoff values of acetabular abduction angle and serum Cr and Co concentration for revision surgery, which were settled as 47.80°, 98.44 μg/L, and 6.95 μg/L, respectively. Overall survival of the prostheses with high acetabular abduction angle (> 47.80°, HR = 70.145, 95% CI 1.558–3158.213, p = 0.029), high serum Cr concentration (98.44 μg/L, HR = 58.956, 95% CI 1.294–2685.203, p = 0.036), and high serum Co concentration (> 6.95 μg/L, HR = 179.511, 95% CI 2.360–13656.941, p = 0.019) decreased significantly than the lower groups.

Conclusions

Evaluation of the DePuy ASR XL articulation demonstrated increased rates of revision following a longer follow-up period. High acetabular abduction angle and serum Cr and Co concentration correlated with worse clinical outcomes and high revision rate. Therefore, we advocate that patients with DePuy ASR XL implants be followed up more closely than those with other implants, especially with high acetabular abduction angle and serum Cr or Co concentration.

Prevalence and natural course of pseudotumours after small-head metal-on-metal total hip arthroplasty: a minimum 18-year follow-up study of a previous report

AIMS

The present study investigated the five-year interval changes in pseudotumours and measured serum metal ions at long-term follow-up of a previous report of 28 mm diameter metal-on-metal (MoM) total hip arthroplasty (THA).

PATIENTS AND METHODS

A total of 72 patients (mean age 46.6 years (37 to 55); 43 men, 29 women; 91 hips) who underwent cementless primary MoM THA with a 28 mm modular head were included. The mean follow-up duration was 20.3 years (18 to 24). All patients had CT scans at a mean 15.1 years (13 to 19) after the index operation and subsequent follow-up at a mean of 20.2 years (18 to 24). Pseudotumour volume, type of mass, and new-onset pseudotumours were evaluated using CT scanning. Clinical outcomes were assessed by Harris Hip Score (HHS) and the presence of groin pain. Serum metal ion (cobalt (Co) and chromium (Cr)) levels were measured at the latest follow-up.

RESULTS

At final follow-up, pseudotumours were observed in 26/91 hips (28.6%). There was an increase in volume of the pseudotumour in four hips (15.4%), no change in volume in 21 hips (80.8%), and a decrease in volume in one hip (3.8%). There were no new-onset pseudotumours. There was no significant difference in HHS between patients with and without pseudotumours. At final follow-up, mean serum Co ion levels and median Co:Cr ratios were significantly greater in patients with pseudotumours, but the serum Cr ion levels were not significantly different.

CONCLUSION

At a mean 20 years of follow-up, pseudotumours were observed in 26/91 hips (28.6%) with no new-onset pseudotumours during subsequent follow-up. Most pseudotumours in small-head MoM THA were static in volume and asymptomatic with normal serum metal ion levels. Cite this article: Bone Joint J 2019;101-B:317-324.

What Is the Clinical Presentation of Adverse Local Tissue Reaction in Metal-on-metal Hip Arthroplasty? An MRI Study

BACKGROUND

Adverse local tissue reaction (ALTR) is not only a prominent cause of metal-on-metal (MoM) implant revision, but may also compromise the result of revision surgery. Patients treated with MoM arthroplasty and subsequently revised as a result of ALTR have been shown to experience worse patient-reported outcomes, inferior survivorship, and more complications when compared with patients receiving MoM implants who were revised for reasons other than ALTR. There is conflicting evidence as to whether the presence of symptoms is associated with ALTR in patients with MoM implants. Blood metal ions are associated with ALTR, but a consensus on appropriate thresholds associated with ALTR risk is lacking.

QUESTIONS/PURPOSES

(1) Was the presence of symptoms as measured by patient-reported outcome measures associated with ALTR presence and severity as noted on metal artifact reduction sequence (MARS)-MRI in patients treated with one design of MoM THA or hip resurfacing arthroplasty (HRA)? (2) Could reliable thresholds for blood metal ion levels be determined that were associated with ALTR presence on MARS-MRI?

METHODS

This retrospective study presents a secondary analysis of data drawn from a prospective, international, multicenter study of the recalled Articular Surface Replacement (ASR) hip system. This larger study aims to identify risk factors for revision and provide followup guidelines for the many unrevised ASR patients. A total of 1721 patients were enrolled from 16 centers in six countries after the device was recalled and are followed annually for 5 years. In the present analysis, data from the enrollment visit (mean time from index surgery, 7.5 years; SD 3.5 years) were considered. Only patients from two centers conducting MARS-MRI on all patients regardless of clinical presentation as a standard of care were included to avoid selection bias. A total of 327 unilateral patients fulfilled our inclusion criteria (90% of those eligible). The level of symptoms was systematically determined using the Harris hip score and a visual analog scale for pain, and whole blood metal ion levels were collected from all patients. MARS-MRIs were analyzed by a single reader for ALTR presence (Anderson classification), diameter, and synovial thickness. A validation series of 35 MARS-MRIs indicated excellent intrareader reproducibility of the evaluations (intraclass correlation = 0.82) and substantial agreement (κ coefficient = 0.64) was achieved between the MARS-MRI reader and a musculoskeletal radiologist with > 10 years of experience with MARS-MRI. Binary logistic regression was used to determine variables independently associated with ALTR. Receiver operator characteristic curves were used to determine sensitive and specific cut points for cobalt and chromium.

RESULTS

After controlling for confounding variables, presence of symptoms was determined to be a risk factor for ALTR (odds ratio, 2.9; p = 0.007) in patients treated with ASR MoM THA. Moreover, among patients undergoing ASR MoM THA with ALTR, synovial thickness correlated with symptomaticity (p = 0.030). For patients undergoing ASR MoM HRA, we found no association between symptoms and ALTR prevalence or severity. A cobalt cutoff of 3.2 parts per billion (ppb) was associated with increased risk of ALTR (p < 0.001; sensitivity, 68%; specificity, 71%) in ASR MoM THA. In patients with ASR MoM HRA, a cobalt threshold of 2.9 ppb was indicative of ALTR (p < 0.001; sensitivity, 79%; specificity, 69%).

CONCLUSIONS

The risk factors identified in the current study may be used to stratify patients receiving MoM implants in terms of ALTR risk. We found that symptoms are associated with an increased likelihood of ALTR presence in ASR MoM THA and that cobalt ion level is associated with ALTR in ASR MoM THA as well as ASR MoM HRA. Importantly, MoM HRA followup protocols that exempt asymptomatic patients from annual followup are not justified because asymptomatic patients are no less likely to have ALTR than symptomatic patients. Blood metal ion levels may reliably be used to screen patients undergoing MoM HRA. For patients undergoing MoM THA, a combination of symptom state and blood metal ion levels may be used to determine ALTR risk.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Reporting the Influence of Sex in Research: Trends at AAOS Annual Meetings

BACKGROUND

Several initiatives have urged the inclusion of sex in data analysis, but few studies have examined the prevalence of sex-specific reporting in musculoskeletal research. This study aims at determining the presence of sex-specific analyses reported in research at American Academy of Orthopaedic Surgeons Annual Meetings.

METHODS

Abstracts listed in the American Academy of Orthopaedic Surgeons Annual Meeting programs from 2006 to 2013 were retrospectively reviewed for the presence of research reporting the results of a sex-specific analysis.

RESULTS

The number of abstracts reporting a sex-specific analysis increased from 48 (2006) to 117 (2013) but accounts for 5.4% of research presented from 2006 to 2013. Hip and knee arthroplasty literature accounted for 37% of included abstracts.

CONCLUSIONS

The reporting of sex-specific analyses has improved over time but accounts for 5.4% of research presented at annual meetings from 2006 to 2013. The inclusion of sex-specific analyses should be required for future research publications to better understand the influence of sex in musculoskeletal medicine.

Revisions of Modular Metal-on-metal THA Have a High Risk of Early Complications

BACKGROUND

The risk of early complications is high after monoblock acetabular metal-on-metal (MoM) THA revisions. However, there is a paucity of evidence regarding clinical complications after isolated head-liner exchange of modular MoM THA.

QUESTIONS/PURPOSES

The purposes of this study were (1) to describe the frequency of early complications after an isolated head-liner exchange revision of modular MoM THA; and (2) to determine whether patients who experienced complications or dislocation after head-liner exchanges had higher serum chromium (Cr) or cobalt (Co) ion levels than those who did not.

METHODS

A review of our institution's total joint registry retrospectively identified 53 patients who underwent 54 liner exchange revisions of a modular acetabular MoM THA. The study period was from April 2008 to April 2016 at a single tertiary care center. During this period, isolated head-liner exchanges (rather than more extensive revisions) were performed in patients if they did not have evidence of loosening of the acetabular or femoral components. Reasons for revision surgery included pain, mechanical symptoms, radiographic evidence of osteolysis, elevated serum metal ions, and MRI abnormalities with 40 of the 54 hips having pain or mechanical symptoms and 38 of 54 hips having multiple reasons for revision before surgery. Patients were excluded if they did not meet the minimum postrevision followup or had the modular liner exchange secondary to infection. All revisions were from a single manufacturer with one head-liner exchange of a MoM THA from another manufacturer excluded during the study period. The mean time from index MoM THA to modular exchange was 96 (SD ± 36) months. Because the focus of this study was early complications, we had a minimum 90-day followup duration for inclusion. Mean followup after revision was 15 months (SD ± 12); a total of 56% (30 of 54) had followup of at least 12 months' duration. Complications (dislocation, infection) and reoperations were obtained by chart review performed by individuals other than the treating physician(s). Serum metal ion levels were obtained before head-liner exchange. The median serum Cr and Co levels were 6 µg/L (range, 0-76 µg/L) and 12 µg/L (range, 0-163 µg/L), respectively.

RESULTS

Of the 54 revision THAs, 15 (28%) developed complications. Nine (17%) occurred within 90 days of the revision surgery and 11 (20%) resulted in reoperation. The most common complication was dislocation (12 of 54 [22%]) with recurrent dislocation noted in eight of these 12 patients. All patients with recurrent dislocation continued to dislocate and underwent repeat revision. Patients with dislocation had higher median serum Cr and Co ion levels than those without dislocation (Cr: 24 [range, 11-76] versus 4 [range, 0-70], p = 0.001 [95% confidence interval {CI}, 10-57]; Co: 41 [range, 6-163] versus 8 [range, 0-133], p = 0.016 [95% CI, 6-141]). Three (6%) of the 54 patients underwent repeat surgery for deep space infection.

CONCLUSIONS

Complications and reoperations are common after modular head-liner exchange in the setting of a failed MoM THA. Our study likely underestimates the frequency of complications and revisions because the followup period in this report was relatively short. Dislocation is the most common complication and elevated serum metal ion levels may be a predictor of dislocation. These findings are concerning and surgeons should be aware of the high complication risk associated with this procedure.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

The correlation between activity level, serum-ion concentrations and pseudotumours in patients with metal-on-metal hip articulations and metal-on-polyethylene total hip articulations

Purpose

Young and physically active patients have mainly received metal-on-metal (MoM) total hip arthroplasty (THA) and resurfacing hip arthroplasty (RHA). However, the correlation between daily physical activity (PA) levels, serum-ion concentrations of chromium and cobalt and pseudotumours formation of patients who underwent MoM THA/RHA is insufficiently explored.

Methods

Ninety-nine patients with 134 hip articulations, 71 MoM THA/RHA and 63 MoP THA participated in a cross-sectional study at XXX University Hospital, Denmark, at mean 7.3 (range: 0.4–21.7) years after surgery. Patients' daily PA was monitored during a two-week period using a triaxial accelerometer. Metal artefact reduction sequence magnetic resonance imaging scans, estimation of serum-ion concentrations of chromium and cobalt and the Copenhagen Hip and Groin Outcome Score (HAGOS) questionnaire were completed on Day 14.

Results

Patients with a pseudotumour who underwent MoM THA/RHA had a higher average cadence of median 101.4 [interquartile range (IQR: 95.5–105)] steps/min than patients without a pseudotumor, median 96.7 (IQR: 92.2–103) steps/min (p = 0.02). Serum-ion concentrations of chromium and cobalt were higher in patients with a pseudotumour who underwent MoM THA/RHA, median 2.57 (IQR: 1.4–3.4) μg/L and 1.80 (IQR: 1.2–2.6) μg/L, respectively, than in patients without a pseudotumour, median 1.85 (IQR: 1.1–3.2) μg/L and 1.34 (IQR: 0.9–2.2) μg/L in MoM THA/RHA (p = 0.04 and p = 0.03). There was no statistical difference in these parameters between patients with and without a pseudotumour who underwent MoP THA. Daily PA levels of patients who underwent MoM THA/RHA were significantly correlated with serum-ion concentrations of chromium (p = 0.0002, r = 0.44) and cobalt (p = 0.005, r = 0.34), whereas no correlations were seen among patients who underwent MoP THA (p > 0.12).

Conclusion

The daily PA level of patients who underwent MoM THA/RHA influences the serum-ion concentrations of chromium and cobalt and the risk of pseudotumour formation.

Translational potential of this article

Results of this article add important knowledge on potential recommendations of prosthesis selection for patients with a high level of physical activity.

MRI findings, metal ion levels and clinical outcome of a complete series of large metal on metal THA: what's really going on?

INTRODUCTION:

Metal-on-metal (MoM) large head total hip arthroplasties (THAs) were discontinued early after their introduction because of the high number of failures due to adverse reaction to metal debris (ARMD). Aim of this study is to report the clinical outcome at a mid-term follow-up (FU) of a series of large-head MoM THA.

METHODS:

In this prospective study, 25 hips (24 patients, 3 males, 21 females, mean age 62.44 years) who have undergone primary THA with large head (diameter ⩾36 mm) MoM prosthesis were evaluated. Each patient underwent a standard follow-up after surgery, that included blood tests with metal ion levels (Co and Cr), x-ray of the pelvis, metal artifact reduction sequence magnetic resonance imaging (MARS-MRI) and clinical evaluation.

RESULTS:

At an average follow-up of 7.3 years, 4 hips have been surgically reviewed: 2 for causes not related to ARMD (1 heterotopic ossification and 1 periprosthetic fracture); the other 2 on the same patient (bilateral) with ARMD, who was eventually found to be allergic to nickel. Increased metal ions, osteolysis and severe MRI alterations were found in patients with ARMD. Asymptomatic alterations at MRI were found in 8 patients. Harris Hip Score improved after surgery from a mean of 51 points to a mean of 90 points ( p < 0.01).

CONCLUSIONS:

The findings of this study show that not all the patients with MoM THA will develop clear symptoms of ARMD at mid-term follow-up. Patients should be closely monitored following protocols such as that proposed in the European Consensus Statement.

Physical Activity Is Associated With the Level of Chromium but Not With Changes in Pseudotumor Size in Patients With Metal-on-Metal Hip Arthroplasty

BACKGROUND

Metal-on-metal (MoM) total hip arthroplasty (THA) and resurfacing hip arthroplasty (RHA) were previously considered an excellent option for young and physically active patients. However, the relationship between MoM THA/RHA patients' daily physical activity (PA), metal ion measurements of chromium and cobalt, and pseudotumor dynamic is insufficiently explored.

METHODS

One hundred eleven patients with 148 hip articulations, 77 MoM THA/RHA and 71 MoP THA, participated in a prospective cohort study, with 5 cross-sectional analyses during a 1-year follow-up. Baseline follow-up was at mean 7.1 (range: 0.2-21.5) years postoperative. At baseline and every 3 months thereafter, patients' daily PA was monitored during a 2-week period using a triaxial accelerometer, and next metal artifact reducing sequence magnetic resonance imaging scans, metal ion measurements of chromium and cobalt, and the Copenhagen Hip and Groin Outcome Score questionnaire were completed.

RESULTS

We found a statistically significant relationship between daily PA and metal ion measurements of chromium at all follow-ups in MoM THA/RHA patients (P ≤ .03) but not in MoP THA patients (P > .35). Patients' daily PA was not related to changes in pseudotumor size at any follow-up (P > .30). Ten of 26 (38%) pseudotumors in MoM THA/RHA and 8 of 29 (28%) pseudotumors in MoP THA changed classification according to the Anderson grading. No pseudotumors transformed in appearance or changed anatomical location.

CONCLUSION

The daily PA of MoM THA/RHA patients is associated with metal ion measurements of chromium but not with changes in pseudotumor size. This is new and important knowledge, which may be useful for hip surgeons in recommendation and monitoration of the consequences of PA in active patients with MoM THA/RHA.

Indications for MARS-MRI in Patients Treated With Articular Surface Replacement XL Total Hip Arthroplasty

BACKGROUND

The purpose of this study was to identify which patient and clinical factors are predictive of adverse local tissue reaction (ALTR) and to use these factors to create a highly sensitive algorithm for indicating metal artifact reduction sequence magnetic resonance imaging (MARS-MRI) in Articular Surface Replacement (ASR) XL total hip arthroplasty patients. Our secondary aim was to compare our algorithm to existing national guidelines on when to take MARS-MRI in metal-on-metal total hip arthroplasty patients.

METHODS

The study consisted of 137 patients treated with unilateral ASR XL implants from a prospective, multicenter study. Patients underwent MARS-MRI regardless of clinical presentation at a mean of 6.2 (range, 3.3-10.4) years from surgery. Univariate and multivariate analyses were conducted to determine which variables were predictive of ALTR. Predictors were used to create an algorithm to indicate MARS-MRI. Finally, we compared our algorithm's ability to detect ALTR to existing guidelines.

RESULTS

We found a visual analog scale pain score ≥2 (odds ratio [OR] = 2.53; P = .023), high blood cobalt (OR = 1.05; P = .023), and male gender (OR = 2.37; P = .034) to be significant predictors of ALTR presence in our cohort. The resultant algorithm achieved 86.4% sensitivity and 60.2% specificity in detecting ALTR within our cohort. Our algorithm had the highest area under the curve and was the only guideline that was significantly predictive of ALTR (P = .014).

CONCLUSION

Our algorithm including patient-reported pain and sex-specific cutoffs for blood cobalt levels could predict ALTR and indicate MARS-MRI in our cohort of ASR XL metal-on-metal patients with high sensitivity.

LEVEL OF EVIDENCE

Level II, diagnostic study.

Higher Prevalence of Mixed or Solid Pseudotumors in Metal-on-Polyethylene Total Hip Arthroplasty Compared With Metal-on-Metal Total Hip Arthroplasty and Resurfacing Hip Arthroplasty

BACKGROUND

Pseudotumors are a common finding in metal-on-metal (MoM) total hip arthroplasty (THA) and resurfacing hip arthroplasty (RHA). However, information on pseudotumors in metal-on-polyethylene (MoP) THA is limited.

METHODS

One hundred eleven patients with 148 hip articulations-30 MoM THA, 47 MoM RHA, and 71 MoP THA-participated in a cross-sectional study at mean 7.1 (range: 0.2-21.5) years postoperatively. Patients were evaluated with metal artifact reducing sequence magnetic resonance imaging, measurements of metal ions, clinical scores of Harris Hip Score, Oxford Hip Score, the Copenhagen Hip and Groin Outcome Score, and conventional radiographs.

RESULTS

Pseudotumors were present in 13 of 30 (43%) MoM THA, 13 of 47 (28%) MoM RHA, and 29 of 71 (41%) MoP THA patients, which was a similar prevalence (P = .10). The prevalence of mixed or solid pseudotumors was significantly higher in patients with MoP THA (n = 10) compared to MoM THA (n = 3) and MoM THA (n = 0), (P = .01). Hips with a mixed or solid pseudotumor had significantly poorer scores of Harris Hip Score (P = .01) and OHS (P = .002) and higher metal ion levels of cobalt (P = .0009) compared to hips without a pseudotumor or with a cystic pseudotumor.

CONCLUSION

Pseudotumors have primarily been associated with MoM hip articulations, but we found a similar pseudotumor prevalence in MoP THA, which is the most common bearing worldwide. Mixed or solid pseudotumors were more often seen in MoP THA compared with MoM hip articulations, and patients with a mixed or solid pseudotumor had poorer clinical scores and higher metal ion levels than patients without a pseudotumor or with a cystic pseudotumor.

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.

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.

Femoral offset found not to affect metal ion levels in metal-on-metal total hip arthroplasty

BACKGROUND

Failure to restore femoral offset in metal on polyethylene total hip arthroplasty (THA) causes polyethylene wear and aseptic loosening. To our knowledge, no study to date has investigated the relationship between femoral offset and wear in metal-on-metal (MOM) THA.

AIMS

In this study, we investigated the relationship between femoral offset and wear by measuring circulating metal ion levels in MOM THA.

METHODS

In this retrospective study, we identified patients who had undergone MOM THA with the ASR XL system (DePuy International Ltd., Leeds, UK). Femoral offset was measured using anteroposterior radiographs, and circulating metal ion levels (cobalt and chromium) were recorded.

RESULTS

In total, 95 patients were included (68 males and 27 females). The mean age at the time of surgery was 64.9. Mean time from surgery to blood sampling was 15.4 months. No statistically significant relationship was found between femoral offset and cobalt (p = 0.313) or chromium (p = 0.401) ions.

CONCLUSION

It is known that failure to restore femoral offset during THA can lead to high rates of wear in metal-on-polyethylene articulations. In our study, no statistically significant relationship was found between femoral offset and serum cobalt or chromium ions. This study adds to the information available to surgeons regarding factors that increase wear in metal-on-metal total hip arthroplasty.

Long-term clinical results of the Metasul metal-on-metal total hip arthroplasty: 12.6 years follow-up of 128 primary total hip replacements

INTRODUCTION

The purpose of the present study is to report the long-term clinical results of an uncemented total hip arthroplasty (THA) using a Metasul metal-on-metal (MoM) 28-mm bearing and to evaluate the long-term serum cobalt levels.

METHODS

At an average of 12.6 years following primary THA, we retrospectively reviewed the clinical results of the first 116 consecutive patients (128 THAs) in our institution who underwent 28-mm Metasul MoM THA. Of the 78 patients who were able to visit our outpatient clinic, serum cobalt levels were evaluated.

RESULTS

The overall survival rate of the cohort was 96.1% (95% confidence interval [CI], 93.2-99.6), 12.6 years (95% CI, 12.3-12.7 years) following surgery. 3 patients had undergone revision due to aseptic loosening of the stem and 2 patients sustained a periprosthetic fracture. The average modified Harris Hip Score was 90 (72-97) and the average Oxford Hip Score was 56 (48-60), representing both excellent outcome scores. The average serum cobalt of the entire cohort was 20.1 nmol/L (range 8.5-227.7 nmol/L). Serum cobalt levels of patients with a bilateral MoM THA were significantly higher (35.0 nmol/l, p<0.01). No relation between serum cobalt levels, subjective outcome, radiolucent lines on radiographs and survivorship of the implant was noted.

CONCLUSIONS

Long-term results of the metasul MoM bearing articulation in THA seem to be excellent, although cobalt serum levels should be monitored closely.

Pseudotumor in metal-on-metal hip arthroplasty: a comparison study of three grading systems with MRI

OBJECTIVE

Pseudotumors, a well-known complication of metal-on-metal total hip arthroplasty (MoM THA), are well identified on metal artifact-reducing sequences magnetic resonance imaging (MARS-MRI). Several MRI grading systems are described in the orthopedic literature, but their validity is unknown in large clinical studies. Our study was undertaken to describe the classification of pseudotumors in a preselected cohort divided into high- and low-risk patients, using three pseudotumor grading systems applied on MARS-MRI, and to determine the interobserver reliability of the grading systems.

PATIENTS AND METHODS

A retrospective study was performed on 377 consecutive patients (240 MRI scans) treated with an M2a-38 and Taperloc stem combination (Biomet, Warsaw, IN, USA). Patients were divided into a high-risk and a low-risk group based on previous published risk factors. Two observers determined the presence of pseudotumors using three different pseudotumor grading systems for classifying MARS-MRI results.

RESULTS

The prevalence of pseudotumors as determined with MARS-MRI was 59% in our high-risk group, 0% in the low-risk group and 43% in the control group. Serum cobalt values were increased in the high-risk group. The kappa values of the Anderson, Hauptfleisch and Matthies grading system scores were 0.43, 0.44, and 0.49 respectively.

CONCLUSIONS

High-risk patients are at a high risk for pseudotumor development. No pseudotumor development was found in low-risk patients. Interobserver reliability scored best with the Matthies system, but all three grading systems showed only a moderate agreement.

Risk factors for mid-term revision surgery in patients with articular surface replacement total hip arthroplasty

INTRODUCTION

This study assessed the associations between gender and implant survival, as well as adverse local tissue reaction (ALTR), in patients with articular surface replacement (ASR) XL total hip arthroplasty (THA). Secondly, we sought to report the differences between genders in metal ion levels and patient reported outcome measures (PROMs) in these patients.

METHODS

563 unilateral ASR XL THA patients were enrolled in a multicentre follow-up study at a mean of 6.4 years after index surgery. All patients had blood metal ion levels and PROMs obtained annually, and a valid anteroposterior pelvis radiograph. A sub-set of patients from a single centre had annual MRI performed and were analysed for the presence of moderate-to-severe ALTR.

RESULTS

60 hips (11%) were revised during the study period. The only variables found to be associated with revision surgery in patients with unilateral THA were VAS pain (hazard ratio [HR], 1.35; p<0.001) and elevated cobalt metal ion levels (HR, 1.05; p<0.001). No variables assessed were found to be associated with prevalence of ALTR. Chromium concentrations were greater in female patients than males, while cobalt levels were similar between genders. Males reported higher HHS, EQ-5D and UCLA scores than females.

CONCLUSIONS

Both males and females with metal-on-metal THA implants should be followed with equal vigilance as gender does not appear to be associated with poor outcomes, such as revision surgery and presence of ALTR.

Mild or moderate renal insufficiency does not increase circulating levels of cobalt and chromium in patients with metal-on-metal hip arthroplasty

Aims

To determine whether there is any association between glomerular filtration rate (GFR) and blood cobalt (Co) and chromium (Cr) levels in patients with metal-on-metal (MoM) hip arthroplasty.

Patients and Methods

We identified 179 patients with a unilateral 36 mm diameter head as part of a stemmed Summit-Pinnacle MoM hip arthroplasty. GFR was calculated using the Modification of Diet in Renal Disease formula.

Results

Normal renal function (GFR ≥ 90 ml/min/1.73 m2) was seen in 74 patients. Mild renal insufficiency (GFR 60 to 89 ml/min/1.73 m2) was seen in 90 patients and moderate renal insufficiency (GFR 30 to 59 ml/min/1.73 m2) in 15. There was no statistical difference in Co and Cr levels between patients with normal renal function and those with mild or moderate renal insufficiency. No correlation was seen between creatinine and blood metal ion levels or between GFR and blood metal ion levels. Linear regression analysis did not show any association between Co and Cr levels and GFR.

Conclusion

We did not find any association between GFR and blood metal ion levels. Consequently, the accumulation of Co and Cr in blood due to renal insufficiency does not seem to be a major risk in patients with mild or moderate renal insufficiency. Cite this article Bone Joint J 2017;99-B:1147–52

Adverse reaction to metal debris in a consecutive series of DUROM™ hip resurfacing: pseudotumour incidence and metal ion concentration

INTRODUCTION

The aim of this study was to evaluate the incidence of adverse reactions to metal debris (ARMD) in a consecutive series of DUROM™ Hip Resurfacing Arthroplasty (HRA) at mid-term follow-up.

METHODS

Between October 2003 and March 2007 a total of 134 consecutive DUROM™ HRA in 121 patients were performed at our institution. Follow-up could be obtained in 101 unrevised patients (83%) at a mean time of 8.51 ± 0.97 years postoperatively and included patient-related outcome measurement, plain radiographs, MARS-MRI as well as whole blood metal ion assessment.

RESULTS

17 (16.5%) out of 103 hips revealed pseudotumour occurrence in MRI investigation, 1 (10.6%) with a diameter of ≥2 cm. Higher incidence of pseudotumours was found patients with femoral component size <50 mm. 38 patients had elevated cobalt levels, 36 of them (35%) in the range of 2-7 μg/l and 2 patients (1.9%) at a rate of >7 μg/l. In contrast to cobalt determination, only elevated chromium values showed a positive association with pseudotumour occurrence and size.

DISCUSSION

A significant proportion of patients developed pseudotumours and metal ion elevation in a consecutive cohort of DUROM™ HRA after mid-term follow-up. The incidence, however, seems not to differ from results of other well performing resurfacing brands; clinical relevance of our findings is unclear. Regarding potential local as well as systemic effects of metal particle release, close follow-up of patients is essential, even with clinically well-performing implants.

Sensitivity and Specificity of Metal Ion Levels in Predicting "Pseudotumors" due to Taper Corrosion in Patients With Dual Taper Modular Total Hip Arthroplasty

BACKGROUND

Currently, no serum metal ion threshold exists to identify adverse tissue reactions in total hip arthroplasty (THA) patients with taper corrosion. Our study aims to investigate the sensitivity and specificity of serum metal ions in detecting taper corrosion related pseudotumors in patients with dual taper modular THA.

METHODS

A total of 148 patients with dual taper modular THA were investigated: (1) 90 patients with pseudotumors detected with metal artifact reduction sequence-magnetic resonance imaging (MARS-MRI) and (2) 58 patients without pseudotumors on MARS-MRI. Receiver operating characteristic curves were constructed to determine the sensitivity and specificity using different metal ion thresholds. The severity of intraoperative tissue damage was correlated with preoperative metal ion levels.

RESULTS

Pseudotumor was associated with higher cobalt (5.0 μg/L vs 3.7 μg/L, P < .01) and Co/Cr ratio (6.0 vs 3.7, P < .01). The sensitivity and specificity for cobalt level of 2.8 μg/L and Co/Cr ratio of 3.8 in detecting taper corrosion-related pseudotumors on MARS-MRI was 88% and 32% and 70% and 50%, respectively. Higher intraoperative tissue damage grades demonstrated significantly higher Co/Cr ratios (8.6 vs 3.4, P = .03).

CONCLUSION

Although metal ion levels alone should not be relied on as the sole parameter to determine revision surgery, cobalt level >2.8 μg/L and the Co/Cr ratio >3.8 are useful clinical diagnostic adjuncts in the systematic clinical evaluation for taper corrosion-related adverse tissue reactions in patients with dual modular taper THA.

The Role of Metal-on-Metal Bearings in Total Hip Arthroplasty and Hip Resurfacing: Review Article

BACKGROUND

The current role of metal-on-metal (MoM) bearings in hip arthroplasty remains controversial. The low wear offered by MoM bearings compared to metal-on-polyethylene and the possibility of a lower risk of dislocation with larger head sizes, encouraged a trend towards the re-introduction of the MoM bearing couple. However, recent evidence has shown that not all designs of the MoM bearing have been successful.

QUESTIONS/PURPOSES

The purpose of this paper is to provide an update on the use of MoM bearings and address the following issues: (1) the reintroduction of metal-on-metal bearings in total hip arthroplasty, (2) the failure of metal-on-metal bearings in stemmed total hip arthroplasty, (3) the role of metal-on-metal hip resurfacing in modern orthopaedics and (4) metal-on-metal hip resurfacing versus total hip arthroplasty.

METHODS

A literature search strategy was conducted using various search terms in MEDLINE and Embase. The highest quality articles that met the inclusion criteria and best answered the topics of focus of this review were selected. Key search terms included 'metal-on-metal', 'total hip arthroplasty' and 'hip resurfacing'.

RESULTS

The initial search retrieved 1240 articles. Twenty-two articles were selected and used in the review.

CONCLUSION

Metal-on-metal hip resurfacing is still a suitable treatment option in specific patient populations with the appropriate implant design and surgical skill, while stemmed metal-on-metal total hip arthroplasty should be avoided in all patient populations. Continued follow-up of patients undergoing metal-on-metal hip resurfacing is critical in order to further understand the long-term outcomes of these patients and why certain complications tend to occur with this procedure.

Management Guidelines for Metal-on-metal Hip Resurfacing Arthroplasty: A Strategy on Followup

Despite the initial promise of metal-on-metal (MoM) implants as the ideal bearing surface for hip replacements and resurfacings, high short term failure rates due to an adverse reaction to metal debris (ARMD) have led to a dramatic reduction in the number of MoM implants used in the modern era. With over one million patients worldwide having undergone hip operations utilizing a MoM bearing surface, the long term outcomes for such patients remains unknown, and there is much debate as to the most effective management of these patients. Although several regulatory bodies have released guidelines on the management of patients with MoM hips, these recommendations remain open to interpretation, and the most effective management for these patients remains unclear. The aim of this review is to compare the current guidelines for managing patients with MoM hips and also to discuss established ARMD risk factors, evidence regarding the optimum management for patients with MoM hips, and the indications for revision surgery. Furthermore, although specialized laboratory tests and imaging can be used to facilitate clinical decision making, over-reliance on any single tool should be avoided in the decision making process, and surgeons should carefully consider all findings when determining the most appropriate course of action.

Do cobalt and chromium levels predict osteolysis in metal-on-metal total hip arthroplasty?

INTRODUCTION

Serum metal ions are part of the regular follow-up routine of patients with metal-on-metal total hip arthroplasties (MoM-THA). Increased cobalt levels have been suggested to indicate implant failure and corrosion.

QUESTIONS

(1) Is there a correlation between the size of the osteolysis measured on a CT scan and metal ion levels? (2) Can metal ion levels predict the presence of osteolysis in MoM-THA? (3) Are cobalt and chromium serum levels or the cobalt-chromium-ratio diagnostic for osteolysis?

MATERIALS AND METHODS

CT scans of patients (n = 75) with a unilateral MoM-THA (Birmingham Hip System, Smith & Nephew, TN, USA) implanted by a single surgeon were reviewed to determine the presence of osteolysis. Statistical analysis was performed to detect its association with metal ion levels at the time of the imaging exam.

RESULTS

The incidence of osteolysis was the same in men and women (35.6 vs 35.7 %). The cobalt-chromium-ratio correlates with the size of the osteolysis on the CT scan and the femoral component size in the overall study population (p = 0.050, p = 0.001) and in men (p = 0.002, p = 0.001) but not in women (p = 0.312, p = 0.344). The AUC for the cobalt-chromium-ratio to detect osteolysis was 0.613 (p = 0.112) for the overall population, 0.710 for men (p = 0.021) and 0.453 (p = 0.684) for women. The data suggest that a cut off level of 1.71 for the cobalt-chromium-ratio has a sensitivity of 62.5 % and specificity of 72.4 % to identify male patients with osteolysis.

CONCLUSIONS

The disproportional increase of cobalt over chromium, especially in male patients with large component sizes can not be explained by wear alone and suggests that other processes (corrosion) might contribute to metal ion levels and might be more pronounced in patients with larger component sizes.

Factors associated with symptomatic pseudotumors following metal-on-metal total hip arthroplasty

Background

Pseudotumors associated with metal-on-metal hips can be symptomatic or asymptomatic. The purpose of this study was to identify the characteristics of pseudotumors associated with pain.

Methods

A total of 239 large-diameter, metal-on-metal total hip arthroplasties (THAs) were performed in 222 patients. Screening for pseudotumors was performed using magnetic resonance imaging (MRI) in all patients who underwent metal-on-metal THA, and 57 patients with 62 affected hips showed pseudotumors. There were 45 women with 49 hips and 12 men with 13 hips affected, with a mean age of 64 years and a mean body mass index (BMI) of 23.9 kg/m². Sixteen hips had symptomatic pseudotumors with pain, and 46 hips were asymptomatic. Pseudotumor size was determined. The anatomical position of pseudotumors was divided into anterior position and posterolateral position. Types of pseudotumors were divided into two types: cystic type; and mixed solid cystic and solid type without a cystic component. The follow-up study of pseudotumors was determined using MRI in 33 patients. The serum cobalt and chromium ion levels were measured in 38 patients after unilateral THA. Univariate and multivariate analyses were performed comparing symptomatic and asymptomatic patients to identify the characteristics of symptomatic pseudotumors.

Results

The mean BMI was 25.4 kg/m² in symptomatic patients and 23.4 kg/m² in asymptomatic patients; a higher BMI was associated with symptoms (P = 0.036). Symptomatic pseudotumors were significantly larger (three-fold) than asymptomatic pseudotumors (1812 mm² vs 642 mm², P = 0.003). Pseudotumors located in the anterior position were associated with symptoms (P = 0.032), and mixed solid cystic and solid type pseudotumors were associated with symptoms (P = 0.007). A multivariate analysis showed significant differences only in size (R² = 0.298, P = 0.031). No asymptomatic patients with pseudotumors became symptomatic during the follow-up period of MRI evaluation.

Conclusion

Larger size was a significant factor for pain on multivariate analysis.

Metal-on-metal total hip arthroplasty: risk factors for pseudotumours and clinical systematic evaluation

The potential advantages of contemporary MoM THA implants include less volumetric wear with subsequent reduction of polyethylene wear-induced osteolysis and greater component stability with use of large-diameter femoral heads. However, there have been concerns regarding significantly elevated revision rates in MoM THA due to MoM-related complications such as adverse local tissue reaction (pseudotumour) formation. The increased failure rate in MoM hip arthroplasty is associated with the generation of biologically active, nanometer sized metal particles from the MoM bearing surfaces and taper junctions, which result in the development of a localized, adverse periprosthetic soft tissue response. The focus of this article is to provide an update on (1) implant, surgical and patient factors associated with adverse local tissue reactions (pseudotumours) and (2) the clinical systematic evaluation and management of patients with MoM hip arthroplasty based on the currently available evidence. There should be a low threshold to conduct a systematic clinical evaluation of patients with MoM hip arthroplasty as early recognition and diagnosis will allow the initiation of prompt and appropriate treatment. As a symptomatic MoM total hip arthroplasty may have intrinsic and extrinsic causes, patients should be evaluated systematically, utilizing risk stratification algorithms. Although specialized laboratory tests such as metal ion levels and cross sectional imaging modalities such as MARS MRI can be used to facilitate clinical decision making, over-reliance on any single investigative tool in the clinical decision-making process should be avoided. Further research is required to obtain a better understanding of implant and patient risk factors associated with tribocorrosion in MoM total hip arthroplasty.

Sequelae of large-head metal-on-metal hip arthroplasties: Current status and future prospects

Large-head metal-on-metal (MoM) bearings were re-popularised in the late 1990s with the introduction of modern hip resurfacing (HR), followed closely by large metal head total hip arthroplasty (THA). A worldwide increase in the use of MoM hip arthroplasty subsequently saw a sharp decline, due to serious complications.MoM was rapidly adopted in the early 2000s until medical device alerts were issued by government regulatory agencies and national and international organisations, leading to post-marketing surveillance and discontinuation of these implants.Guidelines for MoM hip implant follow-up differ considerably between regulatory authorities worldwide; this can in part be attributed to missing or conflicting evidence.The authors consider that the use of large-head MoM THA should be discontinued. MoM HR should be approached with caution and, when considered, should be used only in patients who meet all of the recommended selection criteria, which limits its indications considerably.The phased introduction of new prostheses should be mandatory in future. Close monitoring of outcomes and long-term follow-up is also necessary for the introduction of new prostheses. Cite this article: van Lingen CP, Zagra LM, Ettema HB, Verheyen CC. Sequelae of large-head metal-on-metal hip arthroplasties: current status and future prospects. EFORT Open Rev 2016;1:345-353. DOI: 10.1302/2058-5241.1.160014.

Higher Blood Cobalt and Chromium Levels in Patients With Unilateral Metal-on-Metal Total Hip Arthroplasties Compared to Hip Resurfacings

BACKGROUND

Adverse soft tissue reactions in metal-on-metal (MoM) hip replacements are associated with cobalt (Co) and chromium (Cr) ions in blood. We report the prevalence and risk factors for elevated blood Co and Cr levels in patients with a unilateral MoM hip.

METHODS

From a single institution, blood Co and Cr levels were analyzed in 1748 patients (692 hip resurfacings and 1056 total hip arthroplasties [THAs]). Concentrations exceeding 7 ppb were considered elevated, and the risk factors for elevated levels were calculated with binary logistic regression.

RESULTS

Elevated blood metal ion levels were more common in MoM THA than in resurfacing patients (17.4% vs 5.9%, P < .001), and in 5 of the 7 THA brands, more than 20% of patients had elevated metal ion concentrations, whereas the proportion was less than 10% in all hip resurfacings. In resurfacings, small femoral head (odds ratio [OR] 1.30 per millimeter decrease [CI, 1.12-1.49]), high acetabular inclination (OR 1.15 per degree increase [CI 1.09-1.22]), and young age (OR 1.05 per year decrease [1.02-1.10]) were independent risk factors for elevated ions. In the THA group, female gender (OR 2.04 [CI 1.35-3.06]), longer time between surgery and ion measurement (OR 1.19 per year increase [CI 1.05-1.34]), and large headsize (OR 1.07 per millimeter increase [CI 1.01-1.13]) were risk factors for elevated ions.

CONCLUSION

Given the high percentage of elevated levels, the systematic surveillance of especially large diameter MoM THAs seems justified.

Prevalence of Failure due to Adverse Reaction to Metal Debris in Modern, Medium and Large Diameter Metal-on-Metal Hip Replacements--The Effect of Novel Screening Methods: Systematic Review and Metaregression Analysis

Metal-on-metal (MoM) hip replacements were used for almost a decade before adverse reactions to metal debris (ARMD) were found to be a true clinical problem. Currently, there is a paucity of evidence regarding the usefulness of systematic screening for ARMD. We implemented a systematic review and meta-analysis to establish the prevalence of revision confirmed ARMD stratified by the use of different screening protocols in patients with MoM hip replacements. Five levels of screening were identified: no screening (level 0), targeted blood metal ion measurement and/or cross-sectional imaging (level 1), metal ion measurement without imaging (level 2), metal ion measurement with targeted imaging (level 3) and comprehensive screening (both metal ions and imaging for all; level 4). 122 studies meeting our eligibility criteria were included in analysis. These studies included 144 study arms: 100 study arms with hip resurfacings, 33 study arms with large-diameter MoM total hip replacements (THR), and 11 study arms with medium-diameter MoM THRs. For hip resurfacing, the lowest prevalence of ARMD was seen with level 0 screening (pooled prevalence 0.13%) and the highest with level 4 screening (pooled prevalace 9.49%). Pooled prevalence of ARMD with level 0 screening was 0.29% and with level 4 screening 21.3% in the large-diameter MoM THR group. In metaregression analysis of hip resurfacings, level 4 screening was superior with regard to prevalence of ARMD when compared with other levels. In the large diameter THR group level 4 screening was superior to screening 0,2 and 3. These outcomes were irrespective of follow-up time or study publication year. With hip resurfacings, routine cross-sectional imaging regardless of clinical findings is advisable. It is clear, however, that targeted metal ion measurement and/or imaging is not sufficient in the screening for ARMD in any implant concepts. However, economic aspects should be weighed when choosing the preferred screening level.

Metal-on-metal total hip arthroplasty: is there still a role in 2016?

The use of metal-on-metal (MoM) bearings in total hip arthroplasty (THA) was popularized due to its enhanced wear profile and the ability to use large femoral heads to reduce post-operative instability. However, enthusiasm for the bearing declined following serious complications encountered at the primary articulation. This review discusses the development of MoM and the subsequent unexpected downstream challenges, most notably elevated serum metal ion levels, aseptic lymphocyte-dominated vasculitis-associated lesions (ALVAL), pseudotumor formation, and subsequent soft tissue and bone destruction. Both patient centered risk factors as well as component design led to high early failure rates resulting in product recalls and an overall decline in the use of MoM. In 2016, there is not a role for large-head MoM bearing in THA. Alternatively, the bearing has shown promise in hip resurfacing procedures for carefully selected patients.

Complications Related to Metal-on-Metal Articulation in Trapeziometacarpal Joint Total Joint Arthroplasty

Adverse reactions to metal-on-metal (MoM) prostheses are well known from total hip joint resurfacing arthroplasty with elevated serum chrome or cobalt, pain and pseudo tumor formation. It may, however, also be seen after total joint replacement of the trapeziometacarpal joint using MoM articulation, and we present two cases of failure of MoM prostheses due to elevated metal-serum levels in one case and pseudo tumor formation in another case. Furthermore, we suggest a diagnostic algorithm for joint pain after MoM trapeziometacarpal joint replacement based on published experiences from MoM hip prostheses and adverse reactions to metal.