Large-diameter metal-on-metal total hip arthroplasty: dislocation infrequent but survivorship poor

Choice of Bearings Influences the Implant Survival of Total Hip Arthroplasty in Patients Who Have Osteoarthritis Aged 55 Years or More: Results of 158,044 Patients from the Nordic Arthroplasty Register Association from 2005 to 2017

BACKGROUND

The aim of our study was to compare implant survival rates of different total hip arthroplasty (THA) bearings in the Nordic Arthroplasty Register Association.

METHODS

All conventional primary THAs performed between 2005 and 2017 in patients over 55 years of age who had primary osteoarthritis were studied. Metal-on-highly crosslinked polyethylene (MoXLP), ceramic-on-highly crosslinked polyethylene (CoXLP), ceramic-on-ceramic (CoC), and metal-on-metal (MoM) bearings were included. The outcome was a revision. Kaplan-Meier (KM) estimates were calculated at 5 and 10 years. The risk for revision was analyzed using a flexible parametric survival model (FPSM) adjusted for nation, age, sex, femoral head size, and femoral fixation.

RESULTS

A total of 158,044 THAs were included. The 5-year KM estimates were 95.9% (95% confidence interval [CI] 95.8 to 96.1) in MoXLP, 95.8% (95.6 to 96.1) in CoXLP, 96.7% (96.4 to 97.0) in CoC, and 93.9% (93.5 to 94.4) in MoM. The 10-year KM estimates were 94.2% (94.0 to 94.5) in MoXLP, 94.3% (93.9 to 94.8) in CoXLP, 95.4% (95.0 to 95.9) in CoC, and 85.5% (84.9 to 86.2) in MoM. Compared with MoXLP, the adjusted risk for revision was lower in CoC (hazard ratio [HR] 0.6, CI 0.5 to 0.6), similar in CoXLP (1.0, 0.9 to 1.0), and higher in MoM (1.3, 1.2 to 1.4).

CONCLUSIONS

We found that MoXLP, CoXLP, and CoC bearings evinced comparably high implant survival rates up to 10 years, and they can all be regarded as safe options in this patient group. The MoM bearings were associated with clearly lower survivorship. The CoC bearings had the highest implant survival and a lower adjusted risk for revision compared with XLP bearings.

Magnum metal-on-metal uncemented total hip replacement: 8- to 18-year outcomes of 211 cases

BACKGROUND

Reports of adverse reactions to metal debris contributed in part to a decline in use of large-bearing metal-on-metal total hip devices. We hypothesize an optimal trunnion design may reduce risk of this failure mode in large-bearing total hip arthroplasty systems. The purpose of this study is to report mid- to long-term outcomes for a single-surgeon series of 211 total hip arthroplasties using the large-bearing Biomet Magnum metal-on-metal system.

MATERIALS AND METHODS

Between December 2004 and January 2016, the primary surgeon performed 211 uncemented Magnum total hip arthroplasties in 181 patients. The average length of follow-up was 10.1 ± 3.5 years (range 8-18 years).

RESULTS

Using failure of any component as the endpoint, the overall survivorship rate was 98.1% at 10 years and 97.4% at 18 years. These eight failures (3.8% of cohort) included one case of adverse wear-related failure (0.5%), two cases of acetabular ingrowth failure (0.9%), three cases of trunnion corrosion (1.4%), one failure of late infection (0.5%), and one inappropriate revision of components for trochanteric nonunion without instability (0.5%). Excluding failed cases, all components were radiographically stable with no radiolucencies. Except for the one wear failure, ion testing revealed that 97.2% of cases were within optimal whole blood metal ion levels with the remaining ion test results within acceptable levels.

CONCLUSIONS

With the uncemented Magnum metal-on-metal total hip, we achieved 97.4% 18-year implant survivorship, exceeding the NICE criteria and registry benchmarks for implant survivorship. We observed a trunnion corrosion rate of 1.4% and no cases of instability. The single case of adverse wear-related failure was caused by acetabular component malposition.

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).

Long-term clinical outcomes of the Biomet M2a-38: a retrospective review of 335 total hip arthroplasty cases

BACKGROUND

At the turn of the century, over one-third of total hip arthroplasties comprised metal-on-metal bearings. As this patient population and their implants age, it is crucial to understand associated late failure modes and expected long-term functional outcomes. We report the long-term results of a large metal-on-metal uncemented total hip arthroplasty system with unique design characteristics compared to others that have been reported with high failure rates.

METHODS

We retrospectively analyze our prospective clinical database to determine overall implant survivorship and functional outcomes. Further, we compare these results to the clinical outcomes reported in orthopedic registries and in other published studies with similar metal-on-metal total hip arthroplasty cohorts.

RESULTS

Implant survivorship at 10 years was 99.1% and continued to 97.6% survivorship at 20 years. Implant survivorship at 20 years did not vary significantly between sexes (Male: 98.3%, Female: 97.2%; log-rank p-value = 0.46). Mean whole blood cobalt levels were 2.6 µg/L in unilateral cases, 5.3 µg/L in bilateral patients, and 3.4 µg/L for the combined cohort. Average blood chromium levels were 1.4 µg/L in unilateral patients, 2.9 µg/L in bilateral patients, and 1.8 µg/L for group combined. We observed a 0.9% rate of failure due trunnion corrosion at a mean of 13.1 years postoperatively (10.6-15.6 years) but had no bearing wear failures.

CONCLUSIONS

Our 20-year implant survivorship of 97.6% with the M2a-38 bearing surpassed registry benchmarks for THA. This large-bearing (38 mm), full hemisphere coverage metal-on-metal system had no bearing wear failures, one failure of instability, one failure of fixation, and three trunnion failures, perhaps suggesting an optimum balance between stability of the joint and the trunnion.

Long-term survival analysis of cementless large-diameter head metal-on-metal total hip arthroplasty

INTRODUCTION

The aim of this retrospective study was to study the long-term survival and reasons for revisions of a single-type, large-diameter head (LDH) metal-on-metal (MoM) implant. A special study interest was to find the threshold level for revision in terms of adverse reaction to metal debris (ARMD).

MATERIALS AND METHODS

In this cohort study, we retrospectively reviewed 234 patients (253 hips) who received 38 mm head size LDH MoM total hip arthroplasties (THAs) between 01 January 2004 and 31 December 2009 at our institution. Patient symptoms, conventional radiographs, magnetic resonance imaging (MRI) findings and whole blood metal ions were studied.

RESULTS

The median follow-up time was 11.5 years. The Kaplan-Meier cumulative survival estimate of the implant was 89.6% at 10 years and 82.9% at 14.6 years. Overall, 34/253 (13.4%) hips were revised during the follow-up period and of these; 19/34 (55.9%) were revised due to ARMD. The prevalence of ARMD was 12.4% (29/234 patients).

CONCLUSIONS

The survival of the implant was on a moderate level as the 10-year cumulative survival rate was 89.6%. The exact threshold level for ARMD revision cannot be determined due to multiple variables affecting factors in re-operation decision-making.

Do cobalt and chromium blood metal ion levels normalize after revision of failed metal-on-metal total hip replacements?

INTRODUCTION

Increased cobalt (Co) and chromium (Cr) serum levels are one reason for revision surgery in metal on metal (MoM) total hip arthroplasty (THA) patients. Dual mobility liners are a simple revision option; however, they preserve the metal shell and stem and it is therefore not clear if metal ion levels will fully normalize after revision surgery.

MATERIAL AND METHODS

Between April 2013 and December 2017 25 hips (24 patients) underwent revision from a MoM THA to an off-label dual mobility liner. Five patients were lost to follow-up and one patient refused leaving 18 patients (11 men, 7 female, average age 63.9 years) for pre- and postoperative metal ion level blood tests at a minimum follow-up of 2 years.

RESULTS

Fourteen patients were revised for osteolysis, two for elevated metal ion levels and two for fluid or cysts around the femoral or acetabular component. The average preoperative Co and Cr levels were 8.3 µg/l and 5.0 µg/l, respectively. At a minimum follow-up of 2 years (30-95 months), metal ions dropped to 0.8 µg/l. Harris Hip Score (HHS), Hip Osteoarthritis Outcome Score (HOOS), Visual Analog Scale (VAS) and the UCLA activity score improved non-significantly from pre- to postoperative. There was one postoperative complication in the study cohort. One patient with persisting pain required revision surgery to a standard acetabular component during the follow-up period.

CONCLUSION

The off-label use of a dual-mobility liner in the current study resulted in normalization of the metal ion levels suggesting that preserving the cobalt-chromium acetabular component has little impact on ion levels. In addition, dual mobility liners have a low complication and revision rate.

Survival rates of different bearing surfaces with the same model of stem in total hip arthroplasty: predictive factors for revision surgery

INTRODUCTION

Few studies have examined the survival rates of total hip arthroplasty (THA) with the same femoral stem, and the predictive factors leading to the revision of stemmed metal-on-metal (MoM) THA remain unknown. We determined the long-term survival rate of stemmed MoM THA compared with that of metal-on-polyethylene (MoP) bearing THA, the effect of head size and cup placement angle on revision rate, and predictors of revision.

MATERIALS AND METHODS

A total of 130 hips in 110 patients who underwent primary THA by the same surgeon were included. M2a-RingLoc with a metal-on-polyethylene bearing (group P, 53 hips), M2a-Taper with MoM bearing (group T, 44 hips), and M2a-Magnum with MoM bearing (group M, 33 hips) were used. The mean age at surgery was 63.1 ± 9.5 years, and the mean postoperative follow-up duration was 133.7 ± 39.1 months. Whole blood metal ion concentrations were measured preoperatively and postoperatively, and magnetic resonance imaging was performed to identify aseptic local tissue reactions (ALTRs). Kaplan-Meier survivorship analysis and multiple logistic regression analysis were performed.

RESULTS

The THA survival rate up to the maximum postoperative follow-up period was 96.2% at 173 months, 46.6% at 179 months, and 47.8% at 145 months in groups P, T, and M, respectively, with revision as the endpoint. The stemmed MoM THA recorded a very low survival rate (p < 0.001). The ALTR rates were 70.5% and 63.6% in groups T and M, respectively. The risk factor for revision was the use of MoM bearing, and there was no difference in the results based on the head size in group M. Cobalt levels continued to increase postoperatively, although they were not accurate predictors of revision.

CONCLUSIONS

Stemmed MoM THA has a very low survival rate and should be used with caution. It is important to monitor the patient's symptoms and perform appropriate imaging to ensure timely revision.

Survivorship of a Metal-on-Metal Total Hip Implant With Modular Titanium Adapter

BACKGROUND

Use of metal-on-metal (MoM) articulations in total hip arthroplasty (THA) has sharply declined due to high failure rates from metal-related complications. Although certain MoM designs have demonstrated only 46% survival, not all MoM designs have performed the same. The purpose of this study is to evaluate mid-term to long-term survival of a specific MoM implant with a modular titanium taper adapter.

METHODS

A retrospective review was performed on all patients who underwent primary THA at our center with the M²a-Magnum system (Zimmer Biomet, Warsaw, IN). Of 829 patients (956 hips) identified, 754 patients (869 hips) met inclusion criteria of signed research consent, minimum 2-year follow-up, and/or any revision surgery.

RESULTS

Mean follow-up was 11.0 years (range 2-16; ±3.5). Mean cup angle of inclination was 42.8° (range 24°-70°, ±6.3°), with 88.0% reconstructed within the 40° ± 10° safe zone. There were 64 revisions (7.36%): 7 (0.81%) septic and 57 (6.56%) aseptic. Of those, 32 (3.68%) were adverse reactions to metal debris. Kaplan-Meier survival free of revision for all causes was 88.6% at 16 years (95% confidence interval 86.8-90.4). Univariate analysis of risk factors for all-cause, aseptic, and adverse reaction to metal debris revision found no relationship with female gender, age ≥65 years, body mass index >30 kg/m², higher activity level, or inclination angle outlier.

CONCLUSION

The results of this study demonstrate a more favorable mid-term to long-term survivorship with this specific MoM implant compared to other designs. Although our institution no longer performs MoM THA, further investigation into differences in MoM implant designs is warranted.

Ten-year results of a prospective cohort of large-head metal-on-metal total hip arthroplasty

Aims

Large-diameter metal-on-metal (MoM) total hip arthroplasty (THA) has demonstrated unexpected high failure rates and pseudotumour formation. The purpose of this prospective cohort study is to report ten-year results in order to establish revision rate, prevalence of pseudotumour formation, and relation with whole blood cobalt levels.

Methods

All patients were recalled according to the guidelines of the Dutch Orthopaedic Association. They underwent clinical and radiographical assessments (radiograph and CT scan) of the hip prosthesis and whole blood cobalt ion measurements. Overall, 94 patients (95 hips) fulfilled our requirements for a minimum ten-year follow-up.

Results

Mean follow-up was 10.9 years (10 to 12), with a cumulative survival rate of 82.4%. Reason for revision was predominantly pseudotumour formation (68%), apart from loosening, pain, infection, and osteolysis. The prevalence of pseudotumour formation around the prostheses was 41%, while our previous report of this cohort (with a mean follow-up of 3.6 years) revealed a 39% prevalence. The ten-year revision-free survival with pseudotumour was 66.7% and without pseudotumour 92.4% (p < 0.05). There was poor discriminatory ability for cobalt for pseudotumour formation.

Conclusion

This prospective study reports a minimum ten-year follow-up of large-head MoM THA. Revision rates are high, with the main reason being the sequelae of pseudotumour formation, which were rarely observed after five years of implantation. Blood ion measurements show limited discriminatory capacity in diagnosing pseudotumour formation. Our results evidence that an early comprehensive follow-up strategy is essential for MoM THA to promptly identify and manage early complications and revise on time. After ten years follow-up, we do not recommend continuing routine CT scanning or whole cobalt blood measurements, but instead enrolling these patients in routine follow-up protocols for THA.

Cite this article: Bone Jt Open 2022;3(1):61–67.

Pseudotumors in Small-Head Metal-on-Metal Total Hip Arthroplasties at a Minimum Follow-Up of 20 Years

BACKGROUND

Metal-on-metal (MOM) surfaces in total hip arthroplasty (THA) have been used widely. Serum cobalt and chromium levels have been the standard investigation for follow-up examinations, but magnetic resonance imaging (MRI) with metal artifact reducing sequences has shown good results in detecting pseudotumors. The aim of this study is to survey a significant correlation among MRI findings, serum metal levels, and clinical scores in patients with small-head MOM implants and if serum cobalt and chromium levels are sufficient in detecting patients with pseudotumors in the long-term follow-up.

METHODS

At a minimum follow-up of 20 years, 26 patients (29 THAs) of the original 98 patients (105 THAs) included in this study between November 1992 and May 1994 were available for follow-up examination. Clinical scores, serum metal ion levels, and MRIs were obtained.

RESULTS

We found mean serum cobalt levels of 1.87 μg/L (±3.44) and chromium levels of 2.23 μg/L (±2.96) and very good clinical and functional results (mean Harris Hip Score 88.6) in the long-term follow-up. Pseudotumors were detected in MRIs of 21 hips. There were no significant differences between patients with or without pseudotumors regarding serum metal levels and the correlation for clinical outcome scores, demographic data, and cup inclination. The cumulative rate of survival was still at 91.4% at 22.8 years.

CONCLUSION

This study presents the first published data on small-head MOM hips, comparing metal ion levels, pseudotumors, clinical, and radiological results in a follow-up period of more than 20 years and reveals that serum metal levels are not significantly higher in patients with pseudotumors.

LEVEL OF EVIDENCE

Therapeutic Level III.

Minimum 15-year results of metasul 28-mm metal-on-metal total hip arthroplasty in patients younger than 50 years of age

Background

Some propitious mid- and long-term studies had been reported for MoM bearings; however, most studies have addressed specific patient groups rather than younger, active patients, who probably represent the most suitable population for investigations on wear and osteolysis. The purpose of this study to evaluate the long-term results of second-generation metal-on-metal cementless total hip arthroplasty (THA) in patients aged <50 years.

Methods

From December 1997 to January 2004, primary THA using a metal-on-metal bearing cementless implant was performed in 63 patients (72 hips) aged <50 years. The mean follow-up duration was 18.6 (range, 15.9–22.1) years, and the mean age at initial operation was 39 (range, 22–49) years. Clinical results, complications, survivorship, osteolysis, and aseptic loosening were evaluated.

Results

The mean Harris hip score and Western Ontario and McMaster Universities Arthritis Index scores were improved from 57.8 (range, 28–69) points and 73.4 (range, 63–94) points preoperatively to 91.7 (range, 80–100) points and 25.5 points (range, 17–38) points, respectively, at the last follow-up. Osteolysis lesions were found in 12 hips (acetabulum, 6 and femur, 6). The notching occurred on the femoral stem neck occurred in 12 hips. The mean serum cobalt and chromium concentrations were 2.3 (range, 0.2–10.6) μg/L and 1.7 (range, 0.4–8.1) μg/L, respectively, at a mean follow-up of 12.7 years in 32 patients (50.1%). The Kaplan-Meier survivorship curve analysis with revision for any reason as the endpoint revealed that 93.1% survived at 18.6 years’ follow-up.

Conclusions

Second-generation metal-on-metal cementless THA was found to produce satisfactory clinical and radiographic results with a low revision rate for osteolysis and aseptic loosening in patients aged less than 50 years.

Large Diameter Head in Primary Total Hip Arthroplasty: A Systematic Review

INTRODUCTION

The literature around use of Large Diameter Heads (LDH) is abundantly available for revision Total Hip Arthroplasty (THA) but is lacking for primary uncomplicated THA. This systematic review was undertaken to synthesize data around primary THA involving LDH and analyze the associated complications (dislocation, volumetric wear, implant survivorship and functional score) along with reported effects on range of motion (ROM), patient reported outcomes and impingement rate/groin pain.

METHODS

A PRISMA compliant systematic review was done using extensive search in PubMed database, along with offline search looking for the literature published in English language between 2008 and 2018. The articles providing data on the use of large diameter heads (LDH) (36 mm or larger) on various bearing surfaces were collected. This included robust national joint registries of different countries. Narrative approach to data synthesis was used.

RESULTS

A total of 23 papers met our inclusion criteria, including six national joint registries. It was observed that LDH had significantly low dislocation rates, excellent implant survival rate as per Kaplan-Meier survivorship (> 90% at five years). Surgical approaches, except Minimally Invasive Surgery (MIS), did not increase any risk of dislocation as long as it was meticulously repaired. There was no significant improvement in any functional scores or improved ROM.

CONCLUSIONS

LDH of 32-36 mm are now commonly used in primary THA and is accepted as a popular size. The beneficial effects of a large head size are negated beyond 38 mm. The most favored size for LDH THA, therefore, is 36 mm contrary to the older literature favoring 28 mm.

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.

Risk factors for dislocation after revision total hip arthroplasty with a dual-mobility cup. Matched case-control study (16 cases vs. 48 controls)

BACKGROUND

Reports of high dislocation rates after revision total hip arthroplasty (THA) have encouraged the widespread use of dual-mobility cups. Dislocation has been less common but not fully abolished with dual-mobility cups, and its causes have remained unidentified. The objectives of this retrospective matched case-control study were: 1) to identify risk factors for dislocation, 2) and to assess dislocation outcomes.

HYPOTHESIS

The causes of dislocation after revision THA with a dual-mobility cup can be identified.

MATERIAL AND METHOD

Among 653 consecutive patients identified retrospectively as having undergone revision THA with a dual-mobility cup (Medial Cup, Aston, Saint-Étienne, France) between January 2007 and December 2017, 16 (2.45%) subsequently experienced dislocation, after a mean of 3.6 months (range, 0.9-19 months). For each of these 16 patients, we collected the main patient characteristics (age, sex, body mass index [BMI], ASA score, and reason for the initial arthroplasty procedure), local history (number of previous surgical procedures, reason for revision, femoral and acetabular bony defects classified according to Paprosky, and status of the abductor apparatus), and characteristics of the revision (approach, diameters of the cup and femoral head, cup inclination, femoral offset, lower limb length, and implant anteversion). Controls were patients without dislocation after revision dual-mobility THA. Each of the 16 patients was matched to 3 controls on age (±10 years), sex, year of revision, and whether revision was only acetabular or bipolar. Univariate and multivariate analyses were done to compare the cases and controls, and dislocation outcomes in the cases were evaluated.

RESULTS

By univariate analyses, factors associated with dislocation were BMI>30 (cases, 37.5%; controls, 10.4%; p=0.02), larger number of previous surgical procedures on the same hip (cases, 2.8; controls, 1.8; p=0.004), larger number of arthroplasties (cases, 2.3; controls, 1.5; p=0.004), history of instability (cases, 31% with chronic dislocation and 13% with recurrent dislocation; controls, 6.25% and 2.1%, respectively; p=0.004), and compromised abductor apparatus (cases, 56.25%; controls, 14.6%; p=0.002). Independent risk factors for dislocation identified by multivariate analysis were instability (odds ratio [OR], 14.5; 95% confidence interval [95%CI], 1.5-149.9) and, most importantly, abductor apparatus compromise (OR, 43.1; 95%CI, 3.18-586.3). Of the 16 cases, 1 was lost to follow-up, 1 had contra-indications to anaesthesia, 1 died after several dislocation episodes, and 1 died 3 months after surgical reduction. In 5 cases, there was a single dislocation episode. Further surgery was performed in 8 cases (surgical reduction, n=1; constrained cup, n=3; trochanteric internal fixation, n=1; exchange of the dual-mobility cup, n=2, including 1 with subsequent dislocation episodes; and femoral component exchange followed by a retentive cup due to further dislocation episodes, n=1).

CONCLUSION

Risk factors for dislocation consisted of a history of instability and, most importantly, abductor apparatus compromise. A constrained cup should be considererd in patients with impaired abductor apparatus. No further dislocations occurred after reduction of the first episode in 31.25% of cases. Recurrent dislocation should prompt measures to correct impaired abductor apparatus whenever possible, as well as correction of any component malposition. Whether a retentive cup should be implanted routinely remains unclear.

LEVEL OF EVIDENCE

III, matched case-control study.

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.

Effect of changing femoral head diameter on bony and prosthetic jumping angles

BACKGROUND

In THA, using a larger femoral head can increase the oscillation angle and jumping distance. However, there have been no reports which indicate precisely how increasing the jumping distance leads to an increase in the angle from impingement to dislocation (jumping angle). In this study, we clarified the jumping angle of various head diameters and its relationship with pelvic morphology.

METHODS

Using a three-dimensional templating system, virtual THA and ROM simulations were performed in 82 patients. We investigated the distance between bony and prosthetic impingement points and the head centre and calculated the jumping angle for various head diameters. We measured various pelvic shapes and length to clarify the relationship between pelvic morphology and impingement distance.

RESULTS

Jumping angles were 7.7° ± 3.2°, 12.1° ± 1.6°, 15.4° ± 2.5° and 10.0° ± 3.0° with flexion, internal rotation with 90° flexion (IR), extension and external rotation (ER), respectively, when we used a 22-mm head diameter. Bony jumping angle increased about 0.5°, 0.8°, 1.0° and 0.7° per 2-mm increase in head diameter with flexion, IR, extension and ER. On the other hand, prosthetic jumping angle remained almost stable at about 31°. Impingement distance was related to pelvic morphology in all directions. Bony jumping angles differed with ROM; the biggest was seen with extension, followed by IR, ER and flexion. On the other hand, bony jumping angle was less than prosthetic jumping angle in all cases.

CONCLUSION

Bony jumping angles differed with ROM; the biggest was seen with extension, followed by IR, ER and flexion. Prosthetic impingement angles were stable. In addition, the bony jumping angle was less than the prosthetic jumping angle in all cases.

Five-year follow-up of a prospective randomised trial comparing ceramic-on-metal and metal-on-metal bearing surfaces in total hip arthroplasty

AIMS

The primary aim of this independent prospective randomised trial was to compare serum metal ion levels for ceramic-on-metal (CoM) and metal-on-metal (MoM) bearing surfaces in total hip arthroplasty (THA). Our one-year results demonstrated elevation in metal ion levels above baseline with no significant difference between the CoM and MoM groups. This paper reviews the five-year data.

PATIENTS AND METHODS

The implants used in each patient differed only in respect to the type of femoral head (ceramic or metal). At five-year follow-up of the 83 enrolled patients, data from 67 (36 CoM, 31 MoM) was available for comparison.

RESULTS

The mean serum cobalt (Co) and chromium (Cr) ion levels remained above baseline in both groups (CoM: Co 1.16 μg/l (0.41 to 14.67), Cr 1.05 μg/l (0.16 to 12.58); MoM: Co 2.93 μg/l (0.35 to 30.29), Cr 1.85 μg/l (0.36 to 17.00)) but the increase was significantly less in the CoM cohort (Co difference p = 0.001, Cr difference p = 0.002). These medium-term results, coupled with lower revision rates from national joint registries, suggest that the performance of CoM THA may be superior to that of MoM.

CONCLUSION

While both bearing combinations have since been withdrawn these results provide useful information for planning clinical surveillance of CoM THAs and warrants continued monitoring. Cite this article: Bone Joint J 2017;99-B:1298-1303.

Salvage of a monoblock metal-on-metal cup using a dual mobility liner: a two-year MRI follow-up study

PURPOSE

Revision of failed modular metal-on-metal total hip replacement (MoM-THA) can be technically difficult. A dual mobility liner can help to salvage a well-fixed acetabular component. The present paper reports the clinical and radiographic outcome of revision of failed Birmingham modular MoM-THA using a dual mobility liner.

METHODS

The present study reports on ten patients (3 female and 7 male) with 11 revision THAs. Patients underwent revision an average of 51 months (range 40-73 months) after index procedure. Mean follow-up after the revision was 31 months (range 24-37 months) and all patients underwent an MRI with metal artifact reduction software (MARS) at least two years after revision to assess for local polyethylene wear and osteolysis.

RESULTS

The Harris Hip score improved from 92.2 (range 63.0-100.0) to 100.0 (p = 0.072). One patient had a one-time dislocation within seven days of surgery. No patient required additional surgeries. Radiographs showed no signs of component loosening and osteolysis and MRI imaging revealed no evidence of polyethylene wear or osteolysis.

CONCLUSION

A dual mobility liner in an existing Birmingham cup can provide excellent clinical and radiological short-term results without MRI evidence of increased polyethylene wear. Post-operative hip precautions should be enforced.

Mid-term results of ReCap/Magnum/Taperloc metal-on-metal total hip arthroplasty with mean follow-up of 7.1 years

INTRODUCTION

Despite enthusiasm for metal-on-metal bearings, disappointing short- to mid-term outcomes has all but halted the use of this bearing articulation. This review presents mid-term results for the ReCap Magnum total hip replacement.

PATIENTS AND METHODS

This prospective study evaluated 79 ReCap/Magnum/Taperloc total hip replacements with mean follow-up of 7.1 (range 3.7-9.2) years. 43 were female and 36 male. Metal ions were measured and radiographic measurement included a 'margin of safety' angle to quantify risk of edge loading. When a clinical suspicion of adverse reaction to metal debris was present, patients had metal artefact reduction sequence MRI. Harris Hip Score and Oxford Hip Score evaluated functional outcome and SF-12 and EQ-5L-5D assessed quality of life at final follow-up.

RESULTS

7 hips were revised indicating 91.1% survivorship at 7.1 years. Postoperative Harris Hip Score and Oxford Hip Score significantly improved. Females and symptomatic patients predicted increased metal ions. Margin of safety correlated with postoperative Oxford Hip Score. Symptomatic hips and positive MRI showed reduced survivorship.

CONCLUSIONS

Compared to more traditional bearings like metal or ceramic on polyethylene the overall outcome of this ReCap/Magnum/Taperloc study cohort is modest. It is felt that further failures will occur in this group therefore cautious interpretation of the results is justified given the potential for reduced survival outcomes.

Blood metal ion concentrations in metal-on-metal total hip arthroplasty

INTRODUCTION

The hip placement with a metal-on-metal (MOM) bearing has been used for both surface replacement and total hip arthroplasty (THA). Use of MOM bearing for hip replacement reduces the wear compared to conventional bearings.

METHODS

We prospectively assessed 30 patients who underwent unilateral MOM THA. A control group of 30 patients who underwent metal-on-polyethylene THA using the implants as the other group, except for bearing, were accessed. Blood samples were collected preoperatively and at 3- , 6- , 9- , 12- , 15- , 18- , and 24-month intervals. Changes in mean blood metal ion concentration were compared between the MOM and metal-on-polyethylene groups.

RESULTS

A statistically significant positive correlation was observed between blood cobalt and chromium concentrations in all of the patients. The mean blood ion concentrations of the MOM were significantly higher than those of the metal-on-polyethylene. A statistically significant negative correlation was found between maximum blood cobalt concentration and cup version angle. The maximum blood chromium concentrations in the patients who had larger cup version angles were more likely to decrease.

CONCLUSIONS

We considered that cup version angle is one of the factors that have the greatest effect on blood metal ion concentration, and the target cup version angle that did not induce an increase in blood metal ion concentrations was approximately 20°.

An Assessment of Gender-Specific Risk of Implant Revision After Primary Total Hip Arthroplasty: A Systematic Review and Meta-analysis

BACKGROUND

Total hip arthroplasty (THA) has been a successful reconstructive procedure to mitigate pain associated with diseases of the hip joint. However, some THA procedures require revision due to mechanical or biological failure. The purpose of this study was to synthesize and examine the evidence on the relative risk of revision in men and women after primary THA procedures.

METHODS

We conducted a systematic literature review of cohort studies reporting THA revision risk estimate by gender. Study quality scoring and a random effects meta-analysis were performed to estimate the meta-relative risk (meta-RR) and corresponding 95% confidence interval (95% CI) of revision, comparing men to women.

RESULTS

Males had a statistically significant increased risk of revision after primary THA (meta-RR = 1.33 [95% CI: 1.13-1.57]), when compared to females. When stratified by cause of revision, males had a statistically significant increased risk of revision due to any cause (meta-RR = 1.16 [95% CI: 1.01-1.33]), aseptic loosening (meta-RR = 1.54 [95% CI: 1.05-2.25]), and infection (meta-RR = 1.55 [95% CI: 1.11-2.15]). For primary THA operations performed during the 2000s, males in Europe had a statistically significant increased risk of revision (meta-RR 1.42 [95% CI: 1.25-1.61]) while males in the United States had a statistically significant decreased risk of revision (meta-RR 0.80 [95% CI: 0.72-0.89]).

CONCLUSION

These results provide evidence for an increased risk of revision after THA among males, which may be impacted by geographic location and time period of operation. Findings suggest that a better understanding of the underlying drivers of gender-specific risks would help reduce postsurgery complications.

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.

Metal on Metal or Ceramic on Ceramic for Cementless Total Hip Arthroplasty: A Meta-Analysis

BACKGROUND

Hard bearings, metal on metal (MOM) and ceramic on ceramic (COC), have been developed to overcome polyethylene wear-related osteolysis, but comparisons between these 2 hard bearings are limited. We performed a meta-analysis to determine revision rates for (1) any reason, (2) aseptic loosening, (3) periprosthetic joint infection (PJI), and (4) recurrent dislocation between MOM and COC bearings in cementless total hip arthroplasty.

METHODS

This analysis included 3 studies comparing COC and MOM bearings and 56 studies reporting outcomes of MOM or COC bearings. We conducted a comparison meta-analysis (with a fixed-effects model) on the 3 comparative studies and a proportional meta-analysis on the data from the 59 articles to determine a consensus.

RESULTS

In the comparison meta-analysis, MOM showed higher revision rate than COC for any reason (odds ratio = 2.39, P = .046) and PJI (odds ratio = 6.21, P = .015). In the proportion meta-analysis, the MOM group showed significantly higher revision rate than COC group for any reason, aseptic loosening, and PJI.

CONCLUSION

MOM bearings were associated with a higher risk of revision for any reason and PJI than COC bearings after cementless total hip arthroplasty.

Complications Are Not Increased With Acetabular Revision of Metal-on-metal Total Hip Arthroplasty

BACKGROUND

Isolated revision of the acetabular component in the setting of total hip arthroplasty has an increased risk of dislocation. With local soft tissue destruction frequently associated with failed metal-on-metal (MoM) bearings, it is presumed that acetabular revision of these hips will have even greater risk of complications. However, no study directly compares the complications of MoM with metal-on-polyethylene (MoP) acetabular revisions.

QUESTIONS/PURPOSES

In the context of a large database analysis, we asked the following questions: (1) Are there differences in early medical or wound complications after isolated acetabular revision of MoM and MoP bearing surfaces? (2) Are there differences in the frequency of dislocation, deep infection, and rerevision based on the bearing surface of the original implant?

METHODS

A review of the 100% Medicare database from 2005 to 2012 was performed using International Classification of Diseases, 9th Revision and Current Procedural Terminology codes. We identified 451 patients with a MoM bearing and 628 patients with a MoP bearing who had an isolated acetabular revision and a minimum followup of 2 years. The incidence, odds ratios, and 95% confidence intervals for early medical or wound complications were calculated using a univariate analysis at 30 days with patient sex and age group-adjusted analysis for blood transfusion. The incidence, odds ratio, and 95% confidence intervals for dislocation, deep infection, and rerevision were calculated using a univariate analysis at 30 day, 90 days, 1 year, and 2 years using a subgroup analysis with the Cochran-Mantel-Haenszel test to adjust for patient gender and age groups.

RESULTS

There were no differences between the MoM and MoP isolated acetabular revisions in the incidence of 30-day local complications. There was a greater risk of transfusion in the MoP group than the MoM group (134 of 451 [30%] versus 230 of 628 [37%]; odds ratio [OR], 0.731; 95% confidence interval [CI], 0.565-0.948; p = 0.018). There were no differences at 2 years between the MoM and MoP acetabular revisions in the incidence of dislocation, infection, or rerevision. When analyzed by patient sex and age group, there were more infections in the age 70 to 79 years MoP group compared with MoM (10 of 451 [5%] versus 29 of 628 [10%]; OR, 4.47; CI, 1.699-11.761; p = 0.001).

CONCLUSIONS

There were high rates of dislocation, infection, and rerevision in both revision cohorts. The rate of dislocation was not greater after acetabular revision of MoM bearings at 2 years. Based on these findings, clinicians should counsel these patients preoperatively about the risks of these complications. Dual-mobility and constrained components have specific advantages and disadvantages in these settings and should be further studied.

LEVEL OF EVIDENCE

Level III, therapeutic study.

High Re-Operation Rates Using Conserve Metal-On-Metal Total Hip Articulations

Introduction:

Metal-on-metal hip articulations have been intensely debated after reports of adverse reactions and high failure rates. The aim of this study was to retrospectively evaluate the implant of a metal-on.metal total hip articulation (MOM THA) from a single manufacture in a two-center study.

Materials and Methods:

108 CONSERVE^® MOM THA were implanted in 92 patients between November 2005 and December 2010. Patients had at time of retrospective evaluation their journals reviewed for re-operations and adverse reactions.

Results:

20 hips were re-operated (18.4%) at a mean follow up of 53 months. 4 pseudotumors were diagnosed at time of follow up but no substantiated link was made between adverse reactions and re-operations.

Conclusion:

The high re-operation rates found in this study raised concern about the usage of the MOM THA and subsequently lead to the termination of implantation of this MOM THA at the two orthopaedic departments.

Comparison of Whole-Blood Metal Ion Levels Among Four Types of Large-Head, Metal-on-Metal Total Hip Arthroplasty Implants: A Concise Follow-up, at Five Years, of a Previous Report

Few studies of total hip arthroplasty (THA) implants with a large-diameter femoral head and metal-on-metal design have directly compared the progression of metal ion levels over time and the relationship to complications. As we previously reported, 144 patients received one of four types of large-diameter-head, metal-on-metal THA designs (Durom, Birmingham, ASR XL, or Magnum implants). Cobalt, chromium, and titanium ion levels were measured over five years. We compared ion levels and clinical results over time. The Durom group showed the highest levels of cobalt (p ≤ 0.002) and titanium ions (p ≤ 0.03). Both the Durom and Birmingham groups demonstrated significant ongoing cobalt increases up to five years. Eight patients (seven with a Durom implant and one with a Birmingham implant) developed adverse local tissue reaction. Six Durom implants and one Birmingham implant required revision, with one pseudotumor under surveillance at the time of the most recent follow-up. We found that ion generation and related complications varied among designs. More concerning was that, for some designs, ion levels continued to increase. Coupling a cobalt-chromium adapter sleeve to an unmodified titanium femoral trunnion along with a large metal-on-metal bearing may explain the poor performances of two of the designs in the current study.

Adverse Reactions to Metal on Metal Are Not Exclusive to Large Heads in Total Hip Arthroplasty

BACKGROUND

There is some suggestion that smaller diameter heads in metal-on-metal total hip arthroplasty (MoM THA) may be less prone to the adverse reactions to metal debris (ARMD) seen with large-diameter heads.

QUESTIONS/PURPOSES

We reviewed our population of patients with small head (≤ 32 mm) MoM THA to determine (1) the frequency of ARMD; (2) potential risk factors for ARMD in this population; and (3) the etiology of revision and Kaplan-Meier survivorship with revision for all causes.

METHODS

Small-diameter head MoM devices were used in 9% (347 of 3753) of primary THAs during the study period (January 1996 to March 2005). We generally used these implants in younger, more active, higher-demand patients. Three hundred hips (258 patients) had MoM THA using a titanium modular acetabular component with a cobalt-chromium tapered insert and were available for review with minimum 2-year followup (mean, 10 years; range, 2-19 years). Complete followup was available in 86% of hips (300 of 347). Clinical records and radiographs were reviewed to determine the frequency and etiology of revision. Kaplan-Meier survivorship analysis was performed.

RESULTS

ARMD frequency was 5% (14 of 300 hips) and represented 70% (14 of 20) of revisions performed. Using multivariate analysis, no variable tested, including height, weight, body mass index, age, cup diameter, cup angle, use of screws, stem diameter, stem type, head diameter, preoperative clinical score, diagnosis, activity level, or sex, was significant as a risk factor for revision. Twenty hips have been revised: two for infection, four for aseptic loosening, and 14 for ARMD. Kaplan-Meier analysis revealed survival free of component revision for all causes was 95% at 10 years (95% confidence interval [CI], 91%-97%), 92% at 15 years (95% CI, 87%-95%), and 72% at 19 years (95% CI, 43%-90%), and survival free of component revision for aseptic causes was 96% at 10 years (95% CI, 92%-98%), 92% at 15 years (95% CI, 88%-95%), and 73% at 19 years (95% CI, 43%-90%).

CONCLUSIONS

The late onset and devastating nature of metal-related failures is concerning with this small-diameter MoM device. Although the liner is modular, it cannot be exchanged and full acetabular revision is required. Patients with all MoM THA devices should be encouraged to return for clinical and radiographic followup, and clinicians should maintain a low threshold to perform a systematic evaluation. Symptomatic patients should undergo thorough investigation and vigilant observation for ARMD.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

The biological response to nanometre-sized polymer particles

Recently, nanometre-sized UHMWPE particles generated from hip and knee replacements have been identified in vitro and in vivo. UHMWPE particles in the 0.1-1.0μm size range have been shown to be more biologically active than larger particles, provoking an inflammatory response implicated in late aseptic loosening of total joint replacements. The biological activity of nanometre-sized particles has not previously been studied. The biological response to clinically-relevant UHMWPE wear particles including nanometre-sized and micrometre-sized, along with polystyrene particles (FluoSpheres 20nm, 60nm, 200nm and 1.0μm), and nanometre-sized model polyethylene particles (Ceridust 3615®), was determined in terms of osteolytic cytokine release from primary human peripheral blood mononuclear cells (PBMNCs). Nanometre-sized UHMWPE wear particles, nanometre-sized Ceridust 3615® and 20nm FluoSpheres had no significant effect on TNF-α, IL-1β, IL-6 and IL-8 release from PBMNCs at a concentration of 100μm(3) particles per cell after 12 and 24h. The micrometre-size UHMWPE wear particles (0.1-1.0μm) and 60nm, 200nm and 1.0μm FluoSpheres caused significantly elevated osteolytic cytokine release from PBMNCs. These results indicated that particles below circa 50nm fail to activate PBMNCs and that particle size, composition and morphology played a crucial role in cytokine release by particle stimulated macrophages.

Is there a rationale to use a dual mobility poly insert for failed Birmingham metal-on-metal hip replacements? A retrieval analysis

INTRODUCTION

Previous studies showed poor outcomes for patients undergoing revision of failed metal-on-metal total hip arthroplasty (MoM-THA) and resurfacing (RS) with an increased risk of dislocation. Dual mobility inserts are an option to retain the acetabular component and change the metal-on-metal bearing to plastic-on-metal. The current study analyzes the rationale for the off-label use of a dual mobility poly insert (MDM X3, Stryker, Mahwah, NJ) in a Birmingham metal shell (Smith & Nephew, Memphis, TN).

MATERIALS AND METHODS

Based on retrievals from the implant database the study compared the clearance between 20 BHR shells, 31 MDM poly inserts and 24 ADM acetabular components of different sizes. The radial clearance was calculated for each possible combination of implants [n = 81 (MDM/BHR) and n = 119 (MDM/ADM)].

RESULTS

An MDM mobile bearing poly insert in an ADM shell has an average clearance of 0.314 mm (SD 0.031) compared to 0.234 mm (SD 0.030) in a BHR shell (p < 0.01). The minimal clearance is 0.246 and 0.163 mm, respectively. 30.9 % of the MDM/BHR clearances were within the range of the MDM/ADM bearing and 88.9 % had a clearance of more than 0.2 mm.

CONCLUSION

Clearances of the MDM poly insert in a BHR shell are reduced, and although the majority of combinations appear safe, the indication needs to be made on an individual base carefully considering alternative treatment options.