Metal-on-metal or metal-on-polyethylene for total hip arthroplasty: a meta-analysis of prospective randomized studies

Meta-analysis of the Efficacy of the Anatomical Center and High Hip Center Techniques in the Treatment of Adult Developmental Dysplasia of the Hip

Background. In total hip arthroplasty for the treatment of adult developmental dysplasia of the hip, there is considerable controversy regarding the placement of the acetabular cup, anatomic center, and upward in acetabular reconstruction. This article explores the efficacy of the anatomical center technique and high hip center technique in the treatment of adult developmental dysplasia of the hip. Method. By searching for articles in the Cochrane Library, PubMed, CNKI, and Wanfang databases, we collected the literature on the treatment of adult developmental dysplasia of the hip by anatomical center and high hip center technology and screened the literature according to the inclusion and exclusion criteria. The Cochrane risk of bias assessment tool was used to assess the risk of bias of randomized controlled trials, the quality of the literature in retrospective cohort studies was assessed using the Newcastle–Ottawa scale, and the RevMan 5.4 software was used to analyze the extracted outcome indicators. Results. Nine studies were finally included, including one prospective cohort study, eight retrospective cohort studies, two high-quality studies, and six moderate-quality studies. The meta-analysis results showed that the reconstruction of the acetabulum in two positions was significantly different in terms of operation time ( $\text{WMD}=-37$ , 95% CI: -45.25-28.74, $P<0.00001$ ), intraoperative blood loss ( $\text{WMD}=-91.88$ , 95% CI: -108.57-75.19, $P<0.00001$ ), postoperative drainage volume ( $\text{WMD}=80.55$ , 95% CI: -140.56-301.66, $P=0.48$ ), time to ground ( $\text{WMD}=-0.68$ , 95% CI: -1.37-0.0, $P=0.05$ ), Harris score ( $\text{WMD}=-0.04$ , 95% CI: -0.91-0.82, $P=0.92$ ), lower limb length difference ( $\text{WMD}=0.21$ , 95% CI: -0.22-0.64, $P=0.33$ ), WOMAC score ( $\text{WMD}=-1.24$ , 95% CI: -4.89-2.41, $P=0.51$ ), postoperative complications ( $\text{RD}=-0.02$ , 95% CI: -0.06-0.02, $P=0.44$ ), Trendelenburg sign ( $\text{RD}=-0.02$ , 95% CI: -0.02-0.05, $P=0.31$ ), limb lengthening ( $\text{WMD}=0.85$ , 95% CI: 0.61-1.09, $P<0.00001$ ), prosthesis wear ( $\text{WMD}=0.01$ , 95% CI: 0-0.02, $P=0.17$ ), and prosthesis loosening ( $\text{RD}=0.01$ , 95% CI: -0.02-0.04, $P=0.45$ ). Conclusions. The high hip center technique can reduce operative time, intraoperative blood loss, and downtime. The anatomical center technique is superior to the high hip center technique in terms of limb lengthening. Compared with acetabular anatomical reconstruction, there was no significant difference in postoperative drainage, lower limb length difference, postoperative complications, Trendelenburg sign, and prosthesis survival or wear. For DDH patients who are not severely shortened in the lower limbs and have severe acetabular bone defects, joint surgeons can choose to reconstruct the acetabulum in the upper part to simplify the operation, reduce the trauma of the patient, and accelerate the recovery of the patient, and they can choose to adjust the length of the neck and the angle of the neck shaft to maintain the moment arm of the abductor muscle. A ceramic interface or a highly cross-linked polyethylene interface minimizes the effect of hip response forces. To further evaluate the efficacy of the anatomical center technique and the high hip center technique in the treatment of adult developmental dysplasia of the hip, more large-sample, high-quality, long-term follow-up randomized controlled trials are still needed for verification.

What is the Level of Evidence Substantiating Commercial Payers' Coverage Policies for Total Joint Arthroplasty?

BACKGROUND

The prevalence of total joint arthroplasty (TJA) in the United States has drawn the attention of health care stakeholders. The payers have also used a variety of strategies to regulate the medical necessity of these procedures. The purpose of this study was to examine the level of evidence of the coverage policies being used by commercial payers in the United States.

METHODS

The references of the coverage policies of four commercial insurance companies were reviewed for type of document, level of evidence, applicability to a TJA population, and success of nonoperative treatment in patients with severe degenerative joint disease.

RESULTS

282 documents were reviewed. 45.8% were primary journal articles, 14.2% were level I or II, 41.2% were applicable to patients who were candidates for TJA, and 9.9% discussed the success of nonoperative treatment in patients who would be candidates for TJA.

CONCLUSION

Most of the references cited by commercial payers are of a lower level of scientific evidence and not applicable to patients considered to be candidates for TJA. This is relatively uniform across the reviewed payers. The dearth of high-quality literature cited by commercial payers reflects the lack of evidence and difficulty in conducting high level studies on the outcomes of nonoperative versus operative treatment for patients with severe, symptomatic osteoarthritis. Patients, surgeons, and payers would all benefit from such studies and we encourage professional societies to strive toward that end through multicenter collaboration.

Pseudotumors in Total Joint Arthroplasty

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

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

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

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

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Revision to a non-metal articulation is strongly suggested.

Relationship between Pelvic Incidence Angle and Blood Concentration of Chromium and Cobalt Ions after Metal-on-Metal Hip Replacement: A Brief Report

BACKGROUND AND AIMS

The wear of metal-on-metal hip implants may increase chromium or cobalt ion blood level. This phenomenon may depend among other things on the particularity of spinopelvic anatomy. The effect of pelvic incidence angle on the wear of metal-on-metal hip implants is not known. The objective of the study was to investigate whether such effect does exist.

MATERIAL AND METHODS

The pelvic incidence and inclination of acetabular component angles of 89 patients after unilateral metal-on-metal hip replacement were compared with blood level of chromium and cobalt ions using Pearson correlation coefficient.

RESULTS

No significant correlations between pelvic incidence angle and the metal ion blood levels were observed. The correlation coefficients varied from -0.02 to 0.2 and all p values were >0.05.

CONCLUSION

No evidence was found on the effect of pelvic incidence angle on metal wear after metal-on-metal hip replacement when measured by the blood levels of chromium and cobalt ions. It is reasonable to assume that other factors than pelvic tilt may affect the rate of implant wear.

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.

Gross Trunnion Failure of a Cobalt-Chromium Femoral Head on a Titanium Stem at Midterm Follow-up: A Report of 3 Cases

CASE

Three patients underwent uncomplicated primary total hip arthroplasty with cobalt-chromium femoral heads (36+5 mm) on titanium V40 tapers. At 6 to 9 years of follow-up, severe effects of corrosion at the trunnion were noted in all 3 patients, along with elevated levels of serum cobalt ions and normal levels of serum chromium ions. Gross trunnion failure, apparently caused by corrosion, required femoral stem revision in all of the patients.

CONCLUSION

Decreased neck diameter, longer trunnion length, and large-sized cobalt-chromium heads are possible contributors to early failure after primary total hip arthroplasty due to trunnionosis. Surgeons should be mindful of trunnionosis as a cause of pain and a mechanism of failure following total hip arthroplasty, and serum metal ions should be monitored in these patients.

Blood metal ion levels are not a useful test for adverse reactions to metal debris: A systematic review and meta-analysis

Objectives

Alarm over the reported high failure rates for metal-on-metal (MoM) hip implants as well as their potential for locally aggressive Adverse Reactions to Metal Debris (ARMDs) has prompted government agencies, internationally, to recommend the monitoring of patients with MoM hip implants. Some have advised that a blood ion level >7 µg/L indicates potential for ARMDs. We report a systematic review and meta-analysis of the performance of metal ion testing for ARMDs.

Methods

We searched MEDLINE and EMBASE to identify articles from which it was possible to reconstruct a 2 × 2 table. Two readers independently reviewed all articles and extracted data using explicit criteria. We computed a summary receiver operating curve using a Bayesian random-effects hierarchical model.

Results

Our literature search returned 575 unique articles; only six met inclusion criteria defined a priori. The discriminative capacity of ion tests was homogeneous across studies but that there was substantial cut-point heterogeneity. Our best estimate of the “true” area under curve (AUC) for metal ion testing is 0.615, with a 95% credible interval of 0.480 to 0.735, thus we can state that the probability that metal ion testing is actually clinically useful with an AUC ≥ 0.75 is 1.7%.

Conclusion

Metal ion levels are not useful as a screening test for identifying high risk patients because ion testing will either lead to a large burden of false positive patients, or otherwise marginally modify the pre-test probability. With the availability of more accurate non-invasive tests, we did not find any evidence for using blood ion levels to diagnose symptomatic patients.

Cite this article: M. Pahuta, J. M. Smolders, J. L. van Susante, J. Peck, P. R. Kim, P. E. Beaule. Blood metal ion levels are not a useful test for adverse reactions to metal debris: a systematic review and meta-analysis. Bone Joint Res 2016;5:379–386. DOI: 10.1302/2046-3758.59.BJR-2016-0027.R1.

Metal ion levels post primary unilateral Exeter total hip arthroplasty

BACKGROUND

Metal ion release is common following total hip arthroplasty, yet postoperative levels have not been defined for most stems currently used in clinical practice.

AIM

To assess metal ion release in the serum of patients with well functioning unilateral Exeter V40 primary total hip arthroplasties one year after surgery.

METHODS

Whole blood chromium and serum cobalt levels were measured in 20 patients following primary total hip arthroplasty with the Exeter V40 stem and a variety of acetabular components one year after surgery.

RESULTS

Whole blood chromium levels were within the normal range (10-100 nmol/L), with a single mild elevation of serum cobalt (normal <20 nmol/L).

CONCLUSIONS

In well functioning primary unilateral total hip arthroplasty using the Exeter V40 stem with a variety of acetabular components one year post surgery, whole blood chromium levels are normal and serum cobalt elevations are rare and mild.

Does bearing size influence metal ion levels in large-head metal-on-metal total hip arthroplasty? A comparison of three total hip systems

BACKGROUND

The purpose of the study was twofold: first, to determine whether there is a statistically significant difference in the metal ion levels among three different large-head metal-on-metal (MOM) total hip systems. The second objective was to assess whether position of the implanted prostheses, patient demographics or factors such as activity levels influence overall blood metal ion levels and whether there is a difference in the functional outcomes between the systems.

METHODS

In a cross-sectional cohort study, three different metal-on-metal total hip systems were assessed: two monoblock heads, the Durom socket (Zimmer, Warsaw, IN, USA) and the Birmingham socket (Smith and Nephew, Memphis, TN, USA), and one modular metal-on-metal total hip system (Pinnacle, Depuy Orthopedics, Warsaw, IN, USA). Fifty-four patients were recruited, with a mean age of 59.7 years and a mean follow-up time of 41 months (12 to 60). Patients were evaluated clinically, radiologically and biochemically. Statistical analysis was performed on all collected data to assess any differences between the three groups in terms of overall blood metal ion levels and also to identify whether there was any other factor within the group demographics and outcomes that could influence the mean levels of Co and Cr.

RESULTS

Although the functional outcome scores were similar in all three groups, the blood metal ion levels in the larger monoblock large heads (Durom, Birmingham sockets) were significantly raised compared with those of the Pinnacle group. In addition, the metal ion levels were not found to have a statistically significant relationship to the anteversion or abduction angles as measured on the radiographs.

CONCLUSIONS

When considering a MOM THR, the use of a monoblock large-head system leads to higher elevations in whole blood metal ions and offers no advantage over a smaller head modular system.

Incidence of pseudotumor and acute lymphocytic vasculitis associated lesion (ALVAL) reactions in metal-on-metal hip articulations: a meta-analysis

We systematically reviewed the peer-reviewed literature to determine a pooled estimate of the incidence of pseudotumor and acute lymphocytic vasculitis associated lesions (ALVAL) in adult patients with primary metal-on-metal (MoM) total hip arthroplasty or resurfacing. Fourteen eligible articles were identified, with a total of 13,898 MoM hips. The incidence of pseudotumor/ALVAL ranged from 0% to 6.5% of hips with a mean follow-up ranging from 1.7 to 12.3 years across the studies. The pooled estimated incidence of pseudotumor/ALVAL is 0.6% (95% CI: 0.3% to 1.2%). The rate of revision for any reason ranged from 0% to 14.3% of hips, with a pooled estimate of 3.9% (95% CI: 2.7% to 5.3%).

Chromium and cobalt ion concentrations in blood and serum following various types of metal-on-metal hip arthroplasties: a literature overview

BACKGROUND AND PURPOSE

Widely different metal ion concentrations in blood and serum have been reported with metal-on-metal (MoM) implants. We reviewed the literature on blood and serum ion concentrations of chromium (Cr) and cobalt (Co) following various MoM hip arthroplasties.

METHODS

Studies were searched for in the Medline database, Embase, and the Cochrane Database of Systematic Reviews. Highest mean or median ion concentrations of Cr and Co after a minimum of 1 year of follow-up were extracted and grouped according to sample- and articulation type, and average values were calculated.

RESULTS

43 studies were included and 16 different MoM implants were identified. For the different types of bearings, average ion concentrations and range were calculated from the mean or median ion concentration. The average Cr concentration ranged between 0.5 and 2.5 μg/L in blood and between 0.8 and 5.1 μg/L in serum. For Co, the range was 0.7-3.4 μg/L in blood and 0.3-7.5 μg/L in serum.

INTERPRETATION

When the average blood ion concentrations calculated for the different implants, together with the concentrations measured in the individual studies, were compared with the upper acceptable limit for Cr and Co in blood, no clear pattern was recognized. Furthermore, we were unable to detect any clear difference in ion concentrations between different types of implants (THA and resurfacing).

Metal-on-metal vs conventional total hip arthroplasty: a systematic review and meta-analysis of randomized controlled trials

Metal-on-metal (MOM) hip articulations represent a potential alternative to conventional metal-on-polyethylene total hip arthroplasty (THA). We performed a systematic review of the peer-reviewed literature in search of studies comparing MOM with conventional primary THA with regard to functional outcomes, radiographic outcomes, and complication rates. Four Level I randomized controlled trials remained following our screening process. The data published in these studies were extracted and aggregated using a Mantel-Haenszel cumulative fixed effects meta-analysis. We found no significant difference between MOM and conventional THA with regard to functional outcomes as measured by Harris hip scores and radiographic outcomes as measured by radiolucent lines. Patients with MOM THA did however demonstrate a 3.37 times greater complication rate (1.57, 7.26). In light of the lack of superiority, the increased complication rate, the greater cost, and the potential for adverse medical consequences associated with MOM THA, these bearing surfaces should be used with caution.