Background:. Higher than expected revision rates have been observed in large bearing metal-on-metal total hip replacements. We have introduced a metal on metal hip screening clinic at our unit and report the results. Methods:. All patients who had a metal-on-metal total hip replacement implanted at our unit were recalled to clinic. Screening consisted of clinical examination, Oxford hip score, radiographs, MARS MRI and serum cobalt/chromium ion levels. MRI scans were graded (Norwich Classification) by a single consultant radiologist who was blinded to the history, examination, and metal levels. Patients were sub-classified into 6 groups, which determined further follow up and were either entered into a regular screening programme or referred to a revision arthroplasty surgeon for a decision on whether revision was required. Results:. A total of 278 patients were identified. Four patients had moved away, 2 refused follow-up and 1 patient had died. This left 271 patients in our cohort, having 299
Introduction. It has been speculated that impact deformation of thin 1-piece cups used for modern
Background:. Potential systemic toxicity of metal ions from
Introduction. The MHRA guidelines for metal on metal (MOM) suggest cobalt and chromium levels of more than 7ppb as potential for soft tissue reaction. However, in some patients soft tissue reaction is seen even in the presence of normal serum metal ions levels. Methods. A prospective review of all patients who had
Purpose. There is a postulated association between increased serum metal ions and pseudotumour formation in patients with
Non-large head Metal-on-metal (MoM) hip replacements were seen as a solution to concerns about implant wear in younger patients. Mid-term loosening of once well-fixed hydroxyapatite (HA) coated femoral stems was recently observed in select MoM patients upon revision surgery. Accordingly, an implant retrieval study was undertaken to examine the incidence of aseptic loosening of in HA-coated femoral stems with MoM, ceramic on ceramic (CoC) and metal on polyethylene (MoP) bearing couples. A single-centre implant retrieval lab reviewed 44 hydroxyapatite (HA)-coated titanium wedge taper stems of the same design retrieved over a period of 9 years. Ten were MoM articulations, 23 MoP and 11 CoC. Head sizes ranged from 28 to 40 with only four 40mm heads, all of which were MoM. Reason for revision, duration of implantation, femoral head size, patient age and body mass index was recorded for each retrieval. Goldberg corrosion scores were determined for the taper surfaces of each retrieval, with ‘0’ indicating no corrosion and ‘3’ indicating severe corrosion. Logistic regression analysis, Wilcoxan Rank Sum and Fischer's exact test were used for statistical analysis. Aseptic loosening was the listed reason for revision in 18 of 44 cases. MoM bearing was associated with increased probability of aseptic loosening (Odds ratio 7.1 (95%CI 1.1–47.0) p=0.042). Severity of corrosion was also associated with aseptic loosening (Odds ratio 2.75 (95%CI 1.1–6.6) p=0.02). Head size and patient age had no correlation. Median time to revision of implants for aseptic loosening was 4.5 years (range: 4.2–7.0 years) for MoM versus 1.4 years (range: 0.3–3.0) for other bearing couples (p=0.004). Aseptic loosening was categorised as early (<=2 years) or mid-term (>2 years). No MoM hips were revised for aseptic loosening in the first 2 years while 8 of the 11 mid-term revisions had MoM articulations (p=0.004). Taper corrosion was more severe in mid-term aseptic loosing cases (p=0.049). MoM HA-coated hip replacements appear to be associated with increased mid-term aseptic loosening compared to other bearing couples. Patients with MoM HA-coated hip replacements should be monitored regularly beyond the initial 1 to 2 years following surgery. Future analyses will examine the presence and progression of femoral radiolucency prior to revision surgery to determine an approximate timeline of stem loosening in this patient cohort. This research highlights the importance of implant retrieval programs to assess post-revision implant characteristics for early identification of possible device issues.
The Medicines and Healthcare Products Regulatory Agency (MHRA) of the UK have published guidelines for annual follow up of patients with metal on metal hip replacements following widespread concern regarding metallosis We followed up 718 total hip replacements (594 stemmed hips and 124 resurfacing) with metal on metal bearing, implanted between April 1999 and August 2010 in dedicated clinics with clinical and radiological assessment along with assessment of serum metal ions. Survival was calculated using Kaplan Meier analysis.Introduction
Methods
This study examined whether TiNbN surface characteristics can reduce corrosion and wear of Chrome Cobalt Molybdenum Metal-on Metal bearings. Two series of patients had plasma concentrations of chromium and cobalt at intervals following surgery. The First Series comprised a retrospective analysis of 52 consecutive cases (49 patients, 73–96 months following operation; age at surgery: 33–78) who had undergone an ACCIS (Implantcast, Germany) Modular Large Head hip replacement. The Second Series comprised a prospective, consecutive series of 125 cases (109 patients, 1–61 months following operation; age at surgery: 24–75) who had undergone an ACCIS Resurfacing Hip Replacement in whom pre-operative samples and periodic post-operative metal ion analysis was obtained. Cup inclination and anteversion angles, patient outcome and Harris hip scores at last follow-up were also recorded. The first series revealed medians for [Cr] of 1.2 (range <0.5–2.4) ug/l and [Co] of 3.3 (range <0.15–8.18) ug/l. Four patients were not available for measurement. The second series gave one year [Cr] of 0.8 (range <0.5–1.6) ug/l and [Co] of 0.2 (range <0.15–0.9) ug/l and at two years [Cr] of 0.2 (range <0.5–1.5) ug/l and [Co] of 0.8 (range <0.15–1.0) ug/l. There was no correlation with cup inclination (38° to 62°) or anteversion (0° to 32°) in either group. Mean Harris Hip Scores were 80.9 and 92.3 respectively. Low median levels of metal ions were found in the First Series (despite differing stem type usage). The low median ion levels were more consistent in the Resurfacing patients of the Second Series. The Titanium Niobium Nitride Ceramic Surface Engineering Metal-on-Metal bearing implants appear to protect against raised plasma [Cr] and [Co] both over time and with outlying cup positions. The Harris Hip Scores suggest a good patient outcome for the hip replacements in both series. Further study by a randomised controlled prospective analysis is suggested.
The ACCIS system comprises a bearing of a 5 micron surface ceramic upon a Chrome Cobalt Molybdenum (CrCoMo) substrate which allows for a homogeneous couple. The Titanium Niobium Nitride (TiNbN) microceramic applied by Plasma Vapour Deposition. In comparison with CrCoMo alloy, TiNbN gives a hard (2800 vs 489V), smooth (0.23 vs 0.55Rz), low friction (0.079–0.1 vs 0.11–0.56mu pin on disk test), wetable surface which when combined allows for the potential of gaining fluid film lubrication (lambda>3) on a smaller head diameter than an untreated surface. These properties are postulated to reduce wear and hence lower the release of Cr and Co ions in vivo. The surface microceramic also prevents exposure to release of Cr and Co by corrosion. The surface modified implants were first used in 2003 in large head arthroplasty and later in 2005 with resurfacing implants. Two series of patients implanted by a single surgeon were examined to elucidate the metal ion release of the ACCIS system. The first series retrospectively examined 52 consecutive Large Head Arthroplasty cases for [Cr], [Co] and [Mo] levels. A mean follow-up time of 7.5 yrs (77–101mths) with 9 patients being lost to revision and death by the time of the study. Median levels of [Cr] 1.6, [Co] 4.76 and [Mo] 2.5 µg/l were obtained. The second series prospectively examined the [Cr] and [Co] levels with the pre-operative values as controls in 125 resurfacing cases with the ACCIS microceramic. The second series gave no rising trend observed at up to 5 years ([Cr & Co] (range < 0.5–1.6 µg/l). It is postulated that the ACCIS surface microceramic reduces wear and also reduces the effective patch size for a given load thus allowing for a greater Patch to Edge Distance allowing a greater tolerance to cup positioning. A RCT is currently underway.
The contemporary metal-on-metal (MoM) bearings were reintroduced due to their lower volumetric wear rates in comparison to conventional metal-on-polyethylene bearings. This has the potential to substantially reduce wear-induced osteolysis as the major cause of failure and greater implant stability with the use of large femoral heads. It has been estimated that since 1996 more than 1,000,000 MoM articular couples have been implanted worldwide. However, with increasing clinical experience, the national joint registries have recently reported the failure rate of THA with MoM bearings to be 2–3 fold higher than contemporary THA with non-metal-on-metal bearings. Moreover, adverse periprosthetic tissue reactions have emerged as an important reason for failure in MoM patients. A painful
Metal-on-metal (MOM) hip arthroplasty has been associated with a variety of new failure modes that may be unfamiliar to surgeons who traditionally perform metal-on-polyethylene THR. These failure modes include adverse local tissue reaction to metal debris, hypersensitivity to metal debris, accelerated wear/metallosis, pseudotumours, and corrosion. A significant number of patients with
Summary. We report the first use of synchrotron xray spectroscopy to characterize and compare the chemical form and distribution of metals found in tissues surrounding patients with
Background. Revision surgery for a failed metal on metal (MoM) hip arthroplasty is often unpredictable and challenging due to associated massive soft tissue and bony lesions. We present the analysis and early outcomes of revision surgery in failed
Introduction. Systemic metal ion monitoring (Co;Cr) has proven to be a useful screening tool for implant performance to detect failure at an early stage in
Introduction:. The clinical significance of serum metal ion levels alone in patients with stemmed
Background. The changes in surface roughness occurring during the wear process at the bearing surface are of great importance in trying to understand the failure mechanism of large head
Introduction. Metal-on-Metal (MoM) bearing surfaces were historically used for young patients undergoing total hip arthroplasty, and remain commonplace in modern hip resurfacing. In theory, it has been postulated that metal ions released from such implants may cross the placental barrier and cause harm to the fetus. In light of this potential risk, recommendations against the use of MoM components in women of child-bearing age have been advocated. The purpose of this systematic review was to evaluate: 1) the Metal-on-Metal bearing types and ion levels found; 2) the concentrations of metals in maternal circulation and the umbilical cord; and 3) the presence of abnormalities in the fetus. Methods. A comprehensive literature review was conducted of studies published between January 1st, 1975 and April 1st, 2019 using specific keywords. (See Fig 1). We defined the inclusion criteria for qualifying studies for this review as follows: 1) studies that reported on the women who experienced pregnancy and who had a Metal-on-Metal hip implant; 2) studies that reported on maternal metal ions blood and umbilical cord levels; and 3) studies that reported on the occurrence of fetal complications. Data on cobalt and chromium ion levels in the maternal blood and umbilical cord blood, as well as the presence of adverse effects in the infant were collected. Age at parturition and time from MoM implant to parturition were also collected. A total of 6 studies were included in the final analysis that reported on a total of 21 females and 21 infants born. The mean age at parturition was 40 years (range, 24–41 years), and the mean time from MoM implantation to parturition was 47.2 months (range, 11–119 months). Results. Maternal blood cobalt levels were found as a weighted average of 33.94ug/L (0.972–143), while umbilical cord blood cobalt levels were found to be 22.07 ug/L(0.486–75). Cobalt levels were reduced by an average of 35% between maternal and umbilical cord blood. Maternal cord blood chromium levels were found as a weighted average of 9.25 ug/L (1–25), while umbilical cord chromium levels were found to be 1.30 ug/L(0.288–2.3). Chromium levels were reduced by an average of 86% between maternal and umbilical cord blood. No cobalt or chromium was detected in the umbilical cord blood of three patients. Out of the 21 infants born to women with MoM implants, 20 were born healthy with no adverse effects or complications. Conclusion. To date, there is a lack of consensus as to whether
Introduction. It is well-known that wear debris generated by
Ceramic-on-ceramic bearings are considered in several European and Asian countries a reliable alternative to metal-on-polyethylene, ceramic-on-polyethylene, or metal-on-metal (with small diameter heads) for total hip arthroplasty (THA) management. Reduced joint wear and limited peri-prosthetic osteolytic changes are the main reasons supporting the use of ceramic. So far, the available observational data show a low rate of revision following the use of Ceramic-on-Ceramic bearings, but concern remains regarding the risk of fracture and the prevalence of squeaking noises from the joint. The objective of this study was to use a national arthroplasty registry to assess whether the choice of bearings – metal-on-polyethylene (MoP), ceramic-on-polyethylene (CoP), ceramic-on-ceramic (CoC), or metal-on-metal (MoM) – is associated with differences in the risk of revision. Data from primary THAs were extracted from the New Zealand Joint Registry over a 15-year period. 97,889 hips were available for analysis. The mean age of patients was 68 years (SD +/− 11 years), and 52% were women. The median followup period in this patient population was 9 years (range, 1 to 15 years). The primary endpoint was revision for any reason. Inclusion criteria were degenerative joint disease (84,894), exclusion criteria were previous surgery, trauma, and any other diagnosis (12,566). We also excluded patients operated on with a Ceramic-on-Metal THA, because of the small recorded number (429). There were 54,409 (64.1%) MoP, 16,503 (19.4%) CoP, 9,051 (10.7%) CoC and 4,931 (5.8%)
The role of metal sensitivity or allergy in causing persistent symptoms or failure and need for a revision of a total joint replacement has been the topic of debate and controversy for decades. There was renewed interest in this area with the rise of