Aims. This study investigates head-neck taper
Objectives. This study aimed to characterise and qualitatively grade the severity of the
Aims. To present a surgically relevant update of trunnionosis. . Materials and Methods. Systematic review performed April 2017. Results. Trunnionosis accounts for approximately 2% of the revision total
hip arthroplasty (THA) burden. Thinner (reduced flexural rigidity)
and shorter trunnions (reduced contact area at the taper junction)
may contribute to mechanically assisted
The aim of this study was to assess the effect
of frictional torque and bending moment on fretting
We present a series of 35 patients (19 men and
16 women) with a mean age of 64 years (36.7 to 75.9), who underwent
total hip replacement using the ESKA dual-modular short stem with
metal on-polyethylene bearing surfaces. This implant has a modular
neck section in addition to the modular head. Of these patients,
three presented with increasing post-operative pain due to pseudotumour
formation that resulted from
Aims. Dual mobility implants in total hip arthroplasty are designed to increase the functional head size, thus decreasing the potential for dislocation. Modular dual mobility (MDM) implants incorporate a metal liner (e.g. cobalt-chromium alloy) in a metal shell (e.g. titanium alloy), raising concern for mechanically assisted crevice
Aims. To report our experience with trunnion
Aims. This combined clinical and in vitro study aimed to determine the incidence of liner malseating in modular dual mobility (MDM) constructs in primary total hip arthroplasties (THAs) from a large volume arthroplasty centre, and determine whether malseating increases the potential for fretting and
Aims. Head-taper
Aims. Surgeons have commonly used modular femoral heads and stems from
different manufacturers, although this is not recommended by orthopaedic
companies due to the different manufacturing processes. We compared the rate of
Adverse reaction to wear and
Cemented titanium stems in hip arthroplasty are associated with proximal cement-stem debonding and early failure. This was well publicised with the 3M Capital hip. However,
Aims. We present a case series of ten metal-on-polyethylene total hip
arthroplasties (MoP THAs) with delayed dislocation associated with
unrecognised adverse local tissue reaction due to
We have updated our previous randomised controlled trial comparing release of chromium (Cr) and cobalt (Co) ions and included levels of titanium (Ti) ions. We have compared the findings from 28 mm metal-on-metal total hip replacement, performed using titanium CLS/Spotorno femoral components and titanium AlloFit acetabular components with Metasul bearings, with Durom hip resurfacing using a Metasul articulation or bearing and a titanium plasma-sprayed coating for fixation of the acetabular component. Although significantly higher blood ion levels of Cr and Co were observed at three months in the resurfaced group than in total hip replacement, no significant difference was found at two years post-operatively for Cr, 1.58 μg/L and 1.62 μg/L respectively (p = 0.819) and for Co, 0.67 μg/L and 0.94 μg/L respectively (p = 0.207). A steady state was reached at one year in the resurfaced group and after three months in the total hip replacement group. Interestingly, Ti, which is not part of the bearing surfaces with its release resulting from metal
We report a case of a male patient presenting
with bilateral painful but apparently well-positioned and -fixed
large-diameter metal-on-metal hip replacements four years post-operatively.
Multiple imaging modes revealed a thick-walled, cystic expansile
mass in communication with the hip joint (a pseudotumour). Implant
retrieval analysis and tissue culture eliminated high bearing wear
or infection as causes for the soft-tissue reaction, but noted marked corrosion
of the modular neck taper adaptor and
We sought to determine whether cobalt-chromium alloy (CoCr) femoral
stem tapers (trunnions) wear more than titanium (Ti) alloy stem
tapers (trunnions) when used in a large diameter (LD) metal-on-metal
(MoM) hip arthroplasty system. We performed explant analysis using validated methodology to
determine the volumetric material loss at the taper surfaces of
explanted LD CoCr MoM hip arthroplasties used with either a Ti alloy
(n = 28) or CoCr femoral stem (n = 21). Only 12/14 taper constructs
with a rough male taper surface and a nominal included angle close
to 5.666° were included. Multiple regression modelling was undertaken
using taper angle, taper roughness, bearing diameter (horizontal
lever arm) as independent variables. Material loss was mapped using
a coordinate measuring machine, profilometry and scanning electron
microscopy.Aims
Patients and Methods
Aims. The aim of this study was to evaluate fretting and
Aims. In metal-on-metal (MoM) hip arthroplasties and resurfacings, mechanically induced
Aims. Dual mobility (DM) implants have been shown to reduce the dislocation rate after total hip arthroplasty (THA), but there remain concerns about the use of cobalt chrome liners inserted into titanium shells. The aim of this study was to assess the clinical outcomes, metal ion levels, and periprosthetic femoral bone mineral density (BMD) at mid-term follow-up in young, active patients receiving a modular DM THA. Methods. This was a prospective study involving patients aged < 65 years, with a BMI of < 35 kg/m. 2. , and University of California, Los Angeles activity score of > 6 who underwent primary THA with a modular cobalt chrome acetabular liner, highly cross-linked polyethylene mobile bearing, and a cementless titanium femoral stem. Patient-reported outcome measures, whole blood metal ion levels (μg/l), and periprosthetic femoral BMD were measured at baseline and at one, two, and five years postoperatively. The results two years postoperatively for this cohort have been previously reported. Results. A total of 43 patients were enrolled. At minimum follow-up of five years, 23 (53.4%) returned for clinical and radiological review, 25 (58.1%) had metal ion analysis performed, 19 (44.2%) underwent dual energy x-ray absorptiometry scans, and 25 (58%) completed a pain-drawing questionnaire. The mean modified Harris Hip Scores improved significantly from 54.8 (SD 19) preoperatively to 93.08 (SD 10.5) five years postoperatively (p < 0.001). One patient was revised for aseptic acetabular loosening. The mean cobalt levels increased from 0.065 μg/l (SD 0.03) to 0.08 (SD 0.05) and the mean titanium levels increased from 0.35 (SD 0.13) to 0.78 (SD 0.29). The femoral BMD ratio decreased in Gruen Zone 1 (91.9%) at five years postoperatively compared with the baseline scores at six weeks potoperatively. The femoral BMD ratio was maintained in Gruen zones 2 to 7. Conclusion. The use of a modular DM component and a cementless, tapered femoral stem shows excellent mid-term survivorship with minimal concerns for
Objectives. The use of ceramic femoral heads in total hip arthroplasty (THA) has increased due to their proven low bearing wear characteristics. Ceramic femoral heads are also thought to reduce wear and
This study reports the mid-term results of a large-bearing hybrid metal-on-metal total hip replacement in 199 hips (185 patients) with a mean follow-up of 62 months (32 to 83). Two patients died of unrelated causes and 13 were lost to follow-up. In all, 17 hips (8.5%) have undergone revision, and a further 14 are awaiting surgery. All revisions were symptomatic. Of the revision cases, 14 hips showed evidence of adverse reactions to metal debris. The patients revised or awaiting revision had significantly higher whole blood cobalt ion levels (p = 0.001), but no significant difference in acetabular component size or position compared with the unrevised patients. Wear analysis (n = 5) showed increased wear at the trunnion-head interface, normal levels of wear at the articulating surfaces and evidence of
Aims. Fretting and
Objectives. The diagnosis of periprosthetic joint infection (PJI) is difficult and requires a battery of tests and clinical findings. The purpose of this review is to summarize all current evidence for common and new serum biomarkers utilized in the diagnosis of PJI. Methods. We searched two literature databases, using terms that encompass all hip and knee arthroplasty procedures, as well as PJI and statistical terms reflecting diagnostic parameters. The findings are summarized as a narrative review. Results. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were the two most commonly published serum biomarkers. Most evidence did not identify other serum biomarkers that are clearly superior to ESR and CRP. Other serum biomarkers have not demonstrated superior sensitivity and have failed to replace CRP and ESR as first-line screening tests. D-dimer appears to be a promising biomarker, but more research is necessary. Factors that influence serum biomarkers include temporal trends, stage of revision, and implant-related factors (metallosis). Conclusion. Our review helped to identify factors that can influence serum biomarkers’ level changes; the recognition of such factors can help improve their diagnostic utility. As such, we cannot rely on ESR and CRP alone for the diagnosis of PJI prior to second-stage reimplantation, or in metal-on-metal or
Aims. Modular dual mobility (DM) prostheses in which a cobalt-chromium liner is inserted into a titanium acetabular shell (vs a monoblock acetabular component) have the advantage of allowing supplementary screw fixation, but the potential for
Modern metal-on-metal bearings produce less wear debris and osteolysis, but have the potential adverse effect of release of ions. Improved ceramic-on-ceramic bearings have the lowest wear of all, but the
Tribocorrosion at the head–neck taper interface
– so-called ‘taperosis’ – may be a source of metal ions and particulate
debris in metal-on-polyethylene total hip arthroplasty (THA). We examined the effect of femoral head length on fretting and
corrosion in retrieved head–neck tapers in vivo for a
minimum of two years (mean 8.7 years; 2.6 to 15.9). A total of 56
femoral heads ranging from 28 mm to 3 mm to 28 mm + 8 mm, and 17
femoral stems featuring a single taper design were included in the
study. Fretting and
Large ceramic femoral heads offer several advantages
that are potentially advantageous to patients undergoing both primary
and revision total hip replacement. Many high-quality studies have
demonstrated the benefit of large femoral heads in reducing post-operative instability.
Ceramic femoral heads may also offer an advantage in reducing polyethylene wear
that has been reported in vitro and is starting
to become clinically apparent in mid-term clinical outcome studies.
Additionally, the risk of taper
Dislocation remains among the most common complications
of, and reasons for, revision of both primary and revision total
hip replacements (THR). Hence, there is great interest in maximising
stability to prevent this complication. Head size has been recognised
to have a strong influence on the risk of dislocation post-operatively.
As femoral head size increases, stability is augmented, secondary
to an increase in impingement-free range of movement. Larger head
sizes also greatly increase the ‘jump distance’ required for the
head to dislocate in an appropriately positioned cup. Level-one
studies support the use of larger diameter heads as they decrease
the risk of dislocation following primary and revision THR. Highly cross-linked
polyethylene has allowed us to increase femoral head size, without
a marked increase in wear. However, the thin polyethylene liners
necessary to accommodate larger heads may increase the risk of liner
fracture and larger heads have also been implicated in causing soft-tissue
impingement resulting in groin pain. Larger diameter heads also
impart larger forces on the femoral trunnion, which may contribute
to
Radiostereometric analysis (RSA) is the most accurate radiological method to measure in vivo wear of highly cross-linked polyethylene (XLPE) acetabular components. We have previously reported very low wear rates for a sequentially irradiated and annealed X3 XLPE liner (Stryker Orthopaedics, USA) when used in conjunction with a 32 mm femoral heads at ten-year follow-up. Only two studies have reported the long-term wear rate of X3 liners used in conjunction with larger heads using plain radiographs which have poor sensitivity. The aim of this study was to measure the ten-year wear of thin X3 XLPE liners against larger 36 or 40 mm articulations with RSA. We prospectively reviewed 19 patients who underwent primary cementless THA with the XLPE acetabular liner (X3) and a 36 or 40 mm femoral head with a resultant liner thickness of at least 5.8 mm. RSA radiographs at one week, six months, and one, two, five, and ten years postoperatively and femoral head penetration within the acetabular component were measured with UmRSA software. Of the initial 19 patients, 12 were available at the ten-year time point.Aims
Methods
The risk of mechanical failure of modular revision hip stems is frequently mentioned in the literature, but little is currently known about the actual clinical failure rates of this type of prosthesis. The current retrospective long-term analysis examines the distal and modular failure patterns of the Prevision hip stem from 18 years of clinical use. A design improvement of the modular taper was introduced in 2008, and the data could also be used to compare the original and the current design of the modular connection. We performed an analysis of the Prevision modular hip stem using the manufacturer’s vigilance database and investigated different mechanical failure patterns of the hip stem from January 2004 to December 2022.Aims
Methods
The differential diagnosis of the painful total
hip arthroplasty (resurfacing or total hip) includes infection,
failure of fixation (loosening), tendinitis, bursitis, synovitis,
adverse local tissue reaction (ALTR) to cobalt-chromium alloys,
and non-hip issues, such as spinal disorders, hernia, gynecologic,
and other pelvic pain. Assuming that the hip is the source of pain,
the first level question is prosthetic or non-prosthetic pain generator?
The second level prosthetic question is septic or aseptic? The third
level question (aseptic hips) is well-fixed or loose? ALTR is best
diagnosed by cross-sectional imaging. Successful treatment is dependent
on correct identification and elimination of the pain generator.
Treatment recommendations for ALTR and taper
If a surgeon is faced with altered lesser trochanter
anatomy when revising the femoral component in revision total hip
replacement, a peri-prosthetic fracture, or Paprosky type IIIb or
type IV femoral bone loss, a modular tapered stem offers the advantages
of accurately controlling femoral version and length. The splines
of the taper allow rotational control, and improve the fit in femoral
canals with diaphyseal bone loss. In general, two centimetres of diaphyseal
contact is all that is needed to gain stability with modular tapered
stems. By allowing the proximal body trial to rotate on a well-fixed
distal segment during trial reduction, appropriate anteversion can
be obtained in order to improve intra-operative stability, and decrease
the dislocation risk. However, modular stems should not be used for
all femoral revisions, as implant fracture and
This study reports the ten-year wear rates, incidence of osteolysis, clinical outcomes, and complications of a multicentre randomized controlled trial comparing oxidized zirconium (OxZr) versus cobalt-chrome (CoCr) femoral heads with ultra-high molecular weight polyethylene (UHMWPE) and highly cross-linked polyethylene (XLPE) liners in total hip arthroplasty (THA). Patients undergoing primary THA were recruited from four institutions and prospectively allocated to the following treatment groups: Group A, CoCr femoral head with XLPE liner; Group B, OxZr femoral head with XLPE liner; and Group C, OxZr femoral head with UHMWPE liner. All study patients and assessors recording outcomes were blinded to the treatment groups. The outcomes of 262 study patients were analyzed at ten years’ follow-up.Aims
Methods
The aim of this study was to evaluate the incidence of liner malseating in two commonly used dual-mobility (DM) designs. Secondary aims included determining the risk of dislocation, survival, and clinical outcomes. We retrospectively identified 256 primary total hip arthroplasties (THAs) that included a DM component (144 Stryker MDM and 112 Zimmer-Biomet G7) in 233 patients, performed between January 2012 and December 2019. Postoperative radiographs were reviewed independently for malseating of the liner by five reviewers. The mean age of the patients at the time of THA was 66 years (18 to 93), 166 (65%) were female, and the mean BMI was 30 kg/m2 (17 to 57). The mean follow-up was 3.5 years (2.0 to 9.2).Aims
Methods
Several different designs of hemiarthroplasty are used to treat intracapsular fractures of the proximal femur, with large variations in costs. No clinical benefit of modular over monoblock designs has been reported in the literature. Long-term data are lacking. The aim of this study was to report the ten-year implant survival of commonly used designs of hemiarthroplasty. Patients recorded by the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) between 1 September 1999 and 31 December 2020 who underwent hemiarthroplasty for the treatment of a hip fracture with the following implants were included: a cemented monoblock Exeter Trauma Stem (ETS), cemented Exeter V40 with a bipolar head, a monoblock Thompsons prosthesis (Cobalt/Chromium or Titanium), and an Exeter V40 with a Unitrax head. Overall and age-defined cumulative revision rates were compared over the ten years following surgery.Aims
Methods
A significant reduction in wear at five and ten years was previously reported when comparing Durasul highly cross-linked polyethylene with nitrogen-sterilized Sulene polyethylene in total hip arthroplasty (THA). We investigated whether the improvement observed at the earlier follow-up continued, resulting in decreased osteolysis and revision surgery rates over the second decade. Between January 1999 and December 2001, 90 patients underwent surgery using the same acetabular and femoral components with a 28 mm metallic femoral head and either a Durasul or Sulene liner. A total of 66 hips of this prospective randomized study were available for a minimum follow-up of 20 years. The linear femoral head penetration rate was measured at six weeks, one year, and annually thereafter, using the Dorr method on digitized radiographs with a software package.Aims
Methods
Dislocation remains a leading cause of failure following revision total hip arthroplasty (THA). While dual-mobility (DM) bearings have been shown to mitigate this risk, options are limited when retaining or implanting an uncemented shell without modular DM options. In these circumstances, a monoblock DM cup, designed for cementing, can be cemented into an uncemented acetabular shell. The goal of this study was to describe the implant survival, complications, and radiological outcomes of this construct. We identified 64 patients (65 hips) who had a single-design cemented DM cup cemented into an uncemented acetabular shell during revision THA between 2018 and 2020 at our institution. Cups were cemented into either uncemented cups designed for liner cementing (n = 48; 74%) or retained (n = 17; 26%) acetabular components. Median outer head diameter was 42 mm. Mean age was 69 years (SD 11), mean BMI was 32 kg/m2 (SD 8), and 52% (n = 34) were female. Survival was assessed using Kaplan-Meier methods. Mean follow-up was two years (SD 0.97).Aims
Methods
United Classification System (UCS) B2 and B3 periprosthetic fractures in total hip arthroplasties (THAs) have been commonly managed with modular tapered stems. No study has evaluated the use of monoblock fluted tapered titanium stems for this indication. This study aimed to evaluate the effects of a monoblock stems on implant survivorship, postoperative outcomes, radiological outcomes, and osseointegration following treatment of THA UCS B2 and B3 periprosthetic fractures. A retrospective review was conducted of all patients who underwent revision THA (rTHA) for periprosthetic UCS B2 and B3 periprosthetic fracture who received a single design monoblock fluted tapered titanium stem at two large, tertiary care, academic hospitals. A total of 72 patients met inclusion and exclusion criteria (68 UCS B2, and four UCS B3 fractures). Primary outcomes of interest were radiological stem subsidence (> 5 mm), radiological osseointegration, and fracture union. Sub-analysis was also done for 46 patients with minimum one-year follow-up.Aims
Methods
Several short- and mid-term studies have shown minimal liner wear of highly cross-linked polyethylene (HXLPE) in total hip arthroplasty (THA), but the safety of using thinner HXLPE liners to maximize femoral head size remains uncertain. The objective of this study was to analyze clinical survival and radiological wear rates of patients with HXLPE liners, a 36 mm femoral head, and a small acetabular component with a minimum of ten years’ follow-up. We retrospectively identified 55 patients who underwent primary THA performed at a single centre, using HXLPE liners with 36 mm cobalt-chrome heads in acetabular components with an outer diameter of 52 mm or smaller. Patient demographic details, implant details, death, and all-cause revisions were recorded. Cox regression and Kaplan-Meier survival was used to determine all-cause and liner-specific revision. Of these 55 patients, 22 had a minimum radiological follow-up of seven years and were assessed radiologically for linear and volumetric wear.Aims
Methods
Prior studies have identified that malseating of a modular dual mobility liner can occur, with previous reported incidences between 5.8% and 16.4%. The aim of this study was to determine the incidence of malseating in dual mobility implants at our institution, assess for risk factors for liner malseating, and investigate whether liner malseating has any impact on clinical outcomes after surgery. We retrospectively reviewed the radiographs of 239 primary and revision total hip arthroplasties with a modular dual mobility liner. Two independent reviewers assessed radiographs for each patient twice for evidence of malseating, with a third observer acting as a tiebreaker. Univariate analysis was conducted to determine risk factors for malseating with Youden’s index used to identify cut-off points. Cohen’s kappa test was used to measure interobserver and intraobserver reliability.Aims
Methods
This study aims to assess the relationship between history of pseudotumour formation secondary to metal-on-metal (MoM) implants and periprosthetic joint infection (PJI) rate, as well as establish ESR and CRP thresholds that are suggestive of infection in these patients. We hypothesized that patients with a pseudotumour were at increased risk of infection. A total of 1,171 total hip arthroplasty (THA) patients with MoM articulations from August 2000 to March 2014 were retrospectively identified. Of those, 328 patients underwent metal artefact reduction sequence MRI and had minimum two years’ clinical follow-up, and met our inclusion criteria. Data collected included demographic details, surgical indication, laterality, implants used, history of pseudotumour, and their corresponding preoperative ESR (mm/hr) and CRP (mg/dl) levels. Multivariate logistic regression modelling was used to evaluate PJI and history of pseudotumour, and receiver operating characteristic curves were created to assess the diagnostic capabilities of ESR and CRP to determine the presence of infection in patients undergoing revision surgery.Aims
Methods
Metal-on-metal total hip replacement has been targeted at younger patients with anticipated long-term survival, but the effect of the production of metal ions is a concern because of their possible toxicity to cells. We have reviewed the results of the use of the Ultima hybrid metal-on-metal total hip replacement, with a cemented polished tapered femoral component with a 28 mm diameter and a cobalt-chrome (CoCr) modular head, articulating with a 28 mm CoCr acetabular bearing surface secured in a titanium alloy uncemented shell. Between 1997 and 2004, 545 patients with 652 affected hips underwent replacement using this system. Up to 31 January 2008, 90 (13.8%) hips in 82 patients had been revised. Pain was the sole reason for revision in 44 hips (48.9%) of which 35 had normal plain radiographs. Peri-prosthetic fractures occurred in 17 hips (18.9%) with early dislocation in three (3.3%) and late dislocation in 16 (17.8%). Infection was found in nine hips (10.0%). At operation, a range of changes was noted including cavities containing cloudy fluid under pressure, necrotic soft tissues with avulsed tendons and denuded osteonecrotic upper femora.
Modular dual mobility (MDM) acetabular components are often used with the aim of reducing the risk of dislocation in revision total hip arthroplasty (THA). There is, however, little information in the literature about its use in this context. The aim of this study, therefore, was to evaluate the outcomes in a cohort of patients in whom MDM components were used at revision THA, with a mean follow-up of more than five years. Using the database of
a single academic centre, 126 revision THAs in 117 patients using a single
design of an MDM acetabular component were retrospectively reviewed. A total of 94 revision THAs in 88 patients with a mean follow-up of 5.5 years were included in the study. Survivorship was analyzed with the endpoints of dislocation, reoperation for dislocation, acetabular revision for aseptic loosening, and acetabular revision for any reason. The secondary endpoints were surgical complications and the radiological outcome.Aims
Methods
A recent report from France suggested an association between the use of cobalt-chrome (CoCr) femoral heads in total hip arthroplasties (THAs) and an increased risk of dilated cardiomyopathy and heart failure. CoCr is a commonly used material in orthopaedic implants. If the reported association is causal, the consequences would be significant given the millions of joint arthroplasties and other orthopaedic procedures in which CoCr is used annually. We examined whether CoCr-containing THAs were associated with an increased risk of all-cause mortality, heart outcomes, cancer, and neurodegenerative disorders in a large national database. Data from the National Joint Registry was linked to NHS English hospital inpatient episodes for 374,359 primary THAs with up to 14.5 years' follow-up. We excluded any patients with bilateral THAs, knee arthroplasties, indications other than osteoarthritis, aged under 55 years, and diagnosis of one or more outcome of interest before THA. Implants were grouped as either containing CoCr or not containing CoCr. The association between implant construct and the risk of all-cause mortality and incident heart failure, cancer, and neurodegenerative disorders was examined.Aims
Methods
We have investigated nine patients with cemented Furlong (JRI, London, UK) titanium hip replacements who presented with early pain despite a well-fixed, aseptic prosthesis. All were followed up clinically and radiologically at regular intervals. Pain was located in the thigh and was worse at night. Radiographs showed cortical hypertrophy of the femur around the tip of the stem. Eight of the nine patients subsequently required single-stage revision using an uncemented prosthesis, which relieved the pain. At revision, the pH of the tip of the stem was found to be highly acidic with macroscopic evidence of
We aimed to investigate if the use of the largest possible cobalt-chromium head articulating with polyethylene acetabular inserts would increase the in vivo wear rate in total hip arthroplasty. In a single-blinded randomized controlled trial, 96 patients (43 females), at a median age of 63 years (interquartile range (IQR) 57 to 69), were allocated to receive either the largest possible modular femoral head (36 mm to 44 mm) in the thinnest possible insert or a standard 32 mm head. All patients received a vitamin E-doped cross-linked polyethylene insert and a cobalt-chromium head. The primary outcome was proximal head penetration measured with radiostereometric analysis (RSA) at two years. Secondary outcomes were volumetric wear, periacetabular radiolucencies, and patient-reported outcomes.Aims
Methods
We aimed to evaluate the long-term outcome of highly cross-linked polyethylene (HXLPE) cemented acetabular components and assess whether any radiolucent lines (RLLs) which arose were progressive. We retrospectively reviewed 170 patients who underwent 187 total hip arthroplasties at two hospitals with a minimum follow-up of ten years. All interventions were performed using the same combination of HXLPE cemented acetabular components with femoral stems made of titanium alloy. Kaplan-Meier survival analysis was performed for the primary endpoint of acetabular component revision surgery for any reason and secondary endpoint of the appearance of RLLs. RLLs that had appeared once were observed over time. We statistically assessed potential relationships between RLLs and a number of factors, including the technique of femoral head autografting and the Japanese Orthopaedic Association score.Aims
Methods
This study aimed to determine if macrophages can attach and directly affect the oxide layers of 316L stainless steel, titanium alloy (Ti6Al4V), and cobalt-chromium-molybdenum alloy (CoCrMo) by releasing components of these alloys. Murine peritoneal macrophages were cultured and placed on stainless steel, CoCrMo, and Ti6Al4V discs into a 96-well plate. Cells were activated with interferon gamma and lipopolysaccharide. Macrophages on stainless steel discs produced significantly more nitric oxide (NO) compared to their control counterparts after eight to ten days and remained elevated for the duration of the experiment.Aims
Methods
Hip resurfacing arthroplasty (HRA) is typically indicated for young and active patients. Due to the longevity of arthroplasty, these patients are likely to undergo revision surgery during their lifetime. There is a paucity of information on the long-term outcome of revision surgeries performed after failed HRA. The aim of our study was to provide survivorship data as well as clinical scores after HRA revisions. A total of 42 patients (43 hips) were revised after HRA at our centre to a variety of devices, including four HRA and 39 total hip arthroplasties (THAs). In addition to perioperative complications, University of California, Los Angeles (UCLA) hip scores and 12-Item Short-Form Health Survey questionnaire (SF-12) quality of life scores were collected at follow-up visits after the primary HRA and after revision surgery.Aims
Methods
To find out if there is an inverse association between estimated glomerular filtration rate (eGFR) and whole blood cobalt (Co) and chromium (Cr) levels in patients with metal-on-metal (MoM) hip arthroplasties and renal insufficiency, suggesting that renal insufficiency could cause accumulation of Co and Cr in blood. Out of 2,520 patients with 3,013 MoM hip arthroplasties, we identified 1,244 patients with whole blood Co, Cr, and creatinine measured within no more than a one-year interval. We analyzed the correlation of blood metal ion levels and eGFR to identify a potential trend of accumulating Co or Cr with decreasing eGFR.Aims
Methods
The aim of this study was to develop a novel computational model for estimating head/stem taper mechanics during different simulated assembly conditions. Finite element models of generic cobalt-chromium (CoCr) heads on a titanium stem taper were developed and driven using dynamic assembly loads collected from clinicians. To verify contact mechanics at the taper interface, comparisons of deformed microgroove characteristics (height and width of microgrooves) were made between model estimates with those measured from five retrieved implants. Additionally, these models were used to assess the role of assembly technique—one-hit versus three-hits—on the taper interlock mechanical behaviour.Aims
Methods
Adverse local tissue reactions associated with abnormal wear considerably slowed down the general use of metal-on-metal (MoM) hip resurfacing arthroplasty (HRA), now limited to a few specialized centres. In this study, we provide the clinical results of 400 consecutive MoM HRAs implanted more than 20 years ago in one such centre. A total of 355 patients (400 hips) were treated with Conserve Plus HRA between November 1996 and November 2000. There were 96 female (27%) and 259 male patients (73%). Their mean age was 48.2 years (SD 10.9). The University of California, Los Angeles (UCLA) hip scores and 12-item Short Form Survey (SF-12) quality of life scores were reported. Survivorship was assessed using Kaplan-Meier analyses.Aims
Methods
We evaluated a large database with mechanical failure of a single uncemented modular femoral component, used in revision hip arthroplasty, as the end point and compared them to a control group treated with the same implant. Patient- and implant-specific risk factors for implant failure were analyzed. All cases of a fractured uncemented modular revision femoral component from one manufacturer until April 2017 were identified and the total number of implants sold until April 2017 was used to calculate the fracture rate. The manufacturer provided data on patient demographics, time to failure, and implant details for all notified fractured devices. Patient- and implant-specific risk factors were evaluated using a logistic regression model with multiple imputations and compared to data from a previously published reference group, where no fractures had been observed. The results of a retrieval analysis of the fractured implants, performed by the manufacturer, were available for evaluation.Aims
Methods
We have previously demonstrated raised cobalt and chromium levels in patients with larger diameter femoral heads, following metal-on-polyethylene uncemented total hip arthroplasty. Further data have been collected, to see whether these associations have altered with time and to determine the long-term implications for these patients and our practice. Patients from our previous study who underwent Trident-Accolade primary total hip arthroplasties using a metal-on-polyethylene bearing in 2009 were reviewed. Patients were invited to have their cobalt and chromium levels retested, and were provided an Oxford Hip Score. Serum ion levels were then compared between groups (28 mm, 36 mm, and 40 mm heads) and over time.Aims
Methods
Dual mobility (DM) bearings are an attractive treatment option to obtain hip stability during challenging primary and revision total hip arthroplasty (THA) cases. The purpose of this study was to analyze data submitted to the American Joint Replacement Registry (AJRR) to characterize utilization trends of DM bearings in the USA. All primary and revision THA procedures reported to AJRR from 2012 to 2018 were analyzed. Patients of all ages were included and subdivided into DM and traditional bearing surface cohorts. Patient demographics, geographical region, hospital size, and teaching affiliation were assessed. Associations were determined by chi-squared analysis and logistic regression was performed to assess outcome variables.Aims
Methods
The aim of this study was to evaluate blood metal ion levels, leucocyte profiles, and serum cytokines in patients with a total hip arthroplasty (THA) involving modular dual-mobility components. A total of 39 patients were recruited, with clinical follow-up of up to two years. Outcome was assessed using the Harris Hip Score (HHS, the 12-Item Short-Form Health Survey (SF-12), the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and a visual analogue scale (VAS) for pain. Blood concentrations of cobalt (Co), chromium (Cr), and serum cytokines were measured. Subpopulations of leucocytes were analyzed by flow cytometry.Aims
Patients and Methods
The rate of dislocation when traditional single bearing implants are used in revision total hip arthroplasty (THA) has been reported to be between 8% and 10%. The use of dual mobility bearings can reduce this risk to between 0.5% and 2%. Dual mobility bearings are more expensive, and it is not clear if the additional clinical benefits constitute value for money for the payers. We aimed to estimate the cost-effectiveness of dual mobility compared with single bearings for patients undergoing revision THA. We developed a Markov model to estimate the expected cost and benefits of dual mobility compared with single bearing implants in patients undergoing revision THA. The rates of revision and further revision were calculated from the National Joint Registry of England and Wales, while rates of transition from one health state to another were estimated from the literature, and the data were stratified by sex and age. Implant and healthcare costs were estimated from local procurement prices and national tariffs. Quality-adjusted life-years (QALYs) were calculated using published utility estimates for patients undergoing THA.Aims
Methods
Modular dual-mobility constructs reduce the risk of dislocation after revision total hip arthroplasty (THA). However, questions about metal ions from the cobalt-chromium (CoCr) liner persist, and are particularly germane to patients being revised for adverse local tissue reactions (ALTR) to metal. We determined the early- to mid-term serum Co and Cr levels after modular dual-mobility components were used in revision and complex primary THAs, and specifically included patients revised for ALTR. Serum Co and Cr levels were measured prospectively in 24 patients with a modular dual-mobility construct and a ceramic femoral head. Patients with CoCr heads or contralateral THAs with CoCr heads were excluded. The mean age was 63 years (35 to 83), with 13 patients (54%) being female. The mean follow-up was four years (2 to 7). Indications for modular dual-mobility were prosthetic joint infection treated with two-stage exchange and subsequent reimplantation (n = 8), ALTR revision (n = 7), complex primary THA (n = 7), recurrent instability (n = 1), and periprosthetic femoral fracture (n = 1). The mean preoperative Co and Cr in patients revised for an ALTR were 29.7 μg/l (2 to 146) and 21.5 μg/l (1 to 113), respectively.Aims
Patients and Methods
We investigated the reliability of the cobalt-chromium (CoCr) synovial joint fluid ratio (JFR) in identifying the presence of a severe aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL) response and/or suboptimal taper performance (SOTP) following metal-on-metal (MoM) hip arthroplasty. We then examined the possibility that the CoCr JFR may influence the serum partitioning of Co and Cr. For part A, we included all revision surgeries carried out at our unit with the relevant data, including volumetric wear analysis, joint fluid (JF) Co and Cr concentrations, and ALVAL grade (n = 315). Receiver operating characteristic curves were constructed to assess the reliability of the CoCr JFR in identifying severe ALVAL and/or SOTP. For part B, we included only patients with unilateral prostheses who had given matched serum and whole blood samples for Co and Cr analysis (n = 155). Multiple regression was used to examine the influence of JF concentrations on the serum partitioning of Co and Cr in the blood.Objectives
Methods
Although good clinical outcomes have been reported for monolithic tapered, fluted, titanium stems (TFTS), early results showed high rates of subsidence. Advances in stem design may mitigate these concerns. This study reports on the use of a current monolithic TFTS for a variety of indications. A multi-institutional retrospective study of all consecutive total hip arthroplasty (THA) and revision total hip arthroplasty (rTHA) patients who received the monolithic TFTS was conducted. Surgery was performed by eight fellowship-trained arthroplasty surgeons at four institutions. A total of 157 hips in 153 patients at a mean follow-up of 11.6 months (SD7.8) were included. Mean patient age at the time of surgery was 67.4 years (SD 13.3) and mean body mass index (BMI) was 28.9 kg/m2 (SD 6.5). Outcomes included intraoperative complications, one-year all-cause re-revisions, and subsidence at postoperative time intervals (two weeks, six weeks, six months, nine months, and one year).Aims
Methods
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). 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.Aims
Patients and Methods
Previous studies have suggested that metal-on-metal (MoM) Pinnacle (DePuy Synthes, Warsaw, Indiana) hip arthroplasties implanted after 2006 exhibit higher failure rates. This was attributed to the production of implants with reduced diametrical clearances between their bearing surfaces, which, it was speculated, were outside manufacturing tolerances. This study aimed to better understand the performance of Pinnacle Systems manufactured before and after this event. A total of 92 retrieved MoM Pinnacle hips were analyzed, of which 45 were implanted before 2007, and 47 from 2007 onwards. The ‘pre-2007’ group contained 45 implants retrieved from 21 male and 24 female patients, with a median age of 61.3 years (interquartile range (IQR) 57.1 to 65.5); the ‘2007 onwards’ group contained 47 implants retrieved from 19 male and 28 female patients, with a median age of 61.8 years (IQR 58.5 to 67.8). The volume of material lost from their bearing and taper surfaces was measured using coordinate and roundness measuring machines. These outcomes were then compared statistically using linear regression models, adjusting for potentially confounding factors.Objectives
Methods
There are limited published data detailing the volumetric material loss from tapers of conventional metal-on-polyethylene (MoP) total hip arthroplasties (THAs). Our aim was to address this by comparing the taper wear rates measured in an explanted cohort of the widely used Exeter THA with those measured in a group of metal-on-metal (MoM) THAs. We examined an existing retrieval database to identify all Exeter V40 and Universal MoP THAs. Volumetric wear analysis of the taper surfaces was conducted using previously validated methodology. These values were compared with those obtained from a series of MoM THAs using non-parametric statistical methodology. A number of patient and device variables were accounted for using multiple regression modelling.Aims
Patients and Methods
The aim of this study was to report the initial results of the
Exeter V40 stem, which became available in 2000. A total of 540 total hip arthroplasties (THAs) were performed
in our unit using this stem between December 2000 and May 2002.
Our routine protocol is to review patients postoperatively and at
one, five, and ten years following surgery.Aims
Patients and Methods
Femoral stems with exchangeable (modular) necks were introduced
to offer surgeons an increased choice when determining the version,
offset and length of the femoral neck during total hip arthroplasty
(THA). It was hoped that this would improve outcomes and reduce
complications, particularly dislocation. In 2010, the Australian Orthopaedic
Association National Joint Replacement Registry (AOANJRR) first
reported an increased rate of revision after primary THA using femoral
stems with an exchangeable neck. The aim of this study was to provide
a more comprehensive up-to-date analysis of primary THA using femoral
stems with exchangeable and fixed necks. The data included all primary THA procedures performed for osteoarthritis
(OA), reported to the AOANJRR between 01 September 1999 and 31 December
2014. There were 9289 femoral stems with an exchangeable neck and
253 165 femoral stems with a fixed neck. The characteristics of
the patients and prostheses including the bearing surface and stem/neck
metal combinations were examined using Cox proportional hazard ratios
(HRs) and Kaplan-Meier estimates of survivorship. Aims
Materials and Methods
Modular junctions are ubiquitous in contemporary hip arthroplasty. The head-trunnion junction is implicated in the failure of large diameter metal-on-metal (MoM) hips which are the currently the topic of one the largest legal actions in the history of orthopaedics (estimated costs are stated to exceed $4 billion). Several factors are known to influence the strength of these press-fit modular connections. However, the influence of different head sizes has not previously been investigated. The aim of the study was to establish whether the choice of head size influences the initial strength of the trunnion-head connection. Ti-6Al-4V trunnions (n = 60) and two different sizes of cobalt-chromium (Co-Cr) heads (28 mm and 36 mm; 30 of each size) were used in the study. Three different levels of assembly force were considered: 4 kN; 5 kN; and 6 kN (n = 10 each). The strength of the press-fit connection was subsequently evaluated by measuring the pull-off force required to break the connection. The statistical differences in pull-off force were examined using a Kruskal–Wallis test and two-sample Mann–Whitney U test. Finite element and analytical models were developed to understand the reasons for the experimentally observed differences.Objectives
Materials and Methods
This study presents the long-term survivorship, risk factors for prosthesis survival, and an assessment of the long-term effects of changes in surgical technique in a large series of patients treated by metal-on-metal (MoM) hip resurfacing arthroplasty (HRA). Between November 1996 and January 2012, 1074 patients (1321 hips) underwent HRA using the Conserve Plus Hip Resurfacing System. There were 787 men (73%) and 287 women (27%) with a mean age of 51 years (14 to 83). The underlying pathology was osteoarthritis (OA) in 1003 (75.9%), developmental dysplasia of the hip (DDH) in 136 (10.3%), avascular necrosis in 98 (7.4%), and other conditions, including inflammatory arthritis, in 84 (6.4%).Aims
Patients and Methods
The aim of this study was to compare the design of the generic
OptiStem XTR femoral stem with the established Exeter femoral stem. We obtained five boxed, as manufactured, implants of both designs
at random (ten in total). Two examiners were blinded to the implant
design and independently measured the mass, volume, trunnion surface
topography, trunnion roughness, trunnion cone angle, Caput-Collum-Diaphyseal
(CCD) angle, femoral offset, stem length, neck length, and the width
and roughness of the polished stem shaft using peer-reviewed methods.
We then compared the stems using these parameters.Aims
Materials and Methods
The aim of this study was to determine whether there is a difference
in the rate of wear between acetabular components positioned within
and outside the ‘safe zones’ of anteversion and inclination angle. We reviewed 100 hips in 94 patients who had undergone primary
total hip arthroplasty (THA) at least ten years previously. Patients
all had the same type of acetabular component with a bearing couple
which consisted of a 28 mm cobalt-chromium head on a highly crosslinked
polyethylene (HXLPE) liner. A supine radiostereometric analysis
(RSA) examination was carried out which acquired anteroposterior
(AP) and lateral paired images. Acetabular component anteversion
and inclination angles were measured as well as total femoral head
penetration, which was divided by the length of implantation to
determine the rate of polyethylene wear.Aims
Patients and Methods
For this retrospective cohort study, patients aged ≤ 30 years
(very young) who underwent total hip arthroplasty (THA) were compared
with patients aged ≥ 60 years (elderly) to evaluate the rate of
revision arthroplasty, implant survival, the indications for revision,
the complications, and the patient-reported outcomes. We retrospectively reviewed all patients who underwent primary
THA between January 2000 and May 2015 from our institutional database.
A total of 145 very young and 1359 elderly patients were reviewed.
The mean follow-up was 5.3 years (1 to 18). Logistic generalized
estimating equations were used to compare characteristics and the revision
rate. Survival was evaluated using Kaplan–Meier curves and hazard
rates were created using Cox regression.Aims
Patients and Methods
Tapered fluted titanium stems are increasingly
used for femoral revision arthroplasty. They are available in modular and
non-modular forms. Modularity has advantages when the bone loss
is severe, the proximal femur is mis shapen or the surgeon is unfamiliar
with the implant, but it introduces the risk of fracture of the
stem at the junction between it and the proximal body segment. For
that reason, and while awaiting intermediate-term results of more recently
introduced designs of this junction, non-modularity has attracted
attention, at least for straightforward revision cases. We review the risks and causes of fracture of tapered titanium
modular revision stems and present an argument in favour of the
more selective use of modular designs. Cite this article:
In order to address acetabular defects, porous metal revision acetabular components and augments have been developed, which require fixation to each other. The fixation technique that results in the smallest relative movement between the components, as well as its influence on the primary stability with the host bone, have not previously been determined. A total of 18 composite hemipelvises with a Paprosky IIB defect were implanted using a porous titanium 56 mm multihole acetabular component and 1 cm augment. Each acetabular component and augment was affixed to the bone using two screws, while the method of fixation between the acetabular component and augment varied for the three groups of six hemipelvises: group S, screw fixation only; group SC, screw plus cement fixation; group C, cement fixation only. The implanted hemipelvises were cyclically loaded to three different loading maxima (0.5 kN, 0.9 kN, and 1.8 kN).Objectives
Methods
Few studies have assessed outcomes following non-metal-on-metal hip arthroplasty (non-MoMHA) revision surgery performed for adverse reactions to metal debris (ARMD). We assessed outcomes following non-MoMHA revision surgery performed for ARMD, and identified predictors of re-revision. We performed a retrospective observational study using data from the National Joint Registry for England and Wales. All non-MoMHAs undergoing revision surgery for ARMD between 2008 and 2014 were included (185 hips in 185 patients). Outcome measures following ARMD revision were intra-operative complications, mortality and re-revision surgery. Predictors of re-revision were identified using Cox regression.Objectives
Methods
The early failure and revision of bimodular primary
total hip arthroplasty prostheses requires the identification of the
risk factors for material loss and wear at the taper junctions through
taper wear analysis. Deviations in taper geometries between revised
and pristine modular neck tapers were determined using high resolution
tactile measurements. A new algorithm was developed and validated
to allow the quantitative analysis of material loss, complementing
the standard visual inspection currently used. The algorithm was applied to a sample of 27 retrievals ( Cite this article:
Our first aim was to determine whether there are significant
changes in the level of metal ions in the blood at mid-term follow-up,
in patients with an Articular Surface Replacement (ASR) arthroplasty.
Secondly, we sought to identify risk factors for any increases. The study involved 435 patients who underwent unilateral, metal-on-metal
(MoM) hip resurfacing (HRA) or total hip arthroplasty (THA). These
patients all had one measurement of the level of metal ions in the
blood before seven years had passed post-operatively (early evaluation)
and one after seven years had passed post-operatively (mid-term evaluation).
Changes in ion levels were tested using a Wilcoxon signed-rank test.
We identified subgroups at the highest risk of increase using a
multivariable linear logistic regression model.Aims
Patients and Methods
Many case reports and small studies have suggested that cobalt
ions are a potential cause of cardiac complications, specifically
cardiomyopathy, after metal-on-metal (MoM) total hip arthroplasty
(THA). The impact of metal ions on the incidence of cardiac disease
after MoM THA has not been evaluated in large studies. The aim of
this study was to compare the rate of onset of new cardiac symptoms
in patients who have undergone MoM THA with those who have undergone
metal-on-polyethylene (MoP) THA. Data were extracted from the Standard Analytics Files database
for patients who underwent MoM THA between 2005 and 2012. Bearing
surface was selected using International Classification of Diseases
ninth revision codes. Patients with a minimum five-year follow-up
were selected. An age and gender-matched cohort of patients who underwent
MoP THA served as a comparison group. New diagnoses of cardiac disease
were collected during the follow-up period. Comorbidities and demographics
were identified and routine descriptive statistics were used.Aims
Patients and Methods
Following the recall of modular neck hip stems
in July 2012, research into femoral modularity will intensify over
the next few years. This review aims to provide surgeons with an
up-to-date summary of the clinically relevant evidence. The development
of femoral modularity, and a classification system, is described.
The theoretical rationale for modularity is summarised and the clinical
outcomes are explored. The review also examines the clinically relevant problems
reported following the use of femoral stems with a modular neck. Joint replacement registries in the United Kingdom and Australia
have provided data on the failure rates of modular devices but cannot
identify the mechanism of failure. This information is needed to
determine whether modular neck femoral stems will be used in the
future, and how we should monitor patients who already have them implanted. Cite this article:
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. 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.Aims
Patients and Methods
We wished to investigate the influence of metal debris exposure
on the subsequent immune response and resulting soft-tissue injury
following metal-on-metal (MoM) hip arthroplasty. Some reports have
suggested that debris generated from the head-neck taper junction
is more destructive than equivalent doses from metal bearing surfaces. We investigated the influence of the source and volume of metal
debris on chromium (Cr) and cobalt (Co) concentrations in corresponding
blood and hip synovial fluid samples and the observed agglomerated
particle sizes in excised tissues using multiple regression analysis
of prospectively collected data. A total of 199 explanted MoM hips
(177 patients; 132 hips female) were analysed to determine rates
of volumetric wear at the bearing surfaces and taper junctions. Aims
Patients and Methods
The issues surrounding raised levels of metal
ions in the blood following large head metal-on-metal total hip replacement
(THR), such as cobalt and chromium, have been well documented. Despite
the national popularity of uncemented metal-on-polyethylene (MoP)
THR using a large-diameter femoral head, few papers have reported
the levels of metal ions in the blood following this combination.
Following an isolated failure of a 44 mm Trident–Accolade uncemented
THR associated with severe wear between the femoral head and the
trunnion in the presence of markedly elevated levels of cobalt ions
in the blood, we investigated the relationship between modular femoral head
diameter and the levels of cobalt and chromium ions in the blood
following this THR. A total of 69 patients received an uncemented Trident–Accolade
MoP THR in 2009. Of these, 43 patients (23 men and 20 women, mean
age 67.0 years) were recruited and had levels of cobalt and chromium
ions in the blood measured between May and June 2012. The patients
were then divided into three groups according to the diameter of
the femoral head used: 12 patients in the 28 mm group (controls),
18 patients in the 36 mm group and 13 patients in the 40 mm group.
A total of four patients had identical bilateral prostheses in situ
at phlebotomy: one each in the 28 mm and 36 mm groups and two in
the 40 mm group. There was a significant increase in the mean levels of cobalt
ions in the blood in those with a 36 mm diameter femoral head compared
with those with a 28 mm diameter head (p = 0.013). The levels of
cobalt ions in the blood were raised in those with a 40 mm diameter
head but there was no statistically significant difference between
this group and the control group (p = 0.152). The levels of chromium
ions in the blood were normal in all patients. The clinical significance of this finding is unclear, but we
have stopped using femoral heads with a diameter of ≤ 36 mm, and
await further larger studies to clarify whether, for instance, this
issue particularly affects this combination of components. Cite this article:
As adverse events related to metal on metal hip
arthroplasty have been better understood, there has been increased
interest in toxicity related to the high circulating levels of cobalt ions.
However, distinguishing true toxicity from benign elevations in
cobalt levels can be challenging. The purpose of this review is
to examine the use of cobalt alloys in total hip arthroplasty, to
review the methods of measuring circulating cobalt levels, to define
a level of cobalt which is considered pathological and to review
the pathophysiology, risk factors and treatment of cobalt toxicity.
To the best of our knowledge, there are 18 published cases where
cobalt metal ion toxicity has been attributed to the use of cobalt-chromium
alloys in hip arthroplasty. Of these cases, the great majority reported
systemic toxic reactions at serum cobalt levels more than 100 μg/L.
This review highlights some of the clinical features of cobalt toxicity,
with the goal that early awareness may decrease the risk factors
for the development of cobalt toxicity and/or reduce its severity. Take home message: Severe adverse events can arise from the release
of cobalt from metal-on-metal arthroplasties, and as such, orthopaedic
surgeons should not only be aware of the presenting problems, but
also have the knowledge to treat appropriately. Cite this article:
We compared the incidence of pseudotumours after
large head metal-on-metal (MoM) total hip arthroplasty (THA) with
that after conventional metal-on-polyethylene (MoP) THA and assessed
the predisposing factors to pseudotumour formation. From a previous randomised controlled trial which compared large
head (38 mm to 60 mm) cementless MoM THA with conventional head
(28 mm) cementless MoP THA, 93 patients (96 THAs: 41 MoM (21 males,
20 females, mean age of 64 years, standard deviation ( The incidence of pseudotumours, measured using a standardised
CT protocol was 22 (53.7%) after MoM THA and 12 (21.8%) after MoP
THA. Women with a MoM THA were more likely to develop a pseudotumour
than those with a MoP THA (15 Contrary to popular belief, pseudotumours occur frequently around
MoP THAs. Women with a MoM THA and an elevated cobalt level are
at greatest risk. In this study, pseudotumours had no effect on
the functional outcome after either large head MoM or conventional
MoP THA. Cite this article:
The outcome of 219 revision total hip arthroplasties
(THAs) in 98 male and 121 female patients, using 137 long length
and 82 standard length cemented collarless double-taper femoral
stems in 211 patients, with a mean age of 72 years (30 to 90) and
mean follow-up of six years (two to 18) have been described previously.
We have extended the follow-up to a mean of 13 years (8 to 20) in
this cohort of patients in which the pre-operative bone deficiency Paprosky
grading was IIIA or worse in 79% and 73% of femurs with long and
standard stems, respectively. For the long stem revision group, survival to re-revision for
aseptic loosening at 14 years was 97% (95% confidence interval (CI)
91 to 100) and in patients aged >
70 years, survival was 100%. Two
patients (two revisions) were lost to follow-up and 86 patients
with 88 revisions had died. Worst-case analysis for survival to
re-revision for aseptic loosening at 14 years was 95% (95% CI 89
to 100) and 99% (95% CI 96 to 100) for patients aged >
70 years. One
additional long stem was classified as loose radiographically but
not revised. For the standard stem revision group, survival to re-revision
for aseptic loosening at 14 years was 91% (95% CI 83 to 99). No
patients were lost to follow-up and 49 patients with 51 hips had
died. No additional stems were classified as loose radiographically. Femoral revision using a cemented collarless double-taper stem,
particularly with a long length stem, and in patients aged >
70
years, continues to yield excellent results up to 20 years post-operatively,
including in hips with considerable femoral metaphyseal bone loss. Cite this article:
A retrospective study was conducted to investigate
the changes in metal ion levels in a consecutive series of Birmingham
Hip Resurfacings (BHRs) at a minimum ten-year follow-up. We reviewed
250 BHRs implanted in 232 patients between 1998 and 2001. Implant
survival, clinical outcome (Harris hip score), radiographs and serum chromium
(Cr) and cobalt (Co) ion levels were assessed. Of 232 patients, 18 were dead (five bilateral BHRs), 15 lost
to follow-up and ten had been revised. The remaining 202 BHRs in
190 patients (136 men and 54 women; mean age at surgery 50.5 years
(17 to 76)) were evaluated at a minimum follow-up of ten years (mean
10.8 years (10 to 13.6)). The overall implant survival at 13.2 years
was 92.4% (95% confidence interval 90.8 to 94.0). The mean Harris
hip score was 97.7 (median 100; 65 to 100). Median and mean ion
levels were low for unilateral resurfacings (Cr: median 1.3 µg/l,
mean
1.95 µg/l (<
0.5 to 16.2); Co: median 1.0 µg/l, mean 1.62 µg/l
(<
0.5 to 17.3)) and bilateral resurfacings (Cr: median 3.2 µg/l,
mean 3.46 µg/l (<
0.5 to 10.0); Co: median 2.3 µg/l, mean 2.66
µg/l (<
0.5 to 9.5)). In 80 unilateral BHRs with sequential ion
measurements, Cr and Co levels were found to decrease significantly
(p <
0.001) from the initial assessment at a median of six years
(4 to 8) to the last assessment at a median of 11 years (9 to 13),
with a mean reduction of 1.24 µg/l for Cr and 0.88 µg/l for Co.
Three female patients had a >
2.5 µg/l increase of Co ions, associated with
head sizes ≤ 50 mm, clinical symptoms and osteolysis. Overall, there
was no significant difference in change of ion levels between genders
(Cr, p = 0.845; Co, p = 0.310) or component sizes (Cr, p = 0.505;
Co, p = 0.370). Higher acetabular component inclination angles correlated
with greater change in ion levels (Cr, p = 0.013; Co, p = 0.002).
Patients with increased ion levels had lower Harris hip scores (p
= 0.038). In conclusion, in well-functioning BHRs the metal ion levels
decreased significantly at ten years. An increase >
2.5 µg/l was
associated with poor function. Cite this article:
We conducted a retrospective study to assess
the prevalence of adverse reactions to metal debris (ARMD) in patients
operated on at our institution with metal-on-metal (MoM) total hip
replacements with 36 mm heads using a Pinnacle acetabular shell.
A total of 326 patients (150 males, 175 hips; 176 females, 203 hips)
with a mean age of 62.7 years (28 to 85) and mean follow-up of 7.5
years (0.1 to 10.8) participating in our in-depth modern MoM follow-up
programme were included in the study, which involved recording whole
blood cobalt and chromium ion measurements, Oxford hip scores (OHS)
and plain radiographs of the hip and targeted cross-sectional imaging. Elevated
blood metal ion levels (>
5 parts per billion) were seen in 32 (16.1%)
of the 199 patients who underwent unilateral replacement. At 23
months after the start of our modern MoM follow-up programme, 29
new cases of ARMD had been revealed. Hence, the nine-year survival
of this cohort declined from 96% (95% CI 95 to 98) with the old
surveillance routine to 86% (95% CI 82 to 90) following the new
protocol. Although ARMD may not be as common in 36 mm MoM THRs as
in those with larger heads, these results support the Medicines
and Healthcare Products Regulatory Agency guidelines on regular
reviews and further investigations, and emphasise the need for specific
a follow-up programme for patients with MoM THRs. Cite this article:
High failure rates of metal-on-metal hip arthroplasty implants have highlighted the need for more careful introduction and monitoring of new implants and for the evaluation of the safety of medical devices. The National Joint Registry and other regulatory services are unable to detect failing implants at an early enough stage. We aimed to identify validated surrogate markers of long-term outcome in patients undergoing primary total hip arthroplasty (THA). We conducted a systematic review of studies evaluating surrogate markers for predicting long-term outcome in primary THA. Long-term outcome was defined as revision rate of an implant at ten years according to National Institute of Health and Care Excellence guidelines. We conducted a search of Medline and Embase (OVID) databases. Separate search strategies were devised for the Cochrane database and Google Scholar. Each search was performed to include articles from the date of their inception to June 8, 2015.Objectives
Methods
We report on 397 consecutive revision total hip
replacements in 371 patients with a mean clinical and radiological follow-up
of 12.9 years (10 to 17.7). The mean age at surgery was 69 years
(37 to 93). A total of 28 patients (8%) underwent further revision,
including 16 (4%) femoral components. In all 223 patients (56%,
233 hips) died without further revision and 20 patients (5%, 20
hips) were lost to follow-up. Of the remaining patients, 209 (221
hips) were available for clinical assessment and 194 (205 hips)
for radiological review at mean follow-up of 12.9 years (10 to 17.7). The mean Harris Hip Score improved from 58.7 (11 to 92) points
to 80.7 (21 to 100) (p <
0.001) and the mean Merle d’Aubigné and
Postel hip scores at final follow-up were 4.9 (2 to 6), 4.5 (2 to
6) and 4.3 (2 to 6), respectively for pain, mobility and function.
Radiographs showed no lucencies around 186 (90.7%) femoral stems
with stable bony ingrowth seen in 199 stems (97%). The survival
of the S-ROM femoral stem at 15 years with revision for any reason as
the endpoint was 90.5% (95% confidence interval (CI) 85.7 to 93.8)
and with revision for aseptic loosening as the endpoint 99.3% (95%
CI 97.2 to 99.8). We have shown excellent long-term survivorship and good clinical
outcome of a cementless hydroxyapatite proximally-coated modular
femoral stem in revision hip surgery. Cite this article:
There are many guidelines that help direct the management of
patients with metal-on-metal (MOM) hip arthroplasties. We have undertaken
a study to compare the management of patients with MOM hip arthroplasties in
different countries. Six international tertiary referral orthopaedic centres were
invited to participate by organising a multi-disciplinary team (MDT)
meeting, consisting of two or more revision hip arthroplasty surgeons
and a musculoskeletal radiologist. A full clinical dataset including
history, blood tests and imaging for ten patients was sent to each
unit, for discussion and treatment planning. Differences in the
interpretation of findings, management decisions and rationale for
decisions were compared using quantitative and qualitative methods.Aims
Methods
An ongoing prospective study to investigate failing metal-on-metal
hip prostheses was commenced at our centre in 2008. We report on
the results of the analysis of the first consecutive 126 failed
mated total hip prostheses from a single manufacturer. Analysis was carried out using highly accurate coordinate measuring
to calculate volumetric and linear rates of the articular bearing
surfaces and also the surfaces of the taper junctions. The relationship
between taper wear rates and a number of variables, including bearing
diameter and orientation of the acetabular component, was investigated.Objectives
Methods
Lately, concerns have arisen following the use of large metal-on-metal bearings in hip replacements owing to reports of catastrophic soft-tissue reactions resulting in implant failure and associated complications. This review examines the literature and contemporary presentations on current clinical dilemmas in metal-on-metal hip replacement.
This study compared component wear rates and pre-revision blood metal ions levels in two groups of failed metal-on-metal hip arthroplasties: hip resurfacing and modular total hip replacement (THR). There was no significant difference in the median rate of linear wear between the groups for both acetabular (p = 0.4633) and femoral (p = 0.0872) components. There was also no significant difference in the median linear wear rates when failed hip resurfacing and modular THR hips of the same type (ASR and Birmingham hip resurfacing (BHR)) were compared. Unlike other studies of well-functioning hips, there was no significant difference in pre-revision blood metal ion levels between hip resurfacing and modular THR. Edge loading was common in both groups, but more common in the resurfacing group (67%) than in the modular group (57%). However, this was not significant (p = 0.3479). We attribute this difference to retention of the neck in resurfacing of the hip, leading to impingement-type edge loading. This was supported by visual evidence of impingement on the femur. These findings show that failed metal-on-metal hip resurfacing and modular THRs have similar component wear rates and are both associated with raised pre-revision blood levels of metal ions.
Conventional uncemented femoral implants provide
dependable long-term fixation in patients with a wide range of functional
requirements. Yet challenges associated with proximal–distal femoral
dimensional mismatch, preservation of bone stock, and minimally
invasive approaches have led to exploration into alternative implant designs.
Short stem designs focusing on a stable metaphyseal fit have emerged
to address these issues in total hip replacement (THR). Uncemented
metaphyseal-engaging short stem implants are stable and are associated
with proximal bone remodeling closer to the metaphysis when compared
with conventional stems and they also have comparable clinical performances.
Short stem metaphyseal-engaging implants can meet the goals of a
successful THR, including tolerating a high level of patient function,
as well as durable fixation. Cite this article:
We compared a modular neck system with a non-modular system in a cementless anatomical total hip replacement (THR). Each group consisted of 74 hips with developmental hip dysplasia. Both groups had the same cementless acetabular component and the same articulation, which consisted of a conventional polyethylene liner and a 28 mm alumina head. The mean follow-up was 14.5 years (13 to 15), at which point there were significant differences in the mean total Harris hip score (modular/non-modular: 98.6 (64 to 100)/93.8 (68 to 100)), the mean range of abduction (32° (15° to 40°)/28 (0° to 40°)), use of a 10° elevated liner (31%/100%), the incidence of osteolysis (27%/79.7%) and the incidence of equal leg lengths (≥ 6 mm, 92%/61%). There was no disassociation or fracture of the modular neck. The modular system reduces the need for an elevated liner, thereby reducing the incidence of osteolysis. It gives a better range of movement and allows the surgeon to make an accurate adjustment of leg length.
The aim of this study was to evaluate the ten-year
clinical and functional outcome of hip resurfacing and to compare it
with that of cementless hip arthroplasty in patients under the age
of 55 years. Between 1999 and 2002, 80 patients were enrolled into the study:
24 were randomised (11 to hip resurfacing, 13 to total hip arthroplasty),
18 refused hip resurfacing and chose cementless total hip arthroplasty
with a 32 mm bearing, and 38 insisted on resurfacing. The mean follow-up
for all patients was 12.1 years (10 to 14). Patients were assessed clinically and radiologically at one year,
five years and ten years. Outcome measures included EuroQol EQ5D,
Oxford, Harris hip, University of California Los Angeles and University
College Hospital functional scores. No differences were seen between the two groups in the Oxford
or Harris hip scores or in the quality of life scores. Despite a
similar aspiration to activity pre-operatively, a higher proportion
of patients with a hip resurfacing were running and involved in
sport and heavy manual labour after ten years. We found significantly higher function scores in patients who
had undergone hip resurfacing than in those with a cementless hip
arthroplasty at ten years. This suggests a functional advantage
for hip resurfacing. There were no other attendant problems. Cite this article:
A total of 219 hips in 192 patients aged between
18 and 65 years were randomised to 28-mm metal-on-metal uncemented
total hip replacements (THRs, 107 hips) or hybrid hip resurfacing
(HR, 112 hips). At a mean follow-up of eight years (6.6 to 9.3)
there was no significant difference between the THR and HR groups
regarding rate of revision (4.0% (4 of 99) Cite this article:
Arthroscopy of the native hip is an established diagnostic and therapeutic procedure. Its application in the symptomatic replaced hip is still being explored. We describe the use of arthroscopy of the hip in 24 symptomatic patients following total hip replacement, resurfacing arthroplasty of the hip and partial resurfacing (study group), and compared it with arthroscopy of the native hip in 24 patients (control group). A diagnosis was made or confirmed at arthroscopy in 23 of the study group and a therapeutic arthroscopic intervention resulted in relief of symptoms in ten of these. In a further seven patients it led to revision hip replacement. In contrast, arthroscopy in the control group was diagnostic in all 24 patients and the resulting arthroscopic therapeutic intervention provided symptomatic relief in 21. The mean operative time in the study group (59.7 minutes (35 to 93)) was less than in the control group (71 minutes (40 to 100), p = 0.04) but the arthroscopic approach was more difficult in the arthroplasty group. We suggest that arthroscopy has a role in the management of patients with a symptomatic arthroplasty when other investigations have failed to provide a diagnosis.
We retrospectively analysed concentrations of chromium and cobalt ions in samples of synovial fluid and whole blood taken from a group of 92 patients with failed current-generation metal-on-metal hip replacements. We applied acid oxidative digestion to our trace metal analysis protocol, which found significantly higher levels of metal ion concentrations in blood and synovial fluid than a non-digestive method. Patients were subcategorised by mode of failure as either ‘unexplained pain’ or ‘defined causes’. Using this classification, chromium and cobalt ion levels were present over a wider range in synovial fluid and not as strongly correlated with blood ion levels as previously reported. There was no significant difference between metal ion concentrations and manufacturer of the implant, nor femoral head size below or above 50 mm. There was a moderately positive correlation between metal ion levels and acetabular component inclination angle as measured on three-dimensional CT imaging. Our results suggest that acid digestion of samples of synovial fluid samples is necessary to determine metal ion concentrations accurately so that meaningful comparisons can be made between studies.
Peri-articular soft-tissue masses or ‘pseudotumours’
can occur after large-diameter metal-on-metal (MoM) resurfacing
of the hip and conventional total hip replacement (THR). Our aim
was to assess the incidence of pseudotumour formation and to identify
risk factors for their formation in a prospective cohort study. A total of 119 patients who underwent 120 MoM THRs with large-diameter
femoral heads between January 2005 and November 2007 were included
in the study. Outcome scores, serum metal ion levels, radiographs
and CT scans were obtained. Patients with symptoms or an identified
pseudotumour were offered MRI and an ultrasound-guided biopsy. There were 108 patients (109 hips) eligible for evaluation by
CT scan at a mean follow-up of 3.6 years (2.5 to 4.5); 42 patients
(39%) were diagnosed with a pseudotumour. The hips of 13 patients
(12%) were revised to a polyethylene acetabular component with small-diameter
metal head. Patients with elevated serum metal ion levels had a
four times increased risk of developing a pseudotumour. This study shows a substantially higher incidence of pseudotumour
formation and subsequent revisions in patients with MoM THRs than
previously reported. Because most revision cases were identified
only after an intensive screening protocol, we recommend close monitoring
of patients with MoM THR.
Bioengineering reasons for increased wear and failure of metal-on-metal (MoM) bearings in hip prostheses have been described. Low wear occurs in MoM hips when the centre of the femoral head is concentric with the centre of the acetabular component and the implants are correctly positioned. Translational or rotational malpositioning of the components can lead to the contact-patch of the femoral component being displaced to the rim of the acetabular component, resulting in a ten- to 100-fold increase in wear and metal ion levels. This may cause adverse tissue reactions, loosening of components and failure of the prosthesis.
Dislocation is one of the most common causes
of patient and surgeon dissatisfaction following hip replacement
and to treat it, the causes must first be understood. Patient factors
include age greater than 70 years, medical comorbidities, female
gender, ligamentous laxity, revision surgery, issues with the abductors,
and patient education. Surgeon factors include the annual quantity
of procedures and experience, the surgical approach, adequate restoration
of femoral offset and leg length, component position, and soft-tissue
or bony impingement. Implant factors include the design of the head
and neck region, and so-called skirts on longer neck lengths. There
should be offset choices available in order to restore soft-tissue
tension. Lipped liners aid in gaining stability, yet if improperly placed
may result in impingement and dislocation. Late dislocation may
result from polyethylene wear, soft-tissue destruction, trochanteric
or abductor disruption and weakness, or infection. Understanding
the causes of hip dislocation facilitates prevention in a majority
of instances. Proper pre-operative planning includes the identification
of patients with a high offset in whom inadequate restoration of
offset will reduce soft-tissue tension and abductor efficiency.
Component position must be accurate to achieve stability without impingement.
Finally, patient education cannot be over-emphasised, as most dislocations occur
early, and are preventable with proper instructions. Cite this article: