To quantify and compare peri-acetabular bone mineral density
(BMD) between a monoblock acetabular component using a metal-on-metal
(MoM) bearing and a modular titanium shell with a polyethylene (PE)
insert. The secondary outcome was to measure patient-reported clinical
function. A total of 50 patients (25 per group) were randomised to MoM
or metal-on-polyethlene (MoP). There were 27 women (11 MoM) and
23 men (14 MoM) with a mean age of 61.6 years (47.7 to 73.2). Measurements
of peri-prosthetic acetabular and contralateral hip (covariate)
BMD were performed at baseline and at one and two years’ follow-up.
The Western Ontario and McMaster Universities osteoarthritis index
(WOMAC), University of California, Los Angeles (UCLA) activity score,
Harris hip score, and RAND-36 were also completed at these intervals.Objectives
Methods
Reconstruction of the acetabulum after failed total hip arthroplasty
(THA) can be a surgical challenge in the presence of severe bone
loss. We report the long-term survival of a porous tantalum revision
acetabular component, its radiological appearance and quality of
life outcomes. We reviewed the results of 46 patients who had undergone revision
of a failed acetabular component with a Paprosky II or III bone
defect and reconstruction with a hemispherical, tantalum acetabular
component, supplementary screws and a cemented polyethylene liner.Aims
Patients and Methods
Surgeons remain concerned that ceramic hip prostheses may fail catastrophically if either the head or the liner is fractured. We report two patients, each with a ceramic-on-ceramic total hip replacement who sustained high-energy trauma sufficient to cause a displaced periprosthetic acetabular fracture in whom the ceramic bearings survived intact. Simultaneous fixation of the acetabular fracture, revision of the cementless acetabular prosthesis and exchange of the ceramic bearings were performed successfully in both patients. Improved methods of manufacture of new types of alumina ceramic with a smaller grain size, and lower porosity, have produced much stronger bearings. Whether patients should be advised to restrict high-impact activities in order to protect these modern ceramic bearings from fracture remains controversial.
Joint replacement of the hip and knee remain
very satisfactory operations. They are, however, expensive. The
actual manufacturing of the implant represents only 30% of the final
cost, while sales and marketing represent 40%. Recently, the patents
on many well established and successful implants have expired. Companies
have started producing and distributing implants that purport to
replicate existing implants with good long-term results. The aims of this paper are to assess the legality, the monitoring
and cost saving implications of such generic implants. We also assess
how this might affect the traditional orthopaedic implant companies. Cite this article:
We reviewed the initial post-operative radiographs of the Trident acetabulum and identified a problem with seating of the metal-backed ceramic liner. We identified 117 hips in 113 patients who had undergone primary total hip replacement using the Trident shell with a metal-backed alumina liner. Of these, 19 (16.4%) were noted to have incomplete seating of the liner, as judged by plain anteroposterior and lateral radiographs. One case of complete liner dissociation necessitating early revision was not included in the prevalence figures. One mis-seated liner was revised in the early post-operative period and two that were initially incompletely seated were found on follow-up radiographs to have become correctly seated. There may be technical issues with regard to the implanting of this prosthesis of which surgeons should be aware. However, there is the distinct possibility that the Trident shell deforms upon implantation, thereby preventing complete seating of the liner.
The accuracy and precision of two new methods of model-based
radiostereometric analysis (RSA) were hypothesised to be superior
to a plain radiograph method in the assessment of polyethylene (PE)
wear. A phantom device was constructed to simulate three-dimensional
(3D) PE wear. Images were obtained consecutively for each simulated
wear position for each modality. Three commercially available packages
were evaluated: model-based RSA using laser-scanned cup models (MB-RSA),
model-based RSA using computer-generated elementary geometrical
shape models (EGS-RSA), and PolyWare. Precision (95% repeatability
limits) and accuracy (Root Mean Square Errors) for two-dimensional
(2D) and 3D wear measurements were assessed.Objectives
Methods
The August 2015 Hip &
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Symptomatic cobalt toxicity from a failed total
hip replacement is a rare but devastating complication. It has been reported
following revision of fractured ceramic components, as well as in
patients with failed metal-on-metal articulations. Potential clinical
findings include fatigue, weakness, hypothyroidism, cardiomyopathy,
polycythaemia, visual and hearing impairment, cognitive dysfunction,
and neuropathy. We report a case of an otherwise healthy 46-year-old
patient, who developed progressively worsening symptoms of cobalt
toxicity beginning approximately six months following synovectomy
and revision of a fractured ceramic-on-ceramic total hip replacement
to a metal-on-polyethylene bearing. The whole blood cobalt levels
peaked at 6521 µg/l. The patient died from cobalt-induced cardiomyopathy.
Implant retrieval analysis confirmed a loss of 28.3 g mass of the
cobalt–chromium femoral head as a result of severe abrasive wear
by ceramic particles embedded in the revision polyethylene liner.
Autopsy findings were consistent with heavy metal-induced cardiomyopathy. We recommend using new ceramics at revision to minimise the risk
of wear-related cobalt toxicity following breakage of ceramic components. Cite this article:
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 corrosion at the modular neck-stem
junction. These patients underwent further surgery and aseptic lymphocytic
vaculitis associated lesions were demonstrated on histological analysis. Retrieval analysis of two modular necks showed corrosion at the
neck-stem taper. Blood cobalt and chromium levels were measured
at a mean of nine months (3 to 28) following surgery. These were
compared with the levels in seven control patients (three men and
four women) with a mean age of 53.4 years (32.1 to 64.1), who had
an identical prosthesis and articulation but with a prosthesis that
had no modularity at neck-stem junction. The mean blood levels of
cobalt in the study group were raised at 50.75 nmol/l (5 to 145)
compared with 5.6 nmol/l (2 to 13) in control patients. Corrosion at neck-stem tapers has been identified as an important
source of metal ion release and pseudotumour formation requiring
revision surgery. Finite element modelling of the dual modular stem
demonstrated high stresses at the modular stem-neck junction. Dual
modular cobalt-chrome hip prostheses should be used with caution
due to these concerns.
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 corrosion, metal release, and adverse local tissue reactions.
Alternative large bearings including large ceramic heads and dual
mobility bearings may mitigate some of these risks, and several
of these devices have been used with clinical success. Cite this article:
We investigated the incidence of soft-tissue
lesions after small head metal-on-metal total hip replacement (MoM THR).
Between December 1993 and May 1999, 149 patients (195 hips) underwent
primary cementless MoM THR. During the follow-up period, three patients (five THRs) died
and eight patients (14 THRs) were lost to follow-up. We requested
that all patients undergo CT evaluation. After exclusion of five
patients (six THRs) who had undergone a revision procedure, and
22 (28 THRs) who were unwilling to take part in this study, 111
patients (142 THRs) were evaluated. There were 63 men (88 THRs)
and 48 women (54 THRs) with a mean age of 45.7 years (37 to 56)
at the time of surgery. The mean follow-up was 15.4 years (13 to
19). A soft-tissue lesion was defined as an abnormal peri-prosthetic
collection of fluid, solid lesion or asymmetrical soft-tissue mass. At final follow-up, soft-tissue lesions were found in relation
to 28 THRs (19.7%), including 25 solid and three cystic lesions.
They were found in 20 men and eight women; 26 lesions were asymptomatic
and two were symptomatic. The mean maximal diameter of the soft-tissue
lesion was 42.3 mm (17 to 135). The relatively high rate of soft-tissue lesions
observed with small head MoM THR remains a concern. Cite this article:
We have compared four computer-assisted methods to measure penetration of the femoral head into the acetabular component in total hip replacement. These were the Martell Hip Analysis suite 7.14, Rogan HyperOrtho, Rogan View Pro-X and Roman v1.70. The images used for the investigation comprised 24 anteroposterior digital radiographs and 24 conventional acetate radiographs which were scanned to provide digital images. These radiographs were acquired from 24 patients with an uncemented total hip replacement with a follow-up of approximately eight years (mean 8.1; 6.3 to 9.1). Each image was measured twice by two blinded observers. The mean annual rates of penetration of the femoral head measured in the eight-year single image analysis were: Martell, 0.24 (SD 0.19); HyperOrtho, 0.12 (SD 0.08); View Pro-X, 0.12 (SD 0.06); Roman, 0.12 (SD 0.07). In paired analysis of the six-month and eight-year radiographs: Martell, 0.35 (SD 0.22); HyperOrtho, 0.15 (SD 0.13); View Pro-X, 0.11 (SD 0.06); Roman, 0.11 (SD 0.07). The intra- and inter-observer variability for the paired analysis was best for View Pro-X and Roman software, with intraclass correlations of 0.97, 0.87 and 0.96, 0.87, respectively, and worst for HyperOrtho and Martell, with intraclass correlations of 0.46, 0.13 and 0.33, 0.39, respectively. The Roman method proved the most precise and the most easy to use in clinical practice and the software is available free of charge. The Martell method showed the lowest precision, indicating a problem with its edge detection algorithm on digital images.
We investigated the rate of polyethylene wear of a cementless acetabular component at different periods of follow-up in order to test the hypothesis than an irrecoverable deformation process (creep) was followed by an initially low, but gradually increasing wear rate. We studied prospectively 93 uncemented total hip arthroplasties in 83 patients (mean age 50 years (22 to 63)) with a mean follow-up of 8.2 years (3 to 12). We measured the penetration of the femoral head from radiographs taken immediately after surgery at three, six and nine years, or at the latest follow-up. The median wear rate was 0.17 mm per year in the first three years, a finding which we considered to be caused by creep. Thereafter, the rate of wear declined to 0.07 mm per year (four- to six-year period) and then increased to 0.17 mm per year (seven to nine years) and 0.27 mm per year (more than nine years), which we considered to be a reflection of genuine polyethylene wear. After the nine-year follow-up the wear rates were higher in patients with marked osteolysis. We found no relationship between the inclination angle of the acetabular component or femoral head orientation and the rate of wear. No acetabular component required revision.
We reviewed 123 second-generation uncemented total hip replacements performed on 115 patients by a single surgeon between 1993 and 1994. The acetabular component used in all cases was a fully porous-coated threaded hemispheric titanium shell (T-Tap ST) with a calcium ion stearate-free, isostatically compression-moulded polyethylene liner. The titanium femoral component used was a Taperloc with a reduced distal stem. No patient was lost to follow-up. Complete clinical and radiological follow-up was obtained for all 123 hips at a mean of 14 years (12 to 16). One femoral component was revised after a fracture, and three acetabular components for aseptic loosening. No additional femoral or acetabular components were judged loose by radiological criteria. Mild proximal femoral osteolysis was identified in two hips and minor acetabular osteolysis was present in four. The mean rate of penetration of the femoral head was 0.036 mm/year (0.000 to 0.227). These findings suggest that refinements in component design may be associated with excellent long-term fixation in cementless primary total hip replacement.
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 corrosion products in the
tissues. Therefore, we believe corrosion products from the taper
caused by mismatch of the implant components led to pseudotumour
formation requiring revision.
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:
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During open reduction of an irreducible anterior dislocation of a total hip replacement with an Oxinium femoral head, it was observed that the head had been significantly damaged. Gross and scanning electron microscopic examination revealed cracking, gouging, and delamination of the surface. Because of the risk which this poses for damaging the polyethylene acetabular liner, it is strongly recommended that patients with this type of prosthetic head be carefully monitored after a dislocation.
The conventional method for reconstructing acetabular
bone loss at revision surgery includes using structural bone allograft.
The disadvantages of this technique promoted the advent of metallic
but biocompatible porous implants to fill bone defects enhancing
initial and long-term stability of the acetabular component. This
paper presents the indications, surgical technique and the outcome
of using porous metal acetabular augments for reconstructing acetabular
defects. Cite this article:
In 2012 we reviewed a consecutive series of 92
uncemented THRs performed between 1986 and 1991 at our institution
using the CLS Spotorno stem, in order to assess clinical outcome
and radiographic data at a minimum of 21 years. The series comprised
92 patients with a mean age at surgery of 59.6 years (39 to 77)
(M:F 43;49). At the time of this review, seven (7.6%) patients had died and
two (2.2%) were lost to follow-up. The 23-year Kaplan–Meier survival
rates were 91.5% (95% confidence intervals (CI) 85.4% to 97.6%;
55 hips at risk) and 80.3% (95% CI, 71.8% to 88.7%; 48 hips at risk)
respectively, with revision of the femoral stem or of any component
as endpoints. At the time of this review, 76 patients without stem
revision were assessed clinically and radiologically (mean follow-up
24.0 years (21.5 to 26.5)). For the 76 unrevised hips the mean Harris
hip score was 87.1 (65 to 97). Femoral osteolysis was detected in
five hips (6.6%) only in Gruen zone 7. Undersized stems were at
higher risk of revision owing to aseptic loosening (p = 0.0003).
Patients implanted with the stem in a varus position were at higher risk
of femoral cortical hypertrophy and thigh pain (p = 0.0006 and p
= 0.0007, respectively). In our study, survival, clinical outcome and radiographic data
remained excellent in the third decade after implantation. Nonetheless,
undersized stems were at higher risk of revision owing to aseptic
loosening. Cite this article: