The ideal bearing surface for young patients
undergoing total hip replacement (THR) remains controversial. We report
the five-year results of a randomised controlled trial comparing
the clinical and radiological outcomes of 102 THRs in 91 patients
who were <
65 years of age. These patients were randomised to
receive a cobalt–chrome on ultra-high-molecular-weight polyethylene,
cobalt–chrome on highly cross-linked polyethylene, or a ceramic-on-ceramic
bearing. In all, 97 hip replacements in 87 patients were available
for review at five years. Two hips had been revised, one for infection
and one for peri-prosthetic fracture. At the final follow-up there were no significant differences
between the groups for the mean Western Ontario and McMaster Universities
osteoarthritis index (pain, p = 0.543; function, p = 0.10; stiffness,
p = 0.99), Short Form-12 (physical component, p = 0.878; mental
component, p = 0.818) or Harris hip scores (p = 0.22). Radiological
outcomes revealed no significant wear in the ceramic group. Comparison of standard and highly cross-linked polyethylene,
however, revealed an almost threefold difference in the mean annual
linear wear rates (0.151 mm/year
A moderator and panel of five experts led an
interactive session in discussing five challenging and interesting patient
case presentations involving surgery of the hip. The hip pathologies
reviewed included failed open reduction internal fixation of subcapital
femoral neck fracture, bilateral hip disease, evaluation of pain
after metal-on-metal hip arthroplasty, avascular necrosis, aseptic
loosening secondary to osteolysis and polyethylene wear, and management
of ceramic femoral head fracture.
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:
Ideal placement of the acetabular component remains
elusive both in terms of defining and achieving a target. Our aim
is to help restore original anatomy by using the transverse acetabular
ligament (TAL) to control the height, depth and version of the component.
In the normal hip the TAL and labrum extend beyond the equator of
the femoral head and therefore, if the definitive acetabular component
is positioned such that it is cradled by and just deep to the plane
of the TAL and labrum and is no more than 4mm larger than the original
femoral head, the centre of the hip should be restored. If the face
of the component is positioned parallel to the TAL and psoas groove
the patient specific version should be restored. We still use the
TAL for controlling version in the dysplastic hip because we believe
that the TAL and labrum compensate for any underlying bony abnormality. The TAL should not be used as an aid to inclination. Worldwide,
>
75% of surgeons operate with the patient in the lateral decubitus
position and we have shown that errors in post-operative radiographic
inclination (RI) of >
50° are generally caused by errors in patient positioning.
Consequently, great care needs to be taken when positioning the
patient. We also recommend 35° of apparent operative inclination
(AOI) during surgery, as opposed to the traditional 45°. Cite this article:
Hip implant retrieval analysis is the most important
source of insight into the performance of new materials and designs
of hip arthroplasties. Even the most rigorous
The April 2013 Hip &
Pelvis Roundup360 looks at: hip cartilage and magnets; labral repair or resection; who benefits from injection; rotational osteotomy for osteonecrosis; whether ceramic implants risk fracture; dual articulation; and hydroxyapatite.
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:
Oxidised zirconium (OxZi) has been developed
as an alternative bearing surface for femoral heads in total hip arthroplasty
(THA). This study has investigated polyethylene wear, functional
outcomes and complications, comparing OxZi and cobalt–chrome (CoCr)
as part of a three-arm, multicentre randomised controlled trial.
Patients undergoing THA from four institutions were prospectively
randomised into three groups. Group A received a CoCr femoral head
and highly cross-linked polyethylene (XLPE) liner; Group B received
an OxZi femoral head and XLPE liner; Group C received an OxZi femoral
head and ultra-high molecular weight polyethylene (UHMWPE) liner.
At five years, 368 patients had no statistically significant differences
in short-form-36 (p = 0.176 mental, p = 0.756 physical), Western
Ontario and McMaster Universities Osteoarthritis Index (p = 0.847),
pain scores
(p = 0.458) or complications. The mean rate of linear wear was 0.028
mm/year (standard deviation ( Cite this article:
Ceramic-on-metal (CoM) is a relatively new bearing
combination for total hip arthroplasty (THA) with few reported outcomes.
A total of 287 CoM THAs were carried out in 271 patients (mean age
55.6 years (20 to 77), 150 THAs in female patients, 137 in male)
under the care of a single surgeon between October 2007 and October
2009. With the issues surrounding metal-on-metal bearings the decision
was taken to review these patients between March and November 2011,
at a mean follow-up of 34 months (23 to 45) and to record pain,
outcome scores, radiological analysis and blood ion levels. The
mean Oxford Hip Score was 19.2 (12 to 53), 254 patients with 268
hips (95%) had mild/very mild/no pain, the mean angle of inclination
of the acetabular component was 44.8o (28o to
63o), 82 stems (29%) had evidence of radiolucent lines
of >
1 mm in at least one Gruen zone and the median levels of cobalt
and chromium ions in the blood were 0.83 μg/L (0.24 μg/L to 27.56 μg/L)
and 0.78 μg/L (0.21 μg/L to 8.84 μg/L), respectively. The five-year
survival rate is 96.9% (95% confidence interval 94.7% to 99%). Due to the presence of radiolucent lines and the higher than
expected levels of metal ions in the blood, we would not recommend
the use of CoM THA without further long-term follow-up. We plan
to monitor all these patients regularly. Cite this article:
We compared the clinical and radiological outcomes
of two cementless femoral stems in the treatment of patients with
a Garden III or IV fracture of the femoral neck. A total of 70 patients At final follow-up there were no statistically significant differences
between the short anatomical and the conventional stems with regard
to the mean Harris hip score (85.7 (66 to 100) Our study demonstrated that despite the poor bone quality in
these elderly patients with a fracture of the femoral neck, osseo-integration
was obtained in all hips in both groups. However, the incidence
of thigh pain, pulmonary microemboli and peri-prosthetic fracture
was significantly higher in the conventional stem group than in
the short stem group.
A high radiographic inclination angle (RI) contributes
to accelerated wear and has been associated with dislocation after
total hip arthroplasty (THA). With freehand positioning of the acetabular
component there is a lack of accuracy, with a trend towards a high
radiographic inclination angle. The aim of this study was to investigate
whether the use of a digital protractor to measure the operative
inclination angle (OI) could improve the positioning of the acetabular
component in relation to a ‘safe zone’. We measured the radiographic inclination angles of 200 consecutive
uncemented primary THAs. In the first 100 the component was introduced
freehand and in the second 100 a digital protractor was used to
measure the operative inclination angle. The mean difference between the operative and the radiographic
inclination angles
(∆RI–OI) in the second cohort was 12.3° (3.8° to 19.8°). There was
a strong correlation between the circumference of the hip and ∆RI–OI.
The number of RI outliers was significantly reduced in the protractor
group (p = 0.002). Adjusting the OI, using a digital protractor and taking into
account the circumference of the patient’s hip, improves the RI
significantly (p <
0.001) and does not require additional operating
time. Cite this article:
In this Cite this article:
This review examines the future of total hip arthroplasty, aiming to avoid past mistakes
We reviewed the results of 84 total hip replacements performed with a short metaphyseal-fitting anatomical cementless femoral component in 84 unselected consecutive patients with a mean age of 78.9 years (70 to 88). The mean follow-up was 4.6 years (4 to 5). The mean pre-operative Harris hip score was 26 points (0 to 56), which improved to 89 (61 to 100) at the final follow-up. No patient had thigh pain. The mean pre-operative Western Ontario and McMaster Universities osteoarthritis index score was 61 points (48 to 75), which improved to 21 (6 to 46). The mean University of California, Los Angeles activity score was 5.5 points (3 to 7) at the final follow-up. Osseointegration was seen in all femoral and acetabular components. All hips had grade 1 stress shielding of the proximal femur. No acetabular or femoral osteolysis was identified. These results demonstrate that a short metaphyseal-fitting femoral component achieves optimal fixation without diaphyseal anchorage in elderly patients.
We describe the experience with the first consecutive 230 Birmingham hip resurfacings at our centre. At a mean follow-up of three years (25 to 52 months) survivorship was 99.14% with revision in one patient for a loose acetabular component and one death from unrelated causes. One patient developed a fracture of the femoral neck at six weeks which united unremarkably after a period of non-weight-bearing. The Harris hip score improved from a mean of 62.54 (8 to 92) to 97.74 (61 to 100). The mean flexion improved from 91.52° (25 to 140) to 110.41° (80 to 145). Most patients (97%) considered the outcome to be good or excellent. Our preliminary experience with this implant is encouraging and the results are superior to the earlier generation of resurfacings for the same length of follow-up.
The February 2014 Hip &
Pelvis Roundup360 looks at: length of stay; cementless metaphyseal fixation; mortality trends in over 400,000 total hip replacements; antibiotics in hip fracture surgery; blood supply to the femoral head after dislocation; resurfacing and THR in metal-on-metal replacement; diabetes and hip replacement; bone remodelling over two decades following hip replacement; and whether bisphosphonates affect acetabular fixation.
The October 2013 Hip &
Pelvis Roundup360 looks at: Young and impinging; Clothes, weather and femoral heads?; Go long, go cemented; Surgical repair of the abductors?; Aspirin for DVT prophylaxis?; Ceramic-on-polyethylene: a low-wear solution?; ALVAL and ASR™: the story continues….; Salvaging Legg-Calve-Perthes’ disease
Orientation of the acetabular component influences
wear, range of movement and the incidence of dislocation after total
hip replacement (THR). During surgery, such orientation is often
referenced to the anterior pelvic plane (APP), but APP inclination
relative to the coronal plane (pelvic tilt) varies substantially
between individuals. In contrast, the change in pelvic tilt from
supine to standing (dPT) is small for nearly all individuals. Therefore,
in THR performed with the patient supine and the patient’s coronal
plane parallel to the operating table, we propose that freehand placement
of the acetabular component placement is reliable and reflects standing
(functional) cup position. We examined this hypothesis in 56 hips
in 56 patients (19 men) with a mean age of 61 years (29 to 80) using
three-dimensional CT pelvic reconstructions and standing lateral
pelvic radiographs. We found a low variability of acetabular component
placement, with 46 implants (82%) placed within a combined range
of 30° to 50° inclination and 5° to 25° anteversion. Changing from
the supine to the standing position (analysed in 47 patients) was associated
with an anteversion change <
10° in 45 patients (96%). dPT was
<
10° in 41 patients (87%). In conclusion, supine THR appears
to provide reliable freehand acetabular component placement. In
most patients a small reclination of the pelvis going from supine
to standing causes a small increase in anteversion of the acetabular component Cite this article:
Wear debris released from bearing surfaces has been shown to
provoke negative immune responses in the recipient. Excessive wear
has been linked to early failure of prostheses. Analysis using coordinate
measuring machines (CMMs) can provide estimates of total volumetric
material loss of explanted prostheses and can help to understand
device failure. The accuracy of volumetric testing has been debated,
with some investigators stating that only protocols involving hundreds
of thousands of measurement points are sufficient. We looked to
examine this assumption and to apply the findings to the clinical
arena. We examined the effects on the calculated material loss from
a ceramic femoral head when different CMM scanning parameters were
used. Calculated wear volumes were compared with gold standard gravimetric
tests in a blinded study. Objectives
Methods