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
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
We present the clinical results and survivorship
of consecutive 100 Birmingham Hip Resurfacings in 90 patients at
a minimum follow-up of ten years. All procedures were carried out
by an independent surgeon who commenced a prospective study in 1998.
Patients were assessed clinically using the Western Ontario and
McMaster Universities osteoarthritis index, Short-Form 36, Harris
hip score and University of California, Los Angeles activity score. Radiological
analysis was performed by an independent observer and blood metal
ion levels concentrations were measured at ten years post-operatively
in 62 patients. The median acetabular component inclination was
46.2° (34° to 59°) and anteversion 11.0° (0° to 30°). The median
chromium concentration in the unilateral group was 1.74 (0.41 to
15.23) and for the bilateral group was 2.98 (1.57 to 18.01). The
equivalent values for cobalt were 1.67 (0.54 to 20.4) and 1.88 (1.38
to 19.32). In total there were eight failures giving an overall survival
at ten years of 92% (95% confidence interval (CI) 86.7 to 97.3).
BHR in male patients had an improved survivorship of 94.6% (95%
CI 89.4 to 100) compared with females at 84.6% (95% CI 70.7 to 98.5),
but this did not reach statistical significance (p = 0.119). Four
of the nine BHRs with a bearing diameter of 42 mm failed. The overall results were consistent with data produced from other
centres in that the clinical outcome of large male patients was
extremely encouraging, whereas the survival of the smaller joints
was less satisfactory.
The aim of this retrospective cohort study was
to identify any difference in femoral offset as measured on pre-operative
anteroposterior (AP) radiographs of the pelvis, AP radiographs of
the hip and corresponding CT scans in a consecutive series of 100
patients with primary end-stage osteoarthritis of the hip (43 men
and 57 women with a mean age of 61 years (45 to 74) and a mean body
mass index of 28 kg/m2 (20 to 45)). Patients were positioned according to a standardised protocol
to achieve reproducible projection and all images were calibrated.
Inter- and intra-observer reliability was evaluated and agreement
between methods was assessed using Bland-Altman plots. In the entire cohort, the mean femoral offset was 39.0 mm (95%
confidence interval (CI) 37.4 to 40.6) on radiographs of the pelvis,
44.0 mm (95% CI 42.4 to 45.6) on radiographs of the hip and 44.7
mm (95% CI 43.5 to 45.9) on CT scans. AP radiographs of the pelvis
underestimated femoral offset by 13% when compared with CT (p <
0.001).
No difference in mean femoral offset was seen between AP radiographs
of the hip and CT (p = 0.191). Our results suggest that femoral offset is significantly underestimated
on AP radiographs of the pelvis but can be reliably and accurately
assessed on AP radiographs of the hip in patients with primary end-stage
hip osteoarthritis. We, therefore, recommend that additional AP radiographs of the
hip are obtained routinely for the pre-operative assessment of femoral
offset when templating before total hip replacement.
Fracture of a ceramic component in total hip
replacement is a rare but potentially catastrophic complication.
The incidence is likely to increase as the use of ceramics becomes
more widespread. We describe such a case, which illustrates how
inadequate initial management will lead to further morbidity and
require additional surgery. We present the case as a warning that
fracture of a ceramic component should be revised to another ceramic-on-ceramic
articulation in order to minimise the risk of further catastrophic
wear.
We report the findings of an independent review
of 230 consecutive Birmingham hip resurfacings (BHRs) in 213 patients
(230 hips) at a mean follow-up of 10.4 years (9.6 to 11.7). A total
of 11 hips underwent revision; six patients (six hips) died from
unrelated causes; and 13 patients (16 hips) were lost to follow-up.
The survival rate for the whole cohort was 94.5% (95% confidence
interval (CI) 90.1 to 96.9). The survival rate in women was 89.1%
(95% CI 79.2 to 94.4) and in men was 97.5% (95% CI 92.4 to 99.2).
Women were 1.4 times more likely to suffer failure than men. For
each millimetre increase in component size there was a 19% lower
chance of a failure. The mean Oxford hip score was 45.0 (median
47.0, 28 to 48); mean University of California, Los Angeles activity
score was 7.4 (median 8.0, 3 to 9); mean patient satisfaction score
was 1.4 (median 1.0, 0 to 9). A total of eight hips had lysis in
the femoral neck and two hips had acetabular lysis. One hip had
progressive radiological changes around the peg of the femoral component.
There was no evidence of progressive neck narrowing between five
and ten years. Our results confirm that BHR provides good functional outcome
and durability for men, at a mean follow-up of ten years. We are
now reluctant to undertake hip resurfacing in women with this implant.
Hip arthroscopy is particularly attractive in
children as it confers advantages over arthrotomy or open surgery,
such as shorter recovery time and earlier return to activity. Developments
in surgical technique and arthroscopic instrumentation have enabled
extension of arthroscopy of the hip to this age group. Potential
challenges in paediatric and adolescent hip arthroscopy include
variability in size, normal developmental change from childhood to
adolescence, and conditions specific to children and adolescents
and their various consequences. Treatable disorders include the
sequelae of traumatic and sports-related hip joint injuries, Legg–Calve–Perthes’
disease and slipped capital femoral epiphysis, and the arthritic
and septic hip. Intra-articular abnormalities are rarely isolated and
are often associated with underlying morphological changes. This review presents the current concepts of hip arthroscopy
in the paediatric and adolescent patient, covering clinical assessment
and investigation, indications and results of the experience to
date, as well as technical challenges and future directions.
We have previously described the mid- to long-term
results of conventional simple varus intertrochanteric osteotomy
for osteonecrosis of the femoral head, showing that 19 of the 26
hips had good or excellent results. We extended the follow-up to
a mean of 18.1 years (10.5 to 26) including a total of 34 hips in
28 patients, with a mean age at surgery of 33 years (19 to 53).
There were 18 men and ten women and 25 hips (74%) had a satisfactory
result with a Harris hip score ≥ 80. In all, six hips needed total
hip replacement (THR) or hemiarthroplasty. The collapse of the femoral
head or narrowing of the joint space was found to have progressed
in nine hips (26%). Leg shortening after osteotomy was a mean of
19 mm (8 to 36). With conversion to THR or hemiarthroplasty as the
endpoint, the ten-year survival rate was 88.2% (95% confidence interval
(CI) 82.7 to 93.7) and the 20-year survival rate was 79.7% (95%
CI 72.1 to 87.3); four hips were converted at ten years and other
two hips were converted at 20 years. Shortening of the leg after osteotomy remains a concern; however,
the conventional varus half-wedge osteotomy provides favourable
long-term results in hips with less than two-thirds of the medial
part of the femoral head affected by necrotic bone and with normal
bone superolaterally.
In this prospective study we studied the effect
of the inclination angle of the acetabular component on polyethylene wear
and component migration in cemented acetabular sockets using radiostereometric
analysis. A total of 120 patients received either a cemented Reflection
All-Poly ultra-high-molecular-weight polyethylene or a cemented
Reflection All-Poly highly cross-linked polyethylene acetabular
component, combined with either cobalt–chrome or Oxinium femoral
heads. Femoral head penetration and migration of the acetabular
component were assessed with repeated radiostereometric analysis
for two years. The inclination angle was measured on a standard
post-operative anteroposterior pelvic radiograph. Linear regression
analysis was used to determine the relationship between the inclination
angle and femoral head penetration and migration of the acetabular component. We found no relationship between the inclination angle and penetration
of the femoral head at two years’ follow-up (p = 0.9). Similarly,
our data failed to reveal any statistically significant correlation
between inclination angle and migration of these cemented acetabular
components (p = 0.07 to p = 0.9).
Metal-on-metal (MoM) hip resurfacing was introduced into clinical
practice because it was perceived to be a better alternative to
conventional total hip replacement for young and active patients.
However, an increasing number of reports of complications have arisen
focusing on design and orientation of the components, the generation
of metallic wear particles and serum levels of metallic ions. The
procedure introduced a combination of two elements: large-dimension
components and hard abrasive particles of metal wear. The objective
of our study was to investigate the theory that microseparation
of the articular surfaces draws in a high volume of bursal fluid
and its contents into the articulation, and at relocation under
load would generate high pressures of fluid ejection, resulting
in an abrasive water jet. This theoretical concept using MoM resurfacing components (head
diameter 55 mm) was modelled mathematically and confirmed experimentally
using a material-testing machine that pushed the head into the cup
at a rate of 1000 mm/min until fully engaged.Objectives
Methods
The removal of all prosthetic material and a
two-stage revision procedure is the established standard management of
an infected total hip replacement (THR). However, the removal of
well-fixed femoral cement is time-consuming and can result in significant
loss of bone stock and femoral shaft perforation or fracture. We
report our results of two-stage revision THR for treating infection,
with retention of the original well-fixed femoral cement mantle
in 15 patients, who were treated between 1989 and 2002. Following
partial excision arthroplasty, patients received local and systemic
antibiotics and underwent reconstruction and re-implantation at
a second-stage procedure, when the infection had resolved. The mean follow-up of these 15 patients was 82 months (60 to
192). Two patients had positive microbiology at the second stage
and were treated with six weeks of appropriate antibiotics; one
of these developed recurrent infection requiring further revision.
Successful eradication of infection was achieved in the remaining
14 patients. We conclude that when two-stage revision is used for the treatment
of peri-prosthetic infection involving a THR, a well-fixed femoral
cement mantle can be safely left
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.
We determined the midterm survival, incidence
of peri-prosthetic fracture and the enhancement of the width of
the femur when combining struts and impacted bone allografts in
24 patients (25 hips) with severe femoral bone loss who underwent
revision hip surgery. The pre-operative diagnosis was aseptic loosening
in 16 hips, second-stage reconstruction in seven, peri-prosthetic
fracture in one and stem fracture in one hip. A total of 14 hips
presented with an Endoklinik grade 4 defect and 11 hips a grade
3 defect. The mean pre-operative Merle D’Aubigné and Postel score
was 5.5 points (1 to 8). The survivorship was 96% (95% confidence interval 72 to 98) at
a mean of 54.5 months (36 to 109). The mean functional score was
17.3 points (16 to 18). One patient in which the strut did not completely
bypass the femoral defect was further revised using a long cemented
stem due to peri-prosthetic fracture at six months post-operatively.
The mean subsidence of the stem was 1.6 mm (1 to 3). There was no
evidence of osteolysis, resorption or radiolucencies during follow-up
in any hip. Femoral width was enhanced by a mean of 41% (19% to
82%). A total of 24 hips had partial or complete bridging of the
strut allografts. This combined biological method was associated with a favourable
survivorship, a low incidence of peri-prosthetic fracture and enhancement
of the width of the femur in revision total hip replacement in patients
with severe proximal femoral bone loss.
We report the use of porous metal acetabular
revision shells in the treatment of contained bone loss. The outcomes of
53 patients with
The introduction of a trabecular tantalum rod
has been proposed for the management of early-stage osteonecrosis of
the femoral head but serves as a single-point of support of the
necrotic lesion. We describe a technique using two or three 4.2
mm (or later 4.7 mm) tantalum pegs for the prevention of collapse
of the necrotic lesion. We prospectively studied 21 patients (26
hips) with non-traumatic osteonecrosis of the femoral head treated
in this manner. Of these, 21 patients (24 hips) were available for
radiological and clinical evaluation at a mean follow-up of 46 months
(18 to 67). Radiological assessment showed that only eight hips
deteriorated according to the Association Research Circulation Osseous
classification, and four hips according to the Classification of
the Japanese Investigation Committee of Health and Welfare. Functional
improvement was obtained with an improvement in the mean Harris
hip score from 65.2 (33.67 to 95) to 88.1 (51.72 to 100), the mean
Merle D’Aubigné-Postel score from 13 (6 to 18) to 16 (11 to 18),
a mean visual analogue score for pain from 5.2 (0 to 9.5) to 2.6
(0 to 7), and the mean Short-Form 36 score from 80.4 (56.8 to 107.1)
to 92.4 (67.5 to 115.7). Of these 24 hips followed for a minimum
of 18 months, three were considered as failures at the final follow-up,
having required total hip replacement. One of the hips without full
follow-up was also considered to be a failure. In more than two-thirds
of the surviving hips a satisfactory clinical outcome was achieved
with promising radiological findings. The estimated mean implant
survival was 60 months (95% confidence interval 53.7 to 66.3).
We report the use of a 15° face-changing cementless
acetabular component in patients undergoing total hip replacement
for osteoarthritis secondary to developmental dysplasia of the hip.
The rationale behind its design and the surgical technique used
for its implantation are described. It is distinctly different from
a standard cementless hemispherical component as it is designed
to position the bearing surface at the optimal angle of inclination,
that is, <
45°, while maximising the cover of the component by
host bone.
Peripheral nerve injury is an uncommon but serious
complication of hip surgery that can adversely affect the outcome.
Several studies have described the use of electromyography and intra-operative
sensory evoked potentials for early warning of nerve injury. We
assessed the results of multimodal intra-operative monitoring during
complex hip surgery. We retrospectively analysed data collected
between 2001 and 2010 from 69 patients who underwent complex hip
surgery by a single surgeon using multimodal intra-operative monitoring
from a total pool of 7894 patients who underwent hip surgery during
this period. In 24 (35%) procedures the surgeon was alerted to a
possible lesion to the sciatic and/or femoral nerve. Alerts were
observed most frequently during peri-acetabular osteotomy. The surgeon
adapted his approach based on interpretation of the neurophysiological changes.
From 69 monitored surgical procedures, there was only one true positive
case of post-operative nerve injury. There were no false positives
or false negatives, and the remaining 68 cases were all true negative.
The sensitivity for predicting post-operative nerve injury was 100%
and the specificity 100%. We conclude that it is possible and appropriate
to use this method during complex hip surgery and it is effective
for alerting the surgeon to the possibility of nerve injury.
Persistent groin pain after seemingly successful
total hip replacement (THR) appears to have become more common.
Recent studies have indicated a high incidence after metal-on-polyethylene
and metal-on-metal conventional THR and it has been documented in
up to 18% of patients after metal-on-metal resurfacing. There are many
causes, including acetabular loosening, stress fracture, and iliopsoas
tendonitis and impingement. The evaluation of this problem requires
a careful history and examination, plain radiographs and an algorithmic approach
to special diagnostic imaging and tests. Non-operative treatment
is not usually successful. Specific operative treatment depending
on the cause of the pain usually involves revision of the acetabular
component, iliopsoas tenotomy or other procedures, and is usually
successful. Here, an appropriate algorithm is described.
Alumina–alumina bearings are among the most resistant
to wear in total hip replacement. Examination of their surfaces
is one way of comparing damage caused by wear of hip joints simulated We found that long-term alumina wear in association with a loose
acetabular component could be categorised into three groups. Of
20 specimens, four had ‘low wear’, eight ‘crescent wear’ and eight
‘severe wear’, which was characterised by a change in the physical
shape of the bearing and a loss of volume. This suggests that the
wear in alumina–alumina bearings in association with a loose acetabular
component may be variable in pattern, and may explain, in part,
why the wear of a ceramic head
The purpose of this study was to assess N-acetyl aspartate changes
in the thalamus in patients with osteoarthritis of the hip using
proton magnetic resonance spectroscopy. Nine patients with osteoarthritis of the hip (symptomatic group,
nine women; mean age 61.4 years (48 to 78)) and nine healthy volunteers
(control group, six men, three women; mean age 30.0 years (26 to
38)) underwent proton magnetic resonance spectroscopy to assess
the changes of N-acetyl aspartate in the thalamus. Objectives
Methods