A contact patch to rim (CPR) distance of <
10 mm has been
associated with edge-loading and excessive wear. However, not all
arthroplasties with a low CPR distance show problems with wear.
Therefore, CPR distance may not be the only variable affecting the
post-operative metal ion concentrations. We used multiple logistic regression to determine what variables
differed between the patients who had high and low cobalt (CoS)
and chromium (CrS) serum ion concentrations within a cohort of patients
with low (<
10 mm) CPR distances. A total of 56 patients treated
with unilateral hip resurfacing arthroplasty (HRA) had CoS and CrS
ion studies performed more than one year after surgery. The mean
age of the patients at the time of surgery was 51.7 years (29 to
70), with 38 women (68%) and 18 men (32%).Aims
Patients and 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
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 hypothesis of this study was that thigh circumference, distinct from body mass index (BMI), may be associated with the positioning of components when undertaking total hip arthroplasty (THA) using the direct anterior approach (DAA), and that an increased circumference might increase the technical difficulty. We performed a retrospective review of prospectively collected data involving 155 consecutive THAs among 148 patients undertaken using the DAA at an academic medical centre by a single fellowship-trained surgeon. Preoperatively, thigh circumference was measured at 10 cm, 20 cm, and 30 cm distal to the anterior superior iliac spine, in quartiles. Two blinded reviewers assessed the inclination and anteversion of the acetabular component, radiological leg-length discrepancy, and femoral offset. The radiological outcomes were considered as continuous and binary outcome variables based on Lewinnek’s ‘safe zone’.Aims
Patients and Methods
It is important to consider sagittal pelvic rotation when introducing
the acetabular component at total hip arthroplasty (THA). The purpose
of this study was to identify patients who are at risk of unfavourable
pelvic mobility, which could result in poor outcomes after THA. A consecutive series of 4042 patients undergoing THA had lateral
functional radiographs and a low-dose CT scan to measure supine
pelvic tilt, pelvic incidence, standing pelvic tilt, flexed-seated
pelvic tilt, standing lumbar lordotic angle, flexed-seated lumbar
lordotic angle, and lumbar flexion. Changes in pelvic tilt from
supine-to-standing positions and supine-to-flexed-seated positions
were determined. A change in pelvic tilt of 13° between positions was
deemed unfavourable as it alters functional anteversion by 10° and
effectively places the acetabular component outside the safe zone
of orientation.Aims
Patients and Methods
To determine the effect of a change in design of a cementless
ceramic acetabular component in fixation and clinical outcome after
total hip arthroplasty We compared 342 hips (302 patients) operated between 1999 and
2005 with a relatively smooth hydroxyapatite coated acetabular component
(group 1), and 337 hips (310 patients) operated between 2006 and
2011 using a similar acetabular component with a macrotexture on
the entire outer surface of the component (group 2). The mean age of
the patients was 53.5 (14 to 70) in group 1 and 53.0 (15 to 70)
in group 2. The mean follow-up was 12.7 years (10 to 17) for group
1 and 7.2 years (4 to 10) for group 2.Aims
Patients and Methods
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
We evaluated the short-term functional outcome and prevalence
of bearing-specific generation of audible noise in 301 patients
(336 hips) operated on with fourth generation (Delta) medium diameter
head, ceramic-on-ceramic (CoC) total hip arthroplasties (THAs). There were 191 female (63%) and 110 male patients (37%) with
a mean age of 61 years (29 to 78) and mean follow-up of 2.1 years
(1.3 to 3.4). Patients completed three questionnaires: Oxford Hip
Score (OHS), Research and Development 36-item health survey (RAND-36)
and a noise-specific symptom questionnaire. Plain radiographs were also
analysed. A total of three hips (0.9%) were revised. Aims
Patients and Methods
We conducted a prospective study of a delta ceramic total hip
arthroplasty (THA) to determine the rate of ceramic fracture, to
characterise post-operative noise, and to evaluate the mid-term
results and survivorship. Between March 2009 and March 2011, 274 patients (310 hips) underwent
cementless THA using a delta ceramic femoral head and liner. At
each follow-up, clinical and radiological outcomes were recorded.
A Kaplan-Meier analysis was undertaken to estimate survival.Aims
Patients and Methods
This study aims to: determine the difference in pelvic position that occurs between surgery and radiographic, supine, postoperative assessment; examine how the difference in pelvic position influences subsequent component orientation; and establish whether differences in pelvic position, and thereafter component orientation, exist between total hip arthroplasties (THAs) performed in the supine versus the lateral decubitus positions. The intra- and postoperative anteroposterior pelvic radiographs of 321 THAs were included; 167 were performed with the patient supine using the anterior approach and 154 were performed with the patient in the lateral decubitus using the posterior approach. The inclination and anteversion of the acetabular component was measured and the difference (Δ) between the intra- and postoperative radiographs was determined. The target zone was inclination/anteversion of 40°/20° (± 10°). Changes in the tilt, rotation, and obliquity of the pelvis on the intra- and postoperative radiographs were calculated from Δinclination/anteversion using the Levenberg–Marquardt algorithm.Aims
Patients and Methods
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:
Studies reporting specifically on squeaking in total hip arthroplasty have focused on cementless, and not on hybrid, fixation. We hypothesised that the cement mantle of the femur might have a damping effect on the sound transmitted through the metal stem. The objective of this study was to test the effect of cement on sound propagation along different stem designs and under different fixation conditions. An Objectives
Methods
Noise generation has been reported with ceramic-on-ceramic
articulations in total hip replacement (THR). This study evaluated
208 consecutive Delta Motion THRs at a mean follow-up of 21 months
(12 to 35). There were 141 women and 67 men with a mean age of 59
years (22 to 84). Patients were reviewed clinically and radiologically,
and the incidence of noise was determined using a newly described
assessment method. Noise production was examined against range of
movement, ligamentous laxity, patient-reported outcome scores, activity
level and orientation of the acetabular component. There were 143
silent hips (69%), 22 (11%) with noises other than squeaking, 17
(8%) with unreproducible squeaking and 26 (13%) with reproducible
squeaking. Hips with reproducible squeaking had a greater mean range
of movement (p <
0.001) and mean ligament laxity (p = 0.004), smaller
median head size (p = 0.01) and decreased mean acetabular component
inclination (p = 0.02) and anteversion angle (p = 0.02) compared
with the other groups. There was no relationship between squeaking
and age (p = 0.13), height (p = 0.263), weight (p = 0.333), body
mass index (p = 0.643), gender (p = 0.07) or patient outcome score
(p = 0.422). There were no revisions during follow-up. Despite the
surprisingly high incidence of squeaking, all patients remain satisfied
with their hip replacement. Cite this article:
The purpose of this study was to evaluate whether an innovative
templating technique could predict the need for acetabular augmentation
during primary total hip arthroplasty for patients with dysplastic
hips. We developed a simple templating technique to estimate acetabular
component coverage at total hip arthroplasty, the True Cup: False
Cup (TC:FC) ratio. We reviewed all patients with dysplastic hips
who underwent primary total hip arthroplasty between 2005 and 2012.
Traditional radiological methods of assessing the degree of acetabular dysplasia
(Sharp’s angle, Tönnis angle, centre-edge angle) as well as the
TC:FC ratio were measured from the pre-operative radiographs. A
comparison of augmented and non-augmented hips was undertaken to
determine any difference in pre-operative radiological indices between
the two cohorts. The intra- and inter-observer reliability for all
radiological indices used in the study were also calculated.Aims
Patients and Methods
We report the kinematic and early clinical results
of a patient- and observer-blinded randomised controlled trial in which
CT scans were used to compare potential impingement-free range of
movement (ROM) and acetabular component cover between patients treated
with either the navigated ‘femur-first’ total hip arthroplasty (THA) method
(n = 66; male/female 29/37, mean age 62.5 years; 50 to 74) or conventional
THA (n = 69; male/female 35/34, mean age 62.9 years; 50 to 75).
The Hip Osteoarthritis Outcome Score, the Harris hip score, the
Euro-Qol-5D and the Mancuso THA patient expectations score were
assessed at six weeks, six months and one year after surgery. A
total of 48 of the patients (84%) in the navigated ‘femur-first’
group and 43 (65%) in the conventional group reached all the desirable
potential ROM boundaries without prosthetic impingement for activities
of daily living (ADL) in flexion, extension, abduction, adduction
and rotation (p = 0.016). Acetabular component cover and surface
contact with the host bone were >
87% in both groups. There was
a significant difference between the navigated and the conventional
groups’ Harris hip scores six weeks after surgery (p = 0.010). There
were no significant differences with respect to any clinical outcome
at six months and one year of follow-up. The navigated ‘femur-first’
technique improves the potential ROM for ADL without prosthetic
impingement, although there was no observed clinical difference
between the two treatment groups. Cite this article:
The aims of this study were to compare the diagnostic test characteristics
of ultrasound alone, metal artefact reduction sequence MRI (MARS-MRI)
alone, and ultrasound combined with MARS-MRI for identifying intra-operative
pseudotumours in metal-on-metal hip resurfacing (MoMHR) patients
undergoing revision surgery. This retrospective diagnostic accuracy study involved 39 patients
(40 MoMHRs). The time between imaging modalities was a mean of 14.6
days (0 to 90), with imaging performed at a mean of 5.3 months (0.06
to 12) before revision. The prevalence of intra-operative pseudotumours
was 82.5% (n = 33).Aims
Methods
