We have previously reported on the improved all-cause revision and improved revision for instability risk in lipped liner THAs using the NJR dataset. These findings corroborate studies from the Australian (AOANJRR) and New Zealand (NZOA) joint registries. The optimal orientation of the lip in THAs utilising a lipped liner remains unclear to many surgeons. The aim of this study was to identify impingement-free optimal liner orientations whilst considering femoral stem version, cup inclination and cup version. A cementless THA
Introduction. Golf is a recommended form of physical activity for older adults. However, clinicians have no evidence-based research regarding the demands on the hips of older adults during golf. The purpose of our in vivoobservational study was to quantify the hip biomechanics of older adult golfers. Methods. Seventeen healthy older male golfers(62.2±8.8 years, handicap 8.7±4.9) free from orthopaedic injuries and surgeries volunteered for participation in this IRB-approved study. A 10-camera motion capture system recorded
Aims. The aim of this study was to identify the optimal lip position for total hip arthroplasties (THAs) using a lipped liner. There is a lack of consensus on the optimal position, with substantial variability in surgeon practice. Methods. A model of a THA was developed using a 20° lipped liner.
Patients demonstrate distinct trajectories of recovery after THA. The purpose of this study was to assess the impact of adjacent muscle quality on postoperative hip
Dual Mobility (DM) Total Hip Replacements (THRs), are becoming widely used but function in-vivo is not fully understood. The aim of this study was to compare the incidence of impingement of a modular dual mobility with that of a standard cup. A geometrical model of one subject's bony anatomy \[1\] was developed, a THR was implanted with the cup at a range of inclination and anteversion positions (Corail® stem, Pinnacle® cup (DePuy Synthes)). Two DM variants and one STD acetabular cup were modelled. Joint motions were taken from
A ceramic-on-ceramic hip resurfacing implant (cHRA) was developed and introduced in an MHRA-approved clinical investigation to provide a non metallic alternative hip resurfacing product. This study aimed to examine function and physical activity levels of patients with a cHRA implant using subjective and objective measures both before and 12 months following surgery in comparison with age and gender matched healthy controls. Eighty-two unilateral cHRA patients consented to this study as part of a larger prospective, non-randomised, clinical investigation. In addition to their patient reported outcome measures (PROMs), self- reported measures of physical activity levels and gait analysis were undertaken both pre- operatively (1.5 weeks) and post operatively (52 weeks). This data was then compared to data from a group of 43 age gender and BMI matched group of healthy controls. Kinetics and
The 10 year survivorship of THR is generally over 95%. However, the incidence of revision is usually higher in year one. The most common reason being dislocation which at least in part is driven by inadequate range of motion (ROM) leading to impingement, subluxation and ultimately dislocation which is more frequently posterior. ROM is affected by patient activity, bone and component geometry, and component placement. To reduce the incidence of dislocation, supported by registry data, there has been an increase in the use of so-called ‘lipped’ liners. Whilst this increases joint stability, the theoretical ROM is reduced. The aim of this study was to investigate the effect of lip placement on impingement. A rigid body geometric model was incorporated into a CT scan hemi-pelvis and femur, with a clinically available THR virtually implanted.
Iliopsoas impingement occurs in 4% to 30% of patients after undergoing total hip arthroplasty (THA). Despite a relatively high incidence, there are few attempts at modelling impingement between the iliopsoas and acetabular component, and no attempts at modelling this in a representative cohort of subjects. The purpose of this study was to develop a novel computational model for quantifying the impingement between the iliopsoas and acetabular component and validate its utility in a case-controlled investigation. This was a retrospective cohort study of patients who underwent THA surgery that included 23 symptomatic patients diagnosed with iliopsoas tendonitis, and 23 patients not diagnosed with iliopsoas tendonitis. All patients received postoperative CT imaging, postoperative standing radiography, and had minimum six months’ follow-up. 3D models of each patient’s prosthetic and bony anatomy were generated, landmarked, and simulated in a novel iliopsoas impingement detection model in supine and standing pelvic positions. Logistic regression models were implemented to determine if the probability of pain could be significantly predicted. Receiver operating characteristic curves were generated to determine the model’s sensitivity, specificity, and area under the curve (AUC).Aims
Methods
Spinopelvic pathology increases the risk for instability following total hip arthroplasty (THA), yet few studies have evaluated how pathology varies with age or sex. The aims of this study were: 1) to report differences in spinopelvic parameters with advancing age and between the sexes; and 2) to determine variation in the prevalence of THA instability risk factors with advancing age. A multicentre database with preoperative imaging for 15,830 THA patients was reviewed. Spinopelvic parameter measurements were made by experienced engineers, including anterior pelvic plane tilt (APPT), spinopelvic tilt (SPT), sacral slope (SS), lumbar lordosis (LL), and pelvic incidence (PI). Lumbar flexion (LF), sagittal spinal deformity, and hip user index (HUI) were calculated using parameter measurements.Aims
Methods
Introduction. Spinopelvic mobility has been associated with THA outcome. To-date spine assessments have been made quasi-statically, using radiographs, in standing and seated positions but dynamic spinopelvic mobility has not been well explored. This study aims to determine the association between dynamic (motion analysis) and quasi-static (radiographic) sagittal assessments and examine the association between axial and sagittal spinal
The aim of this study was to evaluate the reliability and validity of a patient-specific algorithm which we developed for predicting changes in sagittal pelvic tilt after total hip arthroplasty (THA). This retrospective study included 143 patients who underwent 171 THAs between April 2019 and October 2020 and had full-body lateral radiographs preoperatively and at one year postoperatively. We measured the pelvic incidence (PI), the sagittal vertical axis (SVA), pelvic tilt, sacral slope (SS), lumbar lordosis (LL), and thoracic kyphosis to classify patients into types A, B1, B2, B3, and C. The change of pelvic tilt was predicted according to the normal range of SVA (0 mm to 50 mm) for types A, B1, B2, and B3, and based on the absolute value of one-third of the PI-LL mismatch for type C patients. The reliability of the classification of the patients and the prediction of the change of pelvic tilt were assessed using kappa values and intraclass correlation coefficients (ICCs), respectively. Validity was assessed using the overall mean error and mean absolute error (MAE) for the prediction of the change of pelvic tilt.Aims
Methods
Femoroacetabular impingement (FAI) patients report exacerbation of hip pain in deep flexion. However, the exact impingement location in deep flexion is unknown. The aim was to investigate impingement-free maximal flexion, impingement location, and if cam deformity causes hip impingement in flexion in FAI patients. A retrospective study involving 24 patients (37 hips) with FAI and femoral retroversion (femoral version (FV) < 5° per Murphy method) was performed. All patients were symptomatic (mean age 28 years (SD 9)) and had anterior hip/groin pain and a positive anterior impingement test. Cam- and pincer-type subgroups were analyzed. Patients were compared to an asymptomatic control group (26 hips). All patients underwent pelvic CT scans to generate personalized CT-based 3D models and validated software for patient-specific impingement simulation (equidistant method).Aims
Methods
Aims. The aim of this study was to examine the real time in
vivo
Hip arthroplasty aims to accurately recreate joint biomechanics. Considerable attention has been paid to vertical and horizontal offset, but femoral head centre in the anteroposterior (AP) plane has received little attention. This study investigates the accuracy of restoration of joint centre of rotation in the AP plane. Postoperative CT scans of 40 patients who underwent unilateral uncemented total hip arthroplasty were analyzed. Anteroposterior offset (APO) and femoral anteversion were measured on both the operated and non-operated sides. Sagittal tilt of the femoral stem was also measured. APO measured on axial slices was defined as the perpendicular distance between a line drawn from the anterior most point of the proximal femur (anterior reference line) to the centre of the femoral head. The anterior reference line was made parallel to the posterior condylar axis of the knee to correct for rotation.Aims
Methods
Aims. Long-term clinical outcomes for ceramic-on-ceramic (CoC) bearings
are encouraging. However, there is a risk of squeaking. Guidelines
for the orientation of the acetabular component are defined from
static imaging, but the position of the pelvis and thus the acetabular
component during activities associated with edge-loading are likely
to be very different from those measured when the patient is supine.
We assessed the functional orientation of the acetabular component. Patients and Methods. A total of 18 patients with reproducible squeaking in their CoC
hips during deep flexion were investigated with a control group
of 36 non-squeaking CoC hips. The two groups were matched for the
type of implant, the orientation of the acetabular component when
supine, the size of the femoral head, ligament laxity, maximum hip
flexion and body mass index. . Results. The mean functional anteversion of the acetabular component at
the point when patients initiated rising from a seated position
was significantly less in the squeaking group than in the control
group, 8.1° (-10.5° to 36.0°) and 21.1° (-1.9° to 38.4°) respectively
(p = 0.002). . Conclusion. The functional orientation of the acetabular component during
activities associated with posterior edge-loading are different
from those measured when supine due to patient-specific pelvic
In the UK, the posterior approach (PA) and direct lateral approach (DLA) are the most common total hip arthroplasty (THA) procedures. Few studies however, have compared the subsequent functional outcomes. This exploratory study aimed to examine the effect of PA and DLA approaches on post-operative hip
Aims. The most effective surgical approach for total hip arthroplasty
(THA) remains controversial. The direct anterior approach may be
associated with a reduced risk of dislocation, faster recovery,
reduced pain and fewer surgical complications. This systematic review
aims to evaluate the current evidence for the use of this approach
in THA. Materials and Methods. Following the Cochrane collaboration, an extensive literature
search of PubMed, Medline, Embase and OvidSP was conducted. Randomised
controlled trials, comparative studies, and cohort studies were
included. Outcomes included the length of the incision, blood loss,
operating time, length of stay, complications, and gait analysis. Results. A total of 42 studies met the inclusion criteria. Most were of
medium to low quality. There was no difference between the direct
anterior, anterolateral or posterior approaches with regards to
length of stay and gait analysis. Papers comparing the length of the incision found similar lengths
compared with the lateral approach, and conflicting results when
comparing the direct anterior and posterior approaches. . Most studies found the mean operating time to be significantly
longer when the direct anterior approach was used, with a steep
learning curve reported by many. Many authors used validated scores including the Harris hip score,
and the Western Ontario and McMaster Universities Arthritis Index.
These mean scores were better following the use of the direct anterior
approach for the first six weeks post-operatively. Subsequently
there was no difference between these scores and those for the posterior
approach. Conclusion . There is little evidence for improved
Aims. The pelvis rotates in the sagittal plane during daily activities.
These rotations have a direct effect on the functional orientation
of the acetabulum. The aim of this study was to quantify changes
in pelvic tilt between different functional positions. Patients and Methods. Pre-operatively, pelvic tilt was measured in 1517 patients undergoing
total hip arthroplasty (THA) in three functional positions – supine,
standing and flexed seated (the moment when patients initiate rising
from a seated position). Supine pelvic tilt was measured from CT
scans, standing and flexed seated pelvic tilts were measured from standardised
lateral radiographs. Anterior pelvic tilt was assigned a positive
value. Results. The mean pelvic tilt was 4.2° (-20.5° to 24.5°), -1.3° (-30.2°
to 27.9°) and 0.6° (-42.0° to 41.3°) in the three positions, respectively.
The mean sagittal pelvic rotation from supine to standing was -5.5°
(-21.8° to 8.4°), from supine to flexed seated was -3.7° (-48.3°
to 38.6°) and from standing to flexed seated was 1.8° (-51.8° to
39.5°). In 259 patients (17%), the extent of sagittal pelvic rotation
could lead to functional malorientation of the acetabular component. Factoring
in an intra-operative delivery error of ± 5° extends this risk to
51% of patients. Conclusion. Planning and measurement of the intended position of the acetabular
component in the supine position may fail to predict clinically
significant changes in its orientation during functional activities,
as a consequence of individual pelvic
Pelvic incidence (PI) is a position-independent spinopelvic parameter traditionally used by spinal surgeons to determine spinal alignment. Its relevance to the arthroplasty surgeon in assessing patient risk for total hip arthroplasty (THA) instability preoperatively is unclear. This study was undertaken to investigate the significance of PI relative to other spinopelvic parameter risk factors for instability to help guide its clinical application. Retrospective analysis was performed of a multicentre THA database of 9,414 patients with preoperative imaging (dynamic spinopelvic radiographs and pelvic CT scans). Several spinopelvic parameter measurements were made by engineers using advanced software including sacral slope (SS), standing anterior pelvic plane tilt (APPT), spinopelvic tilt (SPT), lumbar lordosis (LL), and PI. Lumbar flexion (LF) was determined by change in LL between standing and flexed-seated lateral radiographs. Abnormal pelvic mobility was defined as ∆SPT ≥ 20° between standing and flexed-forward positions. Sagittal spinal deformity (SSD) was defined as PI-LL mismatch > 10°.Aims
Methods
Impingement of total hip replacements (THRs) can cause rim damage of polyethylene liners, and lead to dislocation and/or mechanical failure of liner locking mechanisms[1]. Previous work has focussed on the influence of femoral neck profile on impingement without consideration of neck-shaft angle. This study assessed the occurrence of impingement with two different stem designs (Corail standard [135°] and coxa vara [125°]) under different activities with varying acetabular cup orientation (30° to 70° inclination; 0° to 50° anteversion) using a geometric modelling tool. The tool was created in a computer aided design software programme, and incorporated an individual's hemi-pelvis and femur geometry[3] with a THR (DePuy Synthes Pinnacle. ®. shell and neutral liner; size 12 Corail. ®. standard or coxa vara and 32mm head).