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Volume 101-B, Issue SUPP_6 May 2019 The British Hip Society (BHS) Meeting, Nottingham, England, 27 February – 1 March 2019.

CEL Watkins KM Ghosh S Bhatnagar K Rankin DJ Weir M Hashmi JP Holland

Background

Total hip arthroplasty (THA) in patients with congenital dysplasia of the hip (CDH) is complex and challenging. The Crowe and Hartofilakidis classification systems are the most commonly used. However, neither encompasses the whole spectrum of disease and deformity and therefore does not guide modern surgical options.

We present a new classification system which aims to guide surgical strategy by focusing on the three main areas of disease and deformity: Cup defect; De-rotation of femoral neck ante-version; Height of femoral subluxation. Each component is graded from 1–3 based on the severity of deformity and the potential surgical strategy required (with 3 being the most severe). A total numerical score will reflect the overall degree of difficulty which may be used when assessing surgical outcomes.

The aim of this study is to assess the reliability of this new adult CDH classification system in the setting of THA.

Study design and Methods

A sample size calculation showed 28 evaluations were required to reach a power of 85% (based on a kappa value of 0.4). The anterior-posterior pelvis and lateral hip radiographs of 30 hips, in 26 patients were evaluated by three Consultant Orthopaedic Surgeons using the classification detailed in table 1. A second evaluation, with the case order randomised, was performed after a minimum period of 1month. Randolph's free multi-rater Kappa co-efficient was used to assess for inter and intra- observer reliability and 95% confidence intervals were calculated.


J Verhaegen S Salih S Thiagarajah G Grammatopoulos J Witt

Introduction

Peri-acetabular-osteotomy (PAO) was initially described for the correction of acetabular dysplasia. Anteverting PAO is an established treatment for acetabular retroversion. By reviewing a large cohort, we aimed to (1) Test whether PAO outcome is equivalent in different types of deformity (classic dysplasia vs. retroversion) and (2) Determine whether outcome in acetabular retroversion is different between impinging-only hip and hips with combined pathology (impingement & dysplasia).

Methods

A single-centre, retrospective cohort study was performed on a group of patients (n=183) with acetabular retroversion (n=90) or lateral-under-coverage dysplasia (n=93) treated with PAO. Acetabular deformity was defined on pelvic radiographs and 3-D CTs using a number of parameters. Hips with retroversion, were sub-divided into combined pathology - retroversion with dysplasia (lateral centre-edge [LCEA] < 25°), or retroversion-only (LCEA≥25°). The mean age at time of the procedure was 29+/−7 years and most hips were in females (n=171). Complication (as per Dindo-Clavien)-, re-operation-, hip preservation rates and patient-reported-outcome measures were measured using the Non-Arthroplasty-Hip-Score (NAHS).


S Thiagarajah J Verhaegen P Balijepalli J Bingham G Grammatopoulos J Witt

Introduction

The periacetabular osteotomy (PAO) improves hip joint mechanics in patients with symptomatic dysplasia. As a consequence of the multi-planar acetabular re-orientation, the course of the iliopsoas tendon over the hip may be affected, potentially resulting in iliopsoas tendon-related pain. At present, little information regarding the incidence of iliopsoas-related pathology following PAO exists.

We aimed to identify the incidence of iliopsoas-related pain following PAO. Secondarily, we aimed to identify any risk factors associated with this pathology.

Methods

We retrospectively reviewed the PAO's performed from 2014–2017, for symptomatic dysplasia in our unit (single-surgeon, minimum 1-year follow-up). All patients with adequate pelvic radiographs were included. Radiographic parameters of dysplasia were measured from pre- and post-operative AP pelvic radiographs using a validated software (SHIPS)1. The degree of pubis displacement was classified according to our novel system. Cases were defined as those with evidence of iliopsoas-related pain post PAO (positive response to iliopsoas tendon-sheath steroid/local anaesthetic injection).


S Salih G Grammatopoulos P Beaule J Witt

Introduction

Acetabular retroversion (AR) can cause pain and early osteoarthritis. The sagittal pelvic position or pelvic tilt (PT)has a direct relationship with acetabular orientation. As the pelvis tilts anteriorly, PT reduces and AR increases. Therefore, AR may be a deformity secondary to abnormal PT (functional retroversion) or an anatomical deformity of the acetabulum and/or pelvic ring.

This study aims to:

Define PT at presentation is in AR patients and whether this is different to controls (volunteers without pain).

Assess whether the PT changes following a anteverting periacetabular osteotomy (PAO).

Methods

PT was measured for 51 patients who underwent a successful PAO. Mean age at PAO was 29±6 years and 48 were females. PT, pelvic incidence (PI), anterior pelvic plane (APP), and sacral slope (SS) were measured from CT data in 23 patients and compared to 44 (32±7 years old, 4 females) asymptomatic volunteers. Change in pelvic tilt in all 51 patients was measured using the Sacro-Femoral-Pubic angle (SFP), a validated method, from pre- and post-operative radiographs at a mean interval of 2.5(±2) years.


M Roussot S Salih G Grammatopoulos J Witt

Introduction

Acetabular dysplasia is typically characterised by insufficient antero-superior femoral head coverage. It is postulated (yet unproven) that patients with dysplasia compensate by reducing pelvic tilt (anterior pelvic rotation), effectively retroverting their acetabulum to improve antero-superior cover. We aimed to 1) define pelvic tilt (PT) in patients with bilateral and unilateral dysplasia, and 2) quantify PT changes following a successful periacetabular osteotomy (PAO).

Patients/Materials and Methods

We retrospectively reviewed 16 patients (14 females) who underwent successful, bilateral, staged, PAOs (32 PAOs). These cases were matched for age and gender with 32 unilaterally dysplastic hips that underwent successful PAO for a similar degree of acetabular dysplasia as per pre-operative imaging. Supine and AP radiographs pre-PAO and at latest follow-up were used to measure centre-edge-angle (CEA) and Tönnis-angle (TA). PT was measured using two validated methods (Sacro-Femoral-Pubic (SFP) angle and Pubic-Symphysis to Sacro-Iliac (PS-SI) Index with excellent correlation (ρ=0.8, p<0.001).


R Elwood O El-Hakeem Y Singh O Weiss V Khanduja

Background

Elite performance has tremendous physical demands and places elite athletes at an increased risk of sustaining a variety of orthopaedic injuries (1–4). Pain around the hip is common in high-level athletes representing up to 6% of all athletic injuries (5–7). Expedient diagnosis and effective treatment are paramount for their future sporting careers and to prevent subsequent joint degeneration. The purpose of this systematic review was to evaluate the outcome and the rate of return to play (RTP) following hip arthroscopy in elite athletes.

Methods

A computer-based systematic search followed the PRISMA Guidelines (8) was performed using the 6 most comprehensive databases (CENTRAL, PUBMED, EMBASE, SCOPUS, EBSCO, Google Scholar and Web of Science) and included all published studies from inception until November 1st 2018. Weighted means were calculated for the rate of RTP and duration and for patient reported outcome measures (PROMs).


J Pietrzak K Nortje J Cakic

Background

Hip arthroscopy is a rapidly growing, evolving area within arthroscopic Orthopaedic Surgery, with annual rates increasing as much as 25-fold each year. Despite improvements in equipment and training, it remains a challenging procedure. Rates of revision surgery have been reported as 6.3% to 16.9%.

Objectives

The primary objective was to determine the success of joint preservation after hip arthroscopy. The secondary objective was to determine whether patient characteristics or PROM functional score trends could predict revision hip arthroscopy or Total Hip Arthroplasty (THA).


M Hampton S Salih A Gordon

Introduction

Early surgery for hip fractures is beneficial but is often delayed by anticoagulation. Direct acting anticoagulants (DOAC), Rivaroxaban and Apixiban, are increasingly used in primary and secondary care but there is no specific reversal agent. Current guidance is to delay surgery 48 hours. Anti-factorXa levels < 80 ug/l are considered safe for major surgery and for spinal anaesthesia. We investigated if delay in this cohort of patients can be predicted or reduced.

Patients/Materials & Methods

41 consecutive patients presenting with a hip fracture on therapeutic dose DOAC were identified. Anti- factorXa levels were collected at 24hours and repeated at 48hours if elevated. We investigated if renal function or clotting screen could help predict safe time to surgery.


P Dasaraju M Parker

Continued controversy exists between cemented versus uncemented hemiarthroplasty for an intracapsular hip fracture. To assist in resolving this controversy, 400 patients were randomised between a cemented polished tapered stem hemiarthroplasty and an uncemented Furlong hydroxyapatite coated hemiarthroplasty. Follow-up was by a nurse blinded to the implant used for up to three years from surgery.

Results indicate no difference in the pain scores between implants but a tendency to an improved regain of mobility for those treated with the cemented arthroplasty (1.2 score versus 1.7 at 6 months, p=0.03). There was no difference in early mortality but a tendency to a higher later mortality for the uncemented implants (29% versus 24% at one year, p=0.3). Later peri-prosthetic fracture was more common in the uncemented group (3% versus 1.5%). Revision arthroplasty was required for 2% of cemented cases and 3% of uncemented cases. Surgery for an uncemented hemiarthroplasty was 5 minutes shorter but these patients were more likely to need a blood transfusion (14% versus 7%). Three patients in the cemented group had a major adverse reaction to bone cement leading to their death.

These results indicated that a cemented stem hemiarthroplasty give marginally improved regain of mobility in comparison to a contemporary uncemented hemiarthroplasty. An uncemented hemiarthroplasty still has a place for those considered to be at a high risk of bone cement implantation syndrome.


GS Matharu A Judge K Deere AW Blom MR Reed MR Whitehouse

Introduction

Total hip arthroplasty (THA) is indicated in independently mobile patients sustaining displaced intracapsular hip fractures. Studies presently suggest that the anterolateral approach is preferable to the posterior approach due to a perceived reduced risk of reoperations and dislocations. However, these observations come from small studies with short follow-up. We assessed whether surgical approach in THA performed for hip fractures effects outcomes.

Patients and Methods

A retrospective observational study was performed using data collected prospectively by the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man. All primary stemmed THAs implanted for hip fractures between 2003–2015 were eligible for inclusion (n=19,432). The two surgical approach groups (posterior versus anterolateral) were propensity-score matched for multiple potential patient and surgical confounding factors (n=14,536, with 7,268/group). Outcomes (implant survival, patient survival, intraoperative complications) were compared between the approach groups using regression analysis.


S Jordan A Taylor J Jhaj H Akehurst J Ivory A Ashmore M Rigby RA Brooks

Background

Total hip arthroplasty (THA) is increasingly used for active patients with displaced intracapsular hip fractures. Dislocation rates in this cohort remain high postoperatively compared to elective practice, yet it remains unclear which patients are most at risk. The aim of this study was to determine the dislocation rate for these patients and to evaluate the contributing patient and surgeon factors.

Methods

A five-year retrospective analysis of all patients receiving THA for displaced intracapsular hip fractures from 2013–18 was performed. Data was collected from the institutions' hip fracture database, including data submitted to the National Hip Fracture Database (NHFD). Cox regression analysis and log-rank tests were implemented to evaluate factors associated with THA dislocation. Patient age, sex, ASA grade, surgeon seniority, surgical approach, femoral head diameter and acetabular cup type were all investigated as independent factors.


PSE Davies AIW Mayne J Milton K Kelly F Mackinnon JM Simpson

Introduction

The number of hip fracture admissions is rising; with reduced hospital bed capacity and increasing patient numbers, care pathways must be optimised to maximise inpatient bed efficiency. There is currently significant interest in improving healthcare services across all 7 days in the United Kingdom. It is unclear whether lack of allied healthcare professional review at the weekend is detrimental to hip fracture patient care. This study aims to examine whether providing 7-day physiotherapy and occupational therapy (7DPOT) service improves outcomes for fractured neck of femur patients compared to a 5-day service (5DPOT).

Methods

All patients admitted with an acute neck of femur fracture were grouped into three cohorts, depending on provision of 7DPOT services: the initial cohort received 5DPOT between December 2012 and March 2013. Seven-day physiotherapy and occupational therapy was introduced for one year from October 2014 until September 2015 (2nd cohort). The service then reverted to 5DPOT between January to June 2016 (3rd cohort). The third cohort was utilised to nullify changes in the overall service which had occurred which were not attributable to 7DPOT. Data was collected prospectively using a specially designed audit tool.


GS Matharu S Mouchti S Twigg A Delmestri DW Murray A Judge HG Pandit

Introduction

Smoking, a modifiable factor, may adversely affect post-operative outcomes. Healthcare providers are increasingly denying smokers access to total hip arthroplasty (THA) until they stop smoking. Evidence supporting this is unclear. We assessed the effect of smoking on outcomes following THA.

Patients and Methods

We performed a retrospective observational study involving 60,812 THAs (12.4%=smokers, 31.2%=ex-smokers, 56.4%=non-smokers) from the Clinical Practice Research Datalink. Data were linked with Hospital Episode Statistics and the Office for National Statistics to identify outcomes. The effect of smoking on post-operative outcomes (complications, medications, revision, mortality, PROMs) was assessed using adjusted regression.


WJ Leong M Cook T O'Neill T Board

Background

Antibiotic loaded bone cement (ALBC) is commonly used in cemented total hip arthroplasty (THA) in an attempt to reduce the risk of prosthetic joint infection (PJI). However, its role versus plain cement remains controversial due to the potential risk of developing resistant organisms and potential excess costs incurred from its usage. We investigated the relationship of ALBC and plain cement in affecting outcome of revision surgery after primary THA.

Methodology

We conducted a retrospective study of data collected from National Joint Registry for England and Wales, Northern Ireland and the Isle of Man between 1st September 2005 until 31st August 2017. A logistic regression analysis model was used to investigate the association between ALBC versus plain cement and the odds ratio (OR) for revision, adjusting for age, ASA grade, bearing surfaces, head size and cup and stem fixation. Indications for revision recorded in NJR were considered in separate models.


C Heaver M Hyne JH Kuiper S Lewthwaite B Burston R Banerjee

Background

Greater trochanteric pain syndrome (GTPS) is a common problem affecting 10–25% of the population. Physiotherapy, anti-inflammatories, corticosteroid injections and surgery have all been described in the management of GTPS, all with limited, temporal success. Extracorporeal shockwave therapy (ESWT) has been proposed as a potential management option for this difficult presentation.

Method

We ran a prospective, 2 arm, single blinded, randomised control trial comparing focused shockwave therapy to an ultrasound guided corticosteroid injection. The primary outcome measure was the visual analogue pain score. Secondary outcome measures included the Harris hip score and Trendelenburg test for function; the SF-36 for quality of life (QoL); and a Likert scale question for a subjective assessment of symptom improvement.


GS Matharu F Berryman DJ Dunlop MP Revell A Judge DW Murray HG Pandit

Introduction

We investigated predictors of poor outcomes following metal-on-metal hip arthroplasty (MoMHA) revision surgery performed for adverse reactions to metal debris (ARMD), to help inform the revision threshold and type of reconstruction.

Patients and Methods

A retrospective cohort study was performed involving 346 MoMHAs revised for histologically confirmed ARMD at two specialist centres (245=hip resurfacing, 101=total hip arthroplasty). Numerous preoperative (blood metal ions and imaging) and intraoperative (findings, and components removed/implanted) factors were used to predict poor outcomes. Poor outcomes were postoperative complications (including re-revisions), 90-day mortality, and poor Oxford Hip Scores (<27/48). Multivariable logistic regression models for predicting poor outcomes were developed using stepwise selection methods.


JT Evans AW Blom AJ Timperley MJ Wilson A Sayers MR Whitehouse

Introduction

Analysis of registry data shows that few units achieve results better than 99·98% control limits. Implant selection is considered a predictor of outcome variation in joint replacement. We analysed the outcomes of a unit with statistically “better than expected” results and compared to all other units within the National Joint Registry for England, Wales, Northern Ireland and Isle of Man (NJR). We sought to determine whether improved implant survival following primary total hip replacement (THR) is a centre effect or mediated by implant selection.

Methods

We identified 664,761 THRs in the NJR. The exposure was the unit in which the THR was implanted and the outcome all-cause revision. Net failure was estimated using Kaplan-Meier and adjusted analyses used flexible parametric survival analysis.


K Logishetty B Rudran W Gofton P Beaule R Field JP Cobb

Background

For total hip arthroplasty (THA), cognitive training prior to performing real surgery may be an effective adjunct alongside simulation to shorten the learning curve. This study sought to create a cognitive training tool to perform direct anterior approach THA, validated by expert surgeons; and test its use as a training tool compared to conventional material.

Methods

We employed a modified Delphi method with four expert surgeons from three international centres of excellence. Surgeons were independently observed performing THA before undergoing semi-structured cognitive task analysis (CTA) before completing successive rounds of electronic surveys until consensus. The agreed CTA was incorporated into a mobile and web-based platform. Forty surgical trainees (CT1-ST4) were randomised to CTA-training or a digital op-tech with surgical videos, before performing a simulated DAA THA in a validated fully-immersive virtual reality simulator.


JN Lamb GS Matharu BH van Duren A Redmond A Judge RM West HG Pandit

Introduction

Intraoperative periprosthetic femoral fractures (IOPFF) lead to reduced implant survival. A deeper understanding of predictors enables surgeons to modify techniques and patient selection to reduce the risk of IOPFF. The aim of this study was to estimate predictors of IOPFF and each anatomical subtype (calcar crack, trochanteric fracture, femoral shaft fracture) during primary THA.

Methods

This retrospective cohort study included 793823 primary THAs between 2004 and 2016. Relative risks for patient, surgical and implant factors are estimated for any IOPFF fracture and for all anatomical subtypes of IOPFF.


JN Lamb SW King BH van Duren RM West HG Pandit

Background

Method of fixation in THA is a contentious issue, with proponents of either technique citing improved implant survival and outcomes. Current comparisons rely on insufficiently powered studies with short-term follow up or larger poorly controlled registry studies. Patient factors are considered a key variable contributing to the risk of implant failure. One way to overcome this confounder is to compare the survival of cementless and cemented THAs patients who have undergone bilateral THAs with cemented hip on one side and cementless hip on the other. We compared stem survival of patients who have bilateral THA with one cemented stem in one hip and a cementless stem in the contralateral hip in the National Joint Registry.

Methods

UK National Joint Registry is the largest registry of its kind in the world. This study included 2934 patients with 5868 THAs who underwent bilateral THAs s between 2003 and 2016. These patients had undergone bilateral sequential THAs within 3 years of each other: cemented THA on one side and cementless on the other, Patients had identical pre-operative American Society of Anaesthesiologists group for both THAs and same indication for surgery. Implant survival was compared using Cox regression with an endpoint of stem revision.


K Syam A Saraogi P Siney HW Jones B Purbach H Nagai P Kay

Background

Revision total hip arthroplasty (THA) is a challenging scenario following complex primary THA for developmental dysplasia of hip (DDH). This study envisages the long-term outcomes of revision DDH and the role of lateral structural support in socket fixation in these young patients who may require multiple revisions in their life-time.

Materials and methods

Hundred and eighteen consecutive cemented revision THAs with minimum follow up of 5 years following primary diagnosis of DDH operated by a single unit between January 1974 and December 2012 were analysed for their clinical and radiological outcomes.


R Takada S Whitehouse M Hubble MJ Wilson JR Howell AJ Timperley A Kassam

Introduction

Varus alignment of the femoral component in total hip arthroplasty (THA) is thought to be a risk factor for implant loosening and early revision surgery. The purpose of this study was to evaluate whether the Exeter stem tolerates varus alignment and assess if this theoretical malalignment has an influence on clinical outcomes.

Methods

A total of 4126 consecutive THAs were reviewed for patients between 2006 and 2012 to allow for a minimum five-year follow-up. To determine the effects of the stem alignment on results, the hips were classified into 3 groups on the basis of stem alignment in initial postoperative anteroposterior radiographs. The alignment of the stem was defined as neutral, valgus (≥ 3° of lateral deviation), or varus (≥ 3° of medial deviation). The primary outcome was all cause revision with patient related outcomes assessed with Oxford hip score pre and post-operatively.


B Tsang A Clarke P Dobson P Thomas S Jameson P Baker

Background

There is significant variation and inconsistencies in the current advice and information delivered to patients undergoing total hip replacement (THR). The aim of this study was to assess a locally developed web-based electronic resource system for patients undergoing total hip replacement (THR) surgery to see if this improves and standardises the content, structure, and delivery of information delivered to patients prior to and after surgery.

Patients/Materials and Methods

Prospective study with patients recruited in clinic when listed for THR surgery. Patients are emailed login details for the web based electronic resource system (GoWellHealth). The platform delivers content in a time-lined fashion and is individualised to the patient. Data gathered includes the number of patients registering to use this system, their engagement and use of the resources, and results from forms and questionnaires administered.


AM Kassam S Whitehouse MJ Wilson MW Hubble AJ Timperley JR Howell

Introduction

Rationing of orthopaedic services is increasingly being used by Care Commissioning Groups (CCG) within the United Kingdom to restrict the numbers of patients being referred for Total Hip Arthroplasty (THA). In Devon, only patients with an Oxford Hip Score (OHS) less than 20 are referred on for specialist Orthopaedic Review. The aim of this study was to look at long term outcomes after THA to see if this rationing has any rational base to justify its use

Methods

Consecutive patients undergoing THA in Exeter between 1996 and 2012 had OHS' collected prospectively pre-operatively and a minimum of 4 years post-operatively. These scores were analysed looking for trends in patient related outcome scores.


D Langton R Sidaginamale S Wells B Wainwright J Holland D Deehan T Joyce A Jafri A Nargol S Natu

Introduction

We aimed to identify genes associated with the development of ALVAL at relatively low levels of wear.

Methods

At our unit all patients undergoing revision of a MoM hip prosthesis have periprosthetic tissue samples graded for ALVAL. Explants undergo volumetric wear testing of the bearing and taper surfaces. We identified patients with moderate/severe ALVAL who had been exposed to lower than the median wear rate of all recorded patients who had developed ALVAL (<3mm3/year). This was termed the “ALVAL” group. We then identified all patients whose tissues had shown no signs of ALVAL. The patients in the two groups were sent buccal DNA collection kits. DNA was examined using next generation sequencing. Alleleic frequencies in the two groups were compared using Fisher's test and compared to a background UK population group (n=8514). We then conducted binary logistic regression with patient age, sex, primary source of debris (taper/bearing) and HLA genotype as the predictors. With the hypothesis that a cobalt/albumin metalloprotein acts as the epitope, we used validated binding prediction software to determine the relative affinities of the binding grooves created by different DQA1/DQB1 genetic combinations for albumin derived peptides. Given the protection that male sex and younger age appears to confer against ALVAL, we hypothesized that testosterone peptides may compete for these binding sites.


R King X Wang A Qureshi A Vepa U Rahman A Palit MA Williams M Elliott

Background

Over 10% of total hip arthroplasty (THA) surgeries performed in England and Wales are revision procedures1. Malorientation of the acetabular component in THA may contribute to premature failure due to mechanisms such as edge loading and prosthetic impingement. It is known that the pelvis flexes and extends during activities of daily living (ADLs), and excessive pelvic motion can contribute to functional acetabular malorientation. Preoperative radiographs can be performed to measure changes in pelvic tilt during ADLs to identify high risk individuals and inform surgical decision making. However, radiographs require time-consuming radiation exposure, and are unable to provide truly dynamic 3-dimensional analysis. The purpose of this study was to develop and evaluate a motion capture method using inertial measurement units (IMUs). This would provide a rapid, non-invasive analysis of pelvic tilt which could be used to support surgical planning.

Methods

Patients awaiting THA were fitted with a bespoke device consisting of a 3D-printed clamp which housed the IMU and positioned over the sacrum. A wide elastic belt was fitted around the patient's waist to keep the device in place. Movement data was transmitted wirelessly to a tablet computer. Pelvic tilt was measured in standing, flexed seated and step-up positions while undergoing X-rays with the IMU capturing the data in parallel. Statistical analysis included measures of correlation between the X-ray and IMU measurements.


K Logishetty B Rudran W Gofton P Beaule JP Cobb

Background

Virtual Reality (VR) uses headsets and motion-tracked controllers so surgeons can perform simulated total hip arthroplasty (THA) in a fully-immersive, interactive 3D operating theatre. The aim of this study was to investigate the effect of laboratory-based VR training on the ability of surgical trainees to perform direct anterior approach THA on cadavers.

Methods

Eighteen surgical trainees (CT1-ST4) with no prior experience of direct anterior approach (DAA) THA completed an intensive 1-day course (lectures, dry-bone workshops and technique demonstrations). They were randomised to either a 5-week protocol of VR simulator training or conventional preparation (operation manuals and observation of real surgery). Trainees performed DAA-THA on cadaveric hips, assisted by a passive scrub nurse and surgical assistant. Performance was measured on the Intercollegiate Surgical Curriculum Project (ISCP) procedure-based assessment (PBA), on a 9-point global summary score (Table 1). This was independently assessed by 2 hip surgeons blinded to group allocation. The secondary outcome measure was error in cup orientation from a predefined target (40° inclination and 20° anteversion).


G Pryce M Al-Hajjar R Wilcox J Thompson T Board S Williams

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). Kinematic data of activities associated with dislocation[2], such as stooping to pick an object from the floor was applied and incidences of impingement were recorded.

Predicted implant impingement was influenced by stem design. The coxa vara stem was predicted to cause implant impingement less frequently across the range of activities and cup orientations investigated, compared to the standard stem [Fig. 1]. The cup orientations predicted to cause impingement the least frequently were at lower inclination and anteversion angles, relative to the standard stem [Fig. 1]. The coxa vara stem included a collar, while the standard stem was collarless; additional analysis indicated that differences were due to neck angle and not the presence of a collar.

This study demonstrated that stem neck-shaft angle is an important variable in prosthetic impingement in THR and surgeons should be aware of this when choosing implants. Future work will consider further implant design and bone geometry variables. This tool has the potential for use in optimising stem design and position and could assist with patient specific stem selection based on an individual's activity profile.

For any figures or tables, please contact the authors directly.


F Raheman R Berber L Maercklin E Watson A Brown R Ashford

Introduction

Renal impairment following major surgery is a formidable complication. There is recent evidence suggesting increasing risk of progression to chronic kidney disease and mortality after transient renal impairment. We aimed to evaluate the impact of pre-operative comorbidities on long-term outcomes of renal-function following hip arthroplasty.

Method

Patients listed for hip arthroplasty were pre-assessed according to the Charlson-Comorbidity-index (CCI) in May 2017. Demographic data, established risk factors and preoperative renal-function were collected. Pre-existing renal dysfunction was classified using KDIGO CKD criteria. RIFLE AKIN scores were used to document post-operative renal impairment based on 7-day serum creatinine. Renal function was assessed at 30 day and 1 year. Risk for early and long-term-complications were determined by univariate and multivariate analysis. Mortality and kidney-disease-progression were estimated using Kaplan Meier plots


JN Lamb J Baetz P Messer-Hannemann A Redmond RM West MM Morlock HG Pandit

Background

Post-operative periprosthetic femoral fractures (PFF) are a devastating complication associated with high mortality and are costly. Few risk factors are modifiable apart from implant choice. The design features governing risk of PFF are unknown. We estimated the 90-day risk of revision for PFF associated with design features of cementless femoral stems and to investigate the effect of a collar on early PFF risk using a biomechanical in-vitro model.

Patients, materials and methods

337 647 primary THAs from the National Joint Registry (UK) were included in a multivariable survival and regression analysis to identify the adjusted hazard of PFF revision following primary THA using cementless stems. The effect of a collar in cementless THA on early PFF was evaluated in an in-vitro model using paired fresh frozen cadaveric femora.


L Dall'Ava H Hothi A Di Laura J Henckel P Shearing A Hart

Introduction

Three-dimensional (3D) printing of porous titanium implants marks a revolution in orthopaedics, promising enhanced bony fixation whilst maintaining design equivalence with conventionally manufactured components. No retrieval study has investigated differences between implants manufactured using these two methods. Our study was the first to compare these two groups using novel non-destructive methods.

Materials and methods

We investigated 16 retrieved acetabular cups divided into ‘3D printed’ (n = 6; Delta TT) and ‘conventional’ (n = 10; Pinnacle Porocoat). The groups were matched for age, time to revision, size and gender (Table 1). Reasons for revision included unexplained pain, aseptic loosening, infection and ARMD. Visual inspection was performed to evaluate tissue attachment. Micro-CT was used to assess clinically relevant morphometric features of the porous structure, such as porosity, depth of the porous layer, pore size and strut thickness. Scanning electron microscopy (SEM) was applied to evaluate the surface morphology.


A Palit R King Y Gu J Pierrepont Z Hart MT Elliott MA Williams

Background

It is not always clear why some patients experience recurrent dislocation following total hip arthroplasty (THA). In order to plan appropriate revision surgery for such patients, however, it is important to understand the specific biomechanical basis for the dislocation. We have developed a novel method to analyse the biomechanical profile of the THA, specifically to identify edge loading and prosthetic impingement, taking into account spinopelvic mobility. In this study we compare the results of this analysis in THA patients with and without recurrent dislocation.

Methods

Post-operative CT scans and lateral standing and seated radiographs of 40 THA patients were performed, 20 of whom had experienced postoperative dislocation. The changes in pelvic and femoral positions on the lateral radiographs were measured between the standing and seated positions, and a 3D digital model was then generated to simulate the movement of the hip when rising from a chair for each patient. The path of the joint reaction force (JRF) across the acetabular bearing surface and the motion of the femoral neck relative to the acetabular margin were then calculated for this “sit-to-stand” movement, in order to identify where there was risk of edge loading or prosthetic impingement.


T Harrison

Introduction

Pre-operative aspiration and culture is the gold standard for the diagnosis of peri-prosthetic infection.

This study aimed to ascertain the diagnostic accuracy of culture of joint aspiration with or without saline re-aspiration in the event of a dry-tap.

Patients/Materials & Methods

Retrospective analysis of 343 hip aspirations in patients deemed to have moderate-high risk of infection and ultimately proceeded to revision arthroplasty over 12 years at a large quaternary referral centre where pre-operative aspiration is routine.


JRT Pietrzak Z Maharaj K Sikhauli D van der Jagt L Mokete

Background

The prevalence of immunocompromised patients undergoing Total Hip Arthroplasty (THA) is increasing worldwide as a consequence of advances in treatment. HIV is presenting in an older population group and concerns of higher rates of infection, early failures and dangers posed to healthcare workers exist. This study is imperative to predict future burden of THA and make subsequent provisions

Objectives

The objective was to determine the seroprevalence of HIV in patients presenting for THA in an academic institution in a developing country. Secondarily, the aim was to determine if there is any difference in the seroprevalence of patients undergoing THA and TKA and finally to assess the status of disease control in seropositive patients eligible for TJA on pre-existing HAART.


JRT Pietrzak A Asare-Beidako K Sikhauli DR van der Jagt L Mokete

Introduction

Depression is a common co-morbidity in Total Hip Arthroplasty (THA). Chronic pain and depression influence one another. Postoperative outcomes and satisfaction rates are affected by depression.

Objectives

The aim of the study was to determine the impact of pre-operative depression on patient functional outcomes and satisfaction rates after THA. A secondary objective was to assess potential change in the incidence of depression at mid-term post-operative follow-up.


F Syed M Magra P Saunders A Ugwuoke S Young

Introduction

Primary fixation in uncemented Total Hip Replacement (THR) is achieved by implanting an appropriately sized stem. Last year, in our pilot study, we classified undersizing & reported the incidence of subsidence & radiolucent lines (RLL) in undersized uncemented stems. Now we report on a larger cohort of patients, reporting undersizing and its association with radiolucent lines and subsidence. Secondarily we report on the effect of using a collar, patients' BMI, and in a smaller group the five-year failure rate.

Methods

A retrospective review of electronic records of 1337 cases who underwent THR using the Corail stem was carried out. 1204 (Collared 1042, Uncollared 162) had a minimum follow up of 1 year, 693 of those had a follow up of at least 5 years. Radiological review was carried out by 2 independent investigators.


L Windell A Haque A Kulkarni E Alabort D Barba R Reed HP Singh

Background

Periprosthetic femoral fractures following total hip arthroplasty are relatively uncommon but are associated with significant morbidity. With an increasing number of total hip arthroplasties being carried out in an aging population we need to ensure correct implants are chosen for our patients. A recent review of NJR data suggested a significantly higher revision risk for the Zimmer CPT stems due to periprosthetic fractures when compared to the Stryker Exeter stems.

Objectives

Our aim was to compare the biomechanics of periprosthetic fractures around the CPT and Exeter V40 stems in a composite saw bone model to identify if a difference in fracture risk exists between the two stems. We also compared the engineering design of the two implants in order to analyse the possible effect this may have on fracture risk.


J Viner DH Sochart

Introduction

The Opera acetabular component (Smith & Nephew Ltd) shares many same design features with the Ogee (Depuy Int.). Differences are a malleable flange, instrumentation designed to improve cement pressurisation and the specifics of the UHMW-poly used.

Methods

Data was collected prospectively on 419 consecutive replacements (390 patients), performed between March 2000 and February 2005. A posterior approach was used, and the acetabulum was prepared with multiple key holes. Palacos-R bone cement containing Gentamicin was used with a cement pressuriser.


A Ewen K Deep A Jeldi H Leonard

Introduction

Body mass index (BMI) is a topical area of interest in the field of lower limb arthroplasty. It has been well established that BMI can influence post-operative outcomes. This study compares post-operative outcomes, including satisfaction rates, length of stay (LOS) and radiographic findings in different BMI groups following total hip arthroplasty (THA).

Methods

We retrospectively evaluated all non-navigated THAs performed at our institution from 2006–2016. Case-notes were reviewed for dichotomised satisfaction score, LOS and radiographic parameters including inclination, anteversion, limb length discrepancy (LLD) and offset discrepancy. Patients were classified into 4 groupings based on BMI (underweight (<24.5), healthy (24.5–30), obese (30–40), severely obese (>40)). Appropriate statistical analyses were performed to identify between group differences.


I Vanhegan A Martin R Gundle A Taylor B Kendrick

Introduction

We are a high-volume arthroplasty unit performing over 800 primary THRs annually at an approximate reimbursement of £6.5 million to the Trust. 70% are hybrid and we have been using the Taperfit - Trinity combination (Corin, Cirencester) since March 2016. We aimed to investigate the potential cost-savings and clinical benefits of instrument rationalisation using this system following GIRFT principles.

Methods

Taperfit (ODEP 10A) is a polished, collarless, double tapered stem available in multiple sizes/offsets. Trinity is a hemispherical porous titanium cementless shell. A prospective audit of implant size was performed for the first 50 cases. Based on these findings, instruments were reduced to a single tray per component based on predicted size, named ‘Corin Hip for the Osteoarthritic Patient’ (CHOP). A further re-audit was performed to confirm correct tray constituent sizes. Financial data were calculated using known TSSU costs of approximately £50 per tray.


I Afzal S Radha G Stafford T Smoljanović RE Field

Patients need to know the benefits, risks and alternatives to any proposed treatment. Surgeons discussing the risk of a revision procedure becoming necessary, after a hip replacement can draw upon the orthopaedic literature and arthroplasty registries for long-term implant survival. However, early revision is required in a minority of cases. We have investigated the probability for revision hip replacement patients in terms of time-point and indication for revision.

Of the 9,411 Primary Total Hip Replacements (THR), undertaken by 22 surgeons, over an eleven-year period, between January 2004 and March 2015, 1.70% (160) were subsequently reported to the National Joint Registry (NJR) as revised. Each revision case was reviewed under the supervision of senior hip specialist consultants. The modes of failure of were identified through clinical, laboratory and imaging (x-rays, CT, MRI and Isotope scans) studies.

The revision rate for THRs was 0.58% in the first year. This was statistically higher than all subsequent years, P-Value <0.001. There was no statistical difference between any pair of subsequent years. Thereafter, the average revision rate was 0.30% per annum. The odds ratio for revision during the first post–operative year against the subsequent year average was 1.67.

The indications for the early hip revisions in the first three years were infection, dislocation and peri-prosthetic fracture. The data from this study can help better inform patients of the revision rates after a primary THR and allow surgeons to develop implant surveillance strategies among high-risk patients.


E Holloway S Buckley

Introduction

We aim to evaluate the outcome of debridement and implant retention (DAIR) procedures performed for primary total hip prosthetic joint infections (PJI) and to identify factors correlating with a successful outcome.

Methods

Patients were identified from theatre records. Electronic and paper notes were reviewed.