Current advice regarding implant choice is based on estimates of cost-benefit derived from implant survival to an endpoint of revision. Current estimates do not account for many implant failures which are treated with non-revision surgery and may not be accurate. The aim of this study was to estimate survival of major stem implant design groups to an endpoint of reoperation.

Primary total hip replacement and linked revision form the National Joint Registry (NJR) and Hospital Episode Statistics (HES) data linked by unique identifier were used. Survival of femoral implant groups (cemented stainless steel polished taper [PTSS], cemented cobalt chrome polished taper [PTCC], cemented composite beam [CB], collarless cementless [NCOL] and collared cementless [COL]) was estimated using Kaplan-Meier method.

809,832 patients with valid NJR and HES data from England, were included. Cumulative failure at ten years for PTSS increased overall from 2.9% (95%CI 2.8–2.9) to 3.6% (95%CI 3.6–3.7) after inclusion of reoperations. Cumulative failure at ten years for PTSS increased from 2.5% (95%CI 2.5–2.6) to 3.3% (95%CI 3.2–3.4), for PTCC increased from 3.8% (95%CI 3.5–4.0) to 5.4% (95%CI 5.1–5.6), for CB increased from 3.1% (95%CI 2.9–3.3) to 4.1% (95%CI 3.8–4.3), for NCOL increased from 3.4% (95%CI 3.3–3.5) to 3.9% (95%CI 3.8–4.0), and for COL increased from 2.5% (95%CI 2.4–2.6) to 3.1% (95%CI 2.9–3.2), after inclusion of reoperations.

Re-operation for internal fixation is as significant life event for the patient as revision. When a more inclusive metric is used, the patient and clinician's perspective on what constitutes a GIRFT implant may not be the same. Further work is required to update implant selection guidance in view of the change in implant performance.

Current estimates of periprosthetic fracture risk associated with femoral implants is mostly limited to revision only estimates and does not accurately represent stem performance. The aim of this study was to estimate the risk of surgically treated post-operative periprosthetic femoral fracture (POPFF) more accurately associated with frequently used femoral implants used for total hip arthroplasty (THA).

A cohort study of patients who underwent primary THA in England between January 1, 2004, and December 31, 2020. Periprosthetic fractures were identified from prospectively collected revision records and national procedure coding records. Survival modelling was used to estimate POPFF incidence rates, adjusting for potential confounders. Subgroup analyses were performed for patients over 70 years, with non-osteoarthritic indications, and neck of femur fracture.

POPFF occurred in 0.6% (5100/809,832) of cases during a median (IQR) follow up of 6.5 (3.9 to 9.6) years. The majority of POPFF were treated with fixation after implantation of a cemented stem. Adjusted patient time incidence rates (PTIR) for POPFF varied by stem design, regardless of cement fixation. Cemented composite beam stems (CB stems) demonstrated the lowest risk of POPFF. Collared cementless stems had an equivalent or lower rate of POPFF versus the current gold standard polished taper slip cemented stem.

POPFF account for a quarter of all revisions following primary THA. Cemented CB stems are associated with the lowest POPFF risk. Stem design is strongly associated with POPFF risk, regardless of the presence of cement. Surgeons, policymakers, and patients should consider these findings when recommending femoral implants in those most at risk of POPFF.

Aims

The aim of this study was to compare open reduction and internal fixation (ORIF) with revision surgery for the surgical management of Unified Classification System (UCS) type B periprosthetic femoral fractures around cemented polished taper-slip femoral components following primary total hip arthroplasty (THA).

Periprosthetic femoral fracture (PFF) incidence following hip replacement surgery continues to rise. There is a national drive to centralise PFF treatment within specialist centres to improve clinical outcomes and cost-effectiveness. The financial implications of treating PFFs must be analysed to guide allocation of funding.

Data were collected for 129 PFFs admitted from 02/04/2014–19/05/2020. Financial data were provided by the Patient Level Information and Costing Systems (PLICS) team. Primary outcomes were cost, revenue and margin for each PFF. Additional data were collected on length of stay (LOS), critical care requirements and clinical outcomes. Statistical comparisons were made between treatment type (fixation vs revision). Significance was set to p<0.05.

Across the entire cohort, total cost was £2,389,901, total revenue was £1,695,435 and total loss was £694,481. Highest costs were ward stay (£714,591), theatre utilisation (£382,625), and overheads (£249,110). Median cost was £15,863 (IQR, £11,092-£22,221), median revenue was £11,305 (IQR, £7,147-£15,222) and median loss was £3,795 (IQR, £605-£8687). Median LOS was 21 days (IQR 13–34) and 28.7% patients required critical care admission.

Ninety-six patients were treated operatively with either fixation (n=53) or revision (n=43). Median operating time was lower for fixation versus revision (132 [IQR, 115–185] vs 201 [IQR, 159–229] minutes, p=0.001). Median cost (£17,455 [IQR, £13,095-£22,824] vs £17,399 [£13,394-£23,404]) and median loss (£5,774 [IQR, £2,092-£10,472] vs £3,860 [IQR, £96-£7,601]) were similar for fixation and revision (p=0.99 and p=0.18, respectively). Median revenue was greater for revision versus fixation (£13,925 [IQR, £11,294-£17,037] vs £12,160 [IQR, £8,486-£14,390], p=0.02). There was no difference in LOS (21 [13–34] vs 21 [14–30] days, p=0.94), critical care requirements (20 [37.7%] vs 11 [25.6%], p=0.30), reoperations (3 [5.7%] vs 6 [14.0%], p=0.29], local complications (8 [15.1%) vs 12 [27.9%], p=0.20) or systemic complications (11 [20.8%] vs 11 [25.6%], p=0.75) between fixation and revision.

PFF treatment costs are high with inadequate reimbursement through tariff. Work is needed to address this disparity and reduce costs associated with LOS, theatre utilisation and implants. Treatment cost should not be used when deciding between fixation and revision surgery.

Cemented total hip replacement (THR) provides excellent outcomes and is cost-effective. Polished taper-slip (PTS) stems demonstrate successful results and have overtaken traditional composite-beam (CB) stems. Recent reports indicate they are associated with a higher risk of postoperative periprosthetic femoral fracture (PFF) compared to CB stems. This study evaluates risk factors influencing fracture characteristics around PTS and CB cemented stems.

Data were collected for 584 PFF patients admitted to eight UK centres from 25/05/2006-01/03/2020. Radiographs were assessed for Unified Classification System (UCS) grade and Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association (AO/OTA) type. Statistical comparisons investigated relationships by age, gender, and stem fixation philosophy (PTS versus CB). The effect of multiple variables was estimated using multinomial logistic regression to estimate odds ratios (OR) with 95% confidence intervals (CI).

Median (IQR) age was 79.1 (72.0–86.0) years, 312 (53.6%) patients were female, and 495 (85.1%) stems were PTS. The commonest UCS grade was type B1 (278, 47.6%). The commonest AO/OTA type was spiral (352, 60.3%). Metaphyseal-split fractures occurred only with PTS stems with an incidence of 10.1%. Male gender was associated with a five-fold reduction in odds of a type C fracture (OR 0.22, 95% CI 0.12 to 0.41, p<0.001) compared to a type B fracture. CB stems were associated with significantly increased odds of transverse fracture (OR 9.51, 95% CI 3.72 to 24.34, p <0.001) and wedge fracture (OR 3.72, 95% CI 1.16 to 11.95, p <0.05) compared to PTS stems.

This is the largest study investigating PFF characteristics around cemented stems. The commonest fracture types are B1 and spiral fractures. PTS stems are exclusively associated with metaphyseal-split fractures, but their incidence is low. Males have lower odds of UCS grade C fractures compared to females. CB stems had higher odds of bending type fractures (transverse and wedge) compared to PTS stems. Biomechanical testing is needed for validation and investigation of modifiable factors which may reduce the risk of unstable fracture patterns requiring complex revision surgery over internal fixation.

The aim of this study is to determine whether fixation, as opposed to revision arthroplasty, can be safely used to treat reducible Vancouver B type fractures in association with a cemented collarless polished tapered femoral stem (the Exeter).

This is a retrospective cohort study of 152 operatively managed consecutive unilateral Vancouver B fractures involving Exeter stems. 130 were managed with open reduction and internal fixation (ORIF) and 22 with revision arthroplasty. Radiographs were assessed and classified by 3 observers. The primary outcome measure was revision of ≥1 component. Kaplan Meier survival analysis was performed. Logistic regression was used to identify risk factors for revision following ORIF. Secondary outcomes included any reoperation, complications, blood transfusion, length of hospital stay and mortality.

Fractures (B1 n=74 (49%); B2 n=50 (33%); and B3 n=28 (18%)) occurred at mean 6.7±10.4 years after primary THA (n=143) or hemiarthroplasty (n=15). Mean follow up was 6.5 ±2.6 years (3.2 to 12.1). Rates of revision and reoperation were significantly higher following revision arthroplasty compared to ORIF for B2 (p=0.001) fractures and B3 fractures (p=0.05). Five-year survival was significantly better following ORIF: 92% (86.4 to 97.4 95%CI) Vs 63% (41.7 to 83.3), p<0.001. No independent predictors of revision following ORIF were identified: fixation of B2 or B3 fractures was not associated with an increased risk of revision. Dislocation was the commonest mode of failure after revision arthroplasty. ORIF was associated with reduced blood transfusion requirement and reoperations, but there were no differences in medical complications, hospital stay or mortality between surgical groups.

When the bone-cement interface was intact and the fracture was anatomically reducible, Vancouver B2 fractures around Exeter stems can be treated with fixation as opposed to revision arthroplasty. Fixation of Vancouver B3 fractures can be performed in frail elderly patients without increasing revision risk.

In March 2020, the World Health Organisation declared the COVID-19 outbreak a pandemic. Multiple new guidelines were proposed and existing models of social, domestic and hospital care altered. Most healthcare systems were largely unprepared for this and this pandemic has tested their adaptability. This study is aimed at assessing the impact of covid-19 on the demographics, presentation and clinical management of patients with proximal femoral (hip) fractures.

This retrospective multi-centre cohort study compared all patients admitted with hip fractures, between 1^st March and 30th May 2019 (Group PC: Pre-Covid) with hip fracture patients admitted over the same time period during the pandemic in 2020 (Group C: Covid). The data was obtained from the hospitals' local and National Hip Fracture Databases. Mortality data was checked with the Office for National Statistics (ONS). Primary outcomes were time to theatre, in-patient length of stay and 30-day mortality.

580 patients were included (304 PC, 276 C). Patient Charlson comorbidity index and Nottingham Hip Fracture scores were broadly similar across the two cohorts. There was a significant reduction in percentage of total hip replacements in Group C (11% to 5%, p=0.006). There was an increase in conservative management in group C (1% to 5%, p=0.002). The time to theatre was significantly delayed in Group C (43.7 hours C versus 34.6 hours PC, p<0.001). Overall length of hospital stay was similar in both groups (16.6 days PC versus 15 days C, p=0.089). 30-day mortality rate in Group C was 9.8% compared to 8.2% in Group PC (p=0.431), but for covid (+) patients it was significantly higher at 38.2% versus 5.8% in covid (−) patients (p<0.001).

This is one of the largest multi-centre comparative cohort study in the literature to date, examining the impact of the covid-19 pandemic on the management of hip fracture patients. Whilst mortality rates were similar in both groups, covid patients were almost seven times more likely to die, reflecting the seriousness of the covid-19 infection and its sequelae in such elderly, vulnerable patients.

Post-operative periprosthetic fracture of the femur (POPFF) is a growing problem associated with increased mortality. Most registry derived estimates of mortality only record patients who undergo revision and cohort studies are generally limited to a single center, which makes comparison for the purposes of service improvement difficult. The aim of this study is to perform a systematic review and meta-analysis of cohort studies reporting mortality following POPFF in the last decade.

Study methodology was peer-reviewed (PROSPERO: CRD42020170819). Literature search was conducted using Medline and EMBASE. Primary exposure was the diagnosis of POPFF, and the primary outcome measure was all-cause mortality: whilst an inpatient, within 30-days, within 90-days and within one year of POPFF. Proportion of patients dying (95% CI [confidence interval]) was estimated using metaregression. Results were compared to mortality following neck of femur fracture (NOF) from international NOF registry data.

4841 patients from 35 cohort studies were included. Study quality was generally low with a majority limited to a single centre. Weighted mean follow-up was 2.3 years and the most common POPFF was UCS B. Pooled proportion dying as an inpatient was 2.4% (95% CI 1.6% to 3.4%). Pooled proportion dying within 30 days was 3.3% (95% CI 2.0% to 5.0%). Pooled proportion dying within 90 days was 4.8% (95% CI 3.6% to 6.1%). Pooled proportion dying within one year was 13.4% (95% CI 11.9% to 14.8%). Mortality following POPFF was similar to that of NOF up to 30 days, but better at one year.

3.3% of patients die following POPFF within 30 days of injury. Mortality is similar to that experienced by patients following NOF up to 30 days, but better at one year, which may represent the lower underlying risk of death in the POPFF cohort. These results may form the basis for evaluation of services treating POPFF in the future.

There is a strong association between the presence of a calcar collar on a cementless stem and a reduced risk of revision surgery for periprosthetic fracture of the femur (PFF). A medial calcar collar may act to reduce relative movement between the implant and femur during PFF, through calcar-collar contact (CCC). The aims were:

Estimate the effect of CCC on periprosthetic fracture mechanics.

Three groups of six composite femurs were implanted with a fully coated collared cementless femoral stem. Neck resection differed between groups (group 1 = no additional resection, group 2 = 3mm additional resection, group 3 = 6mm additional resection). PFF were simulated using a previously published technique. Fracture torque and rotational displacement were measured and torsional stiffness and rotational work prior to fracture were estimated. Results between trials where CCC did and did not occur where compared using Mann-Whitney U tests. Logistic regression estimated the odds (OR) of failing with 95% confidence interval (CI) to achieve CCC for a given initial separation.

Where CCC occurred fracture torque was greater (47.33 [41.03 to 50.45] Nm versus 38.26 [33.70 to 43.60] Nm, p= 0.05) and torsional stiffness was greater (151.38 [123.04 to 160.42] rad.Nm⁻¹ versus 96.86 [84.65 to 112.98] rad.Nm⁻¹, p <0.01).

CCC was occurred in all cases in group one, 50% in group two and 0% in group three. OR of failure to obtain CCC increased 3.8 fold (95% CI 1.6 to 30.2, p <0.05) for each millimetre of separation.

Resistance to fracture and construct stiffness increased when a the collar made contact with the calcar prior to fracture and the chances of contact decrease with increasing initial separation at the time of implantation. Surgeons should aim to achieve a calcar-collar distance of less than 1mm following implantation to ensure CCC and to reduce the risk of fracture

Aims

This aim of this study was to assess the reliability and validity of the Unified Classification System (UCS) for postoperative periprosthetic femoral fractures (PFFs) around cemented polished taper-slip (PTS) stems.

Aims

This study evaluates risk factors influencing fracture characteristics for postoperative periprosthetic femoral fractures (PFFs) around cemented stems in total hip arthroplasty.

Aims

The aim of this study was to determine whether fixation, as opposed to revision arthroplasty, can be safely used to treat reducible Vancouver B type fractures in association with a cemented collarless polished tapered femoral stem (the Exeter).

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.

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.

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.

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.

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.

Introduction

Reverse hybrid total hip replacement (THR) offers significant theoretical benefits but is uncommonly used. Our primary objective was to evaluate implant survival with all cause revision and revision for aseptic loosening of either component as endpoints.

Pseudotumours have recently been reported in non-metal-on-metal total hip replacements (non-MoM THRs), however the magnitude and risk factors for this complication are unknown, as is the outcome of its treatment.

3340 primary THR undergoing revision for pseudotumour between 2008 and 2015 were identified in the National Joint Registry for England and Wales. 7.5% (n=249) of these pseudotumour revisions, had non-MoM bearing surfaces. The risk of revision for pseudotumour in non-MoM hips was 0.032% (249/789,397; 95% CI 0.028%–0.036%). The risk of pseudotumour revision was 2.35 times (95% CI 1.76–3.11) higher in ceramic-on-ceramic compared with hard-on-soft bearings, and 2.80 times (95% CI 1.74–4.36) higher in 36mm metal-on-polyethylene bearings compared to 28mm and 32mm metal-on-polyethylene bearings.

The outcome of revision for pseudotumour non-MoM hips was studied in 185 hips. 13.5% (n=25) had re-revisions at a mean of 1.2 years (range 0.1–3.1 years). Infection (32%), dislocation/subluxation (24%), and aseptic loosening (24%) were the commonest indications for re-revision. The 4-year survival rate was 83.8% (95% CI=76.7%–88.9%). Multiple revision indications (Hazard Ratio (HR)=2.78; 95% CI=1.03–7.49) and incomplete revision procedures (HR=5.76; 95% CI=1.28–25.9) increased the risk of re-revision

Although the overall risk of revision for pseudotumour in non-MoM THRs is low, the risk is increasing and is significantly higher in ceramic-on-ceramic and large head metal-on-polyethylene THR. These revisions have a high early failure rate.

Outcomes following metal-on-metal hip replacement (MoMHR) revision surgery for adverse reactions to metal debris (ARMD) have been poor, and inferior compared with non-ARMD revisions. Subsequently, surgeons and worldwide authorities widely recommended early revision for ARMD, with a lower surgical threshold adopted. However, the impact of early surgery for ARMD is unknown. We compared the rates of adverse outcomes following MoMHR revision surgery in matched ARMD and non-ARMD patients.

We performed a retrospective observational study using data from the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man. All MoMHR patients subsequently undergoing revision surgery for any indication between August 2008 and August 2014 were eligible. ARMD and non-ARMD revisions were matched one-to-one for multiple potential confounding factors using propensity scores. Adverse outcomes following revision surgery (intra-operative complications, mortality, re-revision surgery) were compared between matched groups using regression analysis.

In 2,576 matched MoMHR revisions (ARMD=1,288 and non-ARMD=1,288), intra-operative complications were similar between ARMD (2.4%) and non-ARMD (2.5%) revisions (odds ratio=0.97, 95% CI=0.59–1.60; p=0.899). All-cause mortality rates were lower following ARMD revision compared with non-ARMD revision (hazard ratio (HR)=0.43, 95% CI=0.22–0.86; p=0.018). All-cause re-revision rates were lower following ARMD revision compared with non-ARMD revision (HR=0.52, 95% CI=0.36–0.75; p<0.001). Compared with ARMD revision (5-years=94.3%), MoMHR revisions for infection (5-years=81.2%) and dislocation/subluxation (5-years=81.9%) had the lowest implant survival rates.

Contrary to previous observations, MoMHRs revised for ARMD have approximately half the risk of re-revision and death compared to non-ARMD revisions. We suspect worldwide regulatory authorities have positively influenced outcomes following ARMD revision by widely recommending that surgeons exercise a lower revision threshold.

Our findings suggest the threshold for ARMD revision surgery need not be lowered further. The high risk of failure following MoMHR revision for infection and dislocation is concerning.

Recent studies have demonstrated that implant-specific blood metal ion thresholds exist in unilateral and bilateral metal-on-metal (MoM) hip arthroplasty patients, with these thresholds being most effective for identifying patients at low-risk of adverse reactions to metal debris (ARMD). We investigated whether these new blood metal ion thresholds could effectively identify patients at risk of ARMD in an external cohort of MoM hip arthroplasty patients.

We performed a validation study involving 803 MoM hip arthroplasties implanted in 710 patients at three European centres (323=unilateral Birmingham Hip Resurfacing (BHR); 93=bilateral BHR; 294=unilateral Corail-Pinnacle). All patients underwent whole blood metal ion sampling. Patients were divided into those with ARMD (revised for ARMD or ARMD on imaging; n=75), and those without ARMD (n=635). Previously devised implant-specific blood metal ion thresholds (cobalt=2.15μg/l for unilateral BHR; maximum cobalt or chromium=5.5μg/l for bilateral BHR; cobalt=3.57μg/l for unilateral Corail-Pinnacle) were applied to the validation cohort, with receiver operating characteristic curve analysis used to establish the discriminatory characteristics for each respective threshold.

The area under the curve, sensitivity, specificity, positive predictive value and negative predictive value for distinguishing between patients with and without ARMD for each implant-specific threshold were respectively: unilateral BHR=89.4% (95% CI=82.8%-96.0%), 78.9%, 86.7%, 44.1%, 96.9%; bilateral BHR=89.2% (95% CI=81.3%-97.1%), 70.6%, 86.8%, 54.5%, 93.0%; unilateral Corail-Pinnacle=76.9% (95% CI=63.9%-90.0%), 65.0%, 85.4%, 24.5%, 97.1%. The 7μg/l UK MHRA threshold missed significantly more patients with ARMD compared with the implant-specific thresholds (4.9% vs. 2.8%; p=0.0003).

This external multi-centre validation study has confirmed that MoM hip arthroplasty patients with blood metal ion levels below newly devised implant-specific thresholds have a low-risk of ARMD. Compared to implant-specific thresholds, the currently proposed fixed MHRA threshold missed more patients with ARMD.

We recommend using implant-specific thresholds over fixed thresholds when managing MoM hip arthroplasty patients.

Recent studies have reported on non-metal-on-metal hip arthroplasty (non-MoMHA) patients requiring revision surgery for adverse reactions to metal debris (ARMD). Although the outcomes following revision surgery for ARMD in MoMHA patients are known to generally be poor, little evidence exists regarding outcomes following non-MoMHA revision surgery performed for ARMD. We determined the outcomes following non-MoMHA revision surgery performed for ARMD, and identified predictors of re-revision.

We performed a retrospective observational study using data from the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man. All primary non-MoMHA patients who subsequently underwent revision surgery for ARMD between 2008–2014 were included (n=185). Outcome measures following ARMD revision were intraoperative complications, mortality, and re-revision surgery. Predictors of re-revision surgery were identified using Cox regression analysis.

Intra-operative complications occurred in 6.0% (n=11) of ARMD revisions. The cumulative 4-year patient survival rate was 98.2% (95% CI=92.9–99.5%). Re-revision surgery was performed in 13.5% (n=25) of hips at a mean time of 1.2 years (range 0.1–3.1 years) following ARMD revision. Infection (32%), dislocation/subluxation (24%), and aseptic loosening (24%) were the commonest re-revision indications. The cumulative 4-year implant survival rate was 83.8% (95% CI=76.7%-88.9%). Significant predictors of re-revision were: multiple revision indications (Hazard Ratio (HR)=2.78; 95% CI=1.03–7.49; p=0.043), incomplete revision procedures (including modular component exchange only) (HR=5.76; 95% CI=1.28–25.9; p=0.022), and ceramic-on-polyethylene revision bearings (HR=3.08; 95% CI=1.01–9.36; p=0.047).

Non-MoMHA patients undergoing ARMD revision have a high short-term risk of re-revision. Infection, dislocation/subluxation, and aseptic loosening were the commonest re-revision indications. Furthermore, important and potentially modifiable predictors of future re-revision were identified.

Although the poor prognostic factors identified require validation in future studies, our findings may be used to counsel patients about the risks associated with ARMD revision surgery, and guide decisions about the reconstructive procedure.

Aims

Periprosthetic fracture (PF) after primary total hip arthroplasty (THA) is an uncommon but potentially devastating complication. This study aims to investigate the influence of cemented stem designs on the risk of needing a revision for a PF.

Introduction

The impact of pseudotumours associated with metal-on-metal hip resurfacings (MoMHRs) within the second decade is unknown. We investigated: (1) the incidence and risk factors for all-cause and pseudotumour revision following MoMHR at 15-years follow-up, and (2) whether risk factors were gender specific.

Introduction

This study aimed to: (1) compare published follow-up guidelines for metal-on-metal (MoM) hip patients and analyse protocols in relation to current evidence, and (2) assess the financial implications of these guidelines.

We assessed the orientation of the acetabular component in 1070 primary total hip arthroplasties with hard-on-soft, small diameter bearings, aiming to determine the size and site of the target zone that optimises outcome. Outcome measures included complications, dislocations, revisions and ΔOHS (the difference between the Oxford Hip Scores pre-operatively and five years post-operatively). A wide scatter of orientation was observed (2sd 15°). Placing the component within Lewinnek’s zone was not associated withimproved outcome. Of the different zone sizes tested (± 5°, ± 10° and ± 15°), only ± 15° was associated with a decreased rate of dislocation. The dislocation rate with acetabular components inside an inclination/anteversion zone of 40°/15° ± 15° was four times lower than those outside. The only zone size associated with statistically significant and clinically important improvement in OHS was ± 5°. The best outcomes (ΔOHS > 26) were achieved with a 45°/25° ± 5° zone.

This study demonstrated that with traditional technology surgeons can only reliably achieve a target zone of ±15°. As the optimal zone to diminish the risk of dislocation is also ±15°, surgeons should be able to achieve this. This is the first study to demonstrate that optimal orientation of the acetabular component improves the functional outcome. However, the target zone is small (± 5°) and cannot, with current technology, be consistently achieved.

Cite this article: Bone Joint J 2015;97-B:164–72.

Recent events have highlighted the importance of implant design for survival and wear-related complications following metal-on-metal hip resurfacing arthroplasty. The mid-term survival of the most widely used implant, the Birmingham Hip Resurfacing (BHR), has been described by its designers. The aim of this study was to report the ten-year survival and patient-reported functional outcome of the BHR from an independent centre.

In this cohort of 554 patients (646 BHRs) with a mean age of 51.9 years (16.5 to 81.5) followed for a mean of eight years (1 to 12), the survival and patient-reported functional outcome depended on gender and the size of the implant. In female hips (n = 267) the ten-year survival was 74% (95% confidence interval (CI) 83 to 91), the ten-year revision rate for pseudotumour was 7%, the mean Oxford hip score (OHS) was 43 (sd 8) and the mean UCLA activity score was 6.4 (sd 2). In male hips (n = 379) the ten-year survival was 95% (95% CI 92.0 to 97.4), the ten-year revision rate for pseudotumour was 1.7%, the mean OHS was 45 (sd 6) and the mean UCLA score was 7.6 (sd 2). In the most demanding subgroup, comprising male patients aged < 50 years treated for primary osteoarthritis, the survival was 99% (95% CI 97 to 100).

This study supports the ongoing use of resurfacing in young active men, who are a subgroup of patients who tend to have problems with conventional THR. In contrast, the results in women have been poor and we do not recommend metal-on-metal resurfacing in women. Continuous follow-up is recommended because of the increasing incidence of pseudotumour with the passage of time.

Pseudotumour is a rare but important complication of metal-on-metal hip resurfacing that occurs much more commonly in women than in men. We examined the relationship between head-neck ratio (HNR) and pseudotumour formation in 18 resurfaced hips (18 patients) revised for pseudotumour and 42 asymptomatic control resurfaced hips (42 patients).

Patients in whom pseudotumour formation had occurred had higher pre-operative HNR than the control patients (mean 1.37 (sd 0.10) vs mean 1.30 (sd 0.08) p = 0.001). At operation the patients with pseudotumours had a greater reduction in the size of their femoral heads (p = 0.035) and subsequently had greater neck narrowing (mean 10.1% (sd 7.2) vs mean 3.8% (sd 3.2) p < 0.001). No female patient with a pre-operative HNR ≤ 1.3 developed a pseudotumour.

We suggest that reducing the size of the femoral head, made possible by a high pre-operative HNR, increases the risk of impingement and edge loading, and may contribute to high wear and pseudotumour formation. As the incidence of pseudotumour is low in men, it appears safe to perform resurfacing in men. However, this study suggests that it is also reasonable to resurface in women with a pre-operative HNR ≤ 1.3.

Pseudotumours are a rare complication of hip resurfacing. They are thought to be a response to metal debris which may be caused by edge loading due to poor orientation of the acetabular component. Our aim was to determine the optimal acetabular orientation to minimise the risk of pseudotumour formation.

We matched 31 hip resurfacings revised for pseudotumour formation with 58 controls who had a satisfactory outcome from this procedure. The radiographic inclination and anteversion angles of the acetabular component were measured on anteroposterior radiographs of the pelvis using Einzel-Bild-Roentgen-Analyse software. The mean inclination angle (47°, 10° to 81°) and anteversion angle (14°, 4° to 34°) of the pseudotumour cases were the same (p = 0.8, p = 0.2) as the controls, 46° (29° to 60°) and 16° (4° to 30°) respectively, but the variation was greater. Assuming an accuracy of implantation of ± 10° about a target position, the optimal radiographic position was found to be approximately 45° of inclination and 20° of anteversion. The incidence of pseudotumours inside the zone was four times lower (p = 0.007) than outside the zone.

In order to minimise the risk of pseudotumour formation we recommend that surgeons implant the acetabular component at an inclination of 45° (± 10) and anteversion of 20° (± 10) on post-operative radiographs. Because of differences between the radiographic and the operative angles, this may be best achieved by aiming for an inclination of 40° and an anteversion of 25°.

Metal-on-metal hip resurfacing is commonly performed for osteoarthritis in young active patients. We have observed cystic or solid masses, which we have called inflammatory pseudotumours, arising around these devices. They may cause soft-tissue destruction with severe symptoms and a poor outcome after revision surgery. The aim of this study was to determine the incidence of and risk factors for pseudotumours that are serious enough to require revision surgery.

Since 1999, 1419 metal-on-metal hip resurfacings have been implanted by our group in 1224 patients; 1.8% of the patients had a revision for pseudotumour. In this series the Kaplan-Meier cumulative revision rate for pseudotumour increased progressively with time. At eight years, in all patients, it was 4% (95% confidence interval (CI) 2.2 to 5.8). Factors significantly associated with an increase in revision rate were female gender (p < 0.001), age under 40 (p = 0.003), small components (p = 0.003), and dysplasia (p = 0.019), whereas implant type was not (p = 0.156). These factors were inter-related, however, and on fitting a Cox proportional hazard model only gender (p = 0.002) and age (p = 0.024) had a significant independent influence on revision rate; size nearly reached significance (p = 0.08). Subdividing the cohort according to significant factors, we found that the revision rate for pseudotumours in men was 0.5% (95% CI 0 to 1.1) at eight years wheras in women over 40 years old it was 6% (95% CI 2.3 to 10.1) at eight years and in women under 40 years it was 13.1% at six years (95% CI 0 to 27) (p < 0.001).

We recommend that resurfacings are undertaken with caution in women, particularly those under 40 years of age but they remain a good option in young men. Further work is required to understand the aetiology of pseudotumours so that this complication can be avoided.

Inflammatory pseudotumours occasionally occur after metal-on-metal hip resurfacing and often lead to revision. Our aim was to determine the severity of this complication by assessing the outcome of revision in these circumstances and by comparing this with the outcome of other metal-on-metal hip resurfacing revisions as well as that of matched primary total hip replacements.

We identified 53 hips which had undergone metal-on-metal hip resurfacing and required revision at a mean of 1.59 years (0.01 to 6.69) after operation. Of these, 16 were revised for pseudotumours, 21 for fracture and 16 for other reasons. These were matched by age, gender and diagnosis with 103 patients undergoing primary total hip replacement with the Exeter implant.

At a mean follow-up of three years (0.8 to 7.2) the outcome of metal-on-metal hip resurfacing revision for pseudotumour was poor with a mean Oxford hip score of 20.9 (sd 9.3) and was significantly worse (p < 0.001) than the outcome for fracture with a mean Oxford hip score of 40.2 (sd 9.2) or that for other causes with a mean Oxford hip score of 37.8 (sd 9.4). The clinical outcome of revision for pseudotumour was also significantly worse (p < 0.001) than the outcome of matched primary total hip replacements. By contrast, the outcome for fracture and other causes was not significantly different from that of matched primary total hip replacements (p = 0.065). After revision for pseudotumour there were three cases of recurrent dislocation, three of palsy of the femoral nerve, one of stenosis of the femoral artery and two of loosening of the component. Five hips required further revision. In three of these there was evidence of recurrent pseudotumour, and one is currently awaiting further revision. The incidence of major complications after revision for pseudotumour (50%) was significantly higher (p = 0.018) than that after revision for other causes (14%).

The outcome of revision for pseudotumour is poor and consideration should be given to early revision to limit the extent of the soft-tissue destruction. The outcome of resurfacing revision for other causes is good.

We report 17 patients (20 hips) in whom metal-on-metal resurfacing had been performed and who presented with various symptoms and a soft-tissue mass which we termed a pseudotumour. Each patient underwent plain radiography and in some, CT, MRI and ultrasonography were also performed. In addition, histological examination of available samples was undertaken.

All the patients were women and their presentation was variable. The most common symptom was discomfort in the region of the hip. Other symptoms included spontaneous dislocation, nerve palsy, a noticeable mass or a rash. The common histological features were extensive necrosis and lymphocytic infiltration. To date, 13 of the 20 hips have required revision to a conventional hip replacement. Two are awaiting revision.

We estimate that approximately 1% of patients who have a metal-on-metal resurfacing develop a pseudotumour within five years. The cause is unknown and is probably multifactorial. There may be a toxic reaction to an excess of particulate metal wear debris or a hypersensitivity reaction to a normal amount of metal debris. We are concerned that with time the incidence of these pseudotumours may increase. Further investigation is required to define their cause.