Wearable sensor-based measures of step-up transfers are supplementary to patient-reported outcome measures following total joint arthroplasty

PURPOSE

This study investigated the longitudinal assessment of step-up performance in patients undergoing total joint arthroplasty (TJA) and correlation with subjective patient reported outcome measures (PROMs).

METHODS

In this sub-analysis of the ADAPT study, PROMs were assessed using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Block step-up (BS) transfers were assessed by wearable-derived measures of time. 76 patients undergoing TJA were included. Subgroups were formed isolating the worst performing quartile (low functioning (LF)) from the high functioning (HF), and outcomes were compared.

RESULTS

One-year post-surgery, WOMAC function demonstrated strong correlations to WOMAC pain (Pearson's r = 0.67-0.84) and moderate correlations to BS performance (Pearson's r = 0.31-0.54). Both WOMAC and BS significantly improved with a larger effect size for the HF subgroup (0.62 vs. 0.43; p < 0.05). Patients designated to the LF subgroup at 3 months had increased odds of representing the LF subgroup at 12 months (WOMAC = 19; BS = 4). WOMAC defined 18 LF patients at 12 months follow-up. BS performance identified 9 additional LF patients.

CONCLUSIONS

WOMAC function scores seem pain dominated. Measures of BS performance allow assessment of otherwise hidden residual functional impairment. Lower functioning 3 months post-surgery is predictive of longer-term impairment.

Effects of recurrent intra-articular corticosteroid injections for osteoarthritis at 3 months and beyond: a systematic review and meta-analysis in comparison to other injectables

OBJECTIVE

Intra-articular corticosteroid injections (IACIs) provide temporary symptom relief in osteoarthritis (OA). This meta-analysis investigated the effects of recurrent IACIs at 3 months and beyond.

DESIGN

We searched Medline, Embase and Cochrane from inception to January 2021 for randomised controlled trials (RCTs) of patients with OA who received recurrent IACIs compared with other injectables, placebo or no treatment (primary outcomes: pain, function). Mean differences (MDs) with 95% confidence intervals were reported.

RESULTS

Ten RCTs were included (eight knee OA (n = 763), two trapeziometacarpal OA (n = 121)). Patients received between 2 and 8 injections, varying by trial. Trials compared recurrent IACIs with hyaluronic acid (HA), platelet-rich plasma (PRP), saline or orgotein (follow-up 3-24 months). Greater improvements in pain, function and QoL at 3-24 months were noted for the comparators than with IACIs, with comparators demonstrating an equal or superior effect, or the intervention effect attenuated during follow-up. Recurrent IACIs demonstrated no benefits in pain or function over placebo at 12-24 months. No serious adverse events were recorded. No studies reported on time-to-future interventions, risk of future prosthetic joint infection or other adverse events associated with subsequent joint replacement.

CONCLUSIONS

Recurrent IACIs often provide inferior (or non-superior) symptom relief compared with other injectables (including placebo) at 3 months and beyond. Other injectables (HA, PRP) often yielded greater improvements in pain and function up to 24 months post-injection. Existing RCTs on recurrent IACIs lack sufficient follow-up data to assess disease progression and time-to-future interventions.

Projections for primary hip and knee replacement surgery up to the year 2060: an analysis based on data from The National Joint Registry for England, Wales, Northern Ireland and the Isle of Man

INTRODUCTION

We estimated the number of primary total hip and knee replacements (THR and TKR) that will need to be performed up to the year 2060.

METHODS

We used data from The National Joint Registry for England, Wales, Northern Ireland and the Isle of Man on the volume of primary THRs (n=94,936) and TKRs (n=100,547) performed in 2018. We projected future numbers of THR and TKR using a static estimated rate from 2018 applied to population growth forecast data from the UK Office for National Statistics up to 2060.

RESULTS

By 2060, THR and TKR volume would increase from 2018 levels by an estimated 37.7% (n=130,766) and 36.6% (n=137,341), respectively. For both males and females demand for surgery was also higher for patients aged 70 and over, with older patients having the biggest relative increase in volume over time: 70-79 years (44.6% males, 41.2% females); 80-89 years (112.4% males, 85.6% females); 90 years and older (348.0% males, 198.2% females).

CONCLUSION

By 2060 demand for hip and knee joint replacement is estimated to increase by almost 40%. Demand will be greatest in older patients (70+ years), which will have significant implications for the health service requiring forward planning given that morbidity and resource use is higher in this population. These issues, coupled with two waves of COVID-19, will impact the ability of health services to deliver timely joint replacement to many patients for a number of years, requiring urgent planning.

Does the publication of NICE guidelines for venous thromboembolism chemical prophylaxis influence the prescribing patterns of UK hip and knee surgeons?

INTRODUCTION

We assessed the practice of surgeons regarding venous thromboembolism (VTE) chemical prophylaxis for total hip replacement (THR) and total knee replacement (TKR), before and after issuing of updated National Institute for Health and Care Excellence (NICE) guidance in 2018.

METHODS

A survey, circulated through the British Hip Society and regional trainee networks/collaboratives, was completed by 306 UK surgeons at 187 units. VTE chemical prophylaxis prescribing patterns for surgeons carrying out primary THR (n=258) and TKR (n=253) in low-risk patients was assessed after publication of 2018 NICE recommendations. Prescribing patterns before and after the NICE publication were subsequently explored.

RESULTS

Following the new guidance, 34% (n=87) used low-molecular-weight heparin (LMWH) alone, 33% (n=85) aspirin (commonly preceded by LMWH) and 31% (n=81) direct oral anticoagulants (DOACs: with/without preceding LMWH) for THR. For TKR, 42% (n=105) used aspirin (usually monotherapy), 31% (n=78) LMWH alone and 27% (n=68) DOAC (with/without preceding LMWH). NICE guidance changed the practice of 34% of hip surgeons and 41% of knee surgeons, with significantly increased use of aspirin preceded by LMWH for THR (before=25% vs after=73%; p<0.001), and aspirin for TKR (before=18% vs after=84%; p<0.001). Significantly more regimens were NICE guidance compliant after the 2018 update for THR (before=85.7% vs after=92.6%; p=0.011) and TKR (before=87.0% vs after=98.8%; p<0.001).

CONCLUSION

Over one-third of surveyed surgeons changed their VTE chemical prophylaxis in response to 2018 NICE recommendations, with more THR and TKR surgeons now compliant with latest NICE guidance. The major change in practice was an increased use of aspirin for VTE chemical prophylaxis.

Effects of presurgical interventions on chronic pain after total knee replacement: a systematic review and meta-analysis of randomised controlled trials

OBJECTIVE

Nearly 100 000 primary total knee replacements (TKR) are performed in the UK annually. The primary aim of TKR is pain relief, but 10%-34% of patients report chronic pain. The aim of this systematic review was to evaluate the effectiveness of presurgical interventions in preventing chronic pain after TKR.

DESIGN

MEDLINE, Embase, CINAHL, The Cochrane Library and PsycINFO were searched from inception to December 2018. Screening and data extraction were performed by two authors. Meta-analysis was conducted using a random effects model. Risk of bias was assessed using the Cochrane tool and quality of evidence was assessed by Grading of Recommendations Assessment, Development and Evaluation.

PRIMARY AND SECONDARY OUTCOMES

Pain at 6 months or longer; adverse events.

INTERVENTIONS

Presurgical interventions aimed at improving TKR outcomes.

RESULTS

Eight randomised controlled trials (RCTs) with data from 960 participants were included. The studies involved nine eligible comparisons. We found moderate-quality evidence of no effect of exercise programmes on chronic pain after TKR, based on a meta-analysis of 6 interventions with 229 participants (standardised mean difference 0.20, 95% CI -0.06 to 0.47, I²=0%). Sensitivity analysis restricted to studies at overall low risk of bias confirmed findings. Another RCT of exercise with no data available for meta-analysis showed no benefit. Studies evaluating combined exercise and education intervention (n=1) and education alone (n=1) suggested similar findings. Adverse event data were reported by most studies, but events were too few to draw conclusions.

CONCLUSIONS

We found low to moderate-quality evidence to suggest that neither preoperative exercise, education nor a combination of both is effective in preventing chronic pain after TKR. This review also identified a lack of evaluations of other preoperative interventions, such as multimodal pain management, which may improve long-term pain outcomes after TKR.

PROSPERO REGISTRATION NUMBER

CRD42017041382.

Systematic review of the safety and efficacy of osseointegration prosthesis after limb amputation

BACKGROUND

Osseointegration, an approach for direct skeletal attachment of a prosthesis to an amputated limb, may address many of the problems associated with socket prostheses. The safety of osseointegration remains uncertain. The aim of this study was to summarize evidence on functional and clinical outcomes, as well as adverse effects of osseointegration for patients with a limb amputation.

METHODS

MEDLINE, Embase, Web of Science and the Cochrane Library were searched to April 2018. Eligible studies were observational, case and qualitative studies, and RCTs conducted in patients with a limb amputation, who were managed with osseointegrated prostheses and had follow-up data.

RESULTS

Twenty-two eligible articles comprising 13 unique studies were included. No RCT was identified. Apart from three case reports that comprised one to five patients, the sample size of studies ranged from 11 to 100 participants. All relevant studies reported improvement in functional outcomes (walking ability, prosthetic use and mobility), satisfaction and quality of life following osseointegration, compared with their preoperative status or when using a conventional socket prosthesis. Infection rates ranged from 1 (95 per cent c.i. 0 to 5) to 77 (59 to 88) per cent. The majority of infections were described as low-grade soft tissue or superficial infections related to the skin-implant interface, and were treated effectively with antibiotics. None of the studies reported additional amputation or death as a result of osseointegration.

CONCLUSION

Osseointegration after limb amputation improves prosthetic use, comfort when sitting, walking ability, mobility, gait and quality of life. However, it is associated with an increased risk of soft tissue infection.

Using home sensing technology to assess outcome and recovery after hip and knee replacement in the UK: the HEmiSPHERE study protocol

INTRODUCTION

Over 160 000 people with severe hip or knee pain caused by osteoarthritis undergo total hip (THR) or knee replacement (TKR) surgery each year in the UK within the National Health Service (NHS), and this number is expected to increase. Innovative approaches to evaluating surgical outcomes will be needed to respond to the increasing burden of joint replacement surgery. The Sensor Platform for Healthcare in a Residential Environment, Interdisciplinary Research Collaboration (SPHERE-IRC) have developed a system of sensors that can monitor the health-related behaviours of people living at home. The system includes sensors for the home environment (measuring temperature, humidity, room occupancy, water and electricity usage), a wristband body-worn activity monitor and silhouette (body outline) sensors. The aim of HEmiSPHERE (Hip and knEe study of a Sensor Platform of HEalthcare in a Residential Environment) is to (1) determine the accuracy and feasibility of the sensory data as it compares with conventional assessment of health outcomes after surgery using patient self-reported questionnaires, and (2) to explore how the SPHERE system is useful for everyday clinical decision-making.

METHODS AND ANALYSIS

A feasibility study recruiting and installing the SPHERE system in the homes of up to 30 NHS adult patients as they undergo a THR or TKR. Through a mixed-methods design, the SPHERE system will monitor and record continuous measurements of daily behaviour. Main outcomes will assess the relationships between environmental, behavioural and movement data and the parameters of interest from the standard clinical assessments measuring patient outcomes over time. Patient interviews and focus groups with consultant orthopaedic surgeons will provide in-depth understanding of the acceptability, feasibility and accuracy of the data.

ETHICS AND DISSEMINATION

We aim to disseminate the findings through regional talks and seminars, international conferences and peer-reviewed journals and social media.

Is the rate of revision of 36 mm metal-on-metal total hip arthroplasties with Pinnacle acetabular components related to the year of the initial operation? an interrupted time-series analysis using data from the National Joint Registry for England and Wales

AIMS

The aim of this study was to determine whether the rates of revision for metal-on-metal (MoM) total hip arthroplasties (THAs) with Pinnacle components varied according to the year of the initial operation, and compare these with the rates of revision for other designs of MoM THA.

PATIENTS AND METHODS

Data from the National Joint Registry for England and Wales included 36 mm MoM THAs with Pinnacle acetabular components which were undertaken between 2003 and 2012 with follow-up for at least five years (n = 10 776) and a control group of other MoM THAs (n = 13 817). The effect of the year of the primary operation on all-cause rates of revision was assessed using Cox regression and interrupted time-series analysis.

RESULTS

For MoM THAs involving Pinnacle components, those undertaken between 2007 and 2012 had higher rates of revision compared with those undertaken between 2004 and 2006 (hazard ratio (HR) 2.01; 95% confidence interval (CI) 1.57 to 2.57; p < 0.001). For THAs undertaken during and after 2007, the number of revisions per 1000 implant-years at risk significantly increased by 5.20 (95% CI 0.52 to 9.89; p = 0.033) compared with those undertaken before this time. In the control group, THAs undertaken between 2007 and 2012 also had higher rates of revision (HR 1.77; 95% CI 1.49 to 2.10; p < 0.001), with revisions per 1000 implant-years for those undertaken during and after 2007 significantly increasing by 6.13 (95% CI 1.42 to 10.83; p = 0.016).

CONCLUSION

The five-year revision rates were significantly increased for all primary MoM THAs undertaken from 2007 onwards. Contrary to recent reports, this finding was not specific to those involving Pinnacle acetabular components and may be explained by increased surveillance and recent lowering of the threshold for revision. Cite this article: Bone Joint J 2018;100-B:33-41.

The effect of numbness on outcome from total knee replacement

INTRODUCTION Some patients report continuing pain and functional limitations after total knee replacement (TKR). While numbness around the TKR scar is common, the impact of numbness is less clear. One particular activity that could be influenced by numbness is kneeling. The aim of this study was to explore the impact of numbness around TKR scars on health related quality of life and kneeling ability. METHODS Fifty-six patients were recruited one year after primary TKR. Sensation around the knee was assessed through patient self-reporting, monofilament testing and vibration, and patients' distress was measured on a visual analogue scale. Patient reported outcome measures (PROMs) including the Western Ontario and McMaster Universities (WOMAC^®) index, the Knee injury and Osteoarthritis Outcome Score (KOOS), the painDETECT^® (Pfizer, Berlin, Germany) questionnaire and the EQ-5D™ (EuroQol, Rotterdam, Netherlands) questionnaire were used. Participants were also asked about kneeling ability. RESULTS While 68% of patients reported numbness around their TKR scar, there was no statistically significant correlation between numbness and distress at numbness (self-report: 0.23, p=0.08; monofilament: 0.15, p=0.27). Furthermore, numbness did not correlate significantly with joint specific PROMs (WOMAC^®: 0.21, p=0.13; KOOS: 0.18, p=0.19). However, difficulty with kneeling did correlate with both self-reported numbness (0.36, p=0.020) and worse PROM scores (WOMAC^® pain subscale: 0.62, p<0.001; KOOS: 0.64, p<0.001). CONCLUSIONS Numbness after knee replacement is common but is not associated with worse patient reported outcomes.

Revision for prosthetic joint infection following hip arthroplasty: Evidence from the National Joint Registry

Objectives

We used the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man (NJR) to investigate the risk of revision due to prosthetic joint infection (PJI) for patients undergoing primary and revision hip arthroplasty, the changes in risk over time, and the overall burden created by PJI.

Methods

We analysed revision total hip arthroplasties (THAs) performed due to a diagnosis of PJI and the linked index procedures recorded in the NJR between 2003 and 2014. The cohort analysed consisted of 623 253 index primary hip arthroplasties, 63 222 index revision hip arthroplasties and 7585 revision THAs performed due to a diagnosis of PJI. The prevalence, cumulative incidence functions and the burden of PJI (total procedures) were calculated. Overall linear trends were investigated with log-linear regression.

Results

We demonstrated a prevalence of revision THA due to prosthetic joint infection of 0.4/100 procedures following primary and 1.6/100 procedures following revision hip arthroplasty. The prevalence of revision due to PJI in the three months following primary hip arthroplasty has risen 2.3-fold (95% confidence interval (CI) 1.3 to 4.1) between 2005 and 2013, and 3.0-fold (95% CI 1.1 to 8.5) following revision hip arthroplasty. Over 1000 procedures are performed annually as a consequence of hip PJI, an increase of 2.6-fold between 2005 and 2013.

Conclusions

Although the risk of revision due to PJI following hip arthroplasty is low, it is rising and, coupled with the established and further predicted increased incidence of both primary and revision hip arthroplasty, this represents a growing and substantial treatment burden.

Cite this article: E. Lenguerrand, M. R. Whitehouse, A. D. Beswick, S. A. Jones, M. L. Porter, A. W. Blom. Revision for prosthetic joint infection following hip arthroplasty: Evidence from the National Joint Registry. Bone Joint Res 2017;6:391–398. DOI: 10.1302/2046-3758.66.BJR-2017-0003.R1.

Rates of hip and knee joint replacement amongst different ethnic groups in England: an analysis of National Joint Registry data

OBJECTIVE

Despite a health care system that is free at the point of delivery, ethnic minorities may not always get care equitable to that of White patients in England. We examined whether ethnic differences exist in joint replacement rates and surgical practice in England.

DESIGN

373,613 hip and 428,936 knee National Joint Registry (NJR) primary replacement patients had coded ethnicity in Hospital Episode Statistics (HES). Age and gender adjusted observed/expected ratios of hip and knee replacements amongst ethnic groups were compared using indirect standardisation. Associations between ethnic group and type of procedure were explored and effects of demographic, clinical and hospital-related factors examined using multivariable logistic regression.

RESULTS

Adjusted standardised observed/expected ratios were substantially lower in Blacks and Asians than Whites for hip replacement (Blacks 0.33 [95% CI, 0.31-0.35], Asians 0.20 [CI, 0.19-0.21]) and knee replacement (Blacks 0.64 [CI, 0.61-0.67], Asians 0.86 % [CI, 0.84-0.88]). Blacks were more likely to receive uncemented hip replacements (Blacks 52%, Whites 37%, Asians 44%; P < 0.001). Black men and women aged <70 years were less likely to receive unicondylar or patellofemoral knee replacements than Whites (men 10% vs 15%, P = 0.001; women 6% vs 14%, P < 0.001). After adjustment for demographic, clinical and hospital-related factors, Blacks were more likely to receive uncemented hip replacement (OR 1.43 [CI, 1.11-1.84]).

CONCLUSIONS

In England, hip and knee replacement rates and prosthesis type given differ amongst ethnic groups. Whether these reflect differences in clinical need or differential access to treatment requires urgent investigation.

The influence of cemented femoral stem choice on the incidence of revision for periprosthetic fracture after primary total hip arthroplasty

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.

Patients and Methods

We analysed data on 257 202 primary THAs with cemented stems and 390 linked first revisions for PF recorded in the National Joint Registry (NJR) of England, Wales and Northern Ireland to determine if a cemented femoral stem brand was associated with the risk of having revision for a PF after primary THA. All cemented femoral stem brands with more than 10 000 primary operations recorded in the NJR were identified. The four most commonly used cemented femoral stems were the Exeter V40 (n = 146 409), CPT (n = 24 300), C-Stem (n = 15 113) and Charnley (n = 20 182). We compared the revision risk ratios due to PF amongst the stems using a Poisson regression model adjusting for patient factors. Compared with the Exeter V40, the age, gender and ASA grade adjusted revision rate ratio was 3.89 for the cemented CPT stem (95% confidence interval (CI) 3.07 to 4.93), 0.89 for the C-Stem (95% CI 0.57 to 1.41) and 0.41 for the Charnley stem (95% CI 0.24 to 0.70).

Conclusions

The limitations of the study include incomplete data capture, analysis of only PF requiring revision and that observation does not imply causality. Nevertheless, this study demonstrates that the choice of a cemented stem may influence the risk of revision for PF. Cite this article: Bone Joint J 2016;98-B:1347–54.

Central sensitization as a determinant of patients' benefit from total hip and knee replacement

Background

Discrepancies exist between osteoarthritic joint changes and pain severity before and after total hip (THR) and knee (TKR) replacement. This study investigated whether the interaction between pre‐operative widespread hyperalgesia and severity of radiographic osteoarthritis (OA) was associated with pain severity before and after joint replacement.

Methods

Data were analysed from 232 patients receiving THR and 241 receiving TKR. Pain was assessed pre‐operatively and at 12 months post‐operatively using the WOMAC Pain Scale. Widespread hyperalgesia was assessed through forearm pressure pain thresholds (PPTs). Radiographic OA was evaluated using the Kellgren and Lawrence scheme. Statistical analysis was conducted using multilevel models, and adjusted for confounding variables.

Results

Pre‐operative: In knee patients, there was weak evidence that the effect of PPTs on pain severity was greater in patients with more severe OA (Grade 3 OA: ß = 0.96 vs. Grade 4: ß = 4.03), indicating that in these patients higher PPTs (less widespread hyperalgesia) was associated with less severe pain. In hip patients, the effect of PPTs on pain did not differ with radiographic OA (Grade 3 OA: ß = 3.95 vs. Grade 4: ß = 3.67).

Post‐operative: There was weak evidence that knee patients with less severe OA who had greater widespread hyperalgesia benefitted less from surgery (Grade 3 OA: ß = 2.28; 95% CI −1.69 to 6.25). Conversely, there was weak evidence that hip patients with more severe OA who had greater widespread hyperalgesia benefitted more from surgery (Grade 4 OA: ß = −2.92; 95% CI −6.58 to 0.74).

Conclusions

Widespread sensitization may be a determinant of how much patients benefit from joint replacement, but the effect varies by joint and severity of structural joint changes.

Significance

Pre‐operative widespread hyperalgesia and radiographic osteoarthritis (OA) severity may influence how much patients benefit from joint replacement. Patients undergoing knee replacement with less severe OA and greater widespread hyperalgesia benefitted less from surgery than patients with less hyperalgesia. Patients undergoing hip replacement with more severe OA and greater widespread hyperalgesia benefitted more than patients with less hyperalgesia.

Assessment of physical function following total hip arthroplasty: Inertial sensor based gait analysis is supplementary to patient-reported outcome measures

BACKGROUND

Functional outcome assessment after total hip arthroplasty often involves subjective patient-reported outcome measures whereas analysis of gait is more objective. The study's aims were to compare subjective and objective functional outcomes after total hip arthroplasty between patients with low and high self-reported levels of pre-operative physical function.

METHODS

Patients undergoing total hip arthroplasty (n=36; m/f=18/18; mean age=63.9; SD=9.8 years; BMI=26.3; SD=3.5) were divided into a low and high function subgroup, and prospective measures of WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) function score and gait were compared at baseline and 3 and 12 months post-operatively.

FINDINGS

WOMAC function scores significantly improved in both low and high function subgroups at 3 months post-operatively whereas gait parameters only improved in patients with a low pre-operative function. Between 3 and 12 months post-operatively, WOMAC function scores had not significantly further improved whereas several gait parameters significantly improved in the low function group. WOMAC function scores and gait parameters were only moderately correlated (Spearman's r=0.33-0.51).

INTERPRETATION

In a cohort of patients undergoing total hip arthroplasty, pre-operative differences in mean WOMAC function scores and gait parameters between low and high function subgroups disappeared by 3 months post-operatively. Gait parameters only improved significantly during the first 3 post-operative months in patients with a low pre-operative function, highlighting the importance of investigating relative changes rather than the absolute changes and the need to consider patients with high and low functions separately.

A systematic review and meta-analysis of complications following the posterior and lateral surgical approaches to total hip arthroplasty

INTRODUCTION

Total hip arthroplasty is one of the most commonly performed orthopaedic procedures. Despite this, medical evidence to inform the choice of surgical approach is lacking. Currently in the UK, the two most frequently performed approaches to the hip are the posterior and the direct lateral.

METHODS

This systematic review was performed according to Cochrane guidelines following an extensive search for prospective controlled trials published in any language before January 2014. Of the 728 records identified from searches, 6 prospective studies (including 3 randomised controlled trials) involving 517 participants provided data towards this review.

FINDINGS

Compared with the lateral approach, the posterior approach conferred a significant reduction in the risk of Trendelenburg gait (odds ratio [OR]: 0.31, p=0.0002) and stem malposition (OR: 0.24, p=0.02), and a non-significant reduction in dislocation (OR: 0.37, p=0.16) and heterotopic ossification (OR: 0.41, p=0.13). Neither approach conferred a functional advantage. We draw attention to the paucity of evidence and the need for a further randomised trial.

Mortality after total hip replacement surgery: A systematic review

Total hip replacement causes a short-term increase in the risk of mortality. It is important to quantify this and to identify modifiable risk factors so that the risk of post-operative mortality can be minimised. We performed a systematic review and critical evaluation of the current literature on the topic. We identified 32 studies published over the last 10 years which provide either 30-day or 90-day mortality data. We estimate the pooled incidence of mortality during the first 30 and 90 days following hip replacement to be 0.30% (95% CI 0.22 to 0.38) and 0.65% (95% CI 0.50 to 0.81), respectively. We found strong evidence of a temporal trend towards reducing mortality rates despite increasingly co-morbid patients. The risk factors for early mortality most commonly identified are increasing age, male gender and co-morbid conditions, particularly cardiovascular disease. Cardiovascular complications appear to have overtaken fatal pulmonary emboli as the leading cause of death after hip replacement.

Cite this article: Bone Joint Res 2014;3:175–82.

Comparison of patient reported outcomes after Triathlon(®) and Kinemax Plus prostheses

INTRODUCTION

The Triathlon^® (Stryker, Kalamazoo, MI, US) total knee replacement was designed to improve patient function and survivorship. The aim of this study was to determine whether the Triathlon^® prosthesis produces better patient reported outcomes than a previous design by the same manufacturer, the Kinemax Plus.

METHODS

The outcome of 233 knees of patients with a mean age of 68 years (range: 40–80 years) who received the Kinemax Plus prosthesis were compared with the outcomes of 220 knees of patients with a mean age of 70 years (range: 42–90 years) who received the Triathlon^® prosthesis. Data were collected via postal questionnaire prior to surgery as well as at 8–12 weeks and at 1 year following surgery. Validated questionnaires were used including the WOMAC^® (Western Ontario and McMaster Universities) pain and function scales, the Knee injury and Osteoarthritis Outcome Score quality of life scale and the self-administered patient satisfaction scale.

RESULTS

This study found that patients who had the Triathlon^® prosthesis had significantly better pain relief (p<0.0001), function (p=0.028), knee related quality of life (p<0.0001) and satisfaction (p=0.0003) at three months after surgery than those who received the Kinemax Plus prosthesis. In addition, knee related quality of life (p=0.002) and satisfaction (p=0.021) were significantly higher at one year after surgery in Triathlon^® patients.

CONCLUSIONS

The findings suggest that return to function and reduction in pain may occur more quickly in patients with a Triathlon^® prosthesis than in those with the Kinemax Plus.

Osteonecrosis with the use of polymethylmethacrylate cement for hip replacement: thermal-induced damage evidenced in vivo by decreased osteocyte viability

Thermal damage to host bone is a possible source of compromise of fixation in patients undergoing cemented total hip replacement (THR). Data on the subject to date are derived from mathematical modelling powered by animal studies. The aim of this study was to assess the effect of cement thickness on osteocyte viability in a population of patients undergoing cemented THR. An in vivo model was designed and validated by means of a finite element analysis. During standard hip joint replacement in 14 patients, the femoral necks were exposed before final resection to the heat of a curing cement mantle equivalent to 2.5 (Group 1) or 5 mm (Group 2) in vivo in the cemented acetabulum. Matched controls were collected for each patient. Osteocyte counts and viability were assessed by means of haematoxylin and eosin (H&E) stain and lactate dehydrogenase (LDH) assay. Ex vivo experiments were performed to determine the extent of thermal insult. H&E staining proved unreliable for assessing thermal insult in the short term. The LDH assay was reliable and demonstrated a significant reduction in osteocyte viability to a depth of 2.19 mm in group 1 and 9.19 mm in group 2. There was a significant difference between the groups at all depths. The ex vivo experiments revealed thermoclines indicating that host bone in the population undergoing cemented THR is more sensitive to the thermal insult delivered by curing polymethylmethacrylate cement than previously believed. This thermal insult may weaken the fixation between bone and cement and contribute towards aseptic loosening, the commonest cause of failure of THRs.

The role of preoperative self-efficacy in predicting outcome after total knee replacement

OBJECTIVES

The aim of the present study was to determine if self-efficacy is a significant and independent preoperative predictor of patient-reported pain and function at one year after total knee replacement (TKR).

METHODS

Patients listed for a primary TKR because of osteoarthritis were recruited from preoperative assessment clinics at one regional orthopaedic centre. Before surgery, patients completed the Western Ontario and McMasters Osteoarthritis Index (WOMAC) Pain and Function Scale, Pain Self-Efficacy Scale, the Hospital Anxiety and Depression Scale, the Self-Administered Co-morbidity Questionnaire and questions about other painful joints. Patients then completed the WOMAC Pain and Function Scales at one year postoperatively. Regression analysis was performed to determine if self-efficacy was a significant predictor of outcome after TKR.

RESULTS

Overall, 251 patients were recruited into this study, and one-year questionnaire data were available for 220 patients. At one year postoperatively, 7% of patients reported severe pain in their replaced knee and 9% reported severe functional limitations. Self-efficacy was found to be a significant preoperative predictor of functional ability, but not pain, at one year postoperatively, after controlling for age, gender, depression, anxiety, number of medical co-morbidities, preoperative knee status and painful joints elsewhere. Significant predictors of postoperative pain were greater anxiety and higher pain severity. Other significant predictors of postoperative disability were greater anxiety, worse functional disability and a greater number of painful joints elsewhere.

CONCLUSIONS

The present study demonstrated that self-efficacy is a significant preoperative predictor of patient-reported functional ability at one year after TKR. Future research is needed to assess the impact of interventions for enhancing self-efficacy on patient-reported outcomes after TKR.

Role of early intravenous to oral antibiotic switch therapy in the management of prosthetic hip infection treated with one- or two-stage replacement

OBJECTIVES

To determine outcomes for an antibiotic regimen using early switch to oral antibiotics for treatment of infected total hip replacement (THR) treated by either a one-stage or two-stage procedure.

METHODS

Cases of infected THR were identified from the microbiology records on all orthopaedic infections in a 24 month period. Diagnosis was made by microbiological culture of theatre specimens and findings at the time of surgery. A standard approach of 10-14 days intravenous (iv) antibiotic followed by a switch to oral antibiotics either for 6-8 weeks until second-stage re-implantation or for up to 3 months following a one-stage procedure was used. The exact date of oral switch and antibiotic duration was determined by clinical resolution and C-reactive protein (CRP). Outcome was recorded as no microbiological or clinical evidence of relapse of infection or relapse after completing the antibiotic course. Follow-up duration for all cases at the time of study was 24-36 months after completion of antibiotic treatment.

RESULTS

In 24 months, 19 patients underwent two-stage THR for infection, of which 17 were treated with oral antibiotics after a median of 14 days initial iv antibiotics. None relapsed. Four patients underwent one-stage THR and had 12-20 days iv then 6-26 weeks oral antibiotics with no relapse.

CONCLUSIONS

Early oral antibiotic switch therapy was effective in patients treated at the Avon Orthopaedic Centre with infected THR and plays an important role in enabling patients to return to independence after revision surgery and avoid complications of prolonged iv access.

Metal-on-metal bearings: the evidence so far

Lately, concerns have arisen following the use of large metal-on-metal bearings in hip replacements owing to reports of catastrophic soft-tissue reactions resulting in implant failure and associated complications. This review examines the literature and contemporary presentations on current clinical dilemmas in metal-on-metal hip replacement.

Lysophosphatidic acid and calcitriol co-operate to promote human osteoblastogenesis: requirement of albumin-bound LPA

Lysophosphatidic acid (LPA), a pleiotropic signalling lipid is assuming growing significance in osteoblast biology. Although committed osteoblasts from several mammalian species are receptive to LPA far less is known about the potential for LPA to influence osteoblast formation from their mesenchymal progenitors. An essential factor for both bone development and post-natal bone growth and homeostasis is the active metabolite of vitamin D3, calcitriol (D3). Previously we reported how a combination of LPA and D3 synergistically co-operated to enhance the differentiation of immature human osteoblasts. Herein we provide evidence for the formation of human osteoblasts from multiple, primary human bone marrow derived stromal (stem) cells (hBMSCs). Importantly osteoblast development from hBMSCs only occurred when LPA was administered as a complex with albumin, its natural carrier. Collectively our findings support a co-operative role of LPA and D3 in osteoblastogenesis, findings which may aid the development of novel treatment strategies for bone repair.

The failure of survivorship

This editorial considers the shortcomings of assessing outcome after joint replacement only by the survival of the implant.

Clinical outcomes and fusion success associated with the use of BoneSave in spinal surgery

BACKGROUND

Achieving spinal fusion is the guiding principle behind surgical treatment for a range of spinal pathologies, often requiring a substantial amount of bone-graft. Iliac crest autograft represents the gold standard although associated morbidities and limited graft material have led to the development of alternatives. BoneSave (Stryker, UK), a porous tricalcium phosphate-hydroxyapatite ceramic, is one such alternative, employed in spinal fusion over the past few years. Very little research exists into the clinical outcomes associated with its use.

METHODS

Clinical data was collected retrospectively from the case notes of 45 patients who underwent posterolateral inter-transverse spinal fusion involving the application of BoneSave between June 2003 and January 2005. Latest follow-up information was collected via a postal questionnaire (average follow-up of 46 months). Validated outcome instruments employed included the Short Form 36 and Oswestry Disability Index. In addition visual analogue scales for pain, patient global impression of change, work status, persisting symptoms and patient satisfaction data were collected. Radiological evaluation of fusion was carried out from the most recent spinal radiographs available for each patient.

RESULTS

Qualitative post-operative data was available in 96%, with a questionnaire response rate of 68.4%. Radiographical evaluation was possible in 67%. Significant post-operative improvements were seen across all outcome measures in the large majority of cases. Successful fusion was achieved in 56.7% of cases.

CONCLUSIONS

The clinical outcomes associated with the use of BoneSave in spinal fusion are comparable to those available in the literature for more conventional techniques. The fusion rate was not significantly lower.

Skin closure after total hip replacement: a randomised controlled trial of skin adhesive versus surgical staples

We undertook a randomised controlled trial to compare the outcomes of skin adhesive and staples for skin closure in total hip replacement. The primary outcome was the cosmetic appearance of the scar at three months using a surgeon-rated visual analogue scale. In all, 90 patients were randomised to skin closure using either skin adhesive (n = 45) or staples (n = 45). Data on demographics, surgical details, infection and oozing were collected during the in-patient stay. Further data on complications, patient satisfaction and evaluation of cosmesis were collected at three-month follow-up, and a photograph of the scar was taken. An orthopaedic and a plastic surgeon independently evaluated the cosmetic appearance of the scars from the photographs. No significant difference was found between groups in the cosmetic appearance of scars at three months (p = 0.172), the occurrence of complications (p = 0.3), or patient satisfaction (p = 0.42). Staples were quicker and easier to use than skin adhesive and also less expensive. Skin adhesive and surgical staples are both effective skin closure methods in total hip replacement.

Publication rates for hip surgery-related abstracts presented at national and international meetings

Presentation at national and international meetings is a useful way to disseminate new information. Publication in a peer-reviewed journal remains the gold standard. We analyzed the publication rates of oral presentations from the British and European Hip Society, British Orthopaedic Association, and European Federation of Orthopaedics and Traumatology between 2003 and 2006. Multiple databases were used to identify publication of work presented as an abstract at these meetings. The publishing journal, time until publication, impact factor of publishing journal, and rate of publication identified by each database were analyzed. The overall mean publication rate across the 4 meetings was 23.4%; there were no significant differences between the meetings. Google Scholar (P<.01) and Medline (P<.05) identified significantly more publications than EMBASE. There were no significant differences between the mean impact factors of the publishing journals (P=.18). There were no significant differences in abstract publication rate or impact factor between meetings. The overall mean subsequent publication rates for presented abstracts related to hip surgery were low, and data presented but not yet published should be treated with caution. Google Scholar and Medline are superior to EMBASE for identification of peer-reviewed research.

The Harris-Galante porous-coated, hemispherical, polyethylene-lined acetabular component in patients under 50 years of age

We have reviewed 70 Harris-Galante uncemented acetabular components implanted as hybrid hip replacements with cemented stems between 1991 and 1995 in 53 patients whose mean age was 40 years (19 to 49). The mean follow-up was for 13.6 years (12 to 16) with no loss to follow-up. We assessed the patients both clinically and radiologically.

The mean Oxford hip score was 20 (12 to 46) and the mean Harris hip score 81 (37 to 100) at the final review. Radiologically, 27 hips (39%) had femoral osteolysis, 13 (19%) acetabular osteolysis, and 31 (44%) radiolucent lines around the acetabular component. Kaplan-Meier survival curves were constructed for the outcomes of revision of the acetabular component, revision of the component and polyethylene liner, and impending revision for progressive osteolysis.

The cumulative survival for revision of the acetabular component was 94% (95% confidence interval 88.4 to 99.7), for the component and liner 84% (95% confidence interval 74.5 to 93.5) and for impending revision 55.3% (95% confidence interval 40.6 to 70) at 16 years.

Uncemented acetabular components with polyethylene liners undergo silent lysis and merit regular long-term radiological review.

Prevalence and functional impact of patient-perceived leg length discrepancy after hip replacement

The aim of this postal survey was to determine the prevalence and impact of patient-perceived leg length discrepancy (LLD) at 5-8 years after primary total hip replacement (THR). A postal audit survey was undertaken of all consecutive patients who had a primary unilateral THR at one elective orthopaedic centre between April 1993 and April 1996. The questionnaire included the Oxford hip score (OHS) and questions about LLD. Questionnaires were received from 1,114 patients. In total, 329 THR patients (30%) reported an LLD, although radiographic analysis revealed that only 36% of these patients had anatomical LLD. Patients with a perceived LLD had a significantly poorer OHS (p < 0.001) and reported more limping than those patients without a perceived LLD. This study found that a third of patients perceived an LLD after THR and that perceived LLD was associated with a significantly poorer midterm functional outcome.

Ninety-day mortality after elective total hip replacement

Thromboprophylaxis after elective orthopaedic surgery remains controversial. Recent guidelines from the National Institute for Clinical Excellence (NICE) have suggested that low molecular weight heparin should be given to all patients undergoing total hip replacement. The British Orthopaedic Association is currently debating this guideline with NICE, as it is not clear whether published evidence supports this view. We present the early mortality in our unit after total hip replacement using aspirin as chemical thromboprophylaxis. The 30-day and 90-day mortality after primary total hip arthroplasty was zero. We compare this with that reported previously from our unit without using chemical thromboprophylaxis. With the introduction of routine aspirin thromboprophylaxis, deaths from cardiovascular causes have dropped from 0.75% to zero.

These results demonstrate that there is a strong argument for the routine administration of aspirin after elective total hip replacement.

Resistance of disposable drapes to bacterial penetration

PURPOSE

To test the bacterial penetrability of disposable non-woven drapes used specifically for total hip arthroplasty.

METHODS

12 round agar plates were inoculated with 107 colony-forming units/ml of coagulase-negative staphylococci (CNS) and incubated in air at 37 degrees Celsius for 18 hours to obtain a semi-confluent growth of organisms. Six brands of disposable drapes were tested; each was assigned to 2 plates. Each disposable drape was placed between a round agar plate and an inverted square agar plate filled with blood agar. After 30 and 90 minutes, the square agar plates were removed and incubated for 48 hours and inspected for growth of CNS.

RESULTS

Bacterial penetration was time dependant. Certain brands of drapes were more impenetrable than others; none was impenetrable at all time points, but most remained so or allowed passage of fewer than 100 colony-forming units at 90 minutes.

CONCLUSION

It is recommended that drapes be rigorously tested with regard to their resistance to bacterial penetration.

Omnifit acetabular component: a solution to preventing and treating dislocation

PURPOSE

To assess short- to medium-term outcome of the Omnifit constrained acetabular component in preventing dislocation in at-risk patients after total hip arthroplasty (THA).

METHODS

81 patients (mean age, 77 years) underwent either primary or revision THA with an Omnifit constrained acetabular component and were followed up clinically and radiologically for a mean period of 24 months.

RESULTS

There was one dislocation and one revision for avulsion of the acetabulum. The remaining prostheses remained well fixed.

CONCLUSIONS

In the short- to medium-term, the Omnifit constrained acetabular component is effective in preventing primary and recurrent dislocation in at-risk patients. Long-term follow-up is needed to assess whether good fixation is maintained. The Omnifit acetabular cup is recommended for elderly patients with limited life expectancy and functional demands.

Reproducibility of the Gartland classification for supracondylar humeral fractures in children

PURPOSE

To evaluate the intra- and inter-observer reproducibility of the Gartland radiographic classification for supracondylar humeral fractures in children.

METHODS

Anteroposterior and lateral radiographs of 50 supracondylar humeral fractures in children were graded on 2 separate occasions by 4 orthopaedic surgeons according to the Wilkins modification of the Gartland classification. Data were analysed by calculating the Kappa values for intra- and inter-observer agreement to indicate the reproducibility of the classification.

RESULTS

There was moderate inter-observer agreement, except for poor agreement over type I fractures. Type II fractures only showed fair to moderate agreement. Type III fractures and the flexion group showed good to very good agreement. Intra-observer agreement was good to very good.

CONCLUSION

Surgeons should treat paediatric supracondylar humeral fractures based on an assessment of the degree of displacement rather than by employing the Gartland classification.

Thirty-two millimetre heads and accelerated polyethylene wear in total hip arthroplasty

In total hip arthroplasty 32 mm heads are often used as the greater diameter is thought to contribute to improved stability. However, greater head diameter can also lead to greater volumetric wear. We compared polyethylene wear between patients with 32 mm heads and those with smaller heads. All patients who had Harris Galante1 metal-backed, uncemented cups inserted between 1986 and 1996 at our institute were annually reviewed clinically and radiographically. Accelerated polyethylene wear was noted between the fifth and seventh postoperative year in 17 out of 165 total hip replacements with 32 mm heads, but only in 21 out of 961 total hip arthroplasties with smaller femoral heads. In all 17 THRs, accelerated wear was also associated with thin polyethylene (<6 mm). This paper highlights a potentially serious problem. When 32 mm metal heads are used with uncemented cups and polyethylene liners, there is a risk of accelerated acetabular wear in patients with thin polyethylene.

Revision of an acetabular liner has a high risk of dislocation

Polyethylene liners of modular acetabular components wear sometimes need to be replaced, despite the metal shell being well fixed. Replacing the liner is a relatively simple procedure, but very little is known of the outcome of revision. We prospectively followed up 1126 Harris-Galante I metal-backed, uncemented components for between nine and 19 years. We found 38 (3.4%) liners of 1126 acetabular components wore and required revision. These revisions were then followed up for a mean of 4.8 years. The rate of dislocation was 28.9%. Nine of the dislocations occurred once and two were recurrent.

The overall secondary revision rate was three of 38 total hip replacements (7.9%) at a mean follow-up of 4.8 years. This gives a 92.1% survivorship (35 of 38) at under five years. In isolated revision of a liner, we had a complication rate of 23% (three of 13). In revision of a liner combined with revision of the femoral stem, there was a complication rate of 48% (12 of 25). We discuss possible reasons for the high dislocation rates.

Leaving the well-fixed acetabular shell in situ leads to an increased risk of instability. However, this needs to be balanced against the otherwise low complication rate for revision of the liner. Patients should be consented accordingly.

The crescent sign: dissociation of the polyethylene liner from a modular acetabular component in total hip arthroplasty

OBJECTIVE

To study whether there was a common pattern of clinical symptoms, signs and radiographic features for the dissociation of the polyethylene liner from an acetabular component and to postulate reasons for these features.

DESIGN AND PATIENTS

Retrospective study of notes and radiographs of cases of revision hip arthroplasty for polyethylene liner dissociation of the cementless Harris-Galante I porous-coated acetabular component (Zimmer Inc, Warsaw, IN) at the Avon Orthopaedic Centre, Bristol, UK and St. Mary's Hospital, Bristol, UK between 1995 and 2004. Patients were contacted to confirm preoperative symptoms.

RESULTS

Nine cases of late polyethylene liner dissociation of this prosthesis have been revised in these institutions. All patients presented with a reduction in mobility, groin pain and limp. Eight patients reported an audible noise on hip movement. In all cases, radiographs showed radiolucency medial to the femoral neck in association with an eccentrically placed femoral head showing contact with the acetabular metal shell, which we have termed the "crescent sign."

CONCLUSIONS

There is a typical clinical presentation in this study. The diagnosis can be made from a single anteroposterior pelvic radiograph without the need for previous films for comparison, or the need for arthrography. Clinicians should look specifically for the crescent sign when an eccentrically placed femoral head has been noted, in order to differentiate the more unusual diagnosis of dissociation from that of polyethylene wear. Early revision surgery can prevent damage to the femoral head and metal acetabular shell, thus reducing the complexity of revision surgery.

The compatibility of ceramic bone graft substitutes as allograft extenders for use in impaction grafting of the femur

This study investigates the use of porous biphasic ceramics as graft extenders in impaction grafting of the femur during revision hip surgery. Impaction grafting of the femur was performed in four groups of sheep. Group one received pure allograft, group two 50% allograft and 50% BoneSave, group three 50% allograft and 50% BoneSave type 2 and group four 10% allograft and 90% BoneSave as the graft material. Function was assessed using an index of pre- and post-operative peak vertical ground reaction force ratios. Changes in bone mineral density were measured by dual energy X ray absorptiometry (DEXA) scanning. Loosening and subsidence were assessed radiographically and by histological examination of the explanted specimens. There was no statistically significant difference between the four groups after 18 months of unrestricted functional loading for all outcome measures.

Infection after total knee arthroplasty

The aim of our study was to determine the current incidence and outcome of infected total knee arthroplasty (TKA) in our unit comparing them with our earlier audit in 1986, which had revealed infection rates of 4.4% after 471 primary TKAs and 15% after 23 revision TKAs at a mean follow-up of 2.8 years. In the interim we introduced stringent antibiotic prophylaxis, and the routine use of occlusive clothing within vertical laminar flow theatres and 0.05% chlorhexidine lavage during arthroplasty surgery.

We followed up 931 primary TKAs and 69 revision TKAs for a mean of 6.5 years (5 to 8). Patients were traced by postal questionnaire, telephone interview or examination of case notes of the deceased.

Nine (1%) of the patients who underwent primary TKA, and four (5.8%) of those who underwent revision TKA developed deep infection. Two of nine patients (22.2%) who developed infection after primary TKA were successfully treated without further surgery. All four of the patients who had infection after revision TKA had a poor outcome with one amputation, one chronic discharging sinus and two arthrodeses.

Patients who underwent an arthrodesis had comparable Oxford knee scores to those who underwent a two-stage revision. Although infection rates have declined with the introduction of prophylactic measures, and more patients are undergoing TKA, the outcome of infected TKA has improved very little.

Infection after total hip arthroplasty

Our aim in this study was to determine the outcome of hip arthroplasty with regard to infection at our unit. Infection after total joint arthroplasty is a devastating complication. The MRC study in 1984 recommended using vertical laminar flow and prophylactic antibiotics to reduce infection rates. These measures are now routinely used. Between 1993 and 1996, 1727 primary total hip arthroplasties and 305 revision hip arthroplasties were performed and 1567 of the primary and 284 of the revision arthroplasties were reviewed between five and eight years after surgery by means of a postal questionnaire, telephone interview or examination of the medical records of those who had died.

Seventeen (1.08%) of the patients who underwent primary and six (2.1%) of those who underwent revision arthroplasty had a post-operative infection. Only 0.45% of patients who underwent primary arthroplasty required revision for infection.

To our knowledge this is the largest multi-surgeon audit of infection after total hip replacement in the UK. The follow-up of between five and eight years is longer than that of most comparable studies. Our study has shown that a large cohort of surgeons of varying seniority can achieve infection rates of 1% and revision rates for infection of less than 0.5%.

Bacterial contamination of surgical gloves by water droplets spilt after scrubbing

Wound infection and deep sepsis can have disastrous consequences, particularly in orthopaedic surgery. Strict protocols, ultra-clean air, prophylactic antibiotics, and impervious gowns and drapes, have all been shown to diminish wound infection. However it remains a common and significant problem. The water droplets spilt from the surgeons hands after meticulous scrubbing with povidone iodine were cultured. The permeability of the surgical glove packaging to Gram-positive bacteria was also investigated. The water droplets from the surgeon's arms contained environmental and potentially pathogenic bacteria including a micrococcus, a coliform and coagulase-negative staphylococci. The paper packaging for the range of sterile surgical gloves tested was discovered to be permeable to Gram-positive bacteria. In conclusion accidental water droplet contamination of surgical gloves is a potential source of infection. Alternative recommendations are made.

Subsidence in impaction grafting: the effect of adding a ceramic bone graft extender to bone

The incidence of revision total hip arthroplasty is increasing dramatically and the associated demand for allograft bone is likely to exceed the available supply. In addition, allograft presents potential problems with regard to infection, antigenicity, availability, reproducibility and cost. It is therefore desirable to develop an alternative to allograft. This study investigated BoneSave, a porous tricalcium phosphate-hydroxyapatite ceramic for use in impaction grafting of the femur at revision total hip arthroplasty. The findings of an in vitro mechanical study comparing the initial stability of pure allograft, a volume mixture of 50 per cent allograft and 50 per cent BoneSave, and a volume mixture of 10 per cent allograft and 90 per cent BoneSave are reported. The BoneSave-allograft mixtures exhibit both much greater mechanical stability and reproducibility than the pure allograft (p < 0.05) at all tested loads (200-800 N). At high peak loads the high volume (90%, v/v) BoneSave mix also provided higher mechanical stability than the medium volume (50 per cent BoneSave-50 per cent allograft) mix (p < 0.05). These results demonstrate thatfrom a mechanical standpoint the tested ceramic provides adequate initial stability to be used as a bone graft extender with allograft in impaction grafting of the femur.

Bacterial strike-through of re-usable surgical drapes: the effect of different wetting agents

Wound contamination and the resultant postoperative infection is a major problem in all forms of surgery. Air contamination, gloves, surgical instruments and drapes have all been investigated as sources of wound contamination. We investigated the effect of different wetting agents on strike-through rate of bacteria through re-usable polyester/cotton surgical drapes using a newly described method. Within 30 min bacterial strike-through of dry surgical drapes occurs. Wetting drapes with blood or normal saline enhances the strike-through rate of bacteria. Wetting drapes with iodine or chlorhexidine diminishes, but does not stop, bacterial strike-through. The use of re-usable polyester/cotton drapes is a potential source of wound contamination especially when wetted with blood or normal saline.

Direct measurement of bacterial penetration through surgical gowns: a new method

There is a paucity of data on the penetration of bacteria through surgical gowns during operations. A simple new method was developed, using Petri dishes filled with horse blood agar that were attached to the outside of the gown material. This was used to assess bacterial penetration through disposable spun-bonded polyester gowns and re-usable woven polyester gowns during normal use. There was a significant difference between the two gown types when tested in the axilla (P = 0.02), the groin (P = 0.02) and the peri-anal region (P < 0.01), with the disposable gowns performing to a higher standard. Re-usable gowns demonstrated variation in penetrability, and for this reason, may be unsuitable for use in orthopaedic implant surgery.