Incidence, associated disease burden and healthcare utilization due to Staphylococcus aureus prosthetic joint infection in European hospitals: the COMBACTE-NET ARTHR-IS multi-centre study

BACKGROUND

The aim of this study was to estimate the incidence, associated disease burden and healthcare utilization due to Staphylococcus aureus prosthetic joint infections (SA-PJI) after primary hip and knee arthroplasty in European centres.

METHODS

This study was conducted in patients who underwent primary hip and knee arthroplasty in 19 European hospitals between 2014 and 2016. The global incidence of PJI and SA-PJI was calculated. The associated disease burden was measured indirectly as infection-related mortality plus loss of function. For healthcare utilization, number and duration of hospitalizations, number and type of surgical procedures, duration of antibiotic treatments, and number of outpatient visits were collected. Subgroup and regression analyses were used to evaluate the impact of SA-PJI on healthcare utilization, controlling for confounding variables.

RESULTS

The incidence of PJI caused by any micro-organism was 1.41%, and 0.40% for SA-PJI. Among SA-PJI, 20.7% were due to MRSA with substantial regional differences, and were more frequent in partial hip arthroplasty (PHA). Related deaths and loss of function occurred in 7.0% and 10.2% of SA-PJI cases, respectively, and were higher in patients with PHA. Compared with patients without PJI, patients with SA-PJI had a mean of 1.4 more readmissions, 25.1 more days of hospitalization, underwent 1.8 more surgical procedures, and had 5.4 more outpatient visits, controlling for confounding variables. Healthcare utilization was higher in patients who failed surgical treatment of SA-PJI.

CONCLUSIONS

This study confirmed that the SA-PJI burden is high, especially in PHA, and provided a solid basis for planning interventions to prevent SA-PJI.

Laser ablation of the pia mater for insertion of high-density microelectrode arrays in a translational sheep model

Objective. The safe insertion of high density intracortical electrode arrays has been a long-standing practical challenge for neural interface engineering and applications such as brain-computer interfaces (BCIs). However, the pia mater can be difficult to penetrate and causes deformation of underlying cortical tissue during insertion of high-density intracortical arrays. This can lead to neuron damage or failed insertions. The development of a method to ease insertion through the pia mater would represent a significant step toward inserting high density intracortical arrays.Approach. Here we describe a surgical procedure, inspired by laser corneal ablation, that can be used in translational models to thin the pia mater.Main results. We demonstrate that controlled pia removal with laser ablation over a small area of cortex allows for microelectrode arrays to be inserted into the cortex with less force, thus reducing deformation of underlying tissue during placement of the microelectrodes. This procedure allows for insertion of high-density electrode arrays and subsequent acute recordings of spiking neuron activity in sheep cortex. We also show histological and electrophysiological evidence that laser removal of the pia does not acutely affect neuronal viability in the region.Significance. Laser ablation of the pia reduces insertion forces of high-density arrays with minimal to no acute damage to cortical neurons. This approach suggests a promising new path for clinical BCI with high-density microelectrode arrays.

The Argo: a high channel count recording system for neural recording in vivo

OBJECTIVE

Decoding neural activity has been limited by the lack of tools available to record from large numbers of neurons across multiple cortical regions simultaneously with high temporal fidelity. To this end, we developed the Argo system to record cortical neural activity at high data rates.

APPROACH

Here we demonstrate a massively parallel neural recording system based on platinum-iridium microwire electrode arrays bonded to a CMOS voltage amplifier array. The Argo system is the highest channel count in vivo neural recording system, supporting simultaneous recording from 65 536 channels, sampled at 32 kHz and 12-bit resolution. This system was designed for cortical recordings, compatible with both penetrating and surface microelectrodes.

MAIN RESULTS

We validated this system through initial bench testing to determine specific gain and noise characteristics of bonded microwires, followed by in-vivo experiments in both rat and sheep cortex. We recorded spiking activity from 791 neurons in rats and surface local field potential activity from over 30 000 channels in sheep.

SIGNIFICANCE

These are the largest channel count microwire-based recordings in both rat and sheep. While currently adapted for head-fixed recording, the microwire-CMOS architecture is well suited for clinical translation. Thus, this demonstration helps pave the way for a future high data rate intracortical implant.

National survey of occupational advice for lower limb arthroplasty patients

BACKGROUND

Little is known what advice or support patients are given about return to work (RTW) after hip or knee replacement surgery.

AIMS

This study aims to understand the delivery, timing and content of 'RTW' advice currently delivered by surgical teams offering hip and knee replacements across the UK.

METHODS

National online survey exploring five specific areas relating to 'RTW' advice: (i) timings of interactions between hospital orthopaedic teams and patients prior to surgery, (ii) routine delivery of 'RTW' advice, (iii) methods used to deliver 'RTW' advice, (iv) confidence delivering advice and (v) need for an occupational 'RTW' advice intervention.

RESULTS

A total of 152 participants including surgeons, physiotherapists, occupational therapists and nurses from 59 different public and private health providers responded. Only 20% (n = 30) of respondents reported that working patients were identified as a specific subgroup in need of additional support. Overall, 62% (n = 92) stated that they did not routinely offer 'RTW' advice. When given, 'RTW' advice was almost always verbal, generic advice using blanket timescales and based on the respondent's anecdotal experience rather than the patients individualized needs. Overall, 116 (78%) felt an occupational advice intervention was needed.

CONCLUSIONS

This national survey demonstrated wide variation in the timing, content and delivery of information and advice for patients in work and intending to RTW after hip and knee replacement surgery. Current RTW advice provided to hip and knee replacement patients is inadequate.

Revealing Spatial and Temporal Patterns of Cell Death, Glial Proliferation, and Blood-Brain Barrier Dysfunction Around Implanted Intracortical Neural Interfaces

Improving the long-term performance of neural electrode interfaces requires overcoming severe biological reactions such as neuronal cell death, glial cell activation, and vascular damage in the presence of implanted intracortical devices. Past studies traditionally observe neurons, microglia, astrocytes, and blood-brain barrier (BBB) disruption around inserted microelectrode arrays. However, analysis of these factors alone yields poor correlation between tissue inflammation and device performance. Additionally, these studies often overlook significant biological responses that can occur during acute implantation injury. The current study employs additional histological markers that provide novel information about neglected tissue components-oligodendrocytes and their myelin structures, oligodendrocyte precursor cells, and BBB -associated pericytes-during the foreign body response to inserted devices at 1, 3, 7, and 28 days post-insertion. Our results reveal unique temporal and spatial patterns of neuronal and oligodendrocyte cell loss, axonal and myelin reorganization, glial cell reactivity, and pericyte deficiency both acutely and chronically around implanted devices. Furthermore, probing for immunohistochemical markers that highlight mechanisms of cell death or patterns of proliferation and differentiation have provided new insight into inflammatory tissue dynamics around implanted intracortical electrode arrays.

The orthopaedic research scene and strategies to improve it

Trauma and orthopaedics is the largest of the surgical specialties and yet attracts a disproportionately small fraction of available national and international funding for health research. With the burden of musculoskeletal disease increasing, high-quality research is required to improve the evidence base for orthopaedic practice. Using the current research landscape in the United Kingdom as an example, but also addressing the international perspective, we highlight the issues surrounding poor levels of research funding in trauma and orthopaedics and indicate avenues for improving the impact and success of surgical musculoskeletal research.

Is reconstruction the best management strategy for anterior cruciate ligament rupture? A systematic review and meta-analysis comparing anterior cruciate ligament reconstruction versus non-operative treatment

AIMS

The purpose of this study was to determine the optimal clinical and cost-effective strategy for managing people following ACL rupture.

METHODS

A systematic review of the published (AMED, CINAHL, MEDLINE, EMBASE, PubMed, psycINFO and the Cochrane Library) and unpublished literature (OpenGrey, the WHO International Clinical Trials Registry Platform, Current Controlled Trials and the UK National Research Register Archive) was conducted on April 2013. All randomised and non-randomised controlled trials evaluating clinical or health economic outcomes of isolated ligament reconstruction versus non-surgical management following ACL rupture were included. Methodological quality was assessed using the PEDro appraisal tool. When appropriate, meta-analysis was conducted to pool data.

RESULTS

From a total of 943 citations, sixteen studies met the eligibility criteria. These included 1397 participants, 825 who received ACL reconstruction versus 592 who were managed non-surgically. The methodological quality of the literature was poor. The findings indicated that whilst reconstructed ACL offers significantly greater objective tibiofemoral stability (p<0.001), there appears limited evidence to suggest a superiority between reconstruction versus non-surgical management in functional outcomes. There was a small difference between the management strategies in respect to the development of osteoarthritis during the initial 20 years following index management strategy (Odds Ratio 1.56; p=0.05).

CONCLUSIONS

The current literature is insufficient to base clinical decision-making with respect to treatment opinions for people following ACL rupture. Whilst based on a poor evidence, the current evidence would indicate that people following ACL rupture should receive non-operative interventions before surgical intervention is considered.

Distal femoral replacement in periprosthetic fracture around total knee arthroplasty

INTRODUCTION

Total knee arthroplasty is a common orthopaedic procedure in the UK; consequently, revision surgery and periprosthetic fractures are increasing in incidence. Strategies for management of these cases include non-operative strategies, internal plate fixation and revision of the distal femoral component. One under-reported practice is to perform distal femoral replacement in cases with poor distal femoral bone stock.

MATERIALS AND METHODS

The department's electronic database was searched for all patients undergoing revision of total knee arthroplasty. From these, all patients having distal femoral replacement for periprosthetic fracture around the distal femoral component using the Stryker Global Modular Replacement System (GMRS) implant were filtered. A retrospective analysis of the patient notes was performed to examine the patient demographics, surgical factors and postoperative complications. Postoperative scores were performed for these patients.

RESULTS

From 2005 onwards, 11 patients (mean age 81 years, range 61-90 years) had their implants revised with a distal femoral replacement for periprosthetic fracture with associated poor bone stock. Follow up was for a mean of 33 months (range 4-72 months). One of these patients died of causes unrelated to their operation. Of the rest, all implants survived without the need of re-operation. The mean postoperative Oxford Knee Score for these patients was 22.5 (range 5-34).

CONCLUSIONS

Distal femoral replacement for patients with fracture around a total knee arthroplasty has been performed in our department with few complications and acceptable functional outcomes. It is a technically challenging operation and it should be a salvage procedure reserved for patients with poor bone stock and low demands where other methods of fixation are not suitable.

LEVEL OF EVIDENCE

IV.

Mechanical properties of morcellised bone graft with the addition of hydroxyapatite

Mixtures of morcellised bone graft (MBG) and hydroxyapatite (HA) are frequently used in revision arthroplasty surgery. However, the changes in the mechanical properties from adding HA to MBG are unknown. This study used a uniaxial compression test to replicate impaction bone grafting and subsequent early postoperative weightbearing to investigate the effect of adding different proportion of HA to MBG. To achieve this aim, human MBG was subjected to increasing impaction forces and the apparent stiffness and creep for each stress level determined. Subsequently, increasing proportions porous and non porous HA were added to the MBG. The major findings were that the apparent stiffness for MBG increased and the associated creep decreased both with the application of increasing stress and with the addition of increasing proportions of HA. In conclusion, greater proportions of HA in the graft mixture improved the mechanical response compared with MBG impacted under the same force. This improvement replicated the properties of pure MBG under high axial stress. This study indicates that graft mixtures of MBG and HA can be tailormade for patients. The need for less impaction force in MBG:HA mixtures to obtain the same properties as pure MBG may decrease the risk of intraoperative fracture.

Improving the peer review process in orthopaedic journals

The peer review process for the evaluation of manuscripts for publication needs to be better understood by the orthopaedic community. Improving the degree of transparency surrounding the review process and educating orthopaedic surgeons on how to improve their manuscripts for submission will help improve both the review procedure and resultant feedback, with an increase in the quality of the subsequent publications. This article seeks to clarify the peer review process and suggest simple ways in which the quality of submissions can be improved to maximise publication success. Cite this article: Bone Joint Res 2013;2:245-7.

High tibial osteotomy: evolution of research and clinical applications--a Canadian experience

PURPOSE

This narrative review describes experiences at the Fowler Kennedy Sport Medicine Clinic (FKSMC) with high tibial osteotomy (HTO) for patients with varus gonarthrosis, with particular focus on research published from the unit that has guided practice.

METHODS

The goals of surgery are to improve alignment of the weight bearing axis of the lower limb to lessen the load on the medial tibiofemoral compartment and thereby decrease these important risk factors for disease progression. The overall aims are to improve knee function and delay or even prevent the eventual need for arthroplasty. To achieve these aims, a medial opening wedge osteotomy is utilised, deliberately avoiding an over correction of the lower limb, but tailoring the angle of correction to an individual patient's characteristics. With such an approach, patients with a broad range of characteristics (including age, BMI and lateral compartment involvement) can benefit from the procedure. In addition, the HTO can be used with concomitant procedures to address specific presentations, such as large deformities and instability.

RESULTS

The results suggest that correction to a slight valgus alignment produces approximately 50% reduction in medial compartment loads during gait with large, clinically important improvements in patient-reported outcomes at 2-years postoperatively. In patients with substantial bilateral varus deformity, unilateral surgery can lead to increased dynamic knee joint loads on the nonoperative limb after surgery. This means that such patients require the close monitoring of both limbs and consideration of a staged, bilateral procedure if necessary. In patients requiring bilateral surgery, similar results after bilateral HTO to those after unilateral surgery have been reported. For patients requiring large corrections, the need for a concomitant tibial tubercle osteotomy to reduce the potential for iatrogenic patella infera is considered. Finally, HTO procedures can also be used in patients with instability, either to alter both sagittal and coronal alignment to correct instability in complex ligament deficiencies or to undertake simultaneous HTO and ACL reconstruction.

CONCLUSIONS

HTO is being used both alone and in conjunction with concomitant procedures with good clinical results. While continued investigation into patient selection and outcomes are required, current research indicates that HTO offers at least a partial solution for the patient with varus gonarthrosis to prolong the life of their native knee joint.

LEVEL OF EVIDENCE

V.

Classification of subtrochanteric femoral fractures

A review of the literature identified 15 different classification methods for subtrochanteric femoral fractures. Only eight of those classifications defined the area of bone, which constituted a subtrochanteric fracture. The actual length of femur defined as the subtrochanteric zone varied from 3 cm up to the level of the femoral isthmus. There was no agreement between the different classifications regarding the proximal and distal border or for those fractures, which traverse anatomical boundaries. In the various classifications, fractures were subdivided into 2-15 subgroups. The majority of the identified studies were unable to find the classifications useful in either determining treatment or predicting the outcome after treatment. We subdivided subtrochanteric fractures into three types based on the degree of fracture comminution. We examined the inter- and intra-observer agreement of our recommended classification. One orthopaedic consultant, one specialist hip fracture surgeon, two trainee registrar orthopaedic surgeons and one specialty trainee in orthopaedics, on two different occasions, 8 weeks apart, independently classified the radiographs of 20 patients with a subtrochanteric fracture. The mean kappa value for inter- and intra-observer variation was 0.71 and 0.79, respectively, with both showing substantial agreement and, therefore, this simpler classification is recommended. Based on the review of previous classification methods, we also recommend that the subtrochanteric zone be defined as the one in which the fracture line crossing the femur is predominantly within the area of bone extending 5 cm below the lower border of the lesser trochanter.

Impaction grafting of the acetabulum with a mixture of frozen, ground irradiated bone graft and porous synthetic bone substitute (Apapore 60)

The clinical and radiological results of 50 consecutive acetabular reconstructions in 48 patients using impaction grafting have been retrospectively reviewed. A 1:1 mixture of frozen, ground irradiated bone graft and Apapore 60, a synthetic bone graft substitute, was used in all cases. There were 13 complex primary and 37 revision procedures with a mean follow-up of five years (3.4 to 7.6). The clinical survival rate was 100%, with improvements in the mean Harris Hip Scores for pain and function. Radiologically, 30 acetabular grafts showed evidence of incorporation, ten had radiolucent lines and two acetabular components migrated initially before stabilising.

Acetabular reconstruction in both primary and revision surgery using a 1:1 mixture of frozen, ground, irriadiated bone and Apapore 60 appears to be a reliable method of managing acetabular defects. Longer follow-up will be required to establish whether this technique is as effective as using fresh-frozen allograft.

General practitioners' experience of the chronic fatigue syndrome

In order to examine the prevalence of patients with symptoms fulfilling the criteria for the chronic fatigue syndrome an extensive survey was carried out of general practitioners on 10 local government lists in two health boards (91% response rate). At the same time practitioners' attitudes to the syndrome and their experience in terms of workload and the characteristics of patients affected were documented. The majority of general practitioners (71%) accepted the existence of chronic fatigue syndrome, but 22% were undecided. The doctors reported a prevalence among their patients of 1.3 per 1000 patients (range 0.3-2.7 for the 10 areas) with a peak in the 30-44 years age group. Female patients were more commonly affected than males (sex ratio 1.8:1.0), but the severity of illness and the use of general practitioner's time was the same among male and female patients. Patients in occupations where they were exposed to infection were affected (teachers and students, 22% of sample; hospital workers, 7%), but many patients were unskilled (8%) and skilled workers (9%). Patients suffering from the chronic fatigue syndrome appear to be a real and distinct group for general practitioners and may represent a substantial part of the workload of doctors in particular areas.