Abstract

An increasing elderly population means joint replacement surgery numbers are projected to increase, with associated complications such as periprosthetic joint infections (PJI) also rising. PJI are particularly challenging due to antimicrobial resistant biofilm development on implant surfaces and surrounding tissues, with treatment typically involving invasive surgeries and systemic antibiotic delivery. Consequently, functionalisation of implant surfaces to prevent biofilm formation is a major research focus. This study characterises clinically relevant antimicrobials including gentamicin, clindamycin, daptomycin, vancomycin and caspofungin within a silica-based, biodegradable sol-gel coating for prosthetic devices.

Antimicrobial activity of the coatings against clinically relevant microorganisms was assessed via disc diffusion assays, broth microdilution culture methods and the MBEC assay used to determine anti-biofilm activity. Human and bovine cells were cultured in presence of antimicrobial sol-gel to determine cytotoxicity using Alamar blue and antibiotic release was measured by LC-MS. Biodegradability in physiological conditions was assayed by FT-IR, ICP-MS and measuring mass change. Effect of degradation products on osteogenesis were studied by culturing mesenchymal stem cells in the presence of media in which sol-gel samples had been immersed.

Antimicrobial-loaded coatings showed strong activity against a wide range of clinically relevant bacterial and fungal pathogens with no loss of activity from antibiotic alone. The sol-gel coating demonstrated controlled release of antimicrobials and initial sol-gel coatings showed no loss of viability on MSCs with gentamicin containing coatings. Current work is underway investigating cytotoxicity of sol-gel compositions against MG-63 cells and primary osteoblasts.

This research forms part of an extended study into a promising antimicrobial delivery strategy to prevent PJI. The implant coating has potential to advance PJI infection prevention, reducing future burden upon healthcare costs and patient wellbeing.

Abstract

Aims

This study aims to assess the feasibility of conducting a pragmatic, multicentre randomized controlled trial (RCT) to test the clinical and cost-effectiveness of an informal caregiver training programme to support the recovery of people following hip fracture surgery.

Introduction and Objective

Kinesiophobia, the fear of physical movement and activity related to injury vulnerability, has been linked to sub-optimal outcomes following total knee replacement (TKR). This systematic review has two aims: to define the relationship between kinesiophobia and functional outcomes, pain and range of motion following TKR, and to evaluate published treatments for kinesiophobia following TKR.

Aims

Urinary catheter use in the peri-operative and post-operative phase following arthroplasty may be associated with increased risk of urinary tract infection (UTI) and deep prosthetic joint infection (PJI). These can be catastrophic complications in joint arthroplasty. We performed a systematic review of the evidence on routine use of antibiotics for urinary catheter insertion and removal following arthroplasty.

Introduction

Tantalum trabecular metal components are increasingly used to reconstruct major bone defects in revision arthroplasty surgery. It is known that some metals such as silver have antibacterial properties. Recent reports have raised the question as to whether Tantalum components are protective against infection in revision surgery. This is based on a retrospective, single institution review, of revision cases comparing tantalum with titanium acetabular implants, which reported a lower incidence of subsequent infection in the tantalum group.

This laboratory study aimed to establish if tantalum had any intrinsic antibacterial properties against planktonic bacteria or ability to inhibit biofilm formation.

Introduction

Previous systematic reviews have shown that patients experience low physical activity levels following total hip replacement (THR). However no previous systematic reviews have examined the changes between pre- and post-operative physical activity levels.

Introduction

Vancomycin is commonly added to acrylic bone cement during revision arthroplasty surgery. Proprietary cement preparations containing vancomycin are available but significantly more expensive. We investigated whether the antibiotic elution and mechanical strength of ‘home-made’ vancomycin containing bone cement was comparable to commercial vancomycin-impregnated cement.

Introduction

This analysis determined whether the type and level of physical activity changes during the initial 24 months post-total hip (THR) or total knee replacement (TKR) compared to pre-operative levels, and how this change compares to people without arthroplasty or osteoarthritis.

Obesity is a global epidemic of 2.1 billion people and a well known cause of osteoarthritis. Joint replacement in the obese attracts more complications, poorer outcomes and higher revision rates. It is a reversible condition and the fundamental principles of dealing with reversible medical conditions prior to elective total joint replacement should apply to obesity. The dilemma for orthopaedic surgeons is when to offer surgery in the face of a reversible condition, which if treated may obviate joint replacement and reduce the risk and severity of obesity related disease in both the medical arena and the field of orthopaedics.

Enhanced recovery programmes have improved outcomes following elective arthroplasty surgery. Most studies assess whole advanced recovery programmes. There are few studies assessing the role of patient education. We therefore assessed our outcomes.

As part of our enhanced recovery programme at Wrexham Maelor Hospital, all patients are offered the chance to attend ‘joint school’, a preoperative education class. Not all patients attend these sessions allowing comparison of outcomes in these two groups using our prospectively collected database of outcome measures.

Between April 2009 and March 2013, 915 patients underwent elective hip or knee arthroplasty. Revision cases were excluded, leaving 567 knee replacements, 315 hip replacements and 27 unicompartmental knee replacements.

In patients undergoing knee replacement, those attending joint school had shorter length of stay (4.38 vs 4.85 days, p=0.145) and better Oxford Knee Score at 6 months (p=0.026) and two years (p=0.035). Patients undergoing total hip arthroplasty had a statistically significantly shorter length of stay (3.64 vs 4.54 days, p=0.011); increased frequency of mobilising on the day of surgery (28.1% vs 22.6%, p=0.203) and higher Oxford Hip Scores (non-significant) if they attended joint school.

Our retrospective analysis demonstrates that preoperative education for patients undergoing elective total hip arthroplasty produces significantly shorter lengths of stay. There are also effects on mobilisation and outcome scores. These effects are also seen in knee arthroplasty. These results will have clinical and financial implications. Assessing cost of saved bed days alone, joint school saves the trust over £10,000 per year.

Background

Patellar instability is a complex, multi-factorial disorder. Radiological assessment is regarded as an important part of the management of this population. The purpose of this study was to determine the intra- and inter-rater reliability of common radiological measurements used to evaluate patellar instability.

Introduction

Injectable collagenase clostridium histolyticum (CCH) is a minimally invasive non-surgical therapy with efficacy in correcting Dupuytren's contracture (DC). In the concurrently run JOINT I and JOINT II studies, designed to follow clinical practice, we evaluated the efficacy of ?5 CCH injections in patients with DC.

Background and Objectives

Triangular fibrocartilaginous complex (TFCC) tears are common sources of ulna sided wrist pain and resultant functional disability. Diagnosis is based on history, clinical examination and radiological evidence of a TFCC central perforation or radial/ulna tear. The purpose of this study is therefore to evaluate the diagnostic accuracy of Magnetic Resonance Imaging (MRI) and Magnetic Resonance Arthrography (MRA) in the detection of TFCC injury in the adult population.

Materials and Methods: The institution’s prospective database of unicompartmental knee replacements was reviewed for all Oxford Phase III Unicompartmental Knee Replacement (Biomet, UK) undertaken from January 2004 to July 2007. This identified a total of 645 procedures undertaken. We included all cases where there was pre-operative skyline radiographs and American Knee Scores, Oxford Knee Score and SF-12 data, in addition to skyline radiographs, OKS and SF-12 data with a minimum of 2 years follow-up. All patients without this baseline and follow-up data were excluded. This provided a total of 196 knees (162 patients)

Using Altman’s nomogram, the sample size was calculated to be 85 for a power of 90%, with an α significance level of 0.05.

Using this database, digital radiographs were assessed using the institution’s PACS system. Pre-operative and follow-up skyline radiographs following Jones et al’s (1993) patellofemoral scoring system were examined by four assessors utilising Jones’ patellofemoral scoring system. In addition, in cases where patellofemoral joint changes were evident, each assessor acknowledged whether this involved the medial, lateral or bilateral aspects of the patellofemoral joint.

Intra-observer reliability was made comparing the four assessors.

Statistical analysis was performed, using the Statistical Package for the Social Sciences (SPSS) 16.0 for Windows (SPSS Inc, Chicago, Illinois).

In order to determine whether changes in patellofemoral joint status related to patients function or quality of life, the difference in OKS and SF-12 from pre-operative to the follow-up period was assessed.

Results: There was a statistically significant progression of patellofemoral osteoarthritis as found on the preoperative and postoperative radiographs (p< 0.01, Mann Whitney), there was a correlation between a low OKS and Jones patellofemoral score (P< 0.05, Mann-Whitney). However, there was no correlation between the site of patellofemoral involvement and outcome scores.

Conclusion: Due consideration should be taken when offering medial unicompartmental knee replacement to patients with patellofemoral involvement and this is independent of the site of patellofemoral involvement.

One of the ethical and legal requirements of valid consent for treatment is that patients must be fully informed about the complications involved. The General Medical Council (UK) insists that all adverse outcomes of a treatment, which are serious or frequently occurring, must be discussed with the patient.

Previous studies have found a large variance in the risks documented on consent forms for orthopaedic hip operations. The aim of this study was to compare the risks documented for three orthopaedic hip operations against pre-constructed operation-specific consent forms endorsed by the British Orthopaedic Association.

We retrospectively analysed 300 consent forms for total hip replacements, hip hemiarthoplasties and dynamic hip screw operations (n=100 for each) and noted the risks documented, whether the form was completely legible, the grade of the Doctor obtaining consent and whether a copy of the consent form was given to the patient.

We found that of the 300 operations, only 43.1% of the complications were documented as recommended by the British Orthopaedic Association. Furthermore, 26.3 % of consent forms were illegible, 72.7% of patients were consented by the Senior House Officer and only 13.7% of patients were offered a copy of the consent form.

Our results indicate that the Methods: of obtaining consent and filling in the consent forms for orthopaedic hip operations could be vastly improved. One method which could be utilized to achieve this would be the incorporation of procedure specific templates in the consenting process. These templates are already in the public domain and free to use at www.orthoconsent.com. This would allow the patient to weigh up the risks and make a valid informed decision about their treatment and also protect the Doctors from any possible litigation.

Introduction: External fixation is used widely in the management of fractures, despite a relatively high incidence of complication, arising from pin loosening and infection. Diamond like carbon (DLC) is a low surface energy coating that can be applied to external fixator pins and may reduce biofilm formation and infection resulting in a lower incidence of pin loosening. Hydroxyapatite (HA) is well established as a coating to enhance fixation of external fixator pins. This study tests the hypothesis that HA and DLC coatings on stainless steel (SS) external fixator pin shafts modify integration of the implant with soft/hard tissues.

Materials and Methods: An Orthofix external fixator was used to stabilise a tibial osteotomy with 6 self-drilling/tapping 6mm pins in 32 skeletally mature Friesland ewes. Animals were divided into four groups; SS, DLC, HA partially coated (threads only) and HA fully coated (threads and pin shaft). Pin insertion torque was measured using a torque wrench and extraction torque similarly obtained at 10 weeks when animals underwent euthanasia. Pin performance indices (PPI) were calculated as a ratio of extraction to insertion torque x100%. Pin site 2 was preserved for hard grade resin histology and subsequent pin tissue integration analysis. Pin site 3 was used for analysis of the soft tissue pin shaft interface using transmission electron microscopy. Pin site 5 was examined for the presence of biofilm formation using scanning electron microscopy. Pin site 6 was swabbed for microbiological analysis.

Results: SS and DLC pins achieved significantly higher insertion torques compared to HA partially coated pins (p=0.001, 0.002). Both groups of HA coated pins demonstrated a significantly higher, extraction torque and therefore PPI for all pin site positions compared to SS and DLC (p< 0.001– 0.025). The epithelium was found not to be in contact with the pin shaft in all cases. No significant differences were found between the different pin groups for epidermal down growth and dermal contact. Both groups of HA coated pins showed a significantly higher percentage of new bone in direct contact with the embedded threads compared to SS and DLC pins (p< 0.001, p=0.004). The proportion of soft tissue in contact and within the thread, of fully coated HA pins was significantly lower compared to stainless steel (p=0.003, p=0.017), DLC (p=0.004, p=0.002) and HA partially coated pins (p=0.006, p=0.02). Biofilms were evident on all pins except those coated with DLC. More bacteria were observed on the fully HA coated pins. DLC had significantly lower number of bacterial colonies in culture compared to SS (p=0.028) and fully coated HA pins (p=0.005).

Discussion: Coatings of DLC and HA do have a significant affect on hard/soft tissue reactions. However coatings do not have a significant effect on epidermal down growth or dermal attachment to the pin shaft surface. DLC coated pins had the cleanest surface with no bio-film present and significantly lower numbers of bacteria present. Fully HA coated pins despite evidence of bio-film formation, bacteria and high microbiological counts had significantly higher PPI. In addition fully coated HA pins demonstrated significantly reduced amounts of soft tissue at the pin bone interface. Therefore soft tissue reactions may affect bone integration.

Introduction: The main problem facing the longevity of total hip replacements (THR) is wear particle induced osteolysis, particularly around the acetabular component. The articulating surfaces produce wear particles that migrate in the fibrous tissue membrane along the acetabular implant-bone interface causing osteolysis and subsequent implant loosening. The hypothesis that we investigated was that uncemented acetabular interfaces are more effective than cemented implants at resisting progressive osteolysis through bone attachment and the formation of a biological seal.

Methods: THR surgery was performed in an ovine model. Implants remained in vivo for 1 year. Femoral heads were roughened in order to generate wear debris and aseptic loosening of the acetabular component. Sheep were randomly assigned to one of three experimental groups: cemented polyethylene, grit blasted or plasma sprayed porous acetabular components with a polyethylene insert. Ground Reaction Force (GRF) data was collected pre-op and at 12, 24, 36 and 52 weeks post op. Retrieved specimens were analysed radiographically, histologically and using Scanning Electron Microscopy (SEM). A mould was made of the polyethylene liner and head penetration rates quantified using a shadowgraph technique. Thin sections through the acetabuli were prepared and image analysis used to quantify fibrous tissue (FT) thickness at the bone-implant interface. Mann-Whitney U tests were used for comparative statistical analysis where p< 0.05 were classified as significant.

Results: GRF demonstrated functional hips. A gradual increase was seen until week 36 followed by a decrease until retrieval suggesting the onset of aseptic loosening. 42.86% of control, 60% of grit blasted and 50% of porous coated components were deemed radiographically loose. Mean linear penetration rates demonstrated significantly less penetration within the porous cups (p=0.003, control and p=0.036, grit blasted). SEM established that wear particles generated were < 1μm in size. Light microscopy of thin sections revealed the common mechanism of loosening involving a resorption wedge at the interface with progressive bone loss. In all cases, the FT layer was greatest at the rim of the cup and gradually decreased towards the apex. The grit blasted group had the thickest FT layer adjacent to the cup. Under polarised light, wear debris was seen packed within macrophages in all sections.

Discussion: GRF data demonstrated grit blasted cups to have least function. This was confirmed through histology as they had the thickest FT layer surrounding the acetabular shell suggesting increased aseptic loosening of its component due to wear particles being able to access the interface more easily. Data corroborates radiographic results. In conclusion, porous and control cups performed better than grit blasted cups. Acknowledgments: EPSRC.

Introduction: Different tendons and ligaments have a specific elasticity which relates to their role in joint movement and locomotion. To ensure an optimal functional outcome it is essential that this mechanical property is restored following surgical procedures to repair or replace damaged tendons and ligaments. This demands appropriate selection of an autograft or artificial construct aided by an understanding of how molecular composition and morphology determines the stiffness of the material. This study tests the hypothesis that tendons with a higher elastic modulus (stiffer) have larger collagen fibril diameters and lower water and sulphated glycosaminoglycan (GAG) contents.

Methods: The superficial digital flexor tendon (SDFT, 30 pairs), deep digital flexor tendon (DDFT, 6 pairs), suspensory ligament (SL, 6 pairs) and common digital extensor tendon (CDET, 6 pairs) were collected from the forelimbs of horses aged 2–23 years destroyed for reasons other than tendon injuries. Left limb tendons were tested to failure in a hydraulic materials testing machine (Dartec) following measurement of cross sectional area. Collagen fibril diameters, water content and sulphated GAG content were measured in tendon tissue from the right limb. Statistical significance was evaluated using Spearman’s correlation and a general linear model (SPSS software).

Results: The elastic modulus was significantly (p< 0.001) different between the different structures and showed a significant positive correlation with the mass average collagen fibril diameter (MAFD) for the different structures and within the SDFT (FIG. I). The water content showed a significant negative correlation with elastic modulus and significant positive correlation with GAG content.

Discussion and Conclusion: Tendons composed of a stiffer material have larger collagen fibril diameters which are associated with lower water and GAG contents. These characteristics should be considered when choosing suitable replacements in tendon reconstruction procedures. Future work to determine the mechanisms that control collagen fibril diameters and water content will aid in the design of bioengineered constructs.