Pelvic osteomyelitis following pressure ulceration results in substantial patient morbidity. Previous studies have reported a heterogenous approach to diagnosis and medical management by physicians, suggesting equipoise on key clinical questions. This study hypothesised that the same equipoise exists amongst Orthopaedic surgeons. An 18-question multiple-choice questionnaire was designed through an iterative feedback process until the final version was agreed by all authors. Likert-type scale responses were used with graded responses (Aim
Method
Distal femoral and proximal tibial osteotomies are effective procedures to treat degenerative disease of the knee joint. Previously described techniques advocate the use of bone graft to promote healing at the osteotomy site. In this present study a novel technique which utilises the osteogenic potential of the cambial periosteal layer to promote healing “from the outside in” is described. A retrospective analysis of a consecutive single-surgeon series of 23 open wedge osteotomies around the knee was performed. The median age of the patients was 37 years (range 17–51 years). The aetiology of the deformities included primary genu valgum (8/23), fracture malunion (4/23), multiple epiphyseal dysplasia (4/23), genu varum (2/23), hypophosphataemic rickets (1/23), primary osteoarthritis (1/23), inflammatory arthropathy (1/23), post-polio syndrome (1/23), and pseudoachondroplasia (1/23).Introduction
Materials and Methods
Many pre-clinical models of atrophic non-union do not reflect the clinical scenario, some create a critical size defect, or involve cauterization of the tissue which is uncommonly seen in patients. Atrophic non-union is usually developed following high energy trauma leading to periosteal stripping. The most recent reliable model with these aspects involves creating a non-critical gap of 1mm with periosteal and endosteal stripping. However, this method uses an external fixator for fracture fixation, whereas intramedullary nailing is the standard fixation device for long bone fractures. To establish a clinically relevant model of atrophic non-union using intramedullary nail and (1) ex vivo and in vivo validation and characterization of this model, (2) establishing a standardized method for leg positioning for a reliable x-ray imaging. Ex vivo evaluation: 40 rat's cadavers (adult male 5–6 months old), were divided into five groups (n=8 in each): the first group was fixed with 20G intramedullary nail, the second group with 18G nail, the third group with 4-hole plate, the fourth group with 6-hole plate, and the fifth group with an external fixator. Tibiae were harvested by leg disarticulation from the knee and ankle joints. Each group was then subdivided into two subgroups for mechanical testing: one for axial loading (n=4) and one for 4-point bending (n=4) using Zwick/Roell® machine. Statistical analysis was carried out by ANOVA with a fisher post-hoc comparison between groups. A p-value less than 0.05 was considered statistically significant. To maintain the non-critical gap, a spacer was inserted in the gap, the design was refined to minimize the effect on the healing surface area. In vivo evaluation was done to validate and characterize the model. Here, a 1 mm gap was created with periosteal and endosteal stripping to induce non-union. The fracture was then fixed by a hypodermic needle. A proper x-ray technique must show fibula in both views. Therefore, a leg holder was used to hold the knee and ankle joints in 90º flexion and the foot was placed in a perpendicular direction with the x-ray film. Lateral view was taken with the foot parallel to the x-ray film. Ex vivo: axial load stiffness data revealed that intramedullary nails are significantly stronger and stiffer than other devices. Bending load to failure showed that 18G nails are significantly stronger than 20G, thus it is used for the in vivo experiments. In vivo: final iteration revealed 3/3 non-union, and in controls with the periosteum and endosteum intact but with the 1mm non-critical gap, it progressed to 3/3 union. X-ray positioning: A-P view in supine position, there was an unavoidable degree of external rotation in the lower limb, thus the lower part of the fibula appeared behind the tibia. To overcome this, a P-A view of the leg was performed with the body in prone rather, this arrangement allowed both upper and lower parts of the fibula to appear clearly in both views. We report a novel model of atrophic non-union, the surgical procedure is relatively simple and the model is reproducible.OBJECTIVES
There is a lack of evidence as to the best way to deliver rehabilitation following TKA. Previous work has suggested that postoperative physiotherapy applied to all patients is not effective at improving one-year post-surgical outcomes. The aim of this study was to target physiotherapy to those at risk of poor outcome following TKA, and to determine if a therapist-led intervention offered superior results compared to a home-exercise based protocol in this ‘at risk’ group. The Targeted Rehabilitation to Improve Outcomes (TRIO) study was a prospective randomised controlled trial run at 15-centres in the UK. Patients were identified as ‘potential poor outcome’ based on an Oxford Knee Score (OKS) classification at 6-weeks post-surgery and randomised to either therapist-led or home-exercise based protocols. Patients were reviewed by a physiotherapist and commenced 18-exercise sessions over 6-weeks. The therapist-led group undertook a progressive functional protocol (modified weekly in 1-1 contact sessions) in contrast to the static home-exercise based regime. Evaluation took place following rehabilitation intervention, then at 6-months and 1-year post-surgery. Primary outcome was comparative group OKS at 1-year. Secondary outcomes included, ‘worst’ and ‘average’ pain scores, OXS and EQ-5D, and satisfaction questionnaire. Health economic (cost-utility) analysis was undertaken from NHS perspective up to 1-year post-surgery. Incremental cost per Quality Adjusted Life Years (QALYs) were calculated from intervention costs, patient reported primary and secondary care usage, and EQ-5D data. 4264 patients were screened, 1296 were eligible, 334 patients were randomised, 8 were lost to follow-up, therapy compliance was >85%. Clinically meaningful improvement in OKS (between baseline and 1-year) was seen in both arms (p < 0 .001). Between group difference in 1-year OKS was 1.91 (95%CI, −0.17–3.99) points favouring the therapist-led arm (p=0.07). Incorporating all time point data, between group difference in OKS was 2.25 points (95%CI, 0.61–3.90, p=0.008). Small, non-significant reductions (< 5 %) in both worst and average pain scores were observed favouring the therapist-led group. Enhanced satisfaction with pain relief (OR 1.65, p < 0 .02), ability to perform daily functional tasks (OR 1.66, p < 0 .02), and perform heavy functional tasks (OR 1.6, p=0.04) was reported in the therapist-led group. There was a small non-significant difference of 0.02 points (95%CI −0.02–0.06) between groups in EQ-5D, resulting in a £12,125 cost per QALY of delivering the therapist led intervention with a 57% chance of being cost-effective at the standard UK policy threshold of £20,000 per QALY. TRIO is the largest randomised trial of physiotherapy following TKA, and the first to target rehabilitation to patients at risk of poor outcomes. Both therapist-led and home-exercise based rehabilitation groups made clinically meaningful improvements in outcome by 1-year. We observed a modest difference in OKS in favour of therapist-led rehabilitation compared to the home-exercises which was not statistically significant. The relatively tight confidence intervals suggests that any difference which might exist is too small to be clinically relevant. Patient satisfaction with outcome was however higher in those that received greater physiotherapist contact. While cost per QALY estimates were below UK policy threshold, this result is uncertain and insufficient to make accept-decline recommendations.
Staphylococcus aureus is responsible for 60–70% infections of surgical implants and prostheses in Orthopaedic surgery, with cumulative treatment costs for all prosthetic joint infections estimated to be ∼ $1 billion per annum (UK and North America). Its ability to develop resistance or tolerance to a diverse range of antimicrobial compounds, threatens to halt routine elective implant surgery. One strategy to overcome this problem is to look beyond traditional antimicrobial drug therapies and investigate other treatment modalities. Biophysical modalities, such as ultrasound, are poorly explored, but preliminary work has shown potential benefit, especially when combined with existing antibiotics. Low intensity pulsed ultrasound is already licensed for clinical use in fracture management and thus could be translated quickly into a clinical treatment Using a methicillin-sensitive S. aureus reference strain and the dissolvable bead assay, biofilms were challenged with gentamicin +/− low-intensity ultrasound (1.5MHz, 30mW/cm2, pulse duration 200µs/1KHz) for 180 minutes and 20 minutes, respectively. The primary outcome measures were colony-forming units/mL (CFU/mL) and the minimum biofilm eradication concentration (MBEC) of gentamicin. The mean number of S. aureus within control biofilms was 1.04 × 109 CFU/mL. Assessment of cellular metabolism was conducted using a liquid-chromatography-mass spectrometry, as well as a triphenyltetrazolium chloride assay coupled with spectrophotometry. There was no clinically or statistically significant (p=0.531) reduction in viable S. aureus following ultrasound therapy alone. The MBEC of gentamicin for this S. aureus strain was 256 mg/L. The MBEC of gentamicin with the addition of ultrasound was reduced to 64mg/L. Metabolic activity of biofilm-associated S. aureus was increased by 25% following ultrasound therapy (p < 0 .0001), with identification of key biosynthetic pathways activated by non-lethal dispersal. Low intensity pulsed ultrasound was associated with a four-fold reduction in the effective biofilm eradication concentration of gentamicin, bringing the MBEC of gentamicin to within clinically achievable concentrations. The mechanism of action was due to partial disruption of the extracellular matrix which led to an increase of nutrient availability and oxygen tension within the biofilm. This metabolic stimulus was responsible for the reversal of gentamicin tolerance in the biofilm-associated S. aureus.
Trabecular bone is a multiscale hierarchical composite material that is known to display time-dependant properties. However, most biomechanical models treat this material as time independent. Time-dependant properties, such as creep and relaxation, are thought to play an important role in many clinically relevant orthopaedic issues: implant loosening, vertebral collapse, and non-traumatic fractures. In this study compressive multiple-load-creep-unload-recovery (MLCUR) tests were applied to human trabecular bone specimens. 15 female femoral heads were harvested, with full ethical approval and patient consent, at the time of total hip replacement. Central cores were extracted and cut parallel under constant irrigation. Specimens were embedded in end caps using surgical cement, an epoxy tube was secured around the end caps and filled with phosphate buffered saline (PBS) to ensure the specimens remained hydrated throughout. Embedded samples were scanned by microCT (SkyScan 1172, Bruker) at a resolution of 17µm to determine microarchitecture. Bone volume fraction (BVF) was used to represent microarchitecture. Specimens had an effective length of 16.37mm (±1.90SD) with diameter of 8.08mm (±0.05SD), and BVF of 19.22% (±5.61SD). The compressive MLCUR tests were conducted at 5 strain levels, 2000µε, 4000µε, 6000µε, 8000µε and 10000µε. At each strain level, the load required to maintain each strain was held for 200s (creep) then unloaded to 1N for 600s (recovery). The instantaneous, creep, unloading and recovered strains can be easily obtained from the strain-time curves. Stress-strain plots revealed the Young's modulus. Data was modelled using line of best fit with appropriate curve fitting. R2 values were used to indicate association. Mechanical testing demonstrated the expected time independent relationship between BVF and stiffness: higher stiffness was found for specimen with higher BVF and this was consistent for all strain levels. Creep strain was found to depend on instantaneous strain and BVF. At low levels of instantaneous strain, there was a greater amount of creep strain in low BVF samples (R2 = 0.524). This relationship was no longer apparent at higher strain levels (R2 = 0.058). Residual strain also depended on the applied instantaneous strain and BVF: at low levels of strain, residual strain was similar with all BVF (R2 = 0.108) and at high levels of strain, residual strain was greater in low BVF samples (R2 = 0.319). The amount of instantaneous strain applied to each sample is constant, variations in stiffness result in different applied loads. In low BVF bone, the stiffness is also low, therefore the stress required to reach designed strain is also lower: yet, there is more creep and less recovery. We have demonstrated that even at loads below recognised yield levels, time-dependence affects the mechanical response and residual strain is present. In cases of low BVF, deflection due to creep, and increased irrecoverable strain could have clinically relevant consequences, such as implant loosening and vertebral collapse. The role of time-dependant properties of bone is seldom considered. This data could be developed into a constitutive model allowing these time-dependant behaviours to be incorporated in finite element modelling, leading to better predictions of implant loosening, especially for lower quality bone.
Many prosthetic design changes have been introduced in attempt to improve outcomes following TKA; however there is no consensus as to whether these changes confer benefits to patients. This study aimed to assess whether patients treated with a modern implant design had an enhanced patient outcome compared to a traditional model in a double blind randomised controlled trial. 212 consecutive patients were prospectively randomised to receive either a modern (Triathlon) or a traditional (Kinemax) TKA (both Stryker Orthopaedics). 6 surgeons at a single unit performed all procedures in a standardised manner. A single researcher, blinded to implant allocation, performed all assessments. Patients were assessed pre-operatively, and at 6, 26, 52 weeks post-surgery with the Oxford Knee Score (OKS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, goniometry, timed functional assessment, lower limb power (Leg Extensor Power Rig) and pain numerical rating scales (NRS). Change in scores and between group differences were assessed with Two-Way Repeated Measures ANOVAs.Introduction
Methods
The Taylor Spatial Frame (TSF) is an hexapod external ring fixation system that can move with six degrees of freedom to correct complex limb deformities. The lengths of the struts between the rings are independently adjusted to correct the deformity. The struts form an acute and obtuse “ring-strut” angle with the ring with the sum of these angles totalling 180°. In the course of a correction schedule a strut may need to be exchanged for one of longer or shorter length. The manufacturer's instructions direct that a temporary seventh strut can be placed in any orientation to ensure stability during the exchange. We have noted several episodes of temporary frame instability during this procedure resulting in discomfort. The aim of this study was to investigate which temporary strut positions gave maximal stability. A TSF frame was constructed in a neutral alignment with a neutral strut height of 130mm. Strut 1 (red) was identified for exchange. There were 169 theoretical placement options for the temporary strut that were sequentially tested. Fast-FX™ struts were used. Strut 1 was released and the shortening that occurred was recorded using the strut length gauge. Shortening of over 10mm was considered grossly unstable.Introduction
Methods
Osteoarthritis continues to be a major cause of pain and disability. The pathological processes leading to the end-stage of joint degeneration remain poorly understood. Advances in radiological imaging have the potential to improve understanding of the structural and functional changes observed in OA. The aim of this study was to describe the microarchitecture of the femoral head in osteoarthritis. Twenty osteoarthritic femoral heads underwent micro-computed tomography scanning at 30µm. Four parameters of micro-architecture and structure were determined: bone volume ratio (BV:TV), trabecular thickness, structural model index and degree of anisotropy. The femoral head was divided into 27 cubic volumes of interest. Analysis of variance (ANOVA) was used to assess differences between regions. Cystic and sclerotic changes were assessed qualitatively.Introduction
Methods
Fracture non-union is a devastating cause of patient morbidity. The cost of NU treatment ranges from £7,000 to £79,000. With an estimated 11,700 cases in the UK pa the financial implications are huge, potentially costing several hundreds of million of pounds annually. Successful outcome in the management of non-union is based upon correctly identifying the underlying cause(s) and addressing them appropriately. The aim of this study was to assess the causative factors in non-union in order to optimize the management of non-union. The causes of NU were categorized into 4 groups (infection, dead bone/gap, host factors, mechanical).Introduction
Aim
