The primary aim was to assess the reliability of ultrasound in the assessment of humeral shaft fracture healing. The secondary aim was to estimate the accuracy of ultrasound assessment in predicting humeral shaft nonunion.

Twelve patients (mean age 54yrs [20–81], 58% [n=7/12] female) with a non-operatively managed humeral diaphyseal fracture were prospectively recruited and underwent ultrasound scanning at six and 12wks post-injury. Scans were reviewed by seven blinded observers to evaluate the presence of sonographic callus. Intra- and inter-observer reliability were determined using the weighted kappa and intraclass correlation coefficient (ICC). Accuracy of ultrasound assessment in nonunion prediction was estimated by comparing scans for patients that united (n=10/12) with those that developed a nonunion (n=2/12).

At both six and 12wks, sonographic callus was present in 11 patients (10 united, one developed a nonunion) and sonographic bridging callus (SBC) was present in seven patients (all united). Ultrasound assessment demonstrated substantial intra- (6wk kappa 0.75, 95% CI 0.47-1.03; 12wk kappa 0.75, 95% CI 0.46-1.04) and inter-observer reliability (6wk ICC 0.60, 95% CI 0.38-0.83; 12wk ICC 0.76, 95% CI 0.58-0.91). Absence of sonographic callus demonstrated a sensitivity of 50%, specificity 100%, positive predictive value (PPV) 100% and negative predictive value (NPV) 91% in nonunion prediction (accuracy 92%). Absence of SBC demonstrated a sensitivity of 100%, specificity 70%, PPV 40% and NPV 100% (accuracy 75%). Of three patients at risk of nonunion based on reduced radiographic callus formation (Radiographic Union Score for HUmeral fractures <8), one had SBC on 6wk ultrasound (and united) and the other two had non-bridging or absent sonographic callus (both developed a nonunion).

Ultrasound assessment of humeral shaft fracture healing was reliable and predictive of nonunion, and may be a useful tool in defining the risk of nonunion among patients with reduced radiographic callus formation.

To test and evaluate the effectiveness of local injection of autologous fat-derived mesenchymal stem cells (MSCs) into fracture site to prevent non-union in a clinically relevant model.

5 male Wistar rats underwent the same surgical procedure of inducing non-union. A mid-shaft tibial osteotomy was made with 1mm non-critical gap. Periosteum was stripped around the two fracture ends. Then, the fracture was fixed by ante-grade intramedullary nail. The non-critical gap was maintained by a spacer with minimal effect on the healing surface area. At the same surgical time, subcutaneous fat was collected from the ipsilateral inguinal region and stem cells were isolated and cultured in vitro. Within three weeks postoperatively, the number of expanded stem cells reached 5×10⁶ and were injected into the fracture site. Healing was followed up for 8 weeks and the quality was measured by serial x-rays, microCT, mechanical testing and histologically. Quality of healing was compared with that of previously published allogenic, xenogeneic MSCs and Purified Buffered Saline (PBS) controls.

All the five fractures united fully after 8 weeks. There was a progressive increase in the callus radiopacity during the eight-week duration, the average radiopacity in the autologous fat-MSC injected group was significantly higher than that of the allogeneic MSCs, xenogeneic MSCs and the control group, P < 0.0001 for treatment, time after injection, and treatment-time interaction (two-way repeated measure ANOVA). MicroCT, mechanical testing and histology confirmed radiological findings.

The autologous fat-MSCs are effective in prevention of atrophic non-union by stimulation of the healing process leading to a solid union. The quality and speed of repair are higher than those of the other types of cell transplantation tested.

Aim

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.

Abstract

Introduction

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.

Abstract

Abstract

Abstract

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.

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.

To evaluate if clinical recovery following midshaft clavicle fracture is associated with nonunion and determine if this has superior predictive value compared to estimation at time of injury.

A prospective study of all patients (≥16 years) who sustained a displaced midshaft clavicle fracture was performed. We assessed patient demographics, injury factors, functional scores and radiographic predictors with a standardized protocol at six-weeks. Conditional-stepwise regression was used to assess which factors independently predicted nonunion at six-months post-injury determined by CT. The nonunion predictor six-week model (NUP6) was compared against a previously validated model based on factors available at time of injury (NUP0-smoking, comminution and fracture displacement).

200 patients completed follow-up at six months. The nonunion rate was 14% (27/200). Of the functional scores, the QuickDASH had the highest accuracy on receiver-operator-characteristic (ROC) curve analysis with a 39.8 threshold, above which was associated with nonunion (Area Under Curve (AUC) 76.8%, p<0.001).

On regression modelling QuickDASH ≥40 (p=0.001), no callus on radiograph (p=0.004) and fracture movement on examination (p=0.001) were significant predictors of nonunion. If none were present the predicted nonunion risk was 3%, found in 40% of the cohort (n=80/200). Conversely if two or more were present, found in 23.5% of the cohort, the predicted nonunion risk was 60%.

The NUP6 model appeared to have superior accuracy when compared to the NUP0 model on ROC curve analysis (AUC 87.3% vs 64.8% respectively).

Delayed assessment at six-weeks following displaced clavicle fracture enables a more accurate prediction of fracture healing.

Cutting rodent's bone ends and irrigation of the medullary canal is the common method used for cells collection in allogenic transplantation, however it does not yield sufficient cells for autologous transplantation. The aim of this experiment was to establish and validate a method for bone marrow collection for autologous MSCs transplantation. Two collection methods were examined: 1) Transection of the bone ends and irrigation of the medullary canal, 2) Trephining of the bone with a hypodermic needle without aspiration. Then cell harvesting was compared in the idealised laboratory situation and under simulated surgery.

First, two lower limbs were harvested from the same rat cadaver for comparison, bone marrow in one limb was collected by cutting the femoral head and the distal tibia and irrigation of the canal through drilled holes at the distal end of the femur and proximal end of the tibia. Other limb, hypodermic needle was used as a trephining tool into the medullary canal multiple times without applying negative pressure and rinsed from inside and outside. Second, bone marrow was harvested from another rat's cadaver in the surgery room to simulate the conditions needed for autologous transplantation.

The number of cells from irrigation method was 1.28*106 cells, whereas that from trephining method reached 17*106. The number cells from the bone marrow harvested in the surgery room was found 29.6*106. We report a novel technique for harvesting cells for autologous cell therapy from only one limb. A significantly larger number of cells from bone marrow could be collected using the needle trephining method. There is no negative effect on the viability of cells after bone marrow harvesting in the surgery room.

In atrophic non-union models, a minimally invasive technique is used to deliver stem cells into the fracture site via percutaneous injection. This technique is significantly affected by a backflow leakage and the net number of cells might be reduced. The Z-track method is a technique used in clinical practice for intramuscular injections to prevent backflow leakage.

We evaluated the potential of the Z-track injection technique for preventing cell loss in non-union models by determining the behaviour of observable marker fluids. Firstly, toluene blue stain was used as an injection material to allow visual detection of its distribution. Rat's cadaver legs were used and tibias were kept unbroken to ensure intact skin and overlying soft tissue. Technique includes pulling the skin over the shin of tibia towards the ankle and injection of the dye around the mid-shaft. The needle was then partially pulled back, the skin was returned to its normal position and a complete extraction of the needle was followed. Secondly, a mixture of contrast material and toluene blue was used to allow direct visual and radiological detection of the injected material into the fracture site. Ante-grade nailing of tibia via tibial tuberosity was carried out followed by a 3 point closed fracture. Injection was performed into the fracture gap similarly to the steps above. X-rays were taken to visualise the location and distribution of the injected material.

Observation revealed no blue stain could be detected over the skin, X -rays revealed that the radiopaque dye remained around the tibia with no escape of the material into the superficial layers or onto the skin surface. Therefore, the number of cells delivered and maintained at a target site could be increased by the Z-track method and therefore, the therapeutic benefit of stem cell injections could be optimised with this simple technique.

Appropriate in vivo models can be used to understand atrophic non-union pathophysiology. In these models, X-ray assessment is essential and a reliable good quality images are vital in order to detect any hidden callus formation or deficiency. However, the radiographic results are often variable and highly dependent on rotation and positioning from the detector/film. Therefore, standardised A-P and lateral x-ray views are essential for providing a full radiological picture and for reliably assessing the degree of fracture union.

We established and evaluated a method for standardised imaging of the lower limb and for reliably obtaining two perpendicular views (e.g. true A-P and true lateral views). The normal position of fibula in murine models is posterolateral to the tibia, therefore, a proper technique must show fibula in both views. In order to obtain the correct position, the knee joint and ankle joints were flexed to 90 degrees and the foot was placed in a perpendicular direction with the x-ray film. To achieve this, a leg holder was made and used to hold the foot and the knee while the body was in the supine position. Lateral views were obtained by putting the foot parallel to the x-ray film. Adult Wister rat cadavers were used and serial x-rays were taken.

A-P view in supine position showed the upper part of the fibula clearly, however, there was an unavoidable degree of external rotation in the whole lower limb, and the lower part of the fibula appeared behind the tibia. Therefore, a true A-P view whilst the body was in the supine position was difficult. To overcome this, a P-A view of the leg was performed with the body prone position, this allowed both upper and lower parts of the fibula to appear clearly in both views. This method provides two true perpendicular views (P-A and lateral) and helped to optimise radiological assessment.

Staphylococcus aureus is responsible for 60–70% infections of surgical implants and prostheses in Orthopaedic surgery, costing the NHS £120–200 million per annum. Its ability to develop 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 explores, but preliminary work has shown potential benefit, especially when combined with existing antibiotics.

Using a methicillin-sensitive S. aureus reference strain and the dissolvable bead assay, bacterial biofilms were challenged by gentamicin +/− low-intensity ultrasound (1.5MHz, 30W/cm2, pulse duration 200µs/1KHz) for 20 minutes. The 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. 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 64mg/L.

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

Instability accounts for approximately 20% of revision total knee arthroplasty (TKA) operations, however, diagnostic tests remain relatively subjective. The aim of this examination was to evaluate the feasibility of using pressure mat analyses during functional tasks to identify abnormal biomechanics associated with TKA instability.

Five patients (M = 4; age = 69.80±7.05 years; weight = 79.73±20.12 kg) with suspected TKA instability were examined compared to 10 healthy controls (M = 4; age = 44.6±7.52 years; weight = 70.80±14.65). Peak pressure and time parameters were measured during normal gait and two-minute bilateral stance. Side-to-side pressure distribution was calculated over 10-second intervals during the second minute. Mann-Whitney tests compared loading parameters between groups and side-to-side differences in TKA patients (significance level = p<0.05).

Pressure distribution was expressed relative to bodyweight. Notable differences were seen during bilateral stance. Uneven side loading was greater – favouring the non-operated limb – in TKA patients during bilateral stance compared to controls. This was significantly different at 30s (p=0.0336) and 60s (p=0.0336). Gait analyses showed subtle pressure distribution differences in unstable TKA patients. Stance time was indifferent. TKA patients tended to exhibit longer heel contact time (0.76s vs. 0.64s and reduced weight acceptance (50.75% vs. 56.75%) on the operated limb compared to the non-operated limb. Side-to-side differences in peak toe-off forces were significantly more pronounced in TKA patients versus controls (9.25% +/− 1.5% vs. 1.67% +/−5.79%; p=0.0039).

Conclusion: This feasibility work demonstrates subtle differences in limb loading mechanics during simple clinical tests in unstable TKA patients that might be invisible to the naked eye. In the long-term, pressure analyses may be a useful diagnostic tool in identifying patients that would benefit from revision surgery for TKA instability.

There is a growing trend towards using pre-clinical models of atrophic non-union. This study investigated different fixation devices, by comparing the mechanical stability at the fracture site of tibia bone fixed by either intramedullary nail, compression plate or external fixator. 40 tibias from adult male Wistar rats' cadavers were osteotomised at the mid-shaft and a gap of 1 mm was created and maintained at the fracture site to simulate criteria of atrophic non-union model. These 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 external fixator. Tibia was harvested by leg disarticulation from the knee and ankle joints, the soft tissues were carefully removed from the leg, and tibias were kept hydrated throughout the experiment. 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).

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. Axial load to failure data and stiffness data revealed that intramedullary nails are significantly stronger and stiffer than other devices, however there was no statistically significant difference axially between the nail thicknesses. In bending, load to failure revealed that 18G nails are significantly stronger than 20G. We concluded that 18G nail is superior to the other fixation devices, therefore it has been used for in-vivo experiments to create a novel model of atrophic non-union with stable fixation.

Femoral shaft fractures are potentially devastating injuries. Despite this, clinical studies of the biomechanics of this injury are lacking. We aimed to clinically evaluate bone behaviour under high and low energy trauma in paediatric, adult and older patients. Single-centre retrospective study identifying all diaphyseal femoral fractures between Feb 2015-Feb 2017. Peri-prosthetic and pathological fractures were excluded. Patients were subdivided into groups 1 (paediatric, <16yo), 2 (adult, 17–55yo) and 3 (older, >55yo) to reflect immature, peak bone age and osteoporotic bone respectively. Chi-Squared analysis assessed significance of bone age to degree of comminution and fracture pattern. A p-value <0.05 was significant. A total 4130 radiographs were analysed with 206 femoral shaft fractures identified. Forty-three patients were excluded with 163 remaining. Group 1, 2 and 3 included 38, 37 and 88 patients respectively. Mean age 50.8 (SD 32.8) with male-to-female ratio of 1:1.2. Groups 1 and 3 included majority simple fractures (35/38 and 62/88 respectively). Group 2 included more comminuted injuries (33/37). Bone age to degree of comminution proved significant (p<0.05) with a bimodal distribution of simple fractures noted in groups 1 and 3. Energy to fracture was significant in group 2, where a high energy injury was associated with comminution (p<0.05). This study is the first to demonstrate an association between fracture comminution and age. Simple femoral shaft fractures showed a bimodal age distribution in paediatric and older patients regardless of mechanism energy. High energy mechanism trauma was directly related to fracture comminution at peak bone age.

There is a growing trend towards using pre-clinical models of atrophic non-union. This study investigated different fixation devices, by comparing the mechanical stability at the fracture site of tibia bone fixed by either intramedullary nail, compression plate or external fixator. 40 tibias from adult male Wistar rats' cadavers were osteotomised at the mid-shaft and a gap of 1 mm was created and maintained at the fracture site to simulate criteria of atrophic non-union model. These 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 external fixator. Tibia was harvested by leg disarticulation from the knee and ankle joints, the soft tissues were carefully removed from the leg, and tibias were kept hydrated throughout the experiment. 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). 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. Axial load to failure data and stiffness data revealed that intramedullary nails are significantly stronger and stiffer than other devices, however there was no statistically significant difference axially between the nail thicknesses. In bending, load to failure revealed that 18G nails are significantly stronger than 20G. We concluded that 18G nail is superior to the other fixation devices, therefore it has been used for in-vivo experiments to create a novel model of atrophic non-union with stable fixation.

Instability accounts for approximately 20% of all revision total knee arthroplasty (TKA), however diagnostic tests remain crude and subjective. The aim of this examination was to evaluate the feasibility of pressure mat (SB Mat, TekScan) analyses of functional tasks to differentiate instability in a clinical setting. Five patients (M = 4; age = 69.80±7.05 years; weight = 79.73±20.12 kg) with suspected TKA instability were examined compared to five healthy controls (M = 1; age = 46.80±7.85 years; weight = 71.54±16.17 kg). Peak pressure and time parameters were measured during normal gait and two-minute bilateral stance. Side-to-side pressure distribution was calculated over 10-second intervals during the second minute. Pressure distributions were expressed relative to bodyweight (%BW). T-tests compared loading parameters between groups (significance level = p<0.05). Analyses showed subtle differences in pressure distribution in unstable TKA patients versus healthy controls. Stance time during gait was indifferent. TKA patients tended to exhibit longer heel contact time (0.76 vs. 0.64 sec) and reduced weight acceptance (50.75% vs. 56.75%) on the operated versus non-operated limb. Side-to-side differences in toe-off forces were significantly more pronounced in TKA patients versus controls (9.25% vs. 3.75%; p=0.0088). Uneven loading was significantly greater – favouring the non-operated limb – in TKA patients during bilateral stance compared to controls (p<0.05). This feasibility work demonstrates subtle differences in limb loading and biomechanics during simple clinical tests in unstable TKA patients that might be undetectable to the naked eye. Pressure analyses may therefore be a useful diagnostic tool. These findings warrant further investigation.

Aim

To investigate the validity of threshold values for the Oxford Hip and Knee Score (OHS and OKS) for treatment success 12 months after total knee or hip replacement.

Introduction

Carriers of Staphylococcus aureus, both methicillin sensitive (MSSA) and methicillin resistant (MRSA), have an increased risk for health-care associated infections. Despite WHO recommendations there is currently no national screening and eradication policy for the detection of MSSA in the UK or USA. This study aimed to evaluate the effectiveness of current standard MRSA eradication therapies in the context of S. aureus decolonisation prior to joint replacement surgery.

Aim

To evaluate the association of BMI and improvement in patient-reported outcomes after TKA.

Background

There are currently no effective treatments for skeletal muscle fibrosis. Myofibroblasts are the major cellular effectors of fibrosis but their origin in muscle is unknown. We report that PDGFRβ (platelet derived growth factor receptor beta) Cre inactivates genes in murine PDGFRβ+ cells and myofibroblasts in muscle with high efficiency. We used this system to delete the integrin αv subunit because of the suggested role of multiple αv integrins as central mediators of fibrosis in multiple organs.

Scar tissue formation secondary to acute muscle injury, surgical wounding and compartment syndrome can result in significant functional impairment and predispose to further injury. The source of fibroblasts, and the molecular mechanisms driving their activation and persistence in skeletal muscle fibrosis are not known. We hypothesized that cells expressing PDGFRβ become fibroblasts in response to injury and that targeting αv integrins in these cells reduces skeletal muscle fibrosis.

We used double-fluorescent reporter mice to demonstrate that cells expressing PDGFRβ become activated myofibroblasts in response to cardiotoxin (CTX) induced skeletal muscle injury. Following injury, PDGFRβ+ cells moved from perivascular locations into the interstitium in a distribution characteristic of fibroblasts, and showed marked induction of fibroblastic genes including αSMA and collagen1 (all p<0.0001). To confirm that αv integrins present on PDGFRβ cells critically regulate skeletal muscle fibrosis we used Itgavflox/flox;PDGFRβ-Cre mice (transgenic mice in which αv integrins are ‘knocked-down’ in PDGFRβ+ cells). These mice were significantly protected from CTX induced fibrosis (p<0.01). To demonstrate potential clinical utility of targeting αv integrins, we used a small molecule inhibitor of αv integrins (CWHM12). Treatment with CWHM12 significantly reduced fibrosis when delivered from the time of injury (p<0.01) and when delivered after the fibrotic response had become established (p<0.01).

We have identified a core pathway regulating fibrosis in skeletal muscle. Pharmacologic inhibition of αv integrins has potential clinical utility in the treatment and prevention of skeletal muscle fibrosis.

Chondrocytes are essential to the maintenance of articular cartilage and it is thought that chondrocyte death occurs early in septic arthritis. Understanding the causes of chondrocyte death will allow the development of chondroprotective strategies to improve long-term outcomes following septic arthritis.

We utilised a murine model of septic arthritis using intra-articular injection of 10µL of a 10⁷ concentration of S. aureus suspended in PBS. Seventy-five adult male C57/Bl6 mice were randomised to receive injection of either S. aurues 8325-4 (a wild-type of S. aurues capable of alpha toxin production), DU1090 (an isogenic mutant of 8325-4 that is identical to 8325-4 other than being incapable of producing alpha toxin) or a PBS control. Establishment of septic arthritis was confirmed through gait changes (5 mice/group), limb swelling and histological changes (10 mice/group). 10 animals from each group were sacrificed at 48 hours and the injected knee joints were dissected before being stained with CFMDA (labelling live chondrocytes green) and PI (labelling dead chondrocytes red). The samples were imaged using a confocal laser scanning microscope and the percentage of chondrocyte death was calculated.

Mice injected with S. aureus 8325-4 or DU1090 developed septic arthritis with evidence of weight loss, limb swelling and gait changes whereas these were absent in the control group. There was a significantly higher level of chondrocyte death in the group infected with 8325-4 (2.7% chondrocyte viability) when compared to DU1090 (73.9% chondrocyte viability) and PBS injected mice (95% chondrocyte viability). One-Way ANOVA revealed that the difference between each group was statistically different (p < 0.05).

Alpha toxin is the major damaging toxin in S. aurues septic arthritis. Any adverse effect of the immune system is negligible in comparison. Development of treatments counteracting the effect of alpha toxin is required.

Our unpublished data has indicated that the perivascular stem cells (PSCs) have increased chondrogenic potential compared to mesenchymal stem cells (MSCs) derived in culture. There has been a recent change in the theory that stem cells work by a paracrine effect rather than differentiation. There are minimal data demonstrating the persistence of implanted stem cells when used for engraftment. This study aimed to develop an autologous large animal model for perivascular stem cells as well as to determine if cells were retained in the articular cartilage defects.

The reactivity of anti-human and anti-ovine antibodies was ascertained using immunohistochemistry and fluorescence-activated cell sorting (FACS). A panel of antibodies were combined and used to identify and purify pericytes (CD34-CD45-CD146+) and adventitial cells (CD34+CD45-CD146-) using FACS. The purified cells were cultured and their identity checked using FACS. These cultured cells demonstrated osteogenic, adipogenic and chondrogenic potential.

Autologous ovine PSCs (oPSCs) were isolated, cultured and transfected using a GFP virus. The transfection rate was 88%. The cells were implanted into an articular cartilage defect on the medial femoral condyle using a hydrogel, four weeks following implantation the condyle was explanted and confocal laser scanning microscopy demonstrated the presence of oPSCs in the defect. Histology did not demonstrate any repair tissue at this early time point.

These data have confirmed the viability our large animal model and that the implanted stem cells were retained in the defect four weeks following implantation.

Summary Statement

Service industry metrics (the net promoter score) are being introduced as a measure of UK healthcare satisfaction. Lower limb arthroplasty, as a ‘service’, scores comparably with the most successful commercial organisations.

Summary Statement

Using current analysis/methodology, new implant technology is unlikely to demonstrate a large enough change in patient function to impact on the cost-effectiveness of the procedure.

The cartilage diseases such as osteoarthritis and chondral injuries are considered irreversible and the result of recent treatments remains not optimal. One of the reasons is due to the poor understanding of chondrocyte behaviours. To understand more about cartilage, we designed a series of novel experiments. First, a total joint of bovine metatarsophalanges was isolated as our novel model. We chose it because the configuration and the healing potential were similar to human, and many variables of large animal studies could be controlled in laboratory. The model not only provided a good ex vivo platform for cartilage researches but also connected in vitro cellular studies and in vivo animal studies. To mimic joint movement a special driving machine was designed. To characterise the novel model viabilities of chondrocytes and contents of sulphated glycosaminoglycan (GAGs) in extracellular matrixes were measured every seven days. The preliminary results revealed the viabilities of chondrocytes remained above 80% alive in the middle zone after four-weeks culture. The GAGs contents decreased after this culturing period. The experiments still carry on going to compare the static and dynamic models which joint movement could be a determinative factor to the viability of chondrocytes. Cellular treatment is the recent mainstream for cartilage diseases. If advanced knowledge in chondrocyte behaviours could be obtained from this model, development of optimal treatment will be possible in the future.

The aim was to perform a cost-utility analysis of total joint replacement in the current environment.

Arthritis is a disabling condition that leads to long-term deterioration in quality of life. Total joint replacement, despite being one of the greatest advances in medicine in the modern era, has come under recent scrutiny. The National Health Service (NHS) has competing demands and resource allocation is challenging in times of economic restraint.

Patients undergoing total hip (n=348) and knee arthroplasty (n=323), from January to July 2010, were entered into a prospective arthroplasty database. A health utility score was derived from the Euroqol (EQ-5D) score preoperatively, and at one year, and was combined with individual life expectancy to derive the Quality-Adujusted-Life-Years (QALYs) gained. Predicted need for revision surgery was Incorporated in the model. The 2011–12 Scottish Tariff was used. Two-way analysis of variance was used to compare QALYs gained between procedures, while controlling for baseline differences.

The number of QALYs gained was higher in THR versus TKR (6.53 vs 4.04 years, p<0.001). The cost per QALY for THR was £1371 (95% CI £1194 to £1614) compared with £2101 (£1762 to £2620) for TKR. Predictors of an increase in QALYs gained were poorer health prior to surgery (p<0.001) and younger age (p<0.001). General health (EQ-5D VAS) showed greater improvement in THR versus TKR (p<0.001).

This study provides up to date cost-effectiveness data for total joint replacement. THR and TKR are both extremely clinically and cost-effective interventions, with costs that compare favourably with other medical interventions (e.g. laparoscopic hernia repair vs open: £55,548 per QALY; CHD primary prevention with statins: £21,000).

Introduction

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.

Introduction

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.

Introduction

We report 3 cases from different centres of infantile tibia vara in which the deformity was due to slippage of the proximal tibial epiphysis on the metaphysis; the aim of this study was to define the features of this previously unreported condition, and their implications for management.

Introduction

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.

Introduction

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.

Finite element modelling is being extensively used to evaluate the biomechanical behaviour of fractured bone treated with fixation devices. Appropriate modelling of the bone-implant interface is key to quality biomechanical prediction.

The present study considers this interface modelling in the context of locking plates. A majority of previous studies assume the interface to be represented by a tied constraint or a fully bonded interface. Many other studies incorporate a frictional interface but ignore screw threads. This study compares the various interface modelling strategies. An interface with screw threads explicitly included is also considered.

The study finds that interface modelling has significant impact on both the global and local behaviour. Globally, the load-deflection behaviour shows considerable difference depending on the interface model. Locally, the stress-strain environment within the bone close to the screws is significantly altered.

The results show that the widely used tie constraint can overestimate stiffness of a construct which must be correctly predicted to avoid non-union or periprosthetic re-fracture, especially in osteoporotic bone. In addition, the predictions of screw loosening, bone damage and stress shielding are very different when screw threads are included in the model.

Background

Hyperlaxity is associated with a high incidence of shoulder dislocations. Collagen V regulates the diameter of fibrils of the abundant collagen type I. Decorin and biglycan are members of the small leucine rich proteoglycans(SLRP's)family and play important roles in the regulation of collagen fibrillogenesis. The aim of this study was to identify if there was a link in hyperlaxity, capsule strength, collagen V and SLRP's expression.

Background

Hyperlaxity is associated with a high incidence of sporting injuries. Collagen V regulates the diameter of fibrils of the abundant collagen type I. Decorin and biglycan are members of the small leucine rich proteoglycans(SLRP's)family and play important roles in the regulation of collagen fibrillogenesis. The aim of this study was to identify if there was a link in hyperlaxity, tissue strength, collagen V and SLRP's expression.

Approximately 5 – 10% of all bone fractures are associated with impaired healing. It is thought that regenerative medicine has the potential to improve on existing treatments for non-union fractures, and the European market for such treatments is projected to reach £2.2 billion in 2010. The use of scaffolds for the delivery of both growth factors and human Marrow Stromal Cells (hMSCs) is thought to be a promising approach. It may be desirable to promote proliferation and chemotaxis of hMSCs at the defect site shortly after implantation, and differentiation in the longer term. This is likely to require a dual delivery system, capable of releasing multiple drugs with different release profiles. Our aim has been to develop a polymer scaffold capable of releasing bioactive molecules that are able to direct the differentiation of primary hMSCs down the osteoblastic lineage. We have examined two mutually compatible drug delivery systems: collagen coating for short term release, and polymer encapsulation for longer term release.

Polymer scaffolds were manufactured and coated with Type I Collagen containing BMP-7. hMSCs from three different patient sources were exposed to the scaffolds for 14 days. The cells were then histochemically stained for Alkaline Phosphatase (ALP) and photographed. The areas of ALP staining were then normalised against the total cell count.

Normalised ALP expression was increased compared to the controls for three different patients (‘110 ± 39% SE, n=6, p=0.005’, ‘540 ± 270% SE, n=6, p=0.001’, and ‘32 ± 17% SE, n=6’). Scaffolds were also manufactured either with 1,25 Vitamin D3 (another active compound) in a coating of Collagen, or encapsulated using proprietary methodologies. It was found that both treatments significantly increased normalised Alkaline Phosphatase expression within the 14d experimental period demonstrating release of the active 1,25 Vitamin D3 (’88 ± 37% SE, n=6, p=0.012’ and ‘100 ± 32% SE, n=6, p=0.012’ respectively).

Our findings suggest that, subject to future testing and development, such bioactive scaffolds could form the basis for a dual drug delivery system, suitable for applications in bone regenerative medicine.

Fracture repair is a wound healing process that in young healthy patients usually proceeds to uncomplicated union. However, the healing cascade is delayed with increasing age, medication and certain diseases such as rheumatoid arthritis.

Recently the important role of the immune system in fracture repair has become apparent within the emerging subject of Osteoimmunology. Patients with rheumatoid arthritis have an altered immune system and therefore we have investigated the hypothesis that patients with rheumatoid arthritis have a higher incidence of non-union after a fracture compared to patients without rheumatoid arthritis.

Method: The Edinburgh Royal Infirmary computer database was searched over a 10 year period (May 1996- May 2006) to identify all patients with non-union out of the total number of patients presenting with fractures. These patients groups were then subdivided into patients that had and did not have rheumatoid arthritis. Patients were excluded if they were lost to follow up, or if the fracture either occurred before the May 1996 or management continued passed May 2006. In this study non-union was defined as failure to heal within expected timescale and lack of progression at serial x-rays (all non-union were diagnosed at least 3 months from fracture).

Results: From May 1996 through to May 2006, 8,456 patients with fracture were defined. 71 of these patients with fractures had rheumatoid arthritis. Of these patients 63 had union of their fractures whilst 8 patients developed non-union of their fracture (11.3%). In a total of 8385 non rheumatoid arthritis patients 164 developed non-union of their fracture compared to 8221 patients who had union of their fractures (2%). Comparison between these two patient groups suggests rheumatoid arthritis patients are more likely to develop non-union of traumatic fractures (Chi squared test, p value < 0.001).

Patients with rheumatoid arthritis who progressed to non-union were on the following medication, Gold (1), Indomethacin (1), Non steroidal anti-inflammatories (4), Combination analgesia (2), Antihypertensives (2), Omeprazole (1) and Thyroxine (1).

Discussion: The results from this study suggest that patients with rheumatoid arthritis have a greater incidence of non-union after a fracture compared to patients without rheumatoid arthritis. This maybe due to the abnormal immune system in rheumatoid arthritis patients. However rheumatoid arthritis patients are often on a number of medications and these drugs rather than the innate alteration of the immune system may be responsible for the altered healthy response. However whether as a result of the rheumatoid arthritis itself or the medication, our study demonstrates a higher non-union rate in the rheumatoid arthritis patients and this needs to be taken into account when treating rheumatoid arthritis patients with fractures.

Over 1 million fractures occur each year in the UK. Approximately 5-10% of these fractures have problems with healing. The treatments used for these patients often have a poor outcome and are associated with increased morbidity and disability. Application of synthetic peptides such as thrombin degradation peptide (TP508) has been shown to accelerate fracture repair in a closed rat femoral fracture model. Controlled release of TP508 using microspheres has been shown to enhance repair of articular cartilage defects and stimulate bone formation in segmental defects in rabbits. The aim of this study was to determine whether TP508 could bring about healing in an established fracture non-union model.

A validated rat model of fracture non-union was used. The model was created and left for 8 weeks in order to represent a clinically equivalent model of a non union of a fracture. Rats were randomised into two treatment groups receiving 10microg and 1microg doses of TP508 diluted in 50microL of microspheres and delivered directly to the non union site using percutaneous injection 8 weeks after surgery. The control group received no treatment. At 16 weeks post-surgery, osseous bridging was assessed both radiographically and histologically.

Radiographically there was no difference between the control and two treatment groups. However, histomor-phometric analysis demonstrated that bone formation increased by 43.9% in animals that received high dose of TP508 compared to the control animals. The analysis also indicated that administration of the low dose of TP508 increased the amount of bone formation compared to the control by 9.9 %.

Administration of TP508 has been shown to enhance healing of segmental defects in both critically and noncritically sized defects. However, in our model which is an established fracture non-union model, TP508 did not manage to achieve full osseous union. It has been suggested that the action of this peptide is concentration and environment dependent possibly indicating that TP508 might be less effective when administered in a chronic situation such as that associated with the established non-union fracture. However, even in this sub-optimal situation an increased amount of bone formation was observed.

Introduction: Atrophic nonunion is a well recognised complication of long bone fractures. Clinical trials show that BMP-2 accelerates healing and reduces nonunion in open tibial fractures. We are interested in a natural small molecule that has been previously demonstrated to stimulate angiogenesis in vivo. Our aim is to assess the two treatments in the prevention of nonunion. The small animal model we used is a non-critical size defect of the tibia deprived it of its blood supply by surgical stripping of the periosteum and curetting of the local endosteum thus closely reflecting the clinical situation. The outcomes were measured by radiographic assessment and histology.

Methods: Wistar rats were treated with either the angiogenic molecule (0.1% or 0.003%), BMP-2 or vehicle alone (PBS) soaked in a type I collagen sponge. All animals underwent a 2mm osteotomy, stripping of the periosteum and endosteum proximally and distally for the length of the diameter of the tibia. Fluorescent markers were injected at 2 weekly intervals. The rats were sacrificed at 8 weeks. Both tibiae were disarticulated; fixator and soft tissues were removed and AP and lateral X-rays were taken. Subjective assessment of the healing on X-ray was carried out in two ways; using a radiographic scoring system and by grey scale analysis. The samples were embedded, sectioned and stained for new bone formation.

Results: Bridging or potential to bridge was seen in a number of animals on x-ray. Bridging or potential to bridge was judged to be present in 72.22% of the BMP-2 group and 66.67% of the high dose group compared to 22.22% of the control group. Histological analysis is being performed to confirm these findings.

Discussion: Atrophic nonunion is a serious clinical complication, unfortunately BMP-2 is a highly costly treatment option and therefore alternative molecular therapies are much sought after. We describe here an angiogenic molecule has some potential in preventing formation of nonunion.

Thermonecrosis either results in bone loss which may weaken the purchase of surgically-inserted screws leading to loosening or the dead bone may remain in situ and become infected resulting in a ring sequestrum. The aim of this project was to measure the heat generated during drilling of bone. By using a novel realtime thermal camera the thermal events could be visualised topographically.

An experimental setup comprising a force table, an infrared camera, a power drill and a new surgical 2.5mm drill bit was constructed. This enabled measurements of the force applied and temperature changes in sheep cortical bone during a drilling operation. The temperature was observed throughout the drilling period and for further 15s after the drill bit was withdrawn. Images were grabbed using a LAND FTI Mv thermal camera which was driven by LIPS Mini software. Calibration was made in the range 20-200 degrees C, the upper value being provided by a high wattage resistor. Data was processed using routines written in MATLAB.

It was found that 12s were required to drill through a single cortex. Within one second of drilling, the maximum recorded temperature in the vicinity of the drill increased from the baseline of 20 to 170 degrees C. It remained above this temperature for 25s. Immediately after the drill bit was withdrawn, a region of approximately 15mm of diameter of cortical surface had a sustained temperature above 50 degrees C. After 15s of cooling, this diameter had only reduced to 10mm. By modelling the cooling curve, the maximum temperature at the drill tip was extrapolated to be between 500-600 degrees C.

Thermography has proven to be useful in the study of the thermal characteristics of bone during drilling. The process of drilling generates significant increase in temperature in the vicinity of the drill. This temperature elevation has been found to be sustained for a significant period of time.

Imaging of the musculoskeletal system is vital for delivering optimum treatment particularly in the assessment of fracture healing. X-ray and CT are adequate imaging methods for bone but, soft tissue needs other modalities such as MRI and Ultrasound. We propose the use of Freehand 3D Ultrasound to study the early stages of fracture healing by imaging the bone surfaces around the fracture site and monitoring changes in the surrounding soft tissue.

Freehand 3D ultrasound is acquired by attaching a position sensor to the probe of a conventional 2D diagnostic ultrasound machine. As the probe is moved, its position and orientation are recorded along with the 2D ultrasound images. This enables slices through the body to be viewed that would be inaccessible using a normal ultrasound system. Bone surfaces around a fracture site are scanned and the data reconstructed using the Stradx and Stradwin software developed by Cambridge University, to give a 3D visualization of the area.

To assess the feasibility of this proposed method the lower limbs of healthy volunteers were scanned using a 5–10MHz ultrasound probe. The scanning resolution of the system was evaluated using a phantom to ensure millimetre detail could be detected as would be required for imaging early fracture healing. It was found that detail down to 0.8mm could easily be resolved for measurement.

The 3D system could accurately profile the different soft tissue interfaces. The visible surfaces of the tibia were reconstructed to give 3D models. Additional layers of soft tissue interfaces could easily be added to these models to provide more detail.

This imaging modality can provided detailed 3D models of bone the bone surface and surrounding soft tissue. As ultrasound is non-ionizing, rescanning can be conducted more frequently than with CT or x-ray thus offering a more accurate assessment of a patient’s response to healing.

The response of the muscle is critical in determining the functional outcome of limb lengthening. We hypothesised that muscle response would vary with age and therefore studied the response of the muscles during tibial lengthening in ten young and ten mature rabbits. A bromodeoxyuridine technique was used to identify the dividing cells.

The young rabbits demonstrated a significantly greater proliferative response to the distraction stimulus than the mature ones. This was particularly pronounced at the myotendinous junction, but was also evident within the muscle belly.

Younger muscle adapted better to lengthening, suggesting that in patients in whom a large degree of muscle lengthening is required it may be beneficial to carry out this procedure when they are young, in order to achieve the optimal functional result.

Introduction: Evidence exists concerning the anti-oxidant properties of oestrogen in protecting neuronal cells from oxidative stress. The withdrawal of oestrogen after menopause is the major factor determining age related bone loss and apoptotic death of osteocytes. While oestrogen replacement demonstrates clear oestrogen receptor mediated benefits to bone cells little is known regarding oestrogens’ anti-oxidant effects in bone.

Methods: Here we have used MLO-Y4 osteocyte-like cell line to determine whether oestrogen saving effects on osteocytes involves its activities as an anti-oxidant.

MLO-Y4 cells were treated with physiological doses (10⁻⁸)M of either 17-beta E₂ or the oestrogen receptor inactive stereoisomer 17-alpha E₂ with or without the specific oestrogen receptor antagonist ICI 182,780 prior to the addition of 0.4milliM 30% (v/v) H₂O₂. Cellular apoptosis was determined using morphological and biochemical criteria.

Results: H₂O₂ induced an increase in apoptosis of MLO-Y4 (14.3 ± 3 SD vs control 1.4 ± 0.9). Pre-treatment of the cells with 17-beta E₂ significantly reduced H₂O₂ induced apoptosis (2.4 ± 0.96). Pre-treatment of cells with 17-alpha E₂ or ICI 182,780 also reduced oxidant induced apoptosis to 3.4 ± 1.5 SD and 7.0 ± 2.3 respectively.

The cellular production of reactive oxygen species was determined using the free radical indicator 2′7′- dichlorodihydrofluorescein diacetate. H₂O₂ induced increases in the number of ROS positive cells (34.6 ± 9.07 SD vs control 0.22 ± 0.39 SD). In contrast pre-treatment with both 17-beta E₂ and 17-alpha E₂ reduced the number of ROS positive cells associated with H₂O₂ treatment (Fig 1).

Conclusion: These data suggest that oestrogens ability to save osteocytes from oxidant induced death is independent of the oestrogen receptor and may be related to oestrogens known activity as an anti-oxidant. This raises the possibility that loss of osteocytes during oestrogen insufficiency may occur through a failure to suppress the activity of naturally occurring or disease associated production of oxidant molecules.

Introduction: Oxidative stress occurs when reactive oxygen species (ROS) are produced faster than they can be removed by cellular defence mechanisms contributing to ageing, many chronic diseases, such as atherosclerosis, RA, Parkinson and Alzheimer’s disease and skeletal pathologies. Here we address the impact of ROS on the viability of early osteogenic precursors in the bone marrow and study the influence of estrogen on this interaction. Cells have a number of mechanisms to protect themselves from ROS, which are constantly being formed in the cell through normal metabolic pathways, such as Vitamin E, C and estrogen. Estrogen has been shown to prevent intracellular accumulation of peroxide and to attenuate oxidant-induced death of neuronal and endothelial cells. In addition, it contributes significantly to bone turnover and relieves postmenopausal symptoms. This study has focused on the potential anti-oxidant properties of estrogen against oxidative on bone marrow stromal cells. stress induced by H₂O₂

Methods: Primary bone marrow stromal cells were pre-treated with several different doses between 10⁻⁶M – 10⁻⁸M of estrogen prior to H₂O₂ administration at 0.08–0.4 mM 30% (v/v) for 2–24h. The cellular production of ROS was determined by using the free radical indicator DCFH-DA. Apoptosis was determined by morphological criteria.

Results: H₂O₂ induced an increase in apoptosis of osteoprogenitor cells (p< 0.05). Determination of apoptosis and cell number by nuclear staining, indicated that pre-treatment of bone marrow stromal cells with 17-beta estradiol reduced the apoptotic response induced by H₂O₂ (p< 0.05) and restored cell number to control levels. In order to test the anti-oxidant activity of estrogen, the dye DCFH-DA was introduced in a cell free system in the presence or absence of 17-beta estradiol and H₂O₂. The same experiment was repeated in the presence of bone marrow stromal cells. H₂O₂ increased both intracellularly and extracellularly oxidant activity and estradiol has the capacity of modifying this activity both inside and outside the cell.

Discussion: These data demonstrate the ability of estrogen, used at physiological doses, to block oxidant-induced apoptosis of osteoprogenitor cells. Estrogen appears to reduce the generation of ROS in these cells. These data could have important implications on the maintenance of osteogenic stem cells during fractures, ageing and disease.

Distal radial fractures account for 17% of all fractures treated, with peaks in the bimodal distribution corresponding to young and senior patients. External fixation is one of the best techniques to allow quick patient recovery and is necessary for complex fractures, such as that of the distal radius. However, the safe removal time for these frames remains unclear. A conservative approach commonly leaves the external fixator in place for six weeks, which may be unnecessarily prolonged and lead to increased complications. The aim of this work is to develop a technique to quantify, objectively, a safe removal time for these frames. Studies have been conducted on external fixation of tibial fractures, however there are differences that do not allow transfer of these studies to the external fixation of distal radial fractures. These differences include configuration of the fixation frame, bone and fracture geometries, and the application and transfer of the load to the bone. In this work, the dynamic transfer of the load between the fractured bone and the fixator is investigated. An instrumented grip and a measuring device have been developed to monitor the axial force and displacement when the patient applies a load. Using measurements collected by the instrument and data specifying the frame geometry, a finite element model is used to calculate the load carried by the fixator and by the bone, and the rigidity of the new callus is determined. Plotting the rigidity on semi-logarithmic scale the healing rate can be established. This technique has been successfully verified in a laboratory simplified structure representative of bone fracture. The rigidity of several intra-gap materials has been estimated experimentally using the technique, and the results compared to the real value of the material. These measurements do not interfere in any way with the patient treatment and they can be collected from the first day after the operation. The technique has been tested on 14 volunteer patients and the increase in callus rigidity can be detected by measurements during treatment using the technique described. A randomised prospective study has been initiated to validate this technique and investigate the healing process. A positive outcome would enable the rigidity of the new callus bone and the healing rate to be monitored during clinical assessment. Any healing delay or non-union could be promptly detected, improving the quality of the treatment.

Since cementless stem fixation in hip arthroplasty is becoming more and more common, the overall incidence of intraoperative femoral fractures has risen considerably. Depending on primary or revision arthroplasty, literature reports fracture rates between a few percent up to one third of the cases.

In this study, methods commonly applied in the field of structural testing were customized for this specified interference fit situation. A cementless hip system (ABG II, Stryker) was used on animal bones and biomechanical bones.

Transient excitation in the form of regular hammer strokes and sinusoidal excitation using a shaker served as an input. The output of the system under test was measured on the greater trochanter using a piezoelectric accelerometer.

The signals were digitized with a high-speed data acquisition system and analyzed in real-time with spectrum analysis software.

Analysis included threshold detection in the time domain to determine the time delay between the input and output transducer. Spectrum analysis in the frequency domain included FFT analysis and frequency response function analysis to identify shifts of fundamental frequencies and harmonics to describe the vibrational changes with increasing stability.

A digital imaging system was set up to take pictures of the metal-bone site to measure inducible displacement with each hammer impact and correlate it with the vibrometry results. Furthermore a strain gauge circularly mounted around the proximal femur monitored accurately any hairline fracture.

This study shows that changes of the vibrational spectrum are directly related to implant fit. The range of interest is well in the sonic range, which apparently is the reason for many surgeons to listen and ‘feel’ carefully during advancing the broach or the final implant into the femur.

The study is trying to extract critical vibrational parameters correlated with stability and femoral integrity. Due to the different dimensions of the tested animal bones and lack of soft tissue damping, further experiments on cadavers need to be carried out.

Vibrational spectrum analysis could prove to be a useful tool to readily assess implant stability and femoral integrity. It seems to be most beneficial in revision surgery or minimally invasive hip replacement, where the risk of femoral fractures is increased or fissures could easily be missed.