Introduction

Regular, repeated stretching increases joint range of movement (RoM), however the physiology underlying this is not well understood. The traditional view is that increased flexibility after stretching is due to an increase in muscle length or stiffness whereas recent research suggests that increased flexibility is due to modification of tolerance to stretching discomfort/pain. If the pain tolerance theory is correct the same degree of micro-damage to muscle fibres should be demonstrable at the end of RoM before and after a period of stretch training. We hypothesise that increased RoM following a 3 weeks hamstrings static stretching exercise programme may partly be due to adaptive changes in the muscle/tendon tissue.

Summary Statement

Proximal femoral bony deficits present a surgical and biomechanical challenge to implant longevity in revision hip arthroplasty. This work finds comparable primary stability when a distally fixing tapered fluted stem was compared with a conical design in cadaveric tests.

Summary

Cognitive testing scores do not correlate with physical braking performance. Psychological questioning shows patients are more dependent on driving than a control group.

Aims:

With the advent of standing CT and MRI scans, there is increasing interest in establishing the role and usefulness of these investigations. When ordering a standing investigation, we assume that 100% of body weight is loaded through the limb, but most machines have handlebars for support and some have seats to allow patients the opportunity to sit. The aim of this study was to evaluate the amount of load going through the lower limbs in various positions supported and unsupported, to explore the range and variation in measurements obtained.

Introduction

Revision hip arthroplasty is a technically challenging operation as proximal bony deficits preclude the use of standard implants. Longer distally fixing stems are therefore required to achieve primary stability.

Football player's performance during competitive matches greatly depends on fitness and training. The use of GPS (Global Positioning System) has been revolutionary in the monitoring of player intensity during training. The aim of the study was to investigate the difference in training intensity between defenders, midfielders and forwards and if injury sustained was directly related to the intensity of training. GPS (Catapult Minimax GPS 10Hz) was used to collect training data for a professional British football club playing in the Championship, for the year August 2011/April 2012. Each player wore a GPS unit during each training session and the raw data was logged. The GPS calculates the player load which is a measure of intensity of training. It is a summation of instantaneous change of forward, sideway and upward accelerations. Adjustments are made for match days and injuries according to a defined set of rules. A total player load was obtained for each month and at the end of the season. The different injuries sustained throughout the year were logged for each player. This study shows that there is a difference between the intensity of training in different groups of players. The midfielders trained at the highest intensity and, in this group of professional football players, defenders sustained the most injuries GPS technology allows monitoring of player intensity during training. The data obtained will guide training and fitness coaches model training for the individual group of players. This will prepare players for official matches and eventually may help predict and prevent injuries.

Axial musculoskeletal control (AMC) is a widely used concept and has been shown to be an important factor in physical performance, the pathophysiology of back pain and other MSK conditions. However, there is no agreement on a definition of AMC, nor a validated test for AMC and its application in clinical practice. Our aim was to develop a test for AMC using the Delphi method from a panel of experts with video and analysis of the footage. We found that the most commonly used tests were the maintenance of neutral pelvic position in single leg stance, single leg stance with eyes closed and single leg squat. We aim to further validate our findings by comparing this to surface EMG recordings and centre of gravity measurements in stress situations.

We have investigated whether a system of four inertial measurement units (IMUs) attached to the segments of the lower limbs could provide useful information about the kinematics of limb segment movement in gait in a healthy population. Four IMUs were attached to participants over their clothes. Participants then walked at their self-selected speed for 10 metres along a corridor and back. IMUs were removed, data downloaded on to a computer and ranges of motion were calculated for thigh, calf and knee, in addition to stride duration. 128 participants were recruited aged 18–97. There was little variation in most angle parameters up to age of 80. The relationships between angle and age are non-linear. There was a slight increase in stride duration with age of about 0.1% per year. The study concentrated on active subjects, with no specific co-morbidities that might affect gait. Results obtained may represent what is achievable for any given age, and approximate to changes that occur due to primary ageing. We propose that, after the age 80, peak muscle power declines below a threshold, such that muscular activity required to move a limb approaches the peak power available, and that it is the decline in peak muscle power that ultimately limits gait in active older people. Walking ability is important in maintaining independence as people age. It would be more effective to encourage exercises to maintain normal gait at a much earlier age. Deviations from the normal range could be identified early, and appropriate intervention given.

We have studied patients with Joint Hypermobility Syndrome (JHS) admitted to the Royal National Orthopaedic Hospital (RNOH) for a three-week in-patient rehabilitation programme. Ten patients were investigated at the start and end of this programme, and so far eight patients have been followed up at three months review. Postural stability was measured using a force plate, and the path of the centre of force (CoF) was tracked while patients were asked to attempt a series of more challenging tasks: double leg stance with eyes open and then with eyes closed, followed by single leg stance with eyes open and closed. Patients also completed a number of questionnaires at the same time points. We found the results of the double stance eyes closed test of postural stability to be the most informative. The ellipse area (EA) containing 95% of the points of the path of the CoF decreased from 21.5 + 14.8 cm2 to 9.0 + 11.5 cm2 over the course of the in-patient programme. In the eight patients followed up at three months, EA has remained the same (9.6 + 14.6 cm2). We conclude that the effects of the exercise programme and advice on subsequent exercise can be maintained over three months.

Total knee replacement in a commonly performed procedure in the United Kingdom with more than 76000 primary procedures performed in 2010. With so many procedures performed there has to be a robust way of assessing the outcome of the procedure. Gait analysis is a valuable tool in objectively assessing the these patients. Inertial movement units (IMU's) are a fairly new development in gait analysis. The aim of our project is to use IMUs to assess the differences in gait profile between a cohort of healthy controls, a group of pre operative knee replacement patients, a group of 8 week post operative patients and finally a group of post operative knee replacement patients at 1 year. We studied a total of 47 patients. We also had data from a previous study done on healthy controls using the same measurement tool. We measured three parameters: peak swing phase flexion, peak stance phase flexion and stride duration. Our findings indicate that pre-operative patients have a significantly reduced peak flexion in swing and stance with increased stride duration. This shows no improvement at the 8 week mark. At the 1 year mark peak flexion in swing returns to pre operative levels but flexion in stance and stride duration are still poor. These findings may not have been identified without gait analysis. Gait analysis using intertial movement units will add much information to radiographs and clinical examination. This information can also be used to tailor individual patients rehabilitation.

Osteoarthritis (OA) is a common, debilitating joint disease involving degeneration of cartilage and bone. It has been suggested that subtle changes in the molecular structure of subchondral bone may precede cartilaginous changes in the osteoarthritic joint. To explore these changes Raman spectroscopy was employed as a diagnostic tool. Raman spectroscopy measures inelastic scattered laser light produced when photons interact with chemical materials. Resultant changes in wavelength form spectra relative to the chemical composition of the given sample: with bone this includes the mineral and matrix components, unlike conventional X-rays. The aim of our study is to explore the hypothesis: Changes in matrix composition of osteoarthritic subchondral bone can be detected with Raman spectroscopy. pQCT and Raman spectroscopy were employed to determine the bone mineral density (BMD) and bone quality, respectively. Ten medial compartment OA and five control (non-OA) tibial plateaus were interrogated and analysis performed to compare OA to control, and medial to lateral compartments. The subchondral bone of the medial OA compartments had higher BMD (p=0.05) and thickness compared to lateral and control samples. Spectral analysis revealed there is no difference between the medial and lateral compartments within either cohort. However, there is a statistically significant (p=0.02) spectral difference between the OA and control specimens. The detection of bone matrix changes in osteoarthritis using Raman spectroscopy contributes to the understanding of the biochemical signature of subchondral bone across diseased and control tibial plateaus. This technique has potential to shed light on the role of bone in osteoarthritis.

Introduction

Patients undergoing limb reconstruction with the Taylor Spatial Frame (TSF) often perceive that their frame is loose due to the rattle they hear when mobilising. Our aim was to determine how much and where this movement is in the various frame/bone constructs currently on the market.

Synthetic bone grafts are used in several major dental and orthopaedic procedures. Strontium, in the form of strontium ranelate, has been shown to reduce fracture risk when used to treat osteoporosis. The aim of the study was to compare bone repair in femoral condyle defects filled with either a 10% strontium substituted bioactive glass (StronBoneTM) or a TCP-CaSO4 graft. We hypothesise that strontium substituted bioactive glass increases the rate of bone ingrowth into a bone defect when compared to a TCP-CaSO4 ceramic graft.

A critical size defect was created in the medial femoral condyle of 24 sheep; half were treated with a Sr-bioactive glass (StronBoneTM), and in the other animals defects were filled TCP-CaSO4. Two time points of 90 and 180 days were selected. The samples were examined with regard to: bone mineral density (BMD) from peripheral quantitative CT (pQCT), mechanical properties through indentation testing, and bony ingrowth and graft resorption through histomorphometry.

The radiological density of Sr-bioactive glass in the defect is significantly higher than that of the TCP-CaSO4-filled defect at 90 and 180 days, (p=0.035 and p=0.000). At 90 days, the stiffness of the defect containing Sr-bioactive glass and is higher than that of the TCP-CaSO4 filled defect, (p=0.023). At 6 months there is no significant difference between the two materials. Histomorphometry showed no significant difference in bone ingrowth at any time point, however significantly more of the graft is retained for the StronBoneTM treatment group than the TCP-CaSO4 group at both 0 days (p=0.004) and 180 days (p=0.000). The amount of soft tissue within the defect was significantly less in the StronBoneTM group than for the TCP-CaSO4 group at 90 days (p=0.006) and 180 days (p=0.000)

The data shows the mechanical stability of the defect site is regained at a faster rate with the strontium substituted bioglass than the TCP-CaSO4 alternative. Histomorphmetry shows this is not due to increased bone ingrowth but may be due to the incorporation of stiff graft particles into the trabeculae. Sr-bioactive glass produces a stronger repair of a femoral condyle defect at 3 months compared with TCP-CaSO4.

Early diagnosis of delayed- and non-union tibial fractures is difficult, but treatment options are available if timely data are available. Direct correlation between implant forces and healing status is difficult during stance phase loading due to soft tissue forces. This ongoing study seeks to find a minimal set of strain gauge sites needed to determine healing at any of several fracture sites, using isometric loading suitable for routine clinical usage. A series of instrumented tibial nails are being used to help determine whether an alternative technology can replace or augment existing routine methods for assessment of fracture healing.

In a prior study, a single strain gauge positioned close to the fracture site had produced mixed results. In the current study, a TRIGEN META NAIL, 10mm OD x 380mm long, was instrumented with 8 gauged sites spiraled down the nail at 34mm axial and 120deg angular separation (Gen1), and loaded in a Sawbone model in offset axial compression, 3 point bending and torque.

In order to gain early clinical results, and in a design informed by the Gen1 data, a set of instrumented nails have been made for an ovine wireless telemetry study (Gen3a), shortly to commence, in which the tibial nail has been over-gauged enabling multiple d.o.f. measurements to be made during gait, torque, axial compression and 3 point bending; the latter protocols offering more controlled patient postures. This study is to be followed by a similar human study (Gen3) involving five subjects (12 gauges per nail). Meanwhile, a parallel biomechanical study involving six nails with 20 gauges each is also planned.

In the Gen1 study, the strains diminished with distance from the fracture site and with out-of-plane sites during bending. During torque, however, the response was much more uniform for all strain sites. Significant increases in strains due to both loading regimes were seen in the fractured case vs. an intact bone.

Preliminary conclusions are that strains measured due to applied torque may offer a more sensitive and fracture site-independent means of assessing healing than induced bending. We now aim to confirm these observations in animal and human studies.

Introduction

Knowledge of knee kinetics and kinematics contributes to our understanding of the patho-mechanics of knee pathology and rehabilitation and a mobile system for use in the clinic is desirable.

We set out to assess validity and reliability of ambulatory Inertial Motion Unit (IMU) Sensors (Pegasus¯) against an established optoelectronic system (CODA¯).

Pegasus¯ uses inertial sensors placed on subjects' thighs and lower leg segments to directly measure orientation of these segments with respect to gravity. CODA¯) models the position of joint centres based on tracked positions of optical markers placed on a subject, providing 3D kinematics of the subject's hips, knees and ankles in all three planes.

Conventionally, medial malleolus fractures are treated surgically with anatomical reduction and internal fixation using screws. There seems to be no consensus, backed by scientific study on the optimal screw characteristics in the literature.

We retrospectively examined case notes and radiographs of 48 consecutive patients taken from our trauma database (21 male, 27 female) with an average age of 50 years (range 16-85) who had undergone medial malleolus fracture fixation with screws at the Royal Free Hospital, London between January 2009 and June 2010.

The most commonly used screw was the AO 4.0 mm diameter cancellous partially-threaded screw in 40, 45 and 50 mm lengths (40 mm n = 28, 45 mm n = 26, 50 mm n = 23) with the threads passing beyond the physeal scar in all cases. Incomplete reduction defined as > 1mm fracture displacement was observed on post-operative x-rays in 12 out of 48 cases (25%), all of which relied on partially-threaded screw fixation. In 5 cases where AO 4.0 mm diameter fully-threaded screws engaging the physeal scar had been used, no loss of reduction was observed.

This unusual, occasional use of fully-threaded screws prompted us to investigate further using a porcine model and adapted pedo-barographic transducer. We compared pressures generated within the fracture site using AO 4.0 mm partially-threaded cannulated screws, 4.0 mm partially-threaded cancellous screws and 4.0 mm fully-threaded cancellous screws.

Fully-threaded cancellous 4.0 mm diameter screws generated almost 3 times the compression of a partially-threaded cancellous screw with superior stability at the fracture. Partially-threaded screws quickly lost purchase, compression and stability particularly when they were cannulated. We also observed that screw thread purchase seemed enhanced in the physeal region.

We conclude that fully-threaded cancellous 4.0 mm AO screws are superior to longer partially-threaded screws and that use of cannulated 4.0 mm partially-threaded screws should be avoided in fixation of medial malleolus fractures.

Near infrared light between the wavelengths of 700 and 950 nanometers has a relatively low absorption in tissue, and light of these wavelengths is able to penetrate several centimetres into tissue. Absorption of light is primarily due to hemoglobin. The absorption spectra for oxy-hemoglobin and deoxy-hemoglobin are different, and therefore comparison of light absorption at different wavelengths allows an assessment of the relative concentrations of these two chromophores. Light penetrates bone as well as soft-tissue, and near infrared spectroscopy (NIRS) is potentially a relatively simple, low-cost technique for assessing perfusion in bone. However, although absorption of light is low, scattering is high, and the spatial resolution of the measurement is poor. Application of the technique to the study of bone perfusion requires consideration of the potential confounding absorption arising from adjacent tissues that may have higher perfusion.

A clinical problem of interest in our institute is that of vascular changes occurring in bone of patients with spinal cord injury (SCI), and the relationship of these changes to bone density changes. We have, therefore, concentrated on developing NIRS for measurement of the proximal tibia, which is a common site for fractures in these patients. In order to develop a probe for the measurement of bone, experiments were performed with phantoms containing infrared absorbing dyes. Numerical simulations were also performed using the Monte Carlo technique. One of the most important design considerations is the distance between the optode delivering light to the skin, and the collecting optode which detects light. It was found that a separation of 20 mm between the light source and detector was an optimum compromise for minimizing contributions from overlying skin and surrounding muscle, while still being able to detect light efficiently enough to measure dynamic changes in chromophore concentration.

We have now started to apply this technique clinically. Relative changes of oxy- and deoxy-hemoglobin concentration have been measured in response to a range of interventions. Comparison has been made of the effect of different interventions designed to modify perfusion of bone (neuro-muscular stimulation of the calf, intermittent pneumatic compression, low amplitude high frequency vibration, and venous tourniquet). We are studying vascular reactivity in chronic SCI patients and controls and we have also started to investigate the effect of daily neuro-muscular stimulation in acute SCI patients. Preliminary results of these clinical studies will be presented.

Introduction: Conflicting opinions exist as to whether bone healing is affected by the administration of bisphosphonates for osteoporosis. In an animal model, we assessed the effect of bisphosphonates on osteoporotic fracture healing and whether the timing of administration made a difference.

Methods: 36 female Wistar rats underwent a mid-diaphyseal femoral osteotomy six weeks after ovariectomy. They were then divided into 3 groups:

no treatment (control);

Results: Of the 36 rats, 8 were unable to complete the study. Group 3 differed from control in three respects: higher bone mineral content (BMC) and density (BMD); larger callus; lower torsional stiffness. Group 2 did not differ significantly from control. There was a significant positive correlation between stiffness and change in BMC in group 1 (r=0.85, p< 0.001) but not so for group 2 (r=0.2, p> 0.05) and group 3 (r=0.04, p> 0.05). A similar trend existed for all radiographic parameters in the three groups.

Conclusion: The results suggest that, with early bisphosphonate treatment, although there is an increase in the size of the callus, that callus is biomechanically inferior. Furthermore, administration of bisphosphonates at either stage destroys the relationship between radiographic and mechanical parameters used to assess fracture healing.

The healing index, external fixation time divided by length gain, is commonly used as an outcome measure in distraction osteogenesis. This can be imprecise, and experimentally, regenerate stiffness is the accepted measure, but this can be difficult to measure clinically. The aim of this study was to investigate whether radiostereometric analysis (RSA) may be used to determine stiffness of new bone.

Two Ilizarov frames of differing stiffness were constructed around Sawbones tibiae. Known loads were applied to the frames and RSA was used to analyse the movement that occurred at the distraction gap. The axial stiffness of the frames was calculated. The distraction gap was filled with materials with a range of stiffnesses, representative of regenerate at different stages of consolidation. Loads were applied and RSA was used to measure the stiffness of the construct. A simple load share model was then used to estimate stiffness of the materials, and these values compared with those obtained from a materials testing machine.

The measured stiffnesses of the frames were 94N/mm and 55N/mm. RSA tended to underestimate the material properties of the ‘regenerate’, and this effect became greater at higher stiffness. There was also a 30% difference in estimated stiffness of the ‘regenerate’ when comparing the two fixators.

RSA is a very precise non-invasive method for measuring regenerate displacement. However, simple models to estimate stiffness tend to underestimate the true value, and assumptions made in basic engineering models are not valid when the stiffness of the regenerate approaches that of surrounding bone.

Measurement of blood flow to the skeleton is technically challenging. The specific problems of measuring blood flow that are particular to bone are:

i) there are 206 separate bones in the skeleton;

Because of this heterogeneity of the tissue, it is also important to specify precisely the region of bone that is being measured, and this problem accounts for some of the discrepancies in values of bone blood flow quoted in the literature. From a practical orthopaedic perspective, techniques to measure regional blood flow are normally more informative than measurements of total skeletal blood flow.

In experimental studies, the microsphere technique has been used most widely for the quantitative measurement of bone blood flow, and is regarded as the gold standard. Particles of the order of 15 microns in diameter are injected into the ventricle and trapped in the microcirculation during a single passage. The distribution of microspheres in the body is proportional to the distribution of cardiac output, and if a reference arterial blood sample is taken during injection of the microspheres, then blood flow may be calculated. Microspheres are normally labeled with a radioactive tracer or a colored dye, and microsphere number is estimated from assays of the attached label.

The microsphere technique is a specific example of indicator fractionation, and clinically indicator fractionation can be applied using imaging techniques such as magnetic resonance imaging (MRI) or positron emission tomography (PET). MRI-based techniques are based on gadolinium contrast agents, and PET uses positron-emitting isotopes such as oxygen-15 labelled water, fluorine-18 ion, or ¹⁸F-fluorodeoxyglucose. Positron-emitting isotopes are short-lived, and need to be produced daily by a cyclotron, limiting the general utility of the technique. However, dynamic PET measurements with fluorine-18 have been used to assess simultaneously both bone blood flow and bone formation rates.

Blood flow can also be estimated from velocity measurements, e.g. electromagnetic flowmetry, laser Doppler, and ultrasound Doppler. Laser Doppler measurements require contact between the probe and the tissue being measured, and have applications in experimental studies of vascular reactivity in bone. Although ultrasound is reflected very effectively from bone surfaces, ultrasound Doppler has been used to image the lumber arteries in patients with degenerative disc disease.

Bone, like other tissues in the body, is relatively transparent to light in the near-infra red, but there are specific absorption peaks for deoxy- and oxy-hemoglobin. This is the basis of near infra-red spectroscopy for perfusion measurements. However, because of the complexities of light scattering in tissue, spatial resolution is poor. Measurements in the proximal tibia are quite straightforward, and we are currently using this technique in studies of bone loss in spinal cord injury patients.