Introduction

Decreasing endplate porosity has been proposed as a risk factor for intervertebral disc degeneration, because it interferes with disc metabolite transport. However, endplate porosity has recently been shown to increase with age and disc degeneration. We hypothesise that this increase reflects adaptive remodelling in response to altered loading from adjacent discs.

Introduction

Dual energy X-ray absorptiometry (DEXA) is the gold standard for assessing bone mineral density (BMD) and fracture risk in vivo. However, it has limitations in the spine because vertebrae show marked regional variations in BMD that are difficult to detect clinically. This study investigated whether micro-CT can provide improved estimates of BMD that better predict vertebral strength.

Conflict in the Middle East has seen a change in warfare tactics from the use of ballistic missiles to blast weapons. This has resulted in a change in wounding patterns. Due to the severity of the injuries, there have been large numbers of amputations, as life and limb saving procedures.

The purpose of this paper was to retrospectively review all the amputated limbs over the past 8 years of conflict and compare those from the early years to the more recent ones. In particular, the aim was to examine differences in the mechanisms of injury, number of limbs injured, associated injuries, method of amputation, microbiology of contaminating organisms and outcome.

There were significantly more amputations, injured limbs and soft tissue perineal wounds as well as a significantly higher ISS in the later group. There were also significant differences in the surgical techniques, with more guillotine amputations in the early group, and mechanism of injury, with more blast injuries in the late group.

This confirms the clinical impression that there has been a significant change in limb trauma from Iraq to Afghanistan. These injury patterns have significantly different logistical implications, which must be considered when planning the required medical assets in future conflicts.

Ontogeny of long bone cross-sectional geometry has lasting effects on adult bone structure. Growth and development of bone is influenced by biological and mechanical factors but the importance of these factors is poorly understood. A study of prenatal, neonatal and infant development in a bone with simple loading patterns, may improve our understanding. Five vertebral columns aged between 6 months prenatal to 2.5 years postnatal, were analysed to quantify the changes in trabecular architecture before and after birth. Several measures were collected including trabecular: thickness, bone volume fraction, connectivity density, number, structure model index and anisotropy. The findings show that in the first year after birth there is a substantial loss of bone volume via decreasing trabecular thickness and number, which tends to increase after 1.2 years. This sequential pattern of development may be a functional response to the initial requirement for calcium mineral homeostasis before birth, followed by the need for trabecular architecture to adapt to mechanical loading after birth. Calcium is essential for growing neonates and therefore osteoclastic resorbtion is up regulated by increasing parathyroid hormone levels. This may account for the loss of bone between 0–1 year. At one year infants begin to walk bipedally, thus weight bearing and ground reaction forces increase. The stable bone volume and increase in organisation of trabecular architecture after one year may reflect increasing weight bearing and ground reaction forces. These findings suggest that nutritional requirements after birth may have a stronger influence on vertebral trabeculae architecture than learning to walk.

Introduction

Senile kyphosis arises from anterior ‘wedge’ deformity of thoracolumbar vertebrae, often in the absence of trauma. It is difficult to reproduce these deformities in cadaveric spines, because a vertebral endplate usually fails first. We hypothesise that endplate fracture concentrates sufficient loading on to the anterior cortex that a wedge deformity develops subsequently under physiological repetitive loading.

Introduction

Vertebroplasty helps to restore mechanical function to a fractured vertebra. We investigated how the distribution of injected cement benefits both fractured and neighbouring vertebrae.

Infection is a common complication of severe open fractures and compromises bone healing. The present standard of care is a two-stage approach comprising of initial placement of antibiotic-impregnated PMMA beads to control infection followed later by bone grafting. Although the systemic antibiotics and PMMA/antibiotic beads control the infection initially, there are often residual bacteria within the wound. After grafting and definitive closure, the implanted graft is placed in an avascular defect and could function as a nidus for infection. Bioactive porous polyurethane (PUR) scaffolds have been shown to improve bone healing by delivering recombinant human bone morphogenetic protein-2 (BMP-2) and reduce infection by delivering antibiotics. The release kinetics of the BMP-2 were an initial burst to recruit cells and sustained release to induce the migrating cells. The Vancomycin (Vanc) release kinetics were designed to protect the graft from contamination until vascularisation by having an initial burst and then remaining over the MIC for Staph. aueus for two months. In this study, PUR+BMP-2+Vanc scaffolds were first tested in a non-infected critical size rat femoral segmental defect and was found to perform comparably to PUR+BMP-2, thus indicating that Vanc did not hinder bone healing. PUR+BMP-2+Vanc scaffolds were subsequently evaluated in an infected critical size rat femoral segmental defect. The dual delivery approach resulted in significantly more new bone formation and infection control than both PUR+BMP-2 and the collagen+BMP-2 treatments. These data indicate that the dual-delivery strategy effectively protects the graft from infection during wound healing and regenerates more bone in contaminated defects. This moderately osteoconductive bone graft is capable of being injected, provides a more sustained release of BMP-2 than the collagen sponge, and can release antibiotics for over 8 weeks. The dual-delivery approach may improve patient outcomes of open fractures by protecting the osteoinductive graft from colonization until vascularization occurs.

Peripheral nerve injuries (PNI) occur in 10% of combat casualties. In the immediate field-hospital setting, an insensate limb can affect the surgeon's assessment of limb viability and in the long-term PNI remain a source of considerable morbidity. Therefore the aims of this study are to document the recovery of combat PNI, as well as report on the effect of current medical management in improving functional outcome. In this study, we present the largest series of combat related PNI in Coalition troops since World War II.

From May 2007 – May 2010, 100 consecutive patients (261 nerve injuries) were prospectively reviewed in a specialist PNI clinic. The functional recovery of each PNI was determined using the MRC grading classification (good, fair and poor). In addition, the incidence of neuropathic pain, the results of nerve grafting procedures, the return of plantar sensation, and the patients' current military occupational grading was recorded.

At mean follow up 26.7 months, 175(65%) of nerve injuries had a good recovery, 57(21%) had a fair recovery and 39(14%) had a poor functional recovery. Neuropathic pain was noted in 33 patients, with Causalgia present in 5 cases. In 27(83%) patients, pain was resolved by medication, neurolysis or nerve grafting. In 35 cases, nerve repair was attempted at median 6 days from injury. Of these 62%(22) gained a good or fair recovery with 37%(13) having a poor functional result. Forty-two patients (47 limbs) initially presented with an insensate foot. At final follow up (mean 25.4 months), 89%(42 limbs) had a return of protective plantar sensation. Overall, 9 patients were able to return to full military duty (P2), with 45 deemed unfit for military service (P0 or P8).

This study demonstrates that the majority of combat PNI will show some functional recovery. Adherence to the principles of war surgery to ensure that the wound is clear of infection and associated vascular and skeletal injuries are promptly treated will provide the optimal environment for nerve recovery. Although neuropathic pain affects a significant proportion of casualties, pharmacological and surgical intervention can alleviate the majority of symptoms. Finally, the presence of an insensate limb at initial surgery, should not be used as a marker of limb viability. The key to recovery of the PNI patient lies in a multi-disciplinary approach. Essential to this is regular surgical review to assess progress and to initiate prompt surgical intervention when needed. This approach allows early determination of prognosis, which is of huge value to the rehabilitating patient psychologically, and to the whole rehabilitation team.

Introduction

Despite the routine use of irrigation, debridement and systemic antibiotics, there is a high incidence of infection in severe open fractures. The synergistic use of local and systemic antibiotics appreciably reduces infection rates although the time window within which this is effective is unknown. The aim was to determine if delaying treatment of wounds causes higher levels of infection.

To investigate whether restoration of mechanical function and spinal load-sharing following vertebroplasty depends upon cement distribution.

Fifteen pairs of cadaver motion segments (51-91 yr) were loaded to induce fracture. One from each pair underwent vertebroplasty with PMMA, the other with a resin (Cortoss). Various mechanical parameters were measured before and after vertebroplasty. Micro-CT was used to determine volumetric cement fill, and plane radiographs (sagittal, frontal, and axial) to determine areal fill, for the whole vertebral body and for several specific regions. Correlations between volumetric fill and areal fill for the whole vertebral body, and between regional volumetric fill and changes in mechanical parameters following vertebroplasty, were assessed using linear regression.

For Cortoss, areal and volumetric fills were significantly correlated (R=0.58-0.84) but cement distribution had no significant effect on any mechanical parameters following vertebroplasty. For PMMA, areal fills showed no correlation with volumetric fill, suggesting a non-uniform distribution of cement that influenced mechanical outcome. Increased filling of the vertebral body adjacent to the disc was associated with increased intradiscal pressure (R=0.56, p<0.05) in flexed posture, and reduced neural arch load bearing (F_N) in extended posture (R=0.76, p<0.01). Increased filling of the anterior vertebral body was associated with increased bending stiffness (R=0.55, p<0.05).

Cortoss tends to spread evenly within the vertebral body, and its distribution has little influence on the mechanical outcome of vertebroplasty. PMMA spreads less evenly, and its mechanical benefits are increased when cement is concentrated in the anterior vertebral body and adjacent to the intervertebral disc.

The aim of this prospective study was to determine the prevalence of bone marrow oedema (BME) in asymptomatic knees of athletes and to investigate the factors associated with appearance of BME in this group.

A total of 25 asymptomatic athletes who competed at an international, national or county level during their most recent sport season were recruited in this study and had MRI scan of both knees (n=50). MRI scans were reported independently by two experienced musculoskeletal radiologists. Statistical analysis included Cohen's kappa test to identify inter-observer agreement for MRI diagnosis of bone marrow oedema and multiple logistic regression model to identify the factors associated with BME on MRI scan.

There was very good agreement between radiologists for diagnosis of BME (Kappa = 0.896). Seven participants (28%) were found to have BME. Six of the participants had BME in unilateral knees and one participant had BME in bilateral knees. The commonest location of BME was medial femoral condyle (62.5%) The amount of time spent in preseason training (34-38 weeks) was significantly associated with appearance of BME (P=0.048)

BME seems to be common in asymptomatic athletes and one should realize that this finding might not be related to the clinical complaints of the patients. The results of the present study show that there is a training effect associated with BME. Knowing what is a ‘normal’ or ‘abnormal’ scan is important for a competitive athlete, as erroneously diagnosing BME as the underlying cause of athletes' symptoms could lead to decreased playing time or inappropriate therapy.

Background: Despite aggressive debridement, thorough irrigation, systemic antibiotics, and staged treatment, many open fractures still become infected. A graft that can promote bone regeneration and prevent infection could decrease complications. Polyurethane (PUR) scaffolds have previously been shown in separate studies to be nontoxic, osteoconductive, can promote bone growth by delivering BMP, and prevent infection by the sustained release of an antibiotic. This scaffold can deliver both BMP and vancomycin simultaneously; the purpose of this study is to determine if the co-delivery of the antibiotic inhibits bone formation.

Methods: Using an established critical size defect rat femur model, the amount of bone formation created by PUR scaffolds containing low and high doses of rhBMP-2 (2.4 μg and 22.4 μg respectively) and 0.8 mg vancomycin (8% of graft by weight) were compared to scaffolds that contained rhBMP-2 without antibiotics. After 4 weeks, the femurs were harvested and bone growth was assessed using microCT.

Results: There was no significant difference in bone growth between the groups that had the high dose of rhBMP-2. Surprisingly, the scaffolds that had the low dose of rhBMP-2 and vancomycin promoted more bone formation than scaffolds that had rhBMP-2 and no antibiotics.

Conclusions: The addition and co-delivery of vancomycin to the scaffolds did not inhibit bone growth. The addition of vancomycin to the PUR scaffolds may have altered the release kinetics of the rhBMP-2; this may explain the increase of bone formation in this group. This study demonstrates that incorporation of a therapeutic and a clinically-relevant level of vancomycin does not inhibit bone formation. These results suggest that a dual delivery bone graft has potential to reducing complications associated with open fractures.

The biomechanics of civilian fractures have been extensively studied with a view to defining the forces responsible e.g. bending, torsion, compression and crushing. Little equivalent work has been carried out on military fractures, although fractures from gunshot can be divided into direct and indirect. Given that the effects of blast can be sub-divided into primary, secondary, tertiary and quaternary, the aim of this study was to try to determine which effects of the blast are responsible for the bony injury. This may have implications for management and prognosis as well as prevention.

We reviewed emergency department records, case notes, and all radiographs of patients admitted to the British military hospital in Afghanistan over a 6 month period (Apr 08–Sept 08) to identify any fracture caused by an explosive mechanism. In addition we reviewed all relevant radiographs from the same period at the Royal Hospital Haslar, who report all radiographs taken, and keep a copy of the images. Early in the study it became clear that due to the complexity of some of the injuries it was inappropriate to consider bones separately and we used the term ‘fracture zone’ to identify separate areas of injury, which could involve from 1 – 28 bones. It also became clear that the pattern of injury differed considerably between patients in open ground, and those in houses or vehicles. These 2 groups were considered separately and compared.

We identified 86 patients with fractures. The 86 patients had 153 separate fracture zones (range 1–6). 56 casualties in the open sustained 87 fracture zones (mean 1.55 fracture zones per casualty). 30 casualties in a vehicle or other cover sustained 66 fracture zones (2.2 per casualty). Of the casualties in the open, 17 fracture zones were due the primary effects of blast, 10 a combination of primary and secondary effects, 30 due to secondary effects and 30 from the tertiary effects of blast. Of the casualties in vehicles we could not identify anyone with a fracture due to either the primary or secondary effects of blast, all 66 fracture zones appeared to be due to the tertiary effects.

In both groups there appeared to be a significant number of fractures, often with no break in the skin, caused by severe axial loading of the limb. This was possibly due to the casualty impacting against the ground, building or the inside of a vehicle, and this is a group of injuries we are now studying in greater detail.

It has stated that the application of a pre-hospital tourniquet could prevent 7% of combat deaths, but their widespread use has been questioned due to the potential risk from prolonged ischaemia, or local pressure. The debate centres on their ability to improve survival after major haemorrhage, versus the potential risk of limb loss. A recent US military prospective study on their use demonstrated improved survival when a tourniquet was applied, and reported that no limb was lost solely from tourniquet use. However, this study focused on early limb loss, with a median follow-up of only 7 days, and so could not consider later morbidity. The aim of this study was to investigate if the pre-hospital application of a tourniquet resulted in an increase in morbidity following significant ballistic limb injury.

We reviewed members of the UK armed forces who sustained severe limb-threatening injuries in Iraq and Afghanistan, and based on the presence or absence of a pre-hospital tourniquet a cohort study was then performed. Of the 23 lower limbs that definitely had a pre-hospital tourniquet applied it was possible to match 22 limbs with 22 that did not have a pre-hospital tourniquet. The injuries were matched for anatomical location, severity of the bony injury, initial surgical management, Injury Severity Score and Mangled Extremity Severity Score as much as possible.

Of the 22 limbs with a pre-hospital tourniquet applied, 19 limbs had a least 1 complication. Of the 22 with no tourniquet applied, 15 had at least 1 complication (p=0.13). There were 10 limbs with at least 1 major complication in the pre-hospital tourniquet group but only 4 in the group with no tourniquet (p=0.045). There was no difference in the amputation rate.

The significant difference in the incidence of major complications is a concern, particularly as the difference was mainly due to a deep infection rate of 32% vs. 4.5%. Although there are a number of variables which could have influenced these small groups, such as choice of implant, method and timing of wound closure, the use of a cohort and a p < 0.05, does suggest the use of a pre-hospital tourniquet was a factor.

Although the use of pre-hospital tourniquets cannot be decried as a result of this study, there does remain the need to continually review their use, prospectively, to determine their risk/benefit ratio.

Introduction: Previously, 3D finite element models of the midfemoral neck (MFN) predicted maximal compressive stress in the inferior cortex and trabeculae during the heel-strike of normal gait. We hypothesised that older women (compared with younger women) would have relative preservation of inferior trabecular bone, reflecting continued walking activity into old age. Recently, we identified preservation of the infero-anterior femoral neck cortex in old age despite women at 85 having 55–80% thinner superior cortices than women aged 25. Here, we examined regional trabecular bone mineral density in an extended region of interest (ROI) of the MFN, to establish age-associated differences and their likely contribution to hip fracture in a cross-sectional study of 100 women aged 20–90 years using 64-slice computed tomography (CT).

Methods: 100 healthy women were recruited by decade from age 20 to 90 (inter-quartile range 38–72). Participants consented to an extension of a routine clinical pelvic CT scan (Siemens 64-slice CT) using a fixed threshold of 450mg/cm3 and Mindways Software (BIT-2) to analyse both hips (1mm slice thickness, 0.59 mm voxel size). The starting position for cross sections was a 1mm thick MFN slice where the femoral neck height to width ratio was 1.4, since this location along the neck axis has been shown to be highly reproducible and unaffected by age (mean 51%, SE 0.016%). 5 parallel 1mm thick slices were evaluated towards the midline. Age effects on trabecular BMD (tbBMD mg/cm3.) were evaluated using linear regression (by anatomical quadrant).

Results: Trabecular BMD was significantly lower at 85 than at 25 years old amounting to over 50% difference in 3 out of 4 quadrants: Supero-posterior tbBMD difference between 25–85 years by modelling −146mg.cm3., (absolute %) −53%, r 2 (age) 0.61, p < 0.0001; Infero-anterior −25mg.cm3., −24%, r 2 0.094, p < 0.002. In the infero-anterior quadrants (that receive maximal stress at the heel strike in normal gait) there was relative preservation (r squared only 0.094) and only a 24% difference between 85 and 25. Body weight had no association with tbBMD in any quadrant (unlike cortical thickness).

Conclusion: Trabecular bone was better preserved in the infero-anterior quadrant in elderly women than in the other 3 quadrants. Since tbBMD also makes a small but significant contribution to the reduction of the risk of failure of femoral necks ex-vivo, increasing trabecular bone in the remaining quadrants should be included in strategies to prevent hip fracture, alongside efforts to strengthen the cortex.

Over 75% of combat casualties from Iraq and Afghanistan sustain injuries to the extremities, with 70% resulting from the effects of explosions. Damage to peripheral nerves may influence the surgical decision on limb viability in the short-term, as well as result in significant long-term disability. To date, there have been no reports of the incidence and severity of nerve injury in the current conflicts.

A prospective assessment of United Kingdom (UK) Service Personnel attending a specialist nerve injury clinic was performed. For each patient the mechanism, level and severity of injury to the nerve was assessed and associated injuries were recorded.

Fifty-six patients with 117 nerve injuries (median 2, range 1–5) were eligible for inclusion. This represents 12.9% of casualties sustaining an extremity injury. The most commonly injured nerves were the tibial (19%), common peroneal (16%) and ulnar nerves (16%). 25% (29) of nerve injuries were conduction block, 41% (48) axonotmesis and 34% (40) neurotmesis. The mechanism of injury did not affect the severity of injury sustained (explosion vs gunshot wound (GSW), p=0.53). An associated fracture was found in only 48% of nerve injuries and a vascular injury in 35%. The presence of an associated vascular injury resulted in more severe injuries (conduction vs axonotmesis and neurotmesis, p< 0.05). Nerves injured in association with a fracture, were more likely to develop axonotmesis (p< 0.05).

The incidence of peripheral nerve injury from combat wounds is higher than previously reported. This may be related to increasing numbers of casualties surviving with complex extremity wounds. In a polytrauma situation, it may be difficult to assess a discrete peripheral neurological lesion. As only 35% of nerves injured are likely to have anatomical disruption, the presence of an intact nerve at initial surgery should not preclude the possibility of an injury. Therefore, serial examinations combined with appropriate neurophysiologic examination in the post-injury period are necessary to aid diagnosis and to allow timely surgical intervention. In addition, conduction block nerve injuries can be expected to make a full recovery. As this accounts for 25% of all nerve injuries, we recommend that the presence of an insensate extremity should not be used as an indicator for assessing limb viability.

Introduction: Vertebroplasty increases stiffness and partly restores normal load-sharing in the human spine following vertebral fracture. The present study investigated whether the mechanical effects of vertebroplasty are influenced by the distribution of injected cement.

Methods: Ten pairs of cadaver motion segments (58–88 yr) were loaded to induce fracture, after which one from each pair underwent vertebroplasty with polymethyl-methacrylate cement, the other with a resin (Cortoss). Various mechanical parameters were measured before fracture, after fracture and following subsequent vertebroplasty. Micro-computed tomography scans and plane radiographs (sagittal, frontal, and axial) obtained from each augmented vertebral body were analysed to determine percentage cement fill in the whole vertebral body and in selected regions. The relationship between volumetric fill obtained by micro-CT and areal fill obtained by radiography was investigated using linear regression analysis. Regression analysis also indicated whether changes in mechanical parameters following vertebroplasty were dependent upon cement distribution.

Results: Cement type had no significant influence upon regional fill patterns, so data from both cements were pooled for all subsequent analyses. Volumetric fill of the whole vertebral body was predicted best by areal fill in the sagittal plane (R2=0.366, P=0.0047). Restoration of intradiscal pressure and compressive stiffness following vertebroplasty were dependent upon volumetric cement fill both in the whole vertebral body (R2=0.304, P=0.0118 and R2=0.197, P=0.0499 respectively), and in the anterior half (R2=0.293, P=0.0137 and R2=0.358, P=0.0053).

Conclusion: Cement fill patterns can best be assessed radiographically from sagittal plane views. Placement of cement in the anterior vertebral body may help to improve mechanical outcome following vertebroplasty.

Despite modern advances, amputation is still a commonly performed operation in war. It is often difficult to decide whether to amputate following high-energy trauma to the lower extremity. To help guide this assessment, scoring systems have been developed with amputation threshold values. These studies were all conducted on a civilian population, encompassing a wide range of ages and methods of injury. The evidence for their sensitivity and specificity is inconclusive. The purpose of this study was to assess the validity of Mangled Extremity Severity Score (MESS), the only verified score, in a population of military patients with ballistic mangled extremity injuries.

52 military patients with 58 limbs who had ballistic mangled extremity injuries were identified, 13 of whom required amputation. Using both the trauma audit and the hospital notes, demographics were assessed. Patients were retrospectively evaluated with the MESS system for lower extremity trauma.

The MESS would not help in the decision-making. However, we were able to develop an algorithm for management, in particular the need for early amputation.

The management of ballistic extremity injuries in military patients should be considered separate to that of civilians with high-energy trauma extremity injuries. The authors have developed an algorithm to provide guidelines for management.

Extremity injuries on the battlefield are commonly secondary to high energy mechanisms. These cause significant injury to soft tissue and bone and are contaminated. Evacuation to medical care can be difficult in the operational environment and may delay the time to initial surgery. There is already substantial literature on the complications of such injuries but this is the first report from UK forces. Our aim was to assess the complications, but specifically infections, in relation to delay in surgery and also the method of fracture stabilisation.

Military patients who had ballistic mangled extremity injuries were identified from the database (courtesy of ADMEM). Using both the trauma audit and the hospital notes, demographics were assessed. The injuries sustained (including the fractured bones), time to theatre, associated injuries, method of stabilisation at Role 3, definitive fixation and complications were noted.

81 patients were identified with 95 limbs injured (68 lower limb, 27 upper limb). The most commonly fractured bones were the tibia, radius/ulna, femur and humerus. Primary stabilisation was either ExFix (53%) or plaster (44%). Of those stabilised by ExFix, the definitive stabilisation was mainly by either a nail (44%) or plate (17%). Those stabilised by plaster mainly stayed in plaster. 72% of patients developed at least one complication, the most common of which was superficial infections. Other complications were deep infections, delayed union, haematomas, neuropathic pain and flap failures. The main organisms involved were Acinetobacter, Bacillus and Pseudomonas. There was no association between delay to theatre and decision to amputate. There was an association between the use of plaster for definitive stabilisation and superficial infection and plates for definitive stabilisation and deep infections. There was no association between time delay to theatre and infections.

This provides the first report of complications from extremity injuries secondary to ballistic missile devices in UK forces. It allows for comparison with reports from other sources on similar injuries and helps to guide further management of patients. In particular it agrees with recent civilian data that initial surgery does not have to be carried out as soon as possible, which has implications for military planning.

There are well-established guidelines for musculoskeletal and connective tissue disorders in the assessment of potential recruits. There have been no critical appraisals of the application of these guidelines since their recent revision. The aim of this study was to examine whether common presenting conditions are covered by the guidelines and whether there was adherence by the assessor to the recommended outcome. We reviewed 110 potential recruits presenting to an Orthopaedic Consultant. There were a number of conditions not covered and a few occasions when the decision seemed contrary to the guidelines. In particular we think more consideration is needed of congenital deformities.