Currently, there is no animal model in which to evaluate the underlying physiological processes leading to the heterotopic ossification (HO) which forms in most combat-related and blast wounds. We sought to reproduce the ossification that forms under these circumstances in a rat by emulating patterns of injury seen in patients with severe injuries resulting from blasts. We investigated whether exposure to blast overpressure increased the prevalence of HO after transfemoral amputation performed within the zone of injury. We exposed rats to a blast overpressure alone (BOP-CTL), crush injury and femoral fracture followed by amputation through the zone of injury (AMP-CTL) or a combination of these (BOP-AMP). The presence of HO was evaluated using radiographs, micro-CT and histology. HO developed in none of nine BOP-CTL, six of nine AMP-CTL, and in all 20 BOP-AMP rats. Exposure to blast overpressure increased the prevalence of HO.

This model may thus be used to elucidate cellular and molecular pathways of HO, the effect of varying intensities of blast overpressure, and to evaluate new means of prophylaxis and treatment of heterotopic ossification.

Cite this article: Bone Joint J 2015;97-B:572–6

Objectives

There remains conflicting evidence regarding cortical bone strength following bisphosphonate therapy. As part of a study to assess the effects of bisphosphonate treatment on the healing of rat tibial fractures, the mechanical properties and radiological density of the uninjured contralateral tibia was assessed.

We describe the technique and results of medial submuscular plating of the femur in paediatric patients and discuss its indications and limitations. Specifically, the technique is used as part of a plate-after-lengthening strategy, where the period of external fixation is reduced and the plate introduced by avoiding direct contact with the lateral entry wounds of the external fixator pins. The technique emphasises that vastus medialis is interposed between the plate and the vascular structures.

A total of 16 patients (11 male and five female, mean age 9.6 years (5 to 17)), had medial submuscular plating of the femur. All underwent distraction osteogenesis of the femur with a mean lengthening of 4.99 cm (3.2 to 12) prior to plating. All patients achieved consolidation of the regenerate without deformity. The mean follow-up was 10.5 months (7 to 15) after plating for those with plates still in situ, and 16.3 months (1 to 39) for those who subsequently had their plates removed. None developed a deep infection. In two patients a proximal screw fractured without loss of alignment; one patient sustained a traumatic fracture six months after removal of the plate.

Placing the plate on the medial side is advantageous when the external fixator is present on the lateral side, and is biomechanically optimal in the presence of a femoral defect. We conclude that medial femoral submuscular plating is a useful technique for specific indications and can be performed safely with a prior understanding of the regional anatomy.

Cite this article: Bone Joint J 2014;96-B:137–42.

Congenital unilateral anterolateral tibial bowing in combination with a bifid ipsilateral great toe is a very rare deformity which resembles the anterolateral tibial bowing that occurs in association with congenital pseudarthrosis of the tibia. However, spontaneous resolution of the deformity without operative treatment and with a continuously straight fibula has been described in all previously reported cases. We report three additional cases and discuss the options for treatment. We suggest that this is a specific entity within the field of anterolateral bowing of the tibia and conclude that it has a much better prognosis than congenital pseudarthrosis of the tibia, although conservative treatment alone may not be sufficient.

Fracture repair occurs by two broad mechanisms: direct healing, and indirect healing with callus formation. The effects of bisphosphonates on fracture repair have been assessed only in models of indirect fracture healing.

A rodent model of rigid compression plate fixation of a standardised tibial osteotomy was used. Ten skeletally mature Sprague–Dawley rats received daily subcutaneous injections of 1 µg/kg ibandronate (IBAN) and ten control rats received saline (control). Three weeks later a tibial osteotomy was rigidly fixed with compression plating. Six weeks later the animals were killed. Fracture repair was assessed with mechanical testing, radiographs and histology.

The mean stress at failure in a four-point bending test was significantly lower in the IBAN group compared with controls (8.69 Nmm^-2 (sd 7.63) vs 24.65 Nmm^-2 (sd 6.15); p = 0.017). On contact radiographs of the extricated tibiae the mean bone density assessment at the osteotomy site was lower in the IBAN group than in controls (3.7 mmAl (sd 0.75) vs 4.6 mmAl (sd 0.57); p = 0.01). In addition, histological analysis revealed progression to fracture union in the controls but impaired fracture healing in the IBAN group, with predominantly cartilage-like and undifferentiated mesenchymal tissue (p = 0.007).

Bisphosphonate treatment in a therapeutic dose, as used for risk reduction in fragility fractures, had an inhibitory effect on direct fracture healing. We propose that bisphosphonate therapy not be commenced until after the fracture has united if the fracture has been rigidly fixed and is undergoing direct osteonal healing.

Cite this article: Bone Joint J 2013;95-B:1263–8.

Objectives

One commonly used rat fracture model for bone and mineral research is a closed mid-shaft femur fracture as described by Bonnarens in 1984. Initially, this model was believed to create very reproducible fractures. However, there have been frequent reports of comminution and varying rates of complication. Given the importance of precise anticipation of those characteristics in laboratory research, we aimed to precisely estimate the rate of comminution, its importance and its effect on the amount of soft callus created. Furthermore, we aimed to precisely report the rate of complications such as death and infection.

Massive endoprostheses using a cemented intramedullary stem are widely used to allow early resumption of activity after surgery for tumours. The survival of the prosthesis varies with the anatomical site, the type of prosthesis and the mode of fixation. Revision surgery is required in many cases because of aseptic loosening. Insertion of a second cemented endoprosthesis may be difficult because of the poor quality of the remaining bone, and loosening recurs quickly.

We describe a series of 14 patients with triplate fixation in difficult revision or joint-sparing tumour surgery with a minimum follow-up of four years. The triplate design incorporated well within a remodelled cortex to achieve osseomechanical integration with all patients regaining their original level of function within five months.

Our preliminary results suggest that this technique may provide an easy, biomechanically friendly alternative to insertion of a further device with an intramedullary stem, which has a shorter lifespan in revision or joint-sparing tumour surgery. A short segment of bone remaining after resection of a tumour will not accept an intramedullary stem, but may be soundly fixed using this method.

We present our experience of managing patients with iatropathic brachial plexus injury after delayed fixation of a fracture of the clavicle. It is a retrospective cohort study of patients treated at our peripheral nerve injury unit and a single illustrative case report. We identified 21 patients in whom a brachial plexus injury occurred as a direct consequence of fixation of a fracture of the clavicle between September 2000 and September 2011.

The predominant injury involved the C5/C6 nerves, upper trunk, lateral cord and the suprascapular nerve. In all patients, the injured nerve was found to be tethered to the under surface of the clavicle by scar tissue at the site of the fracture and was usually associated with pathognomonic neuropathic pain and paralysis.

Delayed fixation of a fracture of the clavicle, especially between two and four weeks after injury, can result in iatropathic brachial plexus injury. The risk can be reduced by thorough release of the tissues from the inferior surface of the clavicle before mobilisation of the fracture fragments. If features of nerve damage appear post-operatively urgent specialist referral is recommended.

Cite this article: Bone Joint J 2013;95-B:106–10.

This study was designed to test the hypothesis that the sensory innervation of bone might play an important role in sensing and responding to low-intensity pulsed ultrasound and explain its effect in promoting fracture healing. In 112 rats a standardised mid-shaft tibial fracture was created, supported with an intramedullary needle and divided into four groups of 28. These either had a sciatic neurectomy or a patellar tendon resection as control, and received the ultrasound or not as a sham treatment. Fracture union, callus mineralisation and remodelling were assessed using plain radiography, peripheral quantitative computed tomography and histomorphology.

Daily ultrasound treatment significantly increased the rate of union and the volumetric bone mineral density in the fracture callus in the neurally intact rats (p = 0.025), but this stimulating effect was absent in the rats with sciatic neurectomy. Histomorphology demonstrated faster maturation of the callus in the group treated with ultrasound when compared with the control group. The results supported the hypothesis that intact innervation plays an important role in allowing low-intensity pulsed ultrasound to promote fracture healing.

In an interdisciplinary project involving electronic engineers and clinicians, a telemetric system was developed to measure the bending load in a titanium internal femoral fixator. As this was a new device, the main question posed was: what clinically relevant information could be drawn from its application? As a first clinical investigation, 27 patients (24 men, three women) with a mean age of 38.4 years (19 to 66) with femoral nonunions were treated using the system. The mean duration of the nonunion was 15.4 months (5 to 69). The elasticity of the plate-callus system was measured telemetrically until union. Conventional radiographs and a CT scan at 12 weeks were performed routinely, and healing was staged according to the CT scans. All nonunions healed at a mean of 21.5 weeks (13 to 37). Well before any radiological signs of healing could be detected, a substantial decrease in elasticity was recorded. The relative elasticity decreased to 50% at a mean of 7.8 weeks (3.5 to 13) and to 10% at a mean of 19.3 weeks (4.5 to 37). At 12 weeks the mean relative elasticity was 28.1% (0% to 56%). The relative elasticity was significantly different between the different healing stages as determined by the CT scans.

Incorporating load measuring electronics into implants is a promising option for the assessment of bone healing. Future application might lead to a reduction in the need for exposure to ionising radiation to monitor fracture healing.

Objectives

To study the vascularity and bone metabolism of the femoral head/neck following hip resurfacing arthroplasty, and to use these results to compare the posterior and the trochanteric-flip approaches.

Most patients with a nightstick fracture of the ulna are treated conservatively. Various techniques of immobilisation or early mobilisation have been studied. We performed a systematic review of all published randomised controlled trials and observational studies that have assessed the outcome of these fractures following above- or below-elbow immobilisation, bracing and early mobilisation. We searched multiple electronic databases, related bibliographies and other studies. We included 27 studies comprising 1629 fractures in the final analysis. The data relating to the time to radiological union and the rates of delayed union and nonunion could be pooled and analysed statistically.

We found that early mobilisation produced the shortest radiological time to union (mean 8.0 weeks) and the lowest mean rate of nonunion (0.6%). Fractures treated with above- or below-elbow immobilisation and braces had longer mean radiological times to union (9.2 weeks, 9.2 weeks and 8.7 weeks, respectively) and higher mean rates of nonunion (3.8%, 2.1% and 0.8%, respectively). There was no statistically significant difference in the rate of non- or delayed union between those treated by early mobilisation and the three forms of immobilisation (p = 0.142 to p = 1.000, respectively). All the studies had significant biases, but until a robust randomised controlled trial is undertaken the best advice for the treatment of undisplaced or partially displaced nightstick fractures appears to be early mobilisation, with a removable forearm support for comfort as required.

Cite this article: Bone Joint J 2013;95-B:952–9.

Objectives

Small animal models of fracture repair primarily investigate indirect fracture healing via external callus formation. We present the first described rat model of direct fracture healing.

Pathological fractures in children can occur as a result of a variety of conditions, ranging from metabolic diseases and infection to tumours. Fractures through benign and malignant bone tumours should be recognised and managed appropriately by the treating orthopaedic surgeon. The most common benign bone tumours that cause pathological fractures in children are unicameral bone cysts, aneurysmal bone cysts, non-ossifying fibromas and fibrous dysplasia. Although pathological fractures through a primary bone malignancy are rare, these should be recognised quickly in order to achieve better outcomes. A thorough history, physical examination and review of plain radiographs are crucial to determine the cause and guide treatment. In most benign cases the fracture will heal and the lesion can be addressed at the time of the fracture, or after the fracture is healed. A step-wise and multidisciplinary approach is necessary in caring for paediatric patients with malignancies. Pathological fractures do not have to be treated by amputation; these fractures can heal and limb salvage can be performed when indicated.

Platelet-derived growth factor (PDGF) is known to stimulate osteoblast or osteoprogenitor cell activity. We investigated the effect of locally applied PDGF from poly-d,l-lactide (PDLLA)-coated implants on fracture healing in a rat model. A closed fracture of the right tibia of four-month-old Sprague-Dawley rats (n = 40) was stabilised with implants coated with a biodegradable PDLLA versus implants coated with PDLLA and PDGF. Radiographs were taken throughout the study, and a marker of DNA activity, bromodeoxyuridine (BrdU), was injected before the rats were killed at three, seven and ten days. The radiographs showed consolidation of the callus in the PDGF-treated group compared with the control group at all three time points. In the PDGF-treated group, immunohistochemical staining of BrdU showed that the distribution of proliferating cells in all cellular events was higher after ten days compared with that at three and seven days.

These results indicate that local application of PDGF from biodegradable PDLLA-coated implants significantly accelerates fracture healing in experimental animals. Further development may help fracture healing in the clinical situation.

Objectives

This study aims to assess the correlation of CT-based structural rigidity analysis with mechanically determined axial rigidity in normal and metabolically diseased rat bone.

This review is aimed at clinicians appraising preclinical trauma studies and researchers investigating compromised bone healing or novel treatments for fractures. It categorises the clinical scenarios of poor healing of fractures and attempts to match them with the appropriate animal models in the literature.

We performed an extensive literature search of animal models of long bone fracture repair/nonunion and grouped the resulting studies according to the clinical scenario they were attempting to reflect; we then scrutinised them for their reliability and accuracy in reproducing that clinical scenario.

Models for normal fracture repair (primary and secondary), delayed union, nonunion (atrophic and hypertrophic), segmental defects and fractures at risk of impaired healing were identified. Their accuracy in reflecting the clinical scenario ranged greatly and the reliability of reproducing the scenario ranged from 100% to 40%.

It is vital to know the limitations and success of each model when considering its application.

We present two children with massive defects of the tibia and an associated active infection who were treated by medial transport of the fibula using the Ilizarov device. The first child had chronic discharging osteomyelitis which affected the whole tibial shaft. The second had sustained bilateral grade-IIIB open tibial fractures in a motor-car accident. The first child was followed up for three years and the second for two years. Both achieved solid union between the proximal and distal stumps of the tibia and the fibula, with hypertrophy of the fibula. The first child had a normal range of movement at the knee, ankle and foot but there was shortening of 1.5 cm. The second had persistent anterior angulation at the proximal tibiofibular junction and the ankle was stiff in equinus.

We describe a patient with insufficient bone regeneration of the tibia after bone transport over an intramedullary nail, in whom union was ultimately achieved after exchange nailing and intramedullary application of rh-bone morphogenetic protein-7 at the site of distraction.

This randomised study compared outcomes in patients with displaced fractures of the clavicle treated by open reduction and fixation by a reconstruction plate which was placed either superiorly or three-dimensionally. Between 2003 and 2006, 133 consecutive patients with a mean age of 44.2 years (18 to 60) with displaced midshaft fractures of the clavicle were allocated randomly to a three-dimensional (3D) (67 patients) or superior group (66). Outcome measures included the peri-operative outcome index, delayed union, revision surgery and symptoms beyond 16 weeks. CT was used to reconstruct an image of each affected clavicle and Photoshop 7.0 software employed to calculate the percentage of the clavicular cortical area in the sagittal plane. The patients were reviewed clinically and radiographically at four and 12 months after the operation. The superior plate group had a higher rate of delayed union and had more symptomatic patients than the 3D group (p < 0.05). The percentage comparisons of cortical bone area showed that cortical bone in the superior distal segment is thicker than in the inferior segment, it is also thicker in the anterior mid-section than in the posterior (p < 0.05).

If fixation of midshaft fractures of the clavicle with a plate is indicated, a 3D reconstruction plate is better than one placed superiorly, because it is consistent with the stress distribution and shape of the clavicle.