Study Design. Prospective cohort study. Objective. To assess the safety and efficacy of an intra-operative gamma probe in the surgical treatment of osteoid osteomas and osteoblastomas arising from the spine. Summary of background data. Spinal osteoid osteomas and osteoblastomas are difficult to localise and may present adjacent to neural structures. Complete surgical excision of the nidus is a pre-requisite for curative resection. Methods. All patients with a presumptive diagnosis of osteoid osteoma or osteoblastoma were investigated with plain radiography, computed tomography, magnetic resonance imaging and a technitium bone scan. Nine patients underwent surgical excision. 600 MBq of 99m technitium HMDP was administered intravenously three hours prior to surgery. A sterile cadmium telluride detector connected to a digital counter/ratemeter was used to detect gamma radiation emitted by the tumour intra-operatively to assist with localisation and confirmation of complete excision. Results. Between October 1995 and September 2006, nine patients required surgical excision for seven osteoid osteomas and two osteoblastomas arising from the spine. All patients were between the ages of 9-31 years and presented with back or neck pain. All tumours involved the posterior elements of the spine. Three patients had previous failed treatment including CT-guided radiofrequency ablation and surgical excision. In all cases the counts per second (cps) dropped significantly following excision. Histological examination confirmed complete excision in all cases. The mean follow-up was 4.5 years (range 0.5-11 years). All patients reported disappearance of the characteristic pre-operative pain. Conclusions. The use of an intra-operative gamma probe helps to localise and confirm complete excision of osteoid osteoma and osteoblastoma arising from the spine. Accurate localisation results in safe excision with maximal conservation of surrounding normal bone, whilst minimising operative time, blood loss, hospital stay and risk of recurrence

Osteoid osteoma is a benign bone-forming lesion, characterized by its small size, its clearly demarcated outline and by the usual presence of a surrounding zone of reactive bone formation. It often poses a diagnostic challenge due to its ambiguous presentation. The aetiology of osteoid osteoma is poorly understood. The previous suggestion that osteoid osteoma was not associated with trauma or infection has been challenged by more recent literature raising the possibility that it could be a reactive or healing response or a phenomenon associated with the revascularisation process. This case report describes an unusual presentation of a post-traumatic osteoid osteoma. Two years following a diaphyseal, spiral tibial fracture treated nonoperatively, the patient developed new pain at the previous fracture site. The pain was constant, relieved by non-steroidal analgesia and not associated with systemic upset. It was initially attributed to other more likely diagnoses such as osteomyelitis and neuropathic pain. Multiple investigations and interventions were undertaken prior to the definitive diagnosis being obtained by surgical excision of the lesion and histological studies five years after the injury and three years following the initiation of the discomfort. In both English and foreign language literature there are only seven case reports that document osteoid osteoma following fracture, these are predominantly in the lower limb with no predominance to operative or nonoperative management. This case report should raise the index of clinical suspicion of osteoid osteoma occurring post fracture

Aim. This study describes the histologic changes seen with a gentamicin-eluting synthetic bone graft substitute (BGS)(1) in managing bone defects after resection of chronic osteomyelitis (cOM). Method. 154 patients with mean follow-up of 21.8 months (12–56) underwent treatment of cOM with an antibiotic-loaded BGS for defect filling. Nine patients had subsequent surgery, not related to infection recurrence, allowing biopsy of the implanted material. These biopsies were harvested between 19 days and two years after implantation, allowing a description of the material's remodelling over time. Samples were fixed in formalin and stained with haematoxylin-eosin. Immunohistochemistry, using an indirect immunoperoxidase technique, identified the osteocyte markers Dentine Matrix Protein-1 (DMP-1) and Podoplanin, the macrophage/osteoclast marker CD68, and the macrophage marker CD14. Results. The material was actively remodelled and was osteoconductive. There was evidence of osteoblast recruitment, leading to osteoid and intramembranous formation of woven and lamellar bone on the material's surface, seen most prominently in areas of well-vascularised fibrous tissue. Osteocytes in woven bone expressed the markers DMP-1 and Podoplanin. No cartilage or endochondral ossification was seen. There was a prominent (CD14+/ CD68+) macrophage response to the BSG and macrophages within reparative cellular and collagenous fibrous tissue. In biopsies taken between 4 and 5 months, there were bone trabeculae containing BGS of mainly woven but partly lamellar type. Giant cells on the surface of newly formed mineralised osteoid and woven bone expressed an osteoclast phenotype (CD68+/CD14-). In later biopsies (up to 2 years), larger bone trabeculae were seen more frequently within well-vascularised reparative fibrous tissue. The BGS was replaced with predominantly lamellar bone. One biopsy was taken from an extraosseous leak of BGS into the soft tissues, behind the distal tibia. The histology showed a heavy macrophage infiltrate, but notably no evidence of osteoid or bone formation in the material or surrounding soft tissues. Conclusion. There was clear evidence that this BGS is osteoconductive with first osteoid then woven and lamellar bone being formed. DMP-1 and podoplanin-expressing osteocytes present in woven and lamellar bone demonstrate osteoclastic bone remodelling. Increased lamellar bone was noted in later samples and bone formation was most prominent in well-vascularised areas. There was on-going remodelling of the material beyond one year. The BGS did not ossify in soft tissue. The hydroxyapatite scaffold in this material is probably responsible for its high osteoconductivity and potential to be transformed into bone

Aim. To make an inoculum for induction of Implant-Associated Osteomyelitis (IAO) in pigs based on bacterial aggregates resembling those found on the human skin, i.e. aggregates of 5–15 µm with low metabolic activity. The aggregates were evaluated and compared to a standard planktonic bacterial inoculum. Method. The porcine Staphylococcus aureus strain S54F9 was cultured in Tryptone Soya Broth for seven days. Subsequently, the culture was filtered through cell strainers with pore sizes of 15 µm and 5 µm, respectively. The fraction of 5–15 µm aggregates in the top of the 5 µm filter was collected as the aggregate-inoculum. The separation of aggregates into different size fractions was evaluated by light microscopy. The metabolism of the aggregate-inoculum and a standard overnight planktonic inoculum was evaluated with isothermal microcalorimetry. In total, six female minipigs were allocated into three groups (n=2), receiving different inoculums. Group A: overnight planktonic inoculum; 10. 4. CFU S. aureus (S54F9), Group B: seven days old 5–15 µm aggregate-inoculum; 10. 4. CFU S. aureus (S54F9), Group C: saline. All inoculums were placed in a pre-drilled implant cavity in the right tibia of the pig and a sterile stainless-steel implant was inserted. The pigs were euthanized seven days after surgery. Postmortem macroscopic pathology, microbiology, computed tomography and histopathology were performed. Results. The separation of aggregates into different size fractions was done successfully by the filtering method. Isothermal microcalorimetry showed, a delayed Time-to-peak metabolic activity of the aggregate-inoculum compared to the planktonic inoculum. S. aureus was isolated from subcutis, bone and implants from all animals in groups A and B. Both group A animals showed osteomyelitis at gross inspection with suppuration and sequestration, while groups B and C animals had no macroscopic lesions. From CT scans, both group A animals also showed positive signs of osteomyelitis, i.e., osteolysis, while only one animal in group B did, and none in group C. Histopathological examination of the bones showed more extensive inflammation in group A animals compared to those in group B, which showed more osteoid formation. Conclusions. Formation and separation of low metabolism bacterial aggregates into different size fractions was possible. The aggregates can be used as inoculum in the porcine IAO model, with microbiological re-isolation from both implants and tissue. Furthermore, the aggregates caused a less aggressive IAO, than the planktonic counterparts. Using aggregated bacteria as inoculum appears to be more relevant to the clinical situation of infecting bacteria

Bone fracture healing is regulated by a series of complex physicochemical and biochemical processes. One of these processes is bone mineralisation, which is vital for normal bone development, its biomechanical competence and fracture healing. Phosphatase, orphan 1 (PHOSPHO1), a bone-specific phosphatase, has been shown to be involved in the mineralisation of the extracellular matrix in bone. It can hydrolyse phosphoethanolamine and phosphocholine to generate inorganic phosphate, which is crucial for bone mineralisation. Phospho1−/− mice show hypomineralised bone and spontaneous fractures. All these data led to the hypothesis that PHOSPHO1 is essential for bone mineralisation and its structural integrity. However, no study to our knowledge has shown the effects of PHOSPHO1 on bone fracture healing. In this study, we examined how PHOSPHO1-deficiency might affect the healing and quality of the fractured bones in Phospho1−/− mice. We performed rodded immobilised fracture surgery on the right tibia of control wild type (WT) and Phospho1−/− mice (n=16 for each group) at eight weeks of age. Bone was left to heal for four weeks and then the mice were euthanised and their tibias were analysed using Faxitron X-ray analyses, microCT, histology and histomorphometry and three-point bending test. Our microCT and X-ray analyses revealed that the appearance of the callus and several static parameters of bone remodeling at the fracture sites were markedly different in WT and Phospho1−/− mice. We observed a significant increase of BS/BV, BS/TV and trabecular number and decrease in trabecular thickness and separation in Phospho1−/− callus in comparison to the WT callus. These observations were further confirmed by histomorphometry. The increased bone mass at the fracture sites of Phospho1−/− mice appears to be caused by increased bone formation as there is a significant increase of osteoblast number, while osteoclast numbers remained unchanged. There was a marked increase of osteoid volume over bone volume (OV/BV) in the Phospho−/− callus. Interestingly, the amount of osteoid was markedly higher at the fracture sites than that of normal trabecular bones. The three-point bending test showed that Phospho 1 −/− fractured bone had more of an elastic characteristics than the WT bone as they underwent more of a plastic deformity before the breakage point compare to the WT. Our work suggests that PHOSPHO1 plays an integral role during bone fracture repair. PHOSPHO1 can be an interesting target to improve the fracture healing process

Introduction. Bony tumours of the foot account for approximately 3% of all osseous tumours. However, literature regarding os calcis and talar tumours comprises individual case reports, short case series or literature reviews with no recent large series. Methods. We retrospectively reviewed the medical notes and imaging for all patients with calcaneal or talar tumours recorded in the Scottish Bone Tumour Registry since the 1940's. Demographics, presentation, investigation, histology, management and outcome were reviewed. Results. 34 calcaneal tumours and 23 talar tumours were identified. Calcaneal tumours. 2:1 male prevalence, mean age at presentation 30, average length of symptoms 9 months. 4 cases presented with pathological fracture. 21 benign tumours including 6 unicameral bone cysts, 3 chondroblastoma, and a wide variety of individual lesions. 13 malignant tumours comprising 6 osteosarcoma, 5 chondrosarcoma and 2 Ewings sarcoma. Talar Tumours. male to female ratio 3:1, mean age at presentation 28, average length of symptoms 5 months. 20 benign cases including 7 osteoid osteoma, 4 chondroblastoma, and several individual lesions. 3 malignant lesions comprising 2 chondrosarcoma, 1 osteosarcoma. Discussion. Tumours of the hindfoot frequently are delayed in diagnosis due to their rarity and lack of clinician familiarity. They are more common in men, especially talar tumours, which are most commonly benign osteoid osteoma or chondroblastoma. Calcaneal tumours have 1 in 3 risk of malignancy and cover a wider variety of lesions. Osteosarcoma of the foot tends to present later than other anatomical regions. Outcome is dependant on early diagnosis, timely surgery and most importantly neo-adjuvant chemotherapy. Diagnosis is often made on plain radiograph but MRI is the gold standard. Despite their rarity clinicians should maintain a high index of suspicion as accurate and timely diagnosis is important to management and outcome

Purpose. Maintenance of vertebral mechanical stability is of paramount importance to prevent pathologic fractures and resultant neurologic compromise in individuals with spinal metastases. Current non-surgical treatments for vertebral metastases (i.e. chemotherapy, bisphophonates (BP) and radiation) yield variable responses in the tumour and surrounding bone. Photodynamic therapy (PDT) is a novel, minimally-invasive technology that utilizes a drug activated by light at a specific non-thermal wavelength to locally destroy tumour cells. Previously, we observed that PDT can ablate cancer cells within bone and yield short-term (1-week) improvements in vertebral architecture and biomechanical strength, particularly when combined with BP therapy. This study aims to evaluate the effects of PDT in vertebral bone over a longer (6-week) time period, alone and combined with previous BP treatment, to determine if improvements in skeletal architecture and strength are maintained. Method. Fourty healthy rnu/rnu rats were randomly assigned to four treatment groups: (i) untreated control, (ii) BP only, (iii) PDT only and (iv) PDT following BP. BP treatments were administered on day 0 via subcutaneous injection of zoledronic acid. PDT was administered on day 7 via an intravenous injection of BPD-MA photosensitizer. A flat-cut optical fiber was inserted percutaneously adjacent to lumbar vertebra L2. After a 15-minute drug-light interval, 75J of light energy was delivered from a 690nm laser. Six weeks later, animals were euthanized. Structural properties of excised L2 vertebral bodies were quantified through semi-automated analysis of micro-CT images. In of the specimens, mechanical properties were evaluated by loading the L2 vertebral body to failure in axial compression. The remaining L2 vertebrae were analyzed for morphology, osteoid formation and osteoclast activity using histological methods. Results. Combined PDT+BP treatment yielded the largest increases in bone volume fraction (31%), trabecular thickness (45%) and vBMD (37%) and decreases in trabecular number (14%) and separation (26%) compared to untreated controls (n=10, all p<0.05). The cortical shell mass fraction was significantly lower than that of controls (24%) indicating increases in bone structure were primarily due to trabecular changes. Mechanically, PDT+BP treatment demonstrated a trend towards an increase in ultimate force compared to controls (n=5, p=0.176). BP-only and PDT-only treatments demonstrated similar trends to the combined treatment, but with a lower magnitude of effect. Qualitatively, histological analysis suggested more osteoid formation in groups receiving PDT, and a higher proportion of bone in BP-treated groups. Conclusion. PDT has a sustained positive effect on the mechanical and structural integrity of bone, particularly in combination with BP treatment. By ablating tumour tissue and strengthening bone, combined PDT+BP treatment presents as an attractive adjuvant minimally-invasive therapy for spinal metastasis

Aim. This study describes and correlates the radiographic and histologic changes which develop in a Gentamicin-eluting synthetic bone graft substitute. *. in the management of bone defects after resection of chronic osteomyelitis (COM). Method. 100 patients with COM were treated with a single stage procedure, including management of the dead space with insertion of a Gentamicin-eluting synthetic bone graft substitute. *. Radiographs of 73 patients with a follow-up of at least 12 months (range 12–33 months) were available for review. Bone defects were diaphyseal in 32, metaphyseal in 34 and combined in 7 patients. In 3 patients, radiographs were not of sufficient quality to allow analysis. Five patients had subsequent surgery, not related to recurrence of infection, which allowed biopsy of the implanted material. These biopsies were harvested between 12 days and 9 months after implantation. Tissue was fixed in formalin and stained with haematoxylin-eosin and immunohistochemically for bone matrix markers. Results. Radiographic: 31 of 34 diaphyseal implantations (91%) demonstrated remodelling of the biocomposite, gradually over many months, producing new bone and resulting in a “normal post-osteomyelitic” appearance. In metaphyseal implantations, new bone filled two-thirds or more of the defect in 55% of cases, one to two-thirds was filled in 31% and one third or less was filled in 14%. 22% of patients exhibited radiographic signs of dissolution and remodelling which are specific to this material. The ‘Halo’ sign of peripheral zone remodelling, the ‘Marble’ sign of dissolution and the ‘Puddle’ sign of distal migration can be described. Histologic: Histological assessment revealed early active remodelling of the biocomposite. The material was osteoconductive with accumulation of osteoblasts and osteoid and woven bone formation on the surface of the Gentamicin-eluting synthetic bone graft substitute. *. separated by fibrous tissue at the edge of the defect beneath reactive viable host bone. Fibrous tissue contained a heavy macrophage infiltrate and the newly formed matrix contained the specific bone proteins, dentine matrix protein-1 and podoplanin. There was limited evidence of remodelling into lamellar bone at 20 weeks after implantation. Conclusions. The Gentamicin-eluting synthetic bone graft substitute. *. exhibits a specific pattern of radiographic change over many months after implantation. The resolution of the bone defect would appear to be due to bone formation, as seen in the histologic and immunohistochemical analysis

Structural bone allografts are a viable option in reconstructing massive bone defects in patients following musculoskeletal (MSK) tumour resection and revision hip/knee replacements. To decrease infection risk, bone allografts are often sterilised with gamma-irradiation, which consequently degrades the bone collagen connectivity and makes the bone brittle. Clinically, irradiated bone allografts fracture at rates twice that of fresh non-irradiated allografts. Our lab has developed a method that protects the bone collagen connectivity through ribose pre-treatment while still undergoing gamma-irradiation. Biomechanical testing of bone pretreated with our method provided 60–70% protection of toughness and 100% protection of strength otherwise lost with conventional irradiation. This study aimed to determine if the ribose-treated bone allografts are biocompatible with host bone. The New Zealand White rabbit (NZWr) radius segmental defect model was used, in which 15-mm critically-sized defects were created. Bone allografts were first harvested from the radial diaphysis of donor female NZWr, and treated to create 3 graft types: C=untreated controls, I=conventionally-irradiated (33 kGy), R=our ribose pretreated + irradiation method. Recipient female NZWr (n=24) were then evenly randomised into the 3 graft groups. Allografts were surgically fixed with a 0.8-mm Kirschner wire. Post-operative X-rays were taken at 2, 6, and 12 weeks, with bony healing assessed by a blinded MSK radiologist using an established radiographic scoring system. The reconstructed radii were retrieved at 12 weeks and analysed using bone histomorphometry and microCT. Kruskal-Wallis and Mann-Whitney tests were utilised to compare groups, with statistical significance when p<0.05. Radiographic analysis revealed no differences in periosteal reaction and degree of osteotomy site union between the groups at any time point. Less cortical remodeling was observed in R and I grafts compared to untreated controls at 6 weeks (p=0.004), but was no longer evident by 12 weeks. Radiographic union was achieved in all groups by 12 weeks. Histologic and microCT analysis further confirmed union at the graft-host bone interface, with the presence of mineralising callus and osteoid. Histomorphometry also showed the bridging external callus originated from host bone periosteum and a distinct cement line between allograft and host bone was present at the union site. Previous studies have shown that the presence of non-enzymatic glycation end products in bone can impair fracture healing. However, these studies investigated bony healing in the setting of diabetic states. Our findings showed that under normal conditions, ribose pretreated grafts healed at rates similar to controls via mechanisms also seen in retrieved human allografts clinically in use. These findings that grafts pretreated with our method are biocompatible with host bone in the rabbit help to further advance this technology for clinical trials

Introduction. The femoral neck in children is a common site for bone lesions. The majority are benign. However these lesions can cause diagnostic problems. Aim. To present a spectrum of chronic lesions of the femoral neck in children and emphasize the importance of tissue diagnosis. Materials and methods. Thirty two children with isolated chronic bone lesions in the femoral neck treated between 1994 and 2013were retrospectively reviewed. The ages ranged between 1–13 years. Clinical features were pain and limp. Routine blood tests, x-rays and CT scans were done in all and MRI scans in 5 cases. All diagnoses were confirmed histologically. Results. Three radiological patterns were seen: lucent or cystic in 22, infiltrative (permeative)in 2, and localized densities with nidus in 8 cases. Histologically the lesions were subacute osteomyelitis in 4, tuberculosis in 9, simple bone cyst in 7, osteoid osteoma in 7, chondroblastoma in 1, monostotic fibrous dysplasia in 2 and eosinophilic granuloma in 2 cases. Two tuberculous lesions were associated with subluxation of the hip and involvement of the head occurred in 2 others. Treatment and outcome. All lesions were curetted. Bone grafting was done in 10. Immobilisation was by internal fixation in 1, traction in 2 and spica cast in 29 cases. Follow up was 9 months to 11 years. Healing occurred in the majority. Recurrence occurred in 2 cases. Coxa vara developed in 6, and growth disturbance with shortening in 9 patients. Discussion. Femoral neck lesions are mainly benign, present diagnostic difficulty and treatment is challenging. There are problems with immobilization and of purchase with fixation devices due to poor bone stock on the neck of femur. The spica cast is a reliable method of immobilization in children under 10years. Growth disturbance and coxa vara can result after healing. CT scan is useful in assessing the architecture of the bone. NO DISCLOSURES

Purpose of the study. To review the primary bone tumours of the spine treated at our unit. Description of methods. Retrospective review of folders and x-rays of all the patients with primary bone tumours of the spine treated at our unit between 2005 and 2012. All haematological tumours were excluded. Summary of results. We treated 15 cases during this period. The median age at presentation was 36 years (8–65). There was a significant delay from onset of symptoms to diagnosis in most cases (median 7 months). Histological diagnoses included:. -Benign tumours.  Active. Hemangioma. 3. Osteoid osteoma. 1. Eosinophilic granuloma. 1.  Aggressive. Osteoblastoma. 1. Giant cell tumours. 2. Aneurysmal bone cysts. 4. -Malignant tumours.  Osteosarcomas. 2.  Leiomyosarcoma of bone. 1. A variety of definitive surgical methods were utilised. Seven patients had a debulking or intralesional resection of the tumour. Eight patients had an attempted marginal excision. This was achieved through anterior surgery only in 1 case, posterior only surgery in 6 cases and combination anterior and posterior surgery in 8 cases. The anterior and posterior surgery was performed in a single sitting in 5 cases and in a staged fashion in 3 cases. Adjuvant radiotherapy and chemotherapy were used where indicated. Three cases presented with significant neurological impairment. Of these 2 made a significant recovery. There were no cases of neurological deterioration following surgery. All 3 patients with malignant tumours died in the follow up period. We had 1 case of hardware failure due to chronic sepsis. Conclusion. Primary bone tumours of the spine are associated with a significant delay in diagnosis. Surgical treatment options and adjuvant therapy should be tailor made for each case depending on the diagnosis. Acceptable results with minimal complications can be achieved with this approach

Introduction:. 20 cases of bone defect have been treated by the induced membrane technique avoiding allograft, microsurgery and amputation. Material and Methods:. 9 cases of long bone defect (humerus and forearm) and 11 cases of bone defect at the hand have been included in this multicentre prospective study (3 centers). The aetiology in 11 cases was trauma, 7 cases were septic nonunions and 2 cases followed tumors. In the hand the bone loss was at least one phalanx, and for long bones the mean defect was 5 cm (3–11). All cases were treated by the induced membrane technique which consists in stable fixation, flap if necessary and in filling the void created by the bone defect by a cement spacer (PMMA). This technique needs a second stage procedure at the 2. nd. month where the cement is removed and the void is filled by cancellous bone. The key point of this induced membrane technique is to respect the foreign body membrane which appeared around the cement spacer and which creates a biologic chamber for the second procedure. Bone union was evaluated prospectively in each case by a surgeon not involved in the treatment, by X-ray and CT scan. Failure was defined as a nonunion at 1 year, or an uncontrolled sepsis at 1 month. Results:. 3 cases failed to achieve bone union, 2 in the hand and 1 in a long bone. No septic complications occurred and all septic cases healed. In 14 cases bone union was achieved with a delay of 5 months (1, 5–12). 2 biopsies allowed us to prove that osteoid tissue was created by the technique. At hand level all fingers have included. At shoulder and elbow level, function reached 75% of motion of the contralateral side. Discussion:. Masquelet first reported 35 cases of large bone defect of tibia nonunion treated by the induced membrane technique which allow filling a bone defect with cancellous bone alone. The cement spacer induces a foreign body membrane (neo periosteum) which constitute a biological chamber. Animal models showed the properties of the membrane: secretion of growths factors (VEGF, TGFbéta1, BMP2) and osteoinductive activitie of the cells. Conclusion:. This technique is useful in emergency or in septic condition where a bone defect cannot be solved by shortening. The technique avoids the use of microsurgery and the limit is the quantity of available cancellous bone

Aim. This study aims to determine the value of MRI in children with hip pain which remained unexplained following routine investigations including ultrasound examination. Materials and methods. Retrospective review of clinical notes and MRI findings in all children who received and MRI scan for undiagnosed hip pain over three years. Results. Fifty five children underwent an MRI scan of their hips for unexplained hip pain. 29 were male and 26 were female. The mean age was 10.9 years. The MR study provided a diagnosis in 22 children (40%), and was normal in 33 children (60%). Five cases were considered to be due to transient synovitis. Three children were diagnosed as osteoid osteoma. Two children were were found to have trochanteric bursitis. Two children were shown to have muscle trauma (one child with adductor trauma and one child with piriformis trauma). Two children were diagnosed with non-specific bone oedema. The remaining eight children were diagnosed with Perthes' disease, haemarthrosis, sacro-iliac infection, synovitis secondary to juvenile idiopathic arthritis, ischio-pubic osteochondrosis, acetabular dysplasia, Klippel-Trenaunay syndrome and resolution of an eosinophilic granuloma. None of the children discharged following a normal scan has subsequently presented with hip disease. Conclusions. It is concluded that MRI is useful in the diagnosis of hip pain in children in whom routine investigation has not yielded an answer

Introduction. Titanium (Ti) alloys are used as porous bone ingrowth materials on non-cemented knee arthroplasty tibial tray implants. Nano-surface mechanism that increase the osseointegration rate between Ti alloys, and surrounding tissue has been recognized to improve the interface to ultimately allow patients to weight bear on non-cemented arthroplasty implants sooner. Bioactive TiO. 2. nanotube arrays has been shown to accelerate osseointegration. Ideally, these surfaces would both increase the adhesion of bone to the implant and help to reduction of infection to substitute for antibiotic bone cement. This study examines a combination treatment of both TiO. 2. nanotubes combined with silver nano-deposition, that simultaneously enhances osseointegration while improving infection resistance, by testing ex vivo implantation stability in an equine cadaver bone followed by in vitro and in vivo analysis to understand the biocompatibility and early stage osseointegration. Methods. 100nm diameter and 300nm length TiO. 2. nanotubes were formed on a CP titanium surface using anodization method at 20V for 45mins using 1% HF electrolyte. Silver deposition on TiO. 2. nanotubes were performed using 0.1M AgNO. 3. solution at 3V for 45s. Figure 1 shows SEM images showing (a) TiO. 2. nanotubes of 300nm length and (b) nanotubes with silver coating). Ti anodized samples with and without silver nanotubes implanted into an equine cadaver bone in an ex vivo manner to study the stability of nanotubes and the adherence of silver deposition. Silver release study was performed for a period of 14 days in a similar ex vivo manner. Dimensions for implantation samples: 2.5 mm diam. × 15 mm. For cell culture, circular disc samples 12.5mm in diameter and 3 mm in thickness were used to study the bone cell-material interactions using human fetal osteoblast (hFOB) cells. To evaluate the cell proliferation, MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide) assay was used. The in vitro cell-materials interaction study was performed for a period of 4 and 7 days. In vivo study was performed using rat distal femur model for a period of 12 weeks with dense Ti samples as control (Sample dimensions: 3mm diam. × 5mm). At the end of 12 weeks, the samples were analyzed for early stage osseointegration using histological analysis and SEM imaging. Results. No significant changes in the morphology of nanotubes was observed due to the implantation process which signifies the damage resistance these nanotubes can endure during implantation and explantation. Figure 2 shows SEM images of (a) & (b) nanotubes without silver coating before and after implantation and (c) & (d) nanotubes with silver coating before and after implantation respectively. Silver nanocoatings can be observed after implantation which shows the adherence of the antimicrobial nano-coating on the surface of nanotubes. Cumulative release profiles of silver ions after 14 days showed the total release was in the effective range for antimicrobial characteristics and was well below the toxic limit specified for human cells (10 ppm) Figure 3(a) shows cumulative release profile of silver after 14 days. MTT assay and SEM images show good cell proliferation, antimicrobial effect, and increase in cell density after 7 days for samples with nanotubes and silver with no cytotoxic effects and good cell attachment on the samples as shown in Figure 3(b) MTT assay results showing cell densities after 4 and 7 days and Figure 3(c) SEM images showing cell attachment after 4 and 7 days on samples. Histological analysis and SEM images showed osteoid formation around the implant with improved bonding towards the implant and bone showing signs of early stage osseointegration. Figure 4 shows histological and SEM images showing bonding between bone and implant surface for respective samples after 12 weeks. Conclusions. Mechanically stableTiO. 2. nanotubes with strongly adhered antimicrobial silver coating were grown on the surface of titanium which were biocompatible and non-toxic. In vitro and in vivo tests indicate improved cell-materials interaction with signs of early stage osseointegration. This nano-surface treatment shows promise towards simultaneously improving early stage osseointegration and providing an infection barrier on bone ingrowth materials

Purpose. The hip region is the second most common site for tuberculosis following the spine in children. The aim is to describe the variable radiological patterns of presentation and their resemblance to pyogenic infection, tumours and other benign conditions of bone in children. Methods. The clinical and radiological records of 29 children aged 10 months–13 years with confirmed tuberculosis of the hip region seen between 1990 and 2011 were reviewed retrospectively. Clinical features were pain, limp and flexion, adduction contractures. Abscesses and sinuses were seen in 4 children. The ESR ranged between 7–110 mm/hr. Mantoux was positive in 20 children. All cases were histologically confirmed. Treatment involved biopsy, currettage of bone defects, limited synovectomy and adductor tenotomy. Patients were immobilised for 4 weeks on a spica cast or traction. Antituberculous treatment was administered for 9–12 months. Results. Radiologically 9 lesions were extra-articular and 20 involved the joint synovium and articular surface. Extra-articular lesions were seen in the pubis, greater and lesser trochanter, ilium, proximal femur and peri-acetabular regions. Intra-articular lesions were seen in the femoral head, neck and acetabulum. Dislocations and subluxations occurred in 8 patients; various lesions mimicked pyogenic arthritis, idiopathic chondrolysis, chondrobastoma, Perthes disease, eosinophilic granuloma and osteoid osteoma. Follow up ranged between 8 months and 5 years. Good range of movement was seen in 20 children. Nine children had flexion adduction contractures, four of these had ankylosed hips and five required abduction extension osteotomies. Other changes seen were coxa vara (2) coxa magna (1) and avascular necrosis (3). Conclusion. The variable radiological picture of tuberculosis of the hip region can mimic various osteoarticular conditions in children. Biopsy is essential and should be taken from the bony lesion and not the synovium alone. NO DISCLOSURES

Osteocytes (OCY) are the end stage differentiation cells of the osteoblast lineage, and are incorporated in the bone matrix during bone formation. In doing so, OCY control the mineralisation of osteoid. OCY form a dense inter-connected network of cell bodies and cell processes throughout the mineralised matrix of bone. OCY viability depends on interstitial fluid flow along the OCY canaliculi, driven by pulsatile blood flow and loading of the skeleton. Maintenance of the density and viability of OCY are essential for bone health because OCY perform many important functions in bone. Firstly, OCY appear to initiate bone repair of bone microdamage. Secondly, OCY are almost certainly the cells, which initiate new bone formation in response to increased loading of bone. Thirdly, OCY are able to regulate the amount of new bone formation in bone remodelling cycles, at least in part by the production of a molecule called sclerostin (SCL). Mutations in the SCL gene, or deletion of the SCL gene in transgenic mice, are associated with particularly dense, fracture resistant bones. This information has led to development of anti-SCL antibodies as a potential anabolic therapy for bones. Bone loss in ovariectomised aged rats was shown recently to be reversed by treatment with neutralising SCL antibodies. There is also some data to suggest that these antibodies may promote fracture healing. Reduced OCY viability and/or density have been reported in association with osteoporotic fracture. OCY viability seems to be dependent on skeletal loading, adequate skeletal blood flow and estrogen in females. OCY viability is adversely affected by hypoxia, unloading of the skeleton and pharmacobiology, such as chronic exposure to glucocorticoids. Both micro and macro-fractures result in disruption of the OCY network, as do procedures such as drilling and cutting of bone. Because of the important roles of OCY in bone, new approaches to bone health may require the identification of agents to protect these cells from harmful influences in disease and ageing

Peri-prosthetic osteolysis and subsequent aseptic loosening is the most common reason for revising total hip replacements. Wear particles originating from the prosthetic components interact with multiple cell types in the peri-prosthetic region resulting in an inflammatory process that ultimately leads to peri-prosthetic bone loss. These cells include macrophages, osteoclasts, osteoblasts and fibroblasts. The majority of research in peri-prosthetic osteolysis has concentrated on the role played by osteoclasts and macrophages. The purpose of this review is to assess the role of the osteoblast in peri-prosthetic osteolysis.

In peri-prosthetic osteolysis, wear particles may affect osteoblasts and contribute to the osteolytic process by two mechanisms. First, particles and metallic ions have been shown to inhibit the osteoblast in terms of its ability to secrete mineralised bone matrix, by reducing calcium deposition, alkaline phosphatase activity and its ability to proliferate. Secondly, particles and metallic ions have been shown to stimulate osteoblasts to produce pro inflammatory mediators in vitro. In vivo, these mediators have the potential to attract pro-inflammatory cells to the peri-prosthetic area and stimulate osteoclasts to absorb bone. Further research is needed to fully define the role of the osteoblast in peri-prosthetic osteolysis and to explore its potential role as a therapeutic target in this condition.

Cite this article: Bone Joint J 2013;95-B:1021–5.

Nanotechnology is the study, production and controlled manipulation of materials with a grain size < 100 nm. At this level, the laws of classical mechanics fall away and those of quantum mechanics take over, resulting in unique behaviour of matter in terms of melting point, conductivity and reactivity. Additionally, and likely more significant, as grain size decreases, the ratio of surface area to volume drastically increases, allowing for greater interaction between implants and the surrounding cellular environment. This favourable increase in surface area plays an important role in mesenchymal cell differentiation and ultimately bone–implant interactions.

Basic science and translational research have revealed important potential applications for nanotechnology in orthopaedic surgery, particularly with regard to improving the interaction between implants and host bone. Nanophase materials more closely match the architecture of native trabecular bone, thereby greatly improving the osseo-integration of orthopaedic implants. Nanophase-coated prostheses can also reduce bacterial adhesion more than conventionally surfaced prostheses. Nanophase selenium has shown great promise when used for tumour reconstructions, as has nanophase silver in the management of traumatic wounds. Nanophase silver may significantly improve healing of peripheral nerve injuries, and nanophase gold has powerful anti-inflammatory effects on tendon inflammation.

Considerable advances must be made in our understanding of the potential health risks of production, implantation and wear patterns of nanophase devices before they are approved for clinical use. Their potential, however, is considerable, and is likely to benefit us all in the future.

Cite this article: Bone Joint J 2014; 96-B: 569–73.