Introduction. We have developed a new synthetic hydrogel that can be injected directly into the intervertebral disc (IVD) without major surgery. Designed to improve fixation of joint prosthesis, support bone healing or improve spinal fusion, the liquid may support the differentiation of native IVD cells towards osteoblast-like cells cultured within the hydrogel. Here we investigate the potential of this gel system (Bgel) to induce bone formation within intervertebral disc tissue. Methods. IVD tissue obtained from patients undergoing discectomy, or cadaveric samples, were cultured within a novel explant device. The hydrogel was injected, with and without mesenchymal stem cells (MSCs), and cultured under hypoxia, to mimic the degenerate IVD environment, for 4 weeks. Explants were embedded to wax and native cellular migration into the hydrogel was investigated, together with cellular phenotype and matrix deposition. Results. Increased collagen deposition was seen in tissue explants injected with Bgel, with evidence of elevated native cell migration towards the hydrogel. Increased collagen staining was seen in explants injected with Bgel together with MSCs. Alizarin red staining was utilised to investigate calcium deposition. Tissue explants, in the absence of Bgel, showed limited calcium deposition. This was increased in hydrogel-treated samples, with large clumping regions in the tissue that was injected with Bgel and MSCs. Conclusion. The injection of our synthetic hydrogel into disc tissue explants increased the amount of collagen and calcium deposition. This was further enhanced by the incorporation of MSCs, suggesting the promotion of bone formation. Current work is investigating phenotypic markers for bone formation within these tissues. CS and CLM have a patent on the hydrogel system described in this abstract. Funded by EPSRC and Grow MedTech

Background. We have reported an injectable L-pNIPAM-co-DMAc hydrogel with hydroxyaptite nanoparticles (HAPna) which promotes mesenchymal stem cell (MSC) differentiation to bone cells without the need for growth factors. This hydrogel could potentially be used as an osteogenic and osteoconductive bone filler of spinal cages to improve vertebral body fusion. Here we investigated the biocompatibility and efficacy of the hydrogel in vivo using a proof of concept femur defect model. Methods. Rat sub-cut analysis was performed to investigate safety in vivo. A rat femur defect model was performed to evaluate efficacy. Four groups were investigated: sham operated controls; acellular L-pNIPAM-co-DMAc hydrogel; acellular L-pNIPAM-co-DMAc hydrogel with HAPna; L-pNIPAM-co-DMAc hydrogel with rat MSCs and HAPna. Following 4 weeks, defect site and organs were histologically examined to determine integration, repair and inflammatory response, as well as Micro-CT to assess mineralisation. Results. No inflammatory reactions or toxicity were seen in any animal. Enhanced bone healing was observed in aged exbreeder female rats where hydrogel was injected with increased deposition of collagen type I. Integration of the hydrogel with surrounding bone was observed without the need for delivered MSCs; native cell infiltration was also seen and bone formation was observed within all hydrogel systems investigated. Conclusion. This novel hydrogel is biocompatible, facilitates migration of cells, promotes increased bone formation and integrates with surrounding bone. This system could be injected to fill spaces within and surrounding spinal cages to aid in cage fixation and spinal fusion without the need for harvesting of bone autografts, thus reducing operative risk and surgical cost. Conflicts of Interest: None. Source of Funding: BMRC, MERI Sheffield Hallam University

Aims

High-grade dysplastic spondylolisthesis is a disabling disorder for which many different operative techniques have been described. The aim of this study is to evaluate Scoliosis Research Society 22-item (SRS-22r) scores, global balance, and regional spino-pelvic alignment from two to 25 years after surgery for high-grade dysplastic spondylolisthesis using an all-posterior partial reduction, transfixation technique.

Aims

To report the surgical outcome of patients with severe Scheuermann’s kyphosis treated using a consistent technique and perioperative management.

Literature review about the current management strategies for U-shape sacral fractures. A thorough literature search was carried out to find out the current concepts in the management of U-shaped sacral fractures. Meta-analysis of 30 cases of U-Shaped sacral fractures. Radiological assessment for bone healing, and clinical examination for neurological recovery. 7 papers were published in the English literature between 2001 and 2009 about the management of U-shaped sacral fractures. In total 30 cases were included. The most common mechanism of injury was fall or jump from height (63%), followed by road traffic accidents and industrial injuries. Pre-operative neurological deficit was noted in 73% of patients. The average follow up time ranged from 2-12 months. 18 (60%) of patients were treated with sacroiliac screws. In this group pre-operative neurological deficit was found in 12(66%) patients. All of these patients had satisfactory radiological healing at follow up but 5(27%) patients had residual neurological deficit. No immediate complication was reported in this group. Incomplete sacroiliac screw disengagement was reported in one patient without fixation failure. Other procedures performed were lumbopelvic fixation, triangular osteosynthesis and transsacral plating. The most common cause of U-shaped sacral fractures is a fall or jump from height. There is a high association of neurological damage with U-shaped sacral fractures. From the current available evidence sacroiliac screw fixation is the most commonly performed procedure, it is however not possible to deduce which procedure is better in terms of neurological recovery

Background. For bone grafting procedures, the use of autologous bone is considered the gold standard, as it is has a better healing capacity compared to other alternatives as allograft and synthetic bone substitutes. However, as there are several drawbacks related to autografting (infection, nerve- or vascular damage, chronic pain problems, abdominal herniation), there has been a targeted effort to improve the healing capacities of synthetic bone substitutes. Aim. To evaluate the performance of a carbonated osteoionductive hydroxyapatite (CHA) scaffold of clinical relevant size (Ø=15mm, H=50mm) in a sheep model of multi level posterolateral intertransverse lumbar spine fusion after activation with autologous bone marrow nuclear cells (BMNC) in a flow perfusion bioreactor. Method. Two groups were included in the study, autograft (n=6) and CHA scaffold (n=6) CHA. A paired design was used between and within the groups as lumbar posterolateral arthrodesis was performed in sheep on two levels (L2-L3, L5-L6) +/− BMNC, respectively. Before implantation, the CHA scaffold was cultured in a flow perfusion bioreactor system with BMNC for 21 days, and the autograft group was supplemented with isolated BMNC during the procedure. Micro tomography was used to evaluate fusion rate and the microarchitectural properties of the explants after an observation period of four months. Results. In the autograft group, the healing rate was 83.3% irrespective of the presence BMNC, and in the CHA group, 66.7% fused in the presence of BMNC, and 33.3% without. The microarchitectural data suggested the autograft group to be superior to the CHA scaffold regarding mechanical properties, however porosity decreased significantly (p=0.001) in the CHA scaffold group suggesting deposition of mineralized bone matrix. Conclusion. Based on the fusion rate and micro architectural properties, we consider the CHA scaffold fully capable of new bone formation, and that the presence of BMNC has a positive effect on the fusion rate in a challenging model of bone healing

Objectives

Pulsed electromagnetic field (PEMF) stimulation was evaluated after anterior cervical discectomy and fusion (ACDF) procedures in a randomized, controlled clinical study performed for United States Food and Drug Administration (FDA) approval. PEMF significantly increased fusion rates at six months, but 12-month fusion outcomes for subjects at elevated risk for pseudoarthrosis were not thoroughly reported. The objective of the current study was to evaluate the effect of PEMF treatment on subjects at increased risk for pseudoarthrosis after ACDF procedures.

Aim

Many aspects of the surgical treatment of patients with tuberculosis (TB) of the spine, including the use of instrumentation and the types of graft, remain controversial. Our aim was to report the outcome of a single-stage posterior procedure, with or without posterior decompression, in this group of patients.

Objectives

We performed a systematic review of the literature to determine the safety and efficacy of bone morphogenetic protein (BMP) compared with bone graft when used specifically for revision spinal fusion surgery secondary to pseudarthrosis.

Using the United States Nationwide Inpatient Sample, we identified national trends in revision spinal fusion along with a comprehensive comparison of comorbidities, inpatient complications and surgical factors of revision spinal fusion compared to primary spinal fusion.

In 2009, there were 410 158 primary spinal fusion discharges and 22 128 revision spinal fusion discharges. Between 2002 and 2009, primary fusion increased at a higher rate compared with revision fusion (56.4% vs 51.0%; p < 0.001). In 2009, the mean length of stay and hospital charges were higher for revision fusion discharges than for primary fusion discharges (4.2 days vs 3.8 days, p < 0.001; USD $91 909 vs. $87 161, p < 0.001). In 2009, recombinant human bone morphogenetic protein (BMP) was used more in revision fusion than in primary fusion (39.6% vs 27.6%, p < 0.001), whereas interbody devices were used less in revision fusion (41.8% vs 56.6%, p < 0.001).

In the multivariable logistic regression model for all spinal fusions, depression (odds ratio (OR) 1.53, p < 0.001), psychotic disorders (OR 1.49, p < 0.001), deficiency anaemias (OR 1.35, p < 0.001) and smoking (OR 1.10, p = 0.006) had a greater chance of occurrence in revision spinal fusion discharges than in primary fusion discharges, adjusting for other variables. In terms of complications, after adjusting for all significant comorbidities, this study found that dural tears (OR 1.41; p < 0.001) and surgical site infections (OR 3.40; p < 0.001) had a greater chance of occurrence in revision spinal fusion discharges than in primary fusion discharges (p < 0.001). A p-value < 0.01 was considered significant in all final analyses.

Cite this article: Bone Joint J 2014;96-B:807–16.

Osteoporotic vertebral compression fractures (VCFs) are an increasing public health problem. Recently, randomised controlled trials on the use of kyphoplasty and vertebroplasty in the treatment of these fractures have been published, but no definitive conclusions have been reached on the role of these interventions. The major problem encountered when trying to perform a meta-analysis of the available studies for the use of cementoplasty in patients with a VCF is that conservative management has not been standardised. Forms of conservative treatment commonly used in these patients include bed rest, analgesic medication, physiotherapy and bracing.

In this review, we report the best evidence available on the conservative care of patients with osteoporotic VCFs and associated back pain, focusing on the role of the most commonly used spinal orthoses. Although orthoses are used for the management of these patients, to date, there has been only one randomised controlled trial published evaluating their value. Until the best conservative management for patients with VCFs is defined and standardised, no conclusions can be drawn on the superiority or otherwise of cementoplasty techniques over conservative management.