Interbody fusion aims to treat painful disc disease by demobilising the spinal segment through the use of an interbody fusion device (IFD). Diminished contact area at the endplate interface raises the risk of device subsidence, particularly in osteoporosis patients. The aim of the study was to ascertain whether vertebral body (VB) cement augmentation would reduce IFD subsidence following dynamic loading. Twenty-four human two-vertebra motion segments (T6–T11) were implanted with an IFD and distributed into three groups; a control with no cement augmentation; a second with PMMA augmentation; and a third group with calcium phosphate (CP) cement augmentation. Dynamic cyclic compression was applied at 1Hz for 24 hours in a specimen specific manner. Subsidence magnitude was calculated from pre and post-test micro-CT scans. The inferior VB analysis showed significantly increased subsidence in the control group (5.0±3.7mm) over both PMMA (1.6±1.5mm, p=.034) and CP (1.0±1.1mm, p=.010) cohorts. Subsidence in the superior VB to the index level showed no significant differences (control 1.6±3.0mm, PMMA 2.1±1.5mm, CP 2.2±1.2mm, p=.811). In the control group, the majority of subsidence occurred in the lower VB with the upper VB displaying little or no subsidence, which reflects the weaker nature of the superior endplate. Subsidence was significantly reduced in the lower VB when both levels were reinforced regardless of cement type. Both PMMA and CP cement augmentation significantly affected IFD subsidence by increasing VB strength within the motion segment, indicating that this may be a useful method for widening indications for surgical interventions in osteoporotic patients.

INTRODUCTION

Over 85% of patients with multiple myeloma (MM) have bone disease, mostly affecting thoraco-lumbar vertebrae. Vertebral fractures can lead to pain and large spinal deformities requiring application of vertebroplasty (PVP). PVP could be enhanced by use of Coblation technique to remove lesions from compromised MM vertebrae prior to cement injection (C-PVP).

The aim of this study was to prospectively assess the outcome of patients with metastatic spinal disease who underwent minimally invasive fixation of the spine for intractable pain or spinal instability.

This is a prospective audit of patients with metastatic spinal cord disease who have undergone minimally invasive fixation of the spine from August 2009 until the present date. This was assessed by pre and post-operative Oswestry Disability Index (ODI), EQ5D and Tokuhashi scores. Intra- and post-operative complications, time to theatre, length of inpatient stay, analgesia requirements, mobility, chest drain requirement and post-operative HDU and ITU stays were also recorded.

So far, 10 patients have met the criteria. There were no intra-operative complications. Post-operatively, there were no complications, chest drains, increase in analgesia or stay on the HDU or ITU. All patients showed an improvement in mobility. The mean post-operative day of mobilisation was 2 days, post-operative days until discharge 5.3 days and length of inpatient stay was shorter than traditional surgery. Blood loss was minimum except one patient with metastatic renal cell carcinoma who needed transfusion intraoperatively.

ODI, VAS and EQ-5D scores were calculated and were significantly improved compared to preoperatively.

This novel approach to management of metastatic spinal disease has resulted in improved mobility, short inpatient stays without the need for chest drains, HDU or ITU and an improved the quality of life in pallliative patients. This is a completely new strategy to treat the pain in these patients without the usual associated risks of surgery and has major advantages over traditional surgical techniques which may preclude this group of patients having any surgical stabilisation procedure at all

Numerous in vitro studies have utilised bone models for the assessment of orthopaedic medical devices and interventions. The drivers for this usage are the low cost, reduced health concerns and lower inter-specimen variability when compared to animal or human cadaveric tissues. Given this widespread exploitation of these models the push for their use in the assessment of spinal augmentation applications would appear strong. The aim of the research was to investigate the use of surrogate-bone vertebral models in the mechanical assessment of vertebroplasty.

Nine surrogate-bone whole vertebral models with an open-cell trabeculae configuration were acquired. Initial μCT scans were performed and a bone marrow substitute with appropriate rheological properties was injected into the trabeculae. Quasistatic loading was performed to determine the initial fracture strength in a manner previously used with human cadaveric vertebrae. Following fracture, vertebroplasty was undertaken in which there was a nominal 20% volume fill. Following augmentation the VBs were imaged using uCT and then subjected to an axial load using the same protocol.

The surrogate models had a substantially thicker cortex than that of human osteoporotic vertebrae. During compression, the surrogate-bone models did not exhibit the characteristic ‘toe-region’ observed in the load-deformation profile of cadaveric vertebrae. The mean initial and post-augmentation failure strength of the surrogate vertebrae were 1.35kN ± 0.15kN and 1.90kN ± 0.68kN, respectively. This equates to a statistically significant post-vertebroplasty increase by a factor of 1.38. In comparison with human osteoporotic bone, no significant difference was noted in the relative increase in fracture strength between the artificial and human VB following augmentation.

Despite the apparent equivalence of the strength and stiffness of the artificial vertebrae compared to that of the cadaveric specimens, there are significant differences in both pre- and post augmentation behaviour. In particular, the load-deformation curve shows significant differences in shape particularly at the toe end and in post failure behaviour. There are also issues surrounding where the marrow and cement flows during the injection process thus affecting the final distribution of the cement.

Introduction & Aims: The X-stop interspinous process decompression system is being used as an alternative to laminectomy in the treatment of neurogenic claudication. To date the clinical outcomes are favourable, but the economic value has not been established within the NHS financial model.

Objective: To compare the average hospital costs of performing an x-stop procedure (under general or local anaesthetic) to a laminectomy in patients with neurogenic claudication.

Design: A retrospective analysis of average length of stay, anaesthetic and operative times, equipment and anaesthetic agent costs. Sources included theatre management systems, the British National Formulary and Leeds Teaching Hospitals Trust in-patient stay data. The study period was from April 2005 to October 2006. The number of patients in the two groups were 318 (laminectomy) and 75 (X-stop).

Results: In comparison to laminectomy, patients under-going an X-stop procedure have a reduced average length of in-patient stay (3 versus 5 days), reduced anaesthetic time (25 versus 29 minutes) and operative duration (40 versus 128 minutes). The average cost for each procedure is £3346 for an X-stop under general anaesthetic (profit £119), £2835 for a laminectomy (profit £1177) and £2237 for an X-stop as a day case (profit £1228).

Conclusions: Tariff reimbursement is an important consideration to ensure insertion of these devices is profitable for the hospital. Our results show that even with the additional cost of the implant device, an X-stop procedure under general anaesthetic remains profitable in comparison to a laminectomy, whilst a day-case X-stop procedure is more profitable. Additional savings are be made by reduced bed and theatre occupancy. Future studies will differentiate costs of 1- and 2-level X-stop procedures, complication rates and revision surgery.

INTRODUCTION: In the spinal column, bone metastases (BM) and lesions arising from multiple myeloma (MM) can cause severe weakening of the vertebral body (VB) leading to an increased risk of fracture¹. These vertebral fractures may induce severe pain, deformity and increased risk of neurological deficit². At present, however, there is very little known about the mechanical behaviour either of the infiltrated vertebrae or that following vertebroplasty (VP). The purpose of this preliminary investigation was to evaluate (i) the mechanical behaviour of vertebrae with lesion involvement, and (ii) the effectiveness of VP with coblation.

METHODS: Individual vertebrae from two spines, one with MM (n=13) and one with BM secondary to bladder cancer (n=12) were dissected free of soft tissue with the posterior elements retained. Three MM vertebrae with evidence of previous fracture were excluded. Each vertebrae was fractured under an eccentric flexion load from which fracture strength and stiffness were derived³. VBs were then assigned to two groups. In group 1, lesion material was removed by coblation prior to VP and in group 2, no coblation was performed prior to VP. All vertebrae were fractured post-augmentation under the same loading protocol. At each stage microCT assessments were conducted to investigate lesion morphology and cement volume/distribution.

RESULTS: MM vertebrae were characterised by several small lesions, severe bone degradation and multiple compromise of the cortical wall. In contrast, large focal lesions were present in the BM vertebrae and the cortical wall generally remained intact. The initial failure strength of the MM vertebrae were significantly lower than BM vertebrae (L=2200N vs 950N, P< 0.001). A significant improvement in relative fracture strength was found post augmentation for both lesion-types (1.42 ± 0.51, P=0.0006). Coblation provided a marginally significant increase in the same parameter post-augmentation (P=0.08) and, qualitatively, improved the ease of injection.

CONCLUSIONS: Bladder BM and MM vertebral lesions showed significant variations in lesion morphology, bone destruction and the level of cortical wall breach, causing significant changes in the bone fracture behaviour. Account should be taken of these differences to optimise the VP intervention in terms of cement formulation and delivery. Preliminary results suggest the current VP treatment provides significant improvements in failure strength post-fracture.