Poly-lactic acid (PLA) scaffolds are widely used in bone tissue engineering. The introduction of 3D printing has greatly increased the ability for tailoring different geometrical designs of these scaffolds for improved cellular attachment, growth and differentiation. This study aimed to investigate the effect of PLA fibre angle in 3D printed PLA scaffolds on hDPSC attachment and growth in vitro.

Two types of PLA scaffolds were prepared via 3D printing containing fibres angled at either 45° or 90°. hDPSCs (P4, 2*10⁵ cells per scaffold) were statically seeded for 4 hours on to the scaffolds (7×3.5×3 mm³, n=3). Cellular attachment was checked using fluorescence microscopy and the number of unattached cells was counted using a haemocytometer (HCM). The cell-scaffold constructs were then cultured in osteogenic medium for up to 5 weeks. ALP staining and SEM were performed for one construct from each group at week 3. Cellular viability was determined using CMFDA/EHD1 live/dead labelling at week 4. After 5 weeks, constructs were processed for histology.

Fluorescence micrographs showed high numbers of hDPSCs attached to scaffold surfaces in both groups after seeding irrespective of fibre angle. However, HCM cell count revealed that the 45° angled PLA scaffolds had significantly greater cell attachment compared to the 90° angled PLA group (p<0.0001). After 3 weeks in osteogenic culture, both types of construct showed strong ALP staining. SEM showed that in the 45° angled PLA group, almost all macro-pores were fully closed with newly formed cell sheets. In comparison, in the 90° angled group, most of the macro-pores remained open although a limited amount of cellular bridging was present. SEM also detected crystal deposits in different areas within the cell sheets for both construct groups. Most hDPSCs were alive in both groups at week 4 of culture with few dead cells present. After 5 weeks, histology showed marked cellular growth and new matrix formation, with detectable Van Kossa +ve crystal deposits in different areas within all constructs irrespective of PLA fibre angle.

This study showed that 45° angled PLA 3D printed scaffolds enhanced hDPSC attachment and cellular bridging, which may help to rapidly close the macro-pores within the scaffold compared to the 90° angled group. This illustrates the potential of 45° angled 3D printed PLA scaffolds as good candidates for bone tissue engineering.

Introduction

The Delta Motion device (developed by Finsbury Orthopaedics, Leatherhead, United Kingdom, now manufactured by DePuy, Leeds, United Kingdom) is a pre-assembled factory fitted cup. It has been introduced to overcome some of the concerns relating to intra-operative assembly with improper seating of the liner and chipping. This device has a thinner shell and liner in comparison with other cups, allowing the use of larger sized heads which should help reduce the risk of impingement and dislocation. A drawback of the pre-assembled design is the inability to use supplementary screws to achieve stability and the difficulty in obtaining primary stability compared with a thin titanium shell. To date we are not aware of any publications reviewing the outcomes of these devices.

Introduction

Metal on metal (MoM) bearings have been dealt a severe blow in the past few years. The release of metal ions may have arisen from corrosion, wear, or a combination of the two. Edge loading due to implant malposition is thought to cause a failure of lubrication and to contribute to excessive wear and increased metal ion release [1]. Literature reports aseptic lymphocytic vasculitis-associated lesions (ALVAL) are associated with a variety of failures which occur to some degree in all implanted metal femoral components [2, 3]. Moreover, Willert et al [4] has described ALVAL in non-MoM bearing designs too. This paper has investigated the metal ion release due to total hip replacement (THR), Hip Resurfacing (HR) and total knee replacement (TKR).

Growth rods are currently used in young children to hold a scoliosis until the spine has reached a mature length. Only partial deformity correction is achieved upon implantation, and secondary surgeries are required at 6-12 month intervals to lengthen the holding rod as the child grows. This process contains, rather than corrects, the deformity and spinal fusion is required at maturity. This treatment has a significant negative impact on the bio-psychosocial development of the child.

To assess the effectiveness of unilateral sublaminar and concave rib tethering with convex rib resection through the period of peak growth in lambs.

Morphometric growth data from 10 experimental Scottish Blackface sheep were compared to those from 5 control animals (no intervention) over 12 months.

Standardized AP and Lateral radiographs were taken before and at monthly intervals after scoliosis creation. The Cobb angle was measured in the coronal and sagittal planes. Rotational mal-alignment was assessed by axial CT 7 months post surgery.

In the supine position the control animals had no coronal plane deformity and a mean 5° lordosis (T4-T12). These figures did not alter with growth (doubling of body weight). Tethering (at age 5 weeks) produced an immediate scoliosis of 22±11° and a lordosis of 24±8° (means(sd). The degree of scoliosis was maintained over 7 months (at 20°) but lordosis increased (to 59±11°, p<0.01). There was an associated change in vertebral rotation. Surgery had no influence on rate of growth or animal development.

Two animals died from Clostridium associated enterocolitis. There were no deaths associated with the surgical intervention.

This ovine model gives a progressive spinal deformity in the sheep but primarily in the sagittal plane. This fact should be considered in studies designed to evaluate the effectiveness of surgical implants.

Introduction Magnetic resonance imaging (MRI) is a valid investigation for the diagnosis of intervertebral disc disease, including infection, but it is expensive and difficult to access conveniently for research studies on live animals under anaesthesia. The aim of this study was to compare the MRI signal changes in spines from living and recently deceased sheep.

Methods MRI was conducted on the lumbar spines of six adult sheep from research studies investigating bacterial discitis, chemical discitis and disc degeneration resulting from annular incision. The sheep was anaesthetised and the lumbar spines were imaged with a Siemens Magneton Vision MRI (Numaris VB33G software) using T1 SGE, T1 FSE, STIR and T2 FSE sequences. The sheep were killed with an intravenous overdose of barbiturate and identical images were obtained commencing five minutes post mortem.

Results For each of the disease processes under consideration the MRI contrast relationships were maintained between all of the anatomical structures of interest. The post-mortem images provided improved clarity, particularly in the STIR and T2-weighted sequences, due to the absence of pulsation from the CSF and aorta, as well as the absence of respiratory artefact.

Discussion The MRI appearances of spinal tissues following death correlate well with those in the live animal confirming the validity of this method of investigation. This is particularly relevant for optimisation of a busy clinical resource for research purposes.

Study Design: A prospective evaluation of 40 consecutive patients with sciatica who had ‘Normal’ MRI scans, were further investigated with Nerve Root Injections (NRI), and subsequent surgery in those who had relief of symptoms.

Objectives: To evaluate the diagnostic value of NRI’s in the presence of normal MRI scans and to assess the aetiology of the sciatica.

Summary of Background Data: Since the advent of MRI scans the use of NRI’s has been in decline as a diagnostic tool. There has been no study in their usefulness when the MRI has been reported as showing no evidence of nerve root compression, and furthermore what the surgical findings were in the patients who went on to exploration.

Methods: 40 Patients with sciatica, of minimal duration of one year, in whom the MRI scan had been reported as showing no evidence of nerve root compression by an independent observer, had diagnostic NRI’s performed. Those patients that had reproduction of and subsequent temporary relief of their sciatica had surgery.

Outcome Measures: Walking distance, Analgesic Requirements, Sleep disturbance and VAS.

Results: Of the 40 patients, 25 had no benefit, 4 patients had permanent relief and 11 had temporary relief. These 11 patients underwent surgery. All patients undergoing surgery were L5 nerve root explorations. In 9 cases the compression was by the ligamentum flavum and in 2 at the foramen. Of the eleven cases operated on 9 had complete relief of symptoms and 2 were unchanged.

Conclusions: MRI scans do not show a cause for sciatica in all patients as it is not a dynamic test. In the presence of a normal MRI scan, NRI’s should be performed.

Aims: The aim of this study was to investigate the ability of control and degenerate human nucleus pulposis to respond to an exogenous proinßammatory stimulus. Methods: Disc material from patients undergoing surgery for scoliosis, sciatica and low back pain was cultured under basal and lipopolysaccharride (LPS) stimulated conditions using a serumless technique. Levels of IL-1β, TNFα, LTB4, GM-CSF, IL-6, IL-8, MCP-1, PGE2, bFGF and TGFβ-1 in the media were estimated using commercially available enzyme linked immunoabsorbent assay kits. Results: Neither basal nor LPS stimulated control nucleus pulposis (NP) produced detectable levels of IL-1β, TNFα, LTB4 or GM-CSF. LPS induced a significant increase in scoliotic disc IL-8 production, p< .02. LPS induced signiþcant increases in degenerate disc IL-6, IL-8 and PGE2 production, p< .01, p< .001 and p< .005 respectively. LPS signiþcantly increased degenerate disc IL-6, IL-8 and PGE2 production compared to LPS stimulated scoliotic disc, p< .05, p< .02 and p< .003 respectively. Conclusions: Human nucleus pulposus can react to a pro-inßammatory stimulus by secreting IL-6, IL-8 and PGE2, suggesting that the NP may actively participate in the genesis of chemical radiculitis and dis-cogenic back pain.

Recently there has been considerable interest in the role of inflammatory mediator production by herniated degenerate discs. Modic has described MR endplate changes which have an inflammatory appearance and have been linked with discogenic back pain. To date there has been no biomechanical investigation of discs with associated Modic changes.

The aim of this study is to determine if degenerate discs with associated Modic changes have higher levels of pro-inflammatory mediator production than those without Modic changes.

Intervertebral disc tissue was obtained from 52 patients undergoing spinal surgery for sciatica [40] and discogram proven discogenic low back pain [12]. The tissue was cultured and the medium analysed for interleukin-6, interleukin-8 and prostaglandin E2 using an enzyme linked immunoabsorbetn assay method. Preoperative MR images of the patients were examined by a double blinded radiologist to determine the Modic status of the cultured disc level.

Forty percent of patients undergoing surgery for discogenic low back pain had a Modic 1 change compared to only 12.5% of patients undergoing surgery for sciatica [p< .05] There was a statistically significant difference between levels of IL-6, IL-8 and PGE2 production by both the Modic1 [M1] and Modic2 [M2] groups compared to the Modic negative [NEG] group. IL-6:NEGvM1 p< .001, NEG v M2 p< .05, IL-8: NEG v M1 p< .01, NEG v M2 p> .05, PGE2: NEG v M1 p< 01, NEG v M2 p< .05.

Modic changes have been associated with positive provocative discography by a number of authors. Pain generation requires the presence of nerves and hyperalgsia inducing mediators. Both IL-8 and PGE2 are known to induce hyperalgesia. The fact that Modic changes are associated with high levels of production of these mediators supports their role as an objective marker of discogenic low back pain.

Introduction: Increased levels of IL-6 and IL-8 have been found in intervertebral disc (IVD) tissue from patients undergoing fusion for discogenic low back pain. The stimuli that induce these mediators in degenerate discs remain unknown. Impaired diffusion of nutrients and wastes to and from the nucleus pulposus (NP) is believed to be an important factor in the degenerative process. The oxygen tension and pH in the NP of degenerating discs are significantly decreased.

Aims: The aims of this study were to (1) demonstrate the ability of porcine NP to respond to a proinflamma-tory stimulus (lipopolysaccharride) in vitro, (2) investigate the effects of pH, pO₂ and glucose concentration on NP proinflammatory mediator secretion and (3) determine if methylprednisolone or indomethacin can block NP proinflammatory mediator secretion.

Methods: IVDs were harvested from 6-month old pigs and dissected under sterile conditions in the laboratory. 200mg samples of NP were cultured under optimal conditions (control), in a 1% O₂ environment, at pH6 and in culture medium without glucose for 72 hours. Blocking experiments were performed by culturing LPS-stimulated samples with either methylprednisolone or indomethacin for 24 hours. IL-6 and IL-8 levels were estimated by ELISA.

Results: Time and dose-response curves were generated for each experiment (results not shown). Results for the optimum dose and at 72 hours incubation were note.

Data = mean ± standard deviation. Statistical analysis was by students t test. A significant result between control and stimulated groups is indicated by: * p=0.024m, † p=0.0007 or ‡ p=0.012.

Methylprednisolone (2mg/ml) caused a significant (p=0.044) 30-fold reduction in IL-6 production and a significant (p=0.00004) 500-fold reduction in IL-8 levels as compared with nucleus pulposus cultured with 5 μg/ml LPS alone for 24 hours.

Addition of 500 μM indomethacin significantly (p=0.04) decreased IL-6 production by a factor of 120 and IL-8 levels by a factor of 50 (p=0.00004).

Necrotic cell death, as measured by lactate dehydrogenase (LDH) concentration, was not significant in any of the experiments.

Degenerate disc disease is a major cause of low back pain, yet its aetiology is still poorly understood. The intervertebral disc is the largest avascular structure in the body. Cells of the nucleus pulposus, therefore, rely on diffusion of oxygen & nutrients down concentration gradients from peripheral vessels in the cartilage end-plates. Thus, there is a low oxygen tension and cellular respiration is largely anaerobic.

The purpose of this study was to examine the effects of inflammation, hypoxia and acidosis on degeneration and pro-inflammatory mediator production in virgin porcine nucleus pulposus cultures.

Intervertebral discs were harvested from normal 6-month old agricultural pigs slaughtered for other purposes. Nucleus pulposus was contained within the annulus until further dissection under sterile conditions in the laboratory was performed. Nucleus pulposus was harvested, diced and divided into 200mg samples. Samples were incubated under optimal conditions.

Discs were cultured in 5μg/ml E. coli lipopolysaccharide, in a hypoxic environment or at low pH. IL-6, IL-8 and LDH assays were performed by ELISA, in accordance with manufacturer’s instructions.

Time and dose-response curves were generated for each experiment (results not shown). Results at 72 hours incubation are tabulated below:

These results confirm that nucleus pulposus is a biochemically active tissue capable of producing pro-inflammatory mediators in response to environmental stresses. IL-6 and IL-8 are both involved in the inflammatory cascade, causing chemotaxis of neutrophils and macrophages to the area. IL-8 itself causes hyperalgesia. Acidotic and inflammatory conditions, but not hypoxia, stimulated cytokine release. This may indicate a protective reduction in cellular activity in reduced oxygen environments. Necrosis, as measured by LDH production, was negligible.

The role of nucleus pulposus (NP) biology in the genesis of sciatica is being increasingly investigated.

The aim of this study was to examine the ability of control and degenerate human nucleus pulposus to respond to an exogenous pro-inflammatory stimulus.

Control disc material was obtained from surgical procedures for scoliosis and degenerate disc tissue from surgical procedures for sciatica and low back pain. Disc specimens were cultured using a serumless technique under basal and lipopolysaccharride (LPS) stimulated conditions and the media harvested, aliquoted and stored at –80°C for subsequent analysis. Levels of IL-1β,TNFα, LTB4, GM-CSF, IL-6, IL-8, MCP-1, PGE2, bFGF and TGFβ-1 in the media were estimated using commercially available enzyme linked immunoabsorbent assay kits.

Neither basal nor LPS stimulated control or degenerate NP produced detectable levels of IL-1β, TNFα, LTB4 or GM-CSF. Control disc IL-8 secretion increased significantly with LPS stimulation, p< .018. Degenerate disc IL-6, IL-8 and PGE2 production increased significantly with LPS stimulation, p< .01, p< .001 and p< .005 respectively. LPS stimulated degenerate NP secreted significantly more IL-6, IL-8 and PGE2 than LPS stimulated control NP, p < 0.05, 0.02 and 0.003 respectively.

LPS induces an increase in both control and degenerate NP mediator production demonstrating the ability of human NP to react to a noxious stimulus by producing pro-inflammatory mediators. The difference in levels of basal and LPS stimulated mediator production between control and degenerate discs show that as a disc degenerates it increases both its level of inflammatory mediator production and its ability to react to a pro-inflammatory stimulus. The increased sensitivity of degenerating human NP to noxious stimuli and increased ability to respond with inflammatory mediator production support the role of NP as an active participant in the genesis of lumbar radiculopathy and discogenic back pain.

Dupuytren’s contracture is characterised by abnormal fibroblast proliferation and extracellular matrix deposition in the palmar fascia. Fibroblast proliferation and matrix deposition in connective tissues are regulated by cytokines. A number of cytokines including transforming growth factor beta (TGFβ), basic fibroblast growth factor (bFGF), platelet derived growth factor (PDGF) and epidermal growth factor (EGF) are known to have potent anabolic effects on connective tissue. The aim of this study was to investigate the role played by anabolic cytokines in the pathogenesis of Dupuytren’s disease.

Twelve specimens of Dupuytren’s contracture and six control specimens of palmar fascia obtained from patients undergoing carpal tunnel release were cultured using a serumless method under standard conditions for 72 h. Levels of TGFβ-1, bFGF, PDGF and EGF in the medium were estimated using an enzyme linked immunoabsorbent assay technique.

Neither Dupuytren’s tissue nor control palmar fascia produced any EGF. The mean (±S.D.)levels of bFGF, PDGF and TGFβ-1 produced by cultured palmar fascia were: 1270 ± 832, 74 ± 24, < 7, and for Dupuytren’s tissue were 722 ± 237, 139 ± 76.6, 645 ± 332, respectively. The levels of PDGF and TGFβ-1 were significantly higher in Dupuytren’s tissue.

PDGF is produced in increased amounts by Dupuytren’s tissue. This may contribute to the fibroblast proliferation and increased ECM deposition observed in this condition. TGFβ-1 is not produced by normal palmar fascia but is produced in large amounts by Dupuytren’s tissue. The major physiologic role of TGFβ-1 is to stimulate formation of fibrous tissue. It plays a major role in wound healing and also in pathological conditions where fibrosis is a prominent feature. Inappropriate production of TGFβ-1 in the palmar fascia in Dupuytren’s disease may play a central role in initiating and stimulating the abnormal fibroblast proliferation and collagen synthesis seen in this condition.

The pathophysiology of discogenic low back pain is poorly understood. The morphological changes occurring in disc degeneration are well documented but unhelpful in determining if a particular degenerate disc will be painful or not.

Herniated intervertebral disc tisssue has been shown to produce a number of pro-inflammatory mediators and cytokines. No similar studies have to date been done utilising disc material from patients with discogenic low back pain.

The aim of this study was to compare levels of production of interleukin-6 (IL-6), interleukin-8 (IL-8) and Prostaglandin E2 (PGE2) in disc tissue from patients undergoing discectomy for sciatica with that from patients undergoing fusion for discogenic low back pain.

Tissue from 50 patients undergoing discectomy for sciatica and 20 patients undergoing fusion for discogenic low back pain was cultured and the medium harvested for subsequent analysis using an enzyme linked immunoabsorbent assay method. Statistical analysis of the results was performed using the Mann-Whitney test.

Disc specimens from both experimental groups produced measurable levels of all three mediators. Mean production of IL-6, IL-8 and PGE2 in the sciatica group was 26.2±75.7, 247±573 and 2255±3974 respectively. Mean production of IL-6, IL-8 and PGE2 in the low back pain group was 92±154, 776±987 and 3221±3350 respectively (data = mean production pg/ml ± 1 standard deviation).

There was a statistically significant difference between the levels of IL-6 and IL-8 production in the sciatica and low back pain groups (p< 0.006 and p< 0.003 respectively).

The high levels of pro-inflammatory mediator production found in disc tissue from patients undergoing fusion for discogenic LBP may indicate that nucleus pulposis pro-inflammatory mediator production is a major factor in the genesis of a painful lumbar disc. This could explain why some degenerate discs cause LBP while other morphologically similar discs do not.