Summary

Pyogenic spondylodiscitis is an uncommon but severe spinal infection. In majority of cases treatment is based on intravenous antibiotics and rigid brace immobilization. Posterior percutaneous spinal instrumentation is a safe alternative procedure in relieving pain, preventing deformity and neurological compromise.

Summary Statement

DNA damage induced by systemic drugs or local γ-irradiation drives disc degeneration and DNA repair ability is extremely important to help prevent bad effects of genotoxins (DNA damage inducing agents) on disc.

Introduction: Osteoporosis is a disease characterized by a low bone mass and the development of nontraumatic fractures. Approximately 700,000 elderly women in the US are newly diagnosed with osteoporotic vertebral fractures every year. Noninvasive measurements of bone mineral density (BMD) are central to the diagnosis and management of osteoporosis. However, BMD alone is not completely satisfactory in vertebral fracture risk assessment. The aim of this study was to identify clinical and laboratoristic factors associated with an increased risk of vertebral fractures in osteoporotic Caucasian women and to define a new clinically relevant scale of risk.

Methods: 475 patients consecutively admitted at our ambulatory for the treatment of vertebral osteoporosis were included in the study. All patients were affected by post-menopausal osteoporosis according to the WHO classification criteria. Exclusion criteria were major infectious diseases, tumors and major diseases of sense organs. We attempted to determine whether parameters such as age, body mass index, smoking and alcohol habitudes, femoral and lumbar T-scores, femoral and lumbar Z-scores, femoral and lumbar BMD, total and bone alkaline phosphatase and L3 and T7 vertebral volumes were associated with the risk of vertebral fractures.

Results: 173 patients of the entire population presented at least one vertebral fracture for a total of 488 fractures (238 thoracic and 250 lumbar collapses). When considered alone, age (> 65 years-p=0,0001), lumbar T-score (≤-3,5-p=0,0001), lumbar Z-score (≤-2,5-p=0,0050), lumbar BMD (≤0,800-p=0,0017), femoral T-score (≤-3,5-p=0,0090), femoral Z-score (≤-2,5-p=0,0127), L3 volume (≤-2,0SD–p=0,0023) and T7 volume (≤-2,0SD–p=0,0075) were significantly associated with an increased risk of vertebral fractures. Considering only the patients with two fractures or more, the same parameters with the exception of the femoral T-score resulted strongly associated with the risk of new vertebral fractures. Moreover, there was a significantly increased risk of vertebral fractures when two or more of these parameters were present together (p = 0.02). On the base of the obtained data we have then defined a new scale of risk (from grade I-low risk to grade IV-very high risk-p=0.0123) confirmed in a prospective study conducted on 71 osteoporotic patients followed for 30 months.

Conclusion: We propose a new clinical scale to easily identify the osteoporotic patient at risk of new vertebral fractures.

Aims. Gene therapy research in the field of orthopaedics and traumatology have evolved during the last decade, leading to possible applications for the treatment of pathological conditions, such as bone fractures and cartilage defects. In particular, several gene transfer techniques have been employed so far for inducing bone formation in animal models of bone defects. Cell-based approaches, using in vitro and ex vivo genetically modified cells to be implanted in the animal, produced promising results as they enable the production of physiologic doses of an osteoinductive gene product into selected anatomical sites. In this study we used autologous skin fibroblasts, which are very simple to harvest and propagate in culture, transduced ex vivo with the new osteo-genic factor Lim Mineralization Factor-3 (Ad-LMP-3). These engineered cells produced successful bone healing when implanted by the use of a scaffold in rats, validating the in vivo osteoinductive properties of hLMP-3.

Methods. Primary dermal fibroblasts cultures were established using a 1cm² biopsy of shaved skin obtained from the abdomen of each rat after anesthesia. Semi-confluent primary fibroblasts were infected with either AdBMP-2 or AdhLMP-3 or both, using a overall multiplicity of infection (MOI) of 100 viral particles per cell. Cells transduced with Ad-eGFP at the same MOI were used as a viral infection control, while untreated cells served as a negative control. The transduced cells were harvested 24 hours after viral infection, resuspended in sterile PBS, let adsorbed on a Hydroxyapatite/Collagen scaffold and then implanted in a bone defect surgically performed in the mandible of immunocompetent rats. The animals were divided in 4 groups: 9 rats were treated with cells infected with AdLMP-3, 9 rats with cells infected with AdBMP-2 (positive controls), 9 rats with cells transduced with Ad-eGFP and 9 rats with untreated cells (controls). 3 Rats from each group were sacrified at 1, 2 and 3 months after the treatment and studied by x-rays, Micro-CT and histology (Von kossa and Alizarin staining).

Results. All the animals treated with LMP-3 showed healing of the bone defect after 3 months, as confirmed his-tologically and radiographically. On the contrary none of the controls showed bone formation at latest time point.

Conclusions. Recently, Lim Mineralization Proteins (LMP), coded by three different splice variants (LMP-1, LMP-2, LMP-3) of the same gene, have been identified as regulators of the osteoblast differentiation program. We have previously demonstrated that human LMP-3 (hLMP-3) contributes actively to bone formation, acting at least in part, through the BMP-2 signaling pathway, being capable of inducing differentiation of cells of mes-enchymal derivation towards the osteoblastic lineage, through the up-regulation of bone-specific genes, along with ectopic bone formation in vivo and mineralization in vitro. In this study we have analyzed the efficacy of an ex-vivo approach using autologous dermal fibroblasts infected with AdLMP-3. Engineered cells produced bone healing when implanted by the use of a scaffold in a rodent model, validating the in vivo osteoinductive properties of hLMP-3.

Aims: As inflammation plays a key role in the etiology of intervertebral disc degeneration, we suggest a possible contribution of pro-inflammatory gene polymorphisms in the pathogenesis of adolescent idiopathic scoliosis (AIS). The nucleus pulposus of scoliotic discs responds to exogenous stimuli by secreting interleukin-6 (IL-6) and other inflammatory cytokines. The association between matrix metalloproteinases (MMPs) and disc degeneration has been reported by several investigators. A human MMP-3 promoter 5A/6A gene polymorphism regulates MMP-3 genes expression, while the G/C polymorphism of the promoter region of IL-6 gene influences levels and functional activity of the IL-6 protein.

Methods: We conducted a case-control study to investigate whether the 5A/6A polymorphism of the MMP-3 gene and the G/C polymorphism of the promoter region of IL-6 gene were associated with susceptibility to AIS.

Results: The frequency of the 5A/5A genotype of MMP-3 gene polymorphism in patients with scoliosis was almost 3 times higher than in controls (30.2 % vs 11.2 %, p 0.001) and the frequency of the G/G genotype of IL-6 gene polymorphism in patients with scoliosis was almost 2 times higher than in controls (52.8 % vs 26.2 %, p < 0.001). 5A/5A genotype of MMP-3 gene polymorphism and G/G genotype of IL-6 gene polymorphism are independently associated with an higher risk of scoliosis (odds ratio respectively 3.34 and 10.54).

Conclusions: This is the first study that has evaluated the possibility that gene variants of IL-6 and MMPs might be associated with scoliosis and suggests that MMP-3 and IL-6 promoter polymorphisms constitute important factors for the genetic predisposition to scoliosis.

Lim mineralisation protein (LMP) is a new positive regulator of the osteoblast differentiation programme. In humans three “splice variants” of LMP have been identified: LMP-1, LMP-2 and LMP-3. Recent studies demostrated that LMP-1 gene acts as a transcriptional factor inside the cells and is able to induce expression of specific bone genes, like the bone morphogenetic proteins (BMPs), to improve bone formation in vitro and ectopic bone formation in vivo and seems to induce spinal fusion in several animal models.

In order to evaluate the osteoinductive properties of the shorter variant of LMP, plasmidic and adeno-viral vectors expressing the optimised sequence of human LMP-3 have been generated. The osteogenic activity of LMP-3 was evaluated in vitro with experiments of transfection and infection of mesenchymal stem cells, fibroblasts and pre-osteoblasts; in vivo we investigated whether direct gene transfer of LMP-3 in the triceps muscles of immunocompetent mice was able to induce ectopic bone formation. All the animals were studied by histology and X-rays at different time points. In all the experiments BMP-2 was used as positive control.

These experiments demonstrated that the “gene transfer” of LMP-3 in fibroblasts and pre-osteoblasts stimulates production of specific bone proteins, such as osteocalcin, osteopontin and bone sialoprotein, and induces bone mineralisation in vitro. It was also demonstrated that LMP-3 is able to induce, in a dose-dependent manner, bone mineralisation and expression of specific bone genes (BMP-2, OSX, RunX2, alkaline phosphatase) in mesenchymal stem cells. Finally, the experiments showed that direct gene transfer of LMP-3 in the triceps muscle of mice induces ectopic bone formation in all the animals treated more efficiently than BMP-2.

These data demonstrate that gene transfer of LMP-3 could be used, more efficiently than BMP-2, in inducing bone formation in several cell lines and in vivo, establishing the osteoinductive ability of LMP-3. Thus, LMP-3 could represent, in the near future, a therapeutic alternative in several clinical conditions.

Zirconia has considered a good material for manufacturing of ball heads in total hip replacement due to high mechanical properties of this ceramic material. However in the literature the problem of heads biocompatibility is still debated. The Authors reported their experience in ten years of research on the biological properties of this material. In vitro tests were performed onto materials in form of powders, analyzing the inhibitory effects on human lymphocyte mitogenesis, and in form of plates measuring adhesion and spreading of 3T3 fibroblasts. A mutagenic test was also performed. In vivo tests were performed by injection of powders in mice and evaluating the survival of animals according to ASTM F – 750. We also inserted ceramic in form of cylinders into proximal tibial metaphysis of NZW rabbits and analysed local and systemic reaction due to material diffusion. We also developed a system of production of Zirconia particles by inserting ceramics under patellar tendon of NZW rabbits.

In vitro tests showed that Zirconia powders and plates induced a similar effect of Alumina ones; no mutagenic effect were observed using our samples, demonstrating that Zirconia has no carginogenic effects. In any case the diffusion of particles didn’t show modifications into internal organs (lung, kidney, liver, spleen) of mice and rabbits. In time (one year after operation) the connective tissue present at bone ceramic interface is transformed into lamellar bone.

Our experience demonstrates that Zirconia may be considered a good material for prosthetic implants.

The Authors analysed two cases of catastrophic failures of Total Hip Prostheses due to the disruption of the PE inlay and the Ti-alloy metal back of the acetabular components. In the cases reported the PE inlay (4 mm in thickness) was coupled with a 32 mm in diameter Alumina ball heads. At time of revision the alumina ball heads showed many black marks due to the contacts with the Ti-alloy metal back. The sockets showed severe damages, concentrated in the superolateral zone. The PE inlays were disrupted. Almost a third of the metal back is missing. A large metallosis was also visible in the membrane at the interface between implant and bone. Histologic sections showed a large amount of metallic debris in a pseudovillous membrane. At higher magnification oligonuclear cells in a rich in vessels stroma were in contact with metal particles. PE debris with the characteristic birifrangent aspect to the polarised light microscope was contained into polynuclear giant cells. SEM showed that the size of 25% of particles was less than 1 μm, while the size of 53% of wear debris is in the range from 1 to 5 mm. EDAX confirmed that these particles consisted of Ti alloy. The Authors analysed the possible roles of different factors in the etiology of this cup failures and concluded that in both the cases analysed the initiator of the failure was the size selection of the prosthesis, and in particular the PE thickness, followed by the positioning of the acetabular component. The deformation of the PE inlay leads to rupture of the inlay itself, followed by the direct contact between the Alumina ball head and the titanium alloy cup, causing the disruption of the Ti-alloy metal back, with massive release of wear debris in the surrounding tissues.

Aseptic loosening is one of the most frequent cause of total knee arthroplasty (TKA) failure; it is related to a fatigue-type wear which can rapidly break up a tibial polyethylene (PE) inlay. PE debris production is the result of this wear and depend on contact stress between the components. This crucial parameter is more related to conformity than to load tranfer. That is why mobile bearing TKA seems to represent a valid solution to the PE debris production. In fact this implant offers great tibio-femoral conformity without an increased risk of loosening due to increased axial torque. Mobile bearing TKA also eneables the surgeon to self correct tibial component malrotation. On the other hand this implant could lead to new problems such as bearing dislocation or breakage and a possible new wear pattern at the PE-tibial metal tray interface.

We performed 100 consecutive cemented posterior stabilised TKA using randomly in 50 cases a mobile bearing and in 50 cases the same implant with a fixed bearing. The mean follow up was 15 months. The results in mobile bearing group are the following. Hospital for Special Surgery (HSS) score improved from 38 to 91 after the surgery. Preoperative Range of Movement (ROM) was 71 while the post op value was 107. No lucencies > 1 mm were observed. There were no statistically significant differences among the mobile bearing group and the fixed bearing one. Despite our short follow up, this implant offers the same good clinical results if compared to other devices, and allows the surgeons to correct errors in positioning the implant.

In future we have to consider that this possibility will lead to an abnormal load stresses distribution and to a higher risk of late loosening.