Implant-related infections pose a severe economical and societal burden, hence solutions capable of exerting suitable efficacy while not causing toxicity and/or development of resistant bacterial strains are needed. Thus, inorganic antibacterial coatings, and in particular silver coatings, have been extensively studied and used in the clinical practice. However, some drawbacks such as scarce adhesion to the substrate, delamination, or scarce control over silver release have been evidenced. Here, antibacterial nanostructured silver thin films have been developed by a novel plasma-assisted technique. The technique allows deposition on several substrates, including heat sensitive materials and objects of complex shape. Thanks to nanostructured surface, a tuned release can be achieved, preventing citoxicity. Composition (grazing incidence XRD, XPS) and morphology (SEM, AFM, ASTM) of the obtained coatings were characterized, then, their efficacy was validated in vitro against relevant bacterial strains (gram+ S. Aureus and gram– E. Coli). Live/dead kit and confocal microscopy were used to evaluate antibacterial efficacy. Super resolution imaging in the Structured Illumination Microscopy (SIM) setup was used to investigate damage to the bacterial wall. Results indicate that the coatings are composed of nanosized aggregates of metallic silver, indicating a perfect transfer of composition from the deposition target to the coating. Because of the sub-micrometric thickness, they do not alter the micro- and macro- morphology and surface finishing of the implants, developed by the manufacturers to ensure optimal integration in the host bone. Finally, remarkable efficacy was found against both gram+ and gram- bacteria, indicating that the developed coatings are promising for antibacterial applications.

Fabrication of biogenic coatings with suitable mechanical properties is a key goal in orthopedics, to overcome the limitations of currently available coatings and improve the clinical results of coated implants compared to uncoated ones. In this paper, biological-like apatite coatings were deposited from a natural bone-apatite source by a pulsed electron deposition technique (PED).

Bone apatite-like (BAL) films were deposited directly from bone targets, obtained by standard deproteinization of bovine tibial cortical shafts and compared to films deposited by sintered stoichiometric-hydroxyapatite targets (HA). Deposition was performed at room temperature by PED in the Ionized Jet Deposition (IJD) version. Half of the samples was annealed at 400°C for 1h (BAL_400 and HA_400). As-deposited and annealed coatings were characterized in terms of composition and crystallinity (XRD, FT-IR), microstructure and morphology (SEM-EDS, AFM) and mechanical properties (nanoindentation and micro-scratch). For the biological tests, human dental pulp stem cells (hDPSCs) were isolated from dental pulp from patients undergoing a routine tooth extraction, plated on the samples (2500 cells/cm2) and cultured for 3 weeks, when the expression of typical osteogenic markers Runx-2, osteopontin, Osx and Osteocalcin in hDPSCs was evaluated.

Results showed that deposition by PED allows for a close transfer of the targets” composition. As-deposited coatings exhibited low cristallinity, that was significantly increased by post-deposition annealing, up to resembling that of biogenic apatite target. As a result of annealing, mechanical properties increased up to values comparable to those of commercial plasma-sprayed HA-coatings.

In vitro biological tests indicated that BAL_400 promotes hDPSCs proliferation to a higher extent compared to non-annealed bone coating and HA-references. Furher, immunofluorescence and western blot analyses revealed that the typical osteogenic markers were expressed, indicating that BAL_400 alone can efficiently promote the osteogenic commitment of the cells, even in absence of an osteogenic medium.

In conclusion, bone-like apatite coatings were deposited by PED, which closely resembled composition and structure of natural-apatite. Upon annealing at 400°C, the coatings exhibited satisfactory mechanical properties and were capable of providing a suitable microenvironment for hDPSCs adherence and proliferation and for them to reach osteogenic commitment.

These results suggest that bone apatite-like thin films obtained by biogenic source may represent an innovative platform to boost bone regeneration in the orthopedic, maxillofacial and odontoiatric field.

A critical bone defect may be more frequently the consequence of a trauma, especially when a fracture occurs with wide exposure, but also of an infection, of a neoplasm or congenital deformities. This defect needs to be treated in order to restore the limb function. The treatments most commonly performed are represented by implantation of autologous or homologous bone, vascularized fibular grafting with autologous or use of external fixators; all these treatments are characterized by several limitations.

Nowadays bone tissue engineering is looking forward new solutions: magnetic scaffolds have recently attracted significant attention. These scaffolds can improve bone formation by acting as a “fixed station” able to accumulate/release targeted growth factors and other soluble mediators in the defect area under the influence of an external magnetic field. Further, magnetic scaffolds are envisaged to improve implant fixation when compared to not-magnetic implants.

We performed a series of experimental studies to evaluate bone regeneration in rabbit femoral condyle defect by implanting hydroxyapatite (HA), polycaprolactone (PCL) and collagen/HA hybrid scaffolds in combination with permanent magnets.

Our results showed that ostetoconductive properties of the scaffolds are well preserved despite the presence of a magnetic component. Interestingly, we noticed that, using bio-resorbable collagen/HA magnetic scaffolds, under the effect of the static magnetic field generated by the permanent magnet, the reorganization of the magnetized collagen fibers produces a highly-peculiar bone pattern, with highly-interconnected trabeculae orthogonally oriented with respect to the magnetic field lines. Only partial healing of the defect was seen within the not magnetic control groups.

Magnetic scaffolds developed open new perspectives on the possibility to exploiting magnetic forces to improve implant fixation, stimulate bone formation and control the bone morphology of regenerated bone by synergically combining static magnetic fields and magnetized biomaterials. Moreover magnetic forces can be exploited to guide targeted drug delivery of growth factors functionalized with nanoparticles.

Introduction

Protective hard coatings are appealing for several technological applications and even for orthopaedic implants and prosthetic devices. For what concerns the application to prosthetic components, coating of the surface of the metallic part with low-friction and low-wear materials has been proposed [1, 2]; at the same time, concerning use of ceramic materials in joint arthroplasty, zirconia-toughned-alumina (ZTA) ceramic material has shown high strength, fracture toughness, elasticity, hardness, and wear resistance [3, 4]. The purpose of this study was to directly deposit ZTA coatings by using a novel sputter-based electron deposition technique, namely Pulsed Plasma Deposition (PPD) [5]. Preliminary characterization of realized coatings from the point of view of morphology, wettability, adhesion and friction coefficients was performed.

Introduction

Total joint arthroplasty is frequently necessary when a traumatic or degenerative disease leads to develop osteoarthritis (OA). Nowadays, the main reason for long term prosthesis failure is due to osteolysys and aseptic loosening of the implant itself, that are related to UHMWPE wear debris [1–3]. Different solutions to overcome this issue have been proposed, including different couplings like metal-on-metal and ceramic-on-ceramic. Our hypothesis was that a hard ceramic thin film realized on the plastic component (i.e. UHMWPE) could improve the friction and wear performance in a prosthetic coupling. The purpose of the presented study was therefore to characterize from the point of view of structure and mechanical performance of this ceramic-coated plastic component. The thin films were specifically realized by means of the novel Pulsed Plasma Deposition (PPD) technique [4].

Introduction

Protective hard coatings are appealing for several technological applications like solar cells, organic electronics, fuel cells, cutting tools and even for orthopaedic implants and prosthetic devices. At present for what concerns the application to prosthetic components, the coating of the surface of the metallic part with low-friction and low-wear materials has been proposed [1]. Concerning the use of ceramic materials in joint arthroplasty, zirconia-toughned-alumina (ZTA) reported high strength, fracture toughness, elasticity, hardness, and wear resistance [2]. The main goal of this study was to directly deposit ZTA coating by using a novel sputter-based electron deposition technique, namely Pulsed Plasma Deposition (PPD) [3]. The realized coatings have been preliminary characterized from the point of view of morphology, wettability, adhesion and friction coefficients.

Wear of the ultra-high molecular weight polyethylene (UHMWPE) insert is one of the major issue related to orthopaedic implants. In this study, the tribo-mechanical properties of zirconia-coated UHMWPE deposited by means of Pulsed Plasma Deposition (PPD) technique were analyzed. Specifically, strength to local plastic deformation, indentation work portioning and creep behavior were evaluated through nanoindentation and micro-scratch tests, whereas preliminary wear data were obtained by tribology tests. A strong reduction of plastic deformation and a drop of the creep phenomenon for the zirconia-coated UHMWPE were evidenced, whereas - in spite of similar wear data - different wear mechanism was also detected. This study supported the use of hard ceramic thin films to enhance the mechanical performance of the plastic inserts used in orthopaedics.

Introduction

When osteoarthritis occurs, joint replacement is the most frequent treatment. Currently, the mean survival rate for total joint arthroplasty is ∼90% after 10 years: the main reason for long-term implant failure, that generally required a revision surgery, are osteolysis and aseptic loosening of the implant, which are strongly correlated with wear debris formation from the UHMWPE insert [Ingham, 2005], as a consequence of the cyclic loading against the metallic or ceramic counterface [Dumbleton, 2002]. Wear debris bring to chronic inflammation of periprosthetic tissues causing an increase of bone reabsorption that finally provoke aseptic loosening, so implant failure[Holt, 2007]. Different solutions were proposed to reduce wear debris production but agreement has not been achieved yet. Our challenging approach prefigures the direct coating of the plastic component with a hard and well-adherent ceramic film, in order to drastically reduce wear debris formation from the plastic substrate while preserving its well-established bulk mechanical properties, especially under high local loads [Bianchi, 2013].

Introduction

Diaphyseal bone defect represents a significant problem for orthopaedic surgeons and patients. Bone is a complex tissue whose structure and function depend strictly on ultrastructural organization of its components: cells, organic (extracellular matrix, ECM) and inorganic components. The purpose of this study was to evaluate bone regeneration in a critical diaphyseal defect treated by implantation of a magnetic scaffold fixed by hybrid system (magnetic and mechanical), supplied through nanoparticle-magnetic (MNP) functionalized with Vascular Endothelial-Growth-Factor-(VEGF) and magnetic-guiding.

We performed a clinical, instrumental and radiographic study on a highly homogeneous series of 100 consecutive patients with unilateral ACL lesion at 7 years of minimum follow up, alternatively assigned to a single bundle reconstruction using patellar tendon (PT) or to a double bundle reconstruction using hamstrings (DB). Mean Tegner score was 4,8 for PT and 6,5 for DB (p=0,0005). Time for sport resumption was 6,6 months for PT and 3,8 months for DB (p=0,0052). There were no significative differences between the two groups regarding range of motion and functional subjective self-evaluation. Mean anterior displacement at instrumental evaluation performed with KT2000 showed no significative differences between the two groups. Objective clinical evaluation with IKDC was superior for DB group (A=86,5%; B=13,5%) respect to PT group (A=18,7%; B=75%; C=6,3%) (p< 0,0001). We found no differences regarding anterior knee pain between and Ahlback radiographic score the two groups and we have observed no recurrence of instability after surgical treatment. Double bundle ACL reconstruction with hamstrings has showed higher results respect to single bundle ACL reconstruction with patellar tendon in terms of Tegner score, IKDC, time for sport resumption.

We performed a retrospective clinical and radiographic evaluation of 100 cases operated in our institute between February 1996 and March 2003 with a mean follow-up of 60 months to assess the efficiency of UKR performed with a new minimally invasive technique. The aim of this study is to correlate the clinical outcome of the patients with the pre- and post-op alignment, and with implant positioning on coronal and sagittal plane.

100 patients (23 ♂, 64 ♀) underwent cemented UKR (De Puy Preservation Uni with all poly tibial component), both for arthritis and osteonecrosis. At the pre-op clinical and radiographic evaluation, 82 patients presented a varus deformity, 5 patients a valgus deformity. The Hospital for Special Surgery Score (HSS) was used to determine the subjective and objective clinical status of the patients before and after the intervention.

Pre-op antero-posterior (AP) x-rays of the knee were executed to establish the femoro-tibial angle (FTA) and the angle between the affected tibial plateau and the tibial anatomical axis (PTA), while latero-lateral (LL) x-rays were performed to determine the posterior tibial slope (PS). To analyze ligamentous balancing, x-rays were performed both in supine and in plain weight bearing stance. Post-op, we performed supine AP e LL X-rays and at a mean follow-up of sixty months (12–84 months) we performed AP and LL plain weight bearing x-rays.

We considered a knee with FTA > 175° as varus knee, 170°< FTA< 175° as normal knee and an FTA < 170° as valgus knee. Moreover, we assumed a TPA > 90° for valgus knee and a TPA< 90° for varus knee.

According with HSS scoring system, at a mean follow-up of 60 months, 63 (76%) cases were excellent (100-85 points), 15 (18%) cases were good (84-70 points), 5 (6%) bad results (< 60 points). Our results demonstrate that patients with a pre-operative varus alignment of 7 degrees are slightly more likely to be selected for UKR. In our series, patients with an excellent clinical result presented pre-operatively a mean varus deformity of 7,9°. According to literature, we demonstrated that a small amount of undercorrection with a residual varus deformity of 3–5° is the goal to be reached in order to avoid both rapid degeneration of the non-replaced compartment as well as the premature loosening of the replaced compartment. We performed a mean axial correction of 5,1° leaving a mean axial varus deformity of 2,8° in the excellent group. In our series the group with excellent results also showed a post-operative PTS of 7,1°, while mean pre-operative PTS was 6,6°. Moreover, the further our radiographic findings were from the optimal position suggested, the worst were the results : a decrease was evident comparing excellent group with good group and this was even more marked comparing excellent group with bad results group.

Aims: Neutral alignment and soft tissue balance are universally accepted as the most important objectives when performing a total knee replacement regardless of the preoperative deformity and implant type. Nevertheless, there is scarce evidence in the scientific literature of the effect of surgical correction on varus/valgus alignment variation during follow-up. We wanted to verify if the femur-tibial alignment after a total knee replacement was maintained at three years’ follow-up, and whether any variation might be correlated to anatomical characteristics before surgery, and to position and fixation of the tibial component within bone.

Methods: We assessed thirty patients with a cemented TKR implant preoperatively, and at one and three years’ follow-up. Lower limb alignment and tibial component position were evaluated manually from antero-posterior radiographs in weight-bearing position. The tibial component varus/valgus migration was measured by Roentgen Stereophotogrammetry.

Results: In spite of the correct alignment obtained during surgery, at 3 years’ follow-up 40% of patients presented an alignment variation of over 3°. The variation of deformity was not correlated with the preoperative deformity, nor with the tibial component position with respect to the tibial shaft nor with its migration.

Conclusions: After total knee arthroplasty, the recurrence of deformity is a common finding in spite of correct alignment obtained during surgery, but it does not influence the clinical result at mid-term follow-up. Anyway the unbalanced forces determining variation in coronal alignment, at a longer follow-up might produce deficiency of soft tissue structures, loosening of the prosthesis component, or polyethylene failure, leading to revision surgery.

Rotational defects of the lower limb are frequently encountered and often underestimated. In fact, many symptoms in the lower joint can be related to rotational alteration in the lower leg. These problems are often more visible in the knee joint because they reflect the rotational problems of proximal and distal femur and tibia, respectively. The extensor apparatus, due to the fact that it interacts with both bones, is the more affected joint. Many authors have demonstrated that femoral anteversion increases stress on the patello-femoral joint due to excessive lateralisation of the patella. In the same manner, distal femur internal rotation increases the stress due to altered tracking of the patella during ROM.

Valgus knee places stress on the patello-femoral joint, increasing the Q angle and determining a retraction of the lateral structure that causes stress on the lateral patellar face and altered patellar scratch during ROM. External tibial rotation also has been documented to increase the Q angle and patellar tilt, causing excessive stress on the patello-femoral joint. Valgus pronation of the foot, increasing the valgus stress on the knee, can contribute to patello-femoral symptoms, increasing the muscle imbalance at this level.

These documented alterations contribute together with other anatomical abnormalities, such as trochlear dysplasia or muscle hypoplasia, in creating the high variability of patello-femoral symptoms that are observed. Rotational deformity of the lower leg therefore represents a frequently encountered pathological condition that must be taken into account when treating patello-femoral symptoms.

Valgus deformity of the knee in relation to femoral dysplasia and post-traumatic varus deformity in relation to supracondylar fracture often needs to be corrected with varus or valgus distal femoral osteotomy. This procedure must be very precise to avoid compartimental overstress. However, in valgus knee the deformity is very often not only bi-planar but also tri-planar. In fact, the rotational defect of the distal femur can play an important role in determining the clinical symptoms and in altering the pathway of patello-femoral joint.

Therefore, correcting only the valgus deformity does not solve the clinical symptoms related to incorrect rotation of distal femur. The same problem is often encountered in distal femoral deformity in relation to supracondylar fracture. The bad alignment of the healed fracture is very often on the three planes and this fact has always to be taken into account during the pre-operative planning.

The pre-operative planning is fundamental and CT of the knee joint with reference to hip and ankle must be performed to evaluate the degree of rotational deformity that must be corrected. During surgery after the correction of valgus or varus deformity is fundamental to re-check the femur rotation, because the osteotomy automatically changes also the rotation of the distal femur. However, this correction may be insufficient to correct the rotation that can maintain clinical symptoms in the patello-femoral joint. If this is the case, an additional correction in external rotation is usually necessary to achieve an overall correction of distal femoral deformity.

In our opinion, the difficulties and accuracy necessary to correct this type of pathology are often underestimated.