Background. Impaction bone grafting with milled human allograft is the gold standard for replacing lost bone stock during revision hip surgery. Problems surrounding the use of allograft include cost, availability, disease transmission and stem subsidence (usually due to shear failure of the surrounding allograft). Aims. To investigate various polymers for use as substitute allograft. The ideal graft would be a composite with similar mechanical characteristics as allograft, and with the ability to form de novo bone. Methods. High and low molecular weight (MW) forms of three different polymers (polylactic acid (PLA), poly (lactic-co-glycolic) acid (PLGA) and polycaprolactone (PCL)) were milled, impacted into discs, and then tested in a custom built shear testing rig, and compared to allograft. A second stage of the experiment involved the addition of skeletal stem cells (SSC) to each of the milled polymers, impaction, 8 days incubation, and then tests for cell viability and number, via fluorostaining and biochemical (WST-1, DNA) assays. Results. The shear strengths of both high/ low MW PLA, and high/low MW PLGA were significantly higher than those of milled allograft but high and low MW PCL was poor to impact, and had significantly lower shear strengths. Fluorostaining showed good cell survival on high MW PLA, high MW PCL and both high and low MW PLGA. These findings were confirmed on both DNA and WST-1 assays. Conclusions. High MW PLA as well as high and low MW PLGA performed well both in mechanical testing and cell compatibility studies. These three polymers are good contenders to produce a living composite for use as substitute human allograft in impaction bone grafting

Aims

Musculoskeletal infection is a devastating complication in both trauma and elective orthopaedic surgeries that can result in significant morbidity. Aim of this study was to assess the effectiveness and complications of local antibiotic impregnated dissolvable synthetic calcium sulphate beads (Stimulan Rapid Cure) in the hands of different surgeons from multiple centres in surgically managed bone and joint infections.

Bone is the second most commonly transplanted tissue worldwide, with over four million operations using bone grafts or bone substitute materials annually to treat bone defects. However, significant limitations affect current treatment options and clinical demand for bone grafts continues to rise due to conditions such as trauma, cancer, infection and arthritis. The need for a novel, cost effective treatment option for osteochondral defects has therefore never been greater. As an emerging technology, three-dimensional (3D) bioprinting has the capacity to deposit cells, extracellular matrices and other biological materials in user-defined patterns to build complex tissue constructs from the “bottom up”. Through use of extrusion bioprinting and fused deposition modelling (FDM) 3D printing, porous 3D scaffolds were successfully created in this study from hydrogels and synthetic polymers. Mesenchymal stem cells (MSCs) seeded onto polycaprolactone scaffolds with defined pore sizes and porosity maintained viability over a 7-day period, with addition of alginate hydrogel and scaffold surface treatment with NaOH increasing cell adhesion and viability. MSC-laden alginate constructs produced via extrusion bioprinting also maintained structural integrity and cell viability over 7 days in vitro culture. Growth within osteogenic media resulted in successful osteogenic differentiation of MSCs within scaffolds compared to controls (p<0.001). MSC spheroids were also successfully created and bioprinted within a novel, supramolecular hydrogel with tunable stiffness. In conclusion, 3D constructs capable of supporting osteogenic differentiation of MSCs were biofabricated via FDM and extrusion bioprinting. Future work will look to increase osteochondral construct size and complexity, whilst maintaining cell viability

In biomaterial engineering the surface of an implant can influence cell differentiation, adhesion and affinity towards the implant. Increased bone marrow derived mesenchymal stromal cell (BMSC) differentiation towards bone forming osteoblasts, on contact with an implant, can improve osteointegration. The process of micropatterning has been shown to improve osteointegration in polymers, but there are few reports surrounding ceramics. The purpose of this study was to establish a co-culture of BMSCs with osteoclast progenitor cells and to observe the response to micropatterned zirconia toughened alumina (ZTA) ceramics with 30 µm diameter pits. The aim was to establish if the pits were specifically bioactive towards osteogenesis or were generally bioactive and would also stimulate osteoclastogenesis that could potentially lead to osteolysis. We demonstrate specific bioactivity of micropits towards osteogenesis with more nodule formation and less osteoclastogenesis. This may have a role when designing ceramic orthopaedic implants

Nanoscale topography increases the bioactivity of a material and stimulates specific responses (third generation biomaterial properties) at the molecular level upon first generation (bioinert) or second generation (bioresorbable or bioactive) biomaterials. We developed a technique (based upon the effects of nanoscale topography) that facilitated the in vitro expansion of bone graft for subsequent implantation and investigated the optimal conditions for growing new mineralised bone in vitro. Two topographies (nanopits and nanoislands) were embossed into the bioresorbable polymer Polycaprolactone (PCL). Three dimensional cell culture was performed using double-sided embossing of substrates, seeding of both sides, and vertical positioning of substrates. The effect of Hydroxyapatite, and chemical stimulation were also examined. Human bone marrow was harvested from hip arthroplasty patients, the mesenchymal stem cells culture expanded and used for cellular analysis of substrate bioactivity. The cell line specificity and osteogenic behaviour was demonstrated through immunohistochemistry, confirmed by real-time PCR and quantitative PCR. Mineralisation was demonstrated using alizarin red staining. Results showed that the osteoinduction was optimally conferred by the presence of nanotopography, and also by the incorporation of hydroxyapatite (HA) into the PCL. The nanopit topography and HA were both superior to the use of BMP2 in the production of mineralised bone tissue. The protocol from shim production to bone marrow harvesting and vertical cell culture on nanoembossed HaPCL has been shown to be reproducible and potentially applicable to economical larger scale production

Introduction. Current artificial discs include 1 or 2 bearing surfaces, providing 3 or 5 degrees of freedom. The ESP® is a one-piece e implant made of silicon and polycarbonate -urethane securely fixed to titanium endplates. It allows limited rotation and translation with elastic return. This cushion without fixed rotation center achieves 6 degrees of freedom including shock absorption. This objective of this study was to evaluate the safety and efficacy of the concept in a prospective nonrandomized trial. Material and methods. Prior to clinical implantations, the device was endurance tested at least 40 millions cycles. The polymer core weight and properties, the geometrical characteristics and cohesion of the implants remained stable. A prospective trial was initiated in 2004 for L3L4, L4L5 and L5S1 levels. Total disc replacements have been performed in 153 lumbar levels through extra-peritoneal mini-invasive anterior approach with a minimum 2 years follow-up. Results. There was no clinical or radiological device related complication, except 2 early revisions for post-traumatic implant migrations (8, 17 days post-op.). When comparing the device to other implants, clinically relevant improvements in VAS, SF-36 and ODI scores were observed. At ultimate follow-up, the index level was mobile in 83% of the cases (5,3 ° ± 4.1). The mean centre of rotation was in the physiological area in 78% of cases without relevant modification of adjacent disc levels (Spineview® analysis). Conclusion. The 6 years clinical follow-up demonstrate the reliability of the concept and the safety and forgiveness of the implant

Background. Wear particles are considered to be the major culprit for the aseptic loosening. Their characterization is thus crucial for the understanding of their bioreactivity and contribution to the development of aseptic loosening. Methods. Metal wear debris particles were analyzed directly in periprosthetic tissue resins by scanning electron microscopy (SEM) combined with back-scattered electron imaging (BSE) and energy dispersive X-ray spectroscopy (EDS). Four groups of tissue samples retrieved at revision operations of loosened hip implants with different bearing surfaces (metal-on-metal, ceramic-on-polyethylene and metal-on-polyethylene), and different material of the femoral stem (Ti alloy, CoCrMo and polymer combined with stainless steel) were investigated. Tissue samples were first analyzed histologicaly. Sections from the same paraffin blocks were then carbon coated and analyzed using SEM/BSE/EDS method. Results. Metal particles were detected in all samples. Their composition corresponded to the composition of the implant components. The gradation of metal particles ranged from +1 to +3. A considerable number of big metal particles were actually agglomerates of submicron particles visible only at higher magnification. The clustering of particles was observed primarily for CoCrMo and, to a lesser extent, for stainless steels particles. The median sizes of CoCrMo clusters in two groups of samples were 2.9 1.8 m (range, 0.5 to 7.6 m) and 3.2 1.0 m (range, 1.9 to 5.4 m). The effect of clustering was not observed for Ti particles. The median sizes of individual Ti particles determined in two groups of samples were 2.5 3.6 m (range, 0.4 to 17.3 m) and 4.3 2.8 m (range, 0.8 to 11.0 m). Conclusion. Scanning electron microscopy combined with back-scattered electron imaging is an appropriate and selective method to recognize metal particles in tissue sections, without being destructive to specimens. When the size of the particles is considered, however, it should be differed between the size of individual particles and size of clusters of particles. Besides its benefits, this study has some limitations: the detection of particles smaller than 0.4 m is difficult, and this method cannot be used to identify polyethylene particles

Recent findings about UHMWPE oxidation from in vivo stresses lead to the need of a better understanding of which anti-oxidant additivation method is the best option for the use in orthopaedic field. A GUR 1050 crosslinked Vitamin E - blended UHMWPE has been investigated, to provide an accurate outline of its properties. DSC and FTIR measurements, together with ageing and tensile tests were performed on compression moulded blocks, as well as biocompatibility tests, including implantation on rabbits. Moreover, wear simulations on finished components (Delta acetabular liners) have been completed. All the test procedures have been repeated for a reference material, a GUR 1050 crosslinked and remelted standard UHMWPE (commercial name UHMWPE X-Lima), and the outcomes have been compared to the crosslinked Vitamin E - blended UHMWPE ones. On the additivated UHMWPE, we found a ultimate tensile strength of 43 MPa, a yield strength value of 25 MPa, and an elongation to breakage equal to 320%. The degree of cristallinity was 45 ± 2%, and no signal of creation of oxidation products was detected up to 2000 h of permanence in oxidant ambient after the ageing test. The reference material showed comparable mechanical resistance values (∗ = 40 MPa, y = 20 MPa, 350% elongation), a cristallinity of 46 ± 2%, and the creation of oxidation products starting from 700 h in oxidant ambient. The biocompatibility tests indicate that the additivated material is biocompatible, as the reference X-Lima UHMWPE. Wear tests gave a wear rate of 5,09 mg/million cycles against 6,13 mg/million cycles of the reference material, and no sign of run in wear rate. Our results indicate that there is no change in mechanical properties in respect to the reference material. This is confirmed by DSC measurements, that show no change in cristallinity. The blend between polymer and additive assures an uniform concentration of Vitamin E across the whole thickness of the moulded block, and ageing test results on additivated UHMWPE have shown that the material possess a superior resistance to degradation phenomena. Biocompatibility assess that the presence of Vitamin E is not detrimental for the in vivo use of the material, and wear results indicate a better wear resistance of the material, especially in the first stages of the wear process. From these considerations, it can be concluded that the material, in respect to the standard UHMWPE, is highly resistant to oxidation phenomena, therefore it is expected to have superior in vivo endurance performance

Introduction. Vitamin E stabilization of radiation crosslinked UHMWPE is done by (1) blending into the resin powder, consolidating and irradiating or (2) diffusing into already consolidated and irradiated UHMWPE and terminally gamma sterilizing. With blending, a higher radiation dose is required for crosslinking to the same level as virgin UHMWPE. With diffusion, the vitamin E amount used is not limited by the crosslink density, but, vitamin E is exposed to terminal sterilization dose of 25–40 kGy, less than the 100–150 kGy used with blending, which may decrease the grafting of the antioxidant onto the polymer. We investigated the efficiency of grafted vitamin E against squlene-initiated accelerated aging. Methods. Medical grade GUR1050 UHMWPE with vitamin E (0.1 wt%) was irradiated to 150 kGy. Tibial knee insert preforms were irradiated to 100 kGy, diffused with vitamin E using a doping and homogenization procedure. This UHMWPE was used either before or after gamma sterilization. One set of machined blocks (10 × 10 × 6 mm; n = 6) were extracted in boiling hexane for 4 days, then dried. The extracted blocks were doped with squalene at 120°C for 2 hours. One block each was analyzed after doping. The rest were accelerated aged at 70°C and 5 atm. of oxygen for 6 (n = 2) and 14 days (n = 3). Thin sections (150 micron thick) were microtomed and analyzed by Fourier Transform Infrared Spectroscopy to determine a vitamin E index (1245–1275 cm. −1. normalized to 1850–1985 cm. −1. ) and an oxidation index (1700 cm. −1. normalized to 1370 cm. −1. ) after extraction with boiling hexane for 16 hours and drying. Results. After extraction, 92% of the original vitamin E was removed from diffused and sterilized UHMWPE and 99% of the vitamin E was removed from the diffused and unsterilized UHMWPE. Vitamin E content of the blended, irradiated UHMWPEs could not be detected. As a result of accelerated aging in the presence of squalene, all extracted vitamin E-stabilized UHMWPEs showed increased oxidation except diffused, sterilized UHMWPE. The small amount grafted vitamin E in these samples (8%, ∼0.02 wt%) protected irradiated UHMWPE under these conditions. All vitamin E-stabilized, extracted UHMWPEs showed higher oxidative stability than irradiated and melted virgin UHMWPE in the presence of squalene. In the blended, irradiated UHMWPE, there was less effective vitamin E compared to the diffused, sterilized UHMWPE due to the high dose irradiation. Conclusions. Radiation grafting of vitamin E onto UHMWPE was effective against squalene initiated oxidation in accelerated aging. Vitamin E-diffused, sterilized UHMWPE showed no oxidation and diffused, unsterilized UHMWPE and blended, irradiated UHMWPE showed higher oxidative resistance than irradiated/melted UHMWPE

Aims

To compare the cost-utility of standard dressing with incisional negative-pressure wound therapy (iNPWT) in adults with closed surgical wounds associated with major trauma to the lower limbs.

Our aim was to compare polylevolactic acid screws with titanium screws when used for fixation of the distal tibiofibular syndesmosis at mid-term follow-up. A total of 168 patients, with a mean age of 38.5 years (18 to 72) who were randomly allocated to receive either polylevolactic acid (n = 86) or metallic (n = 82) screws were included. The Baird scoring system was used to assess the overall satisfaction and functional recovery post-operatively. The demographic details and characteristics of the injury were similar in the two groups. The mean follow-up was 55.8 months (48 to 66). The Baird scores were similar in the two groups at the final follow-up. Patients in the polylevolactic acid group had a greater mean dorsiflexion (p = 0.011) and plantar-flexion of the injured ankles (p < 0.001). In the same group, 18 patients had a mild and eight patients had a moderate foreign body reaction. In the metallic groups eight had mild and none had a moderate foreign body reaction (p <  0.001). In total, three patients in the polylevolactic acid group and none in the metallic group had heterotopic ossification (p = 0.246).

We conclude that both screws provide adequate fixation and functional recovery, but polylevolactic acid screws are associated with a higher incidence of foreign body reactions.

Cite this article: Bone Joint J 2014;96-B:548–54.

Objectives

Deep bone and joint infections (DBJI) are directly intertwined with health, demographic change towards an elderly population, and wellbeing.

The elderly human population is more prone to acquire infections, and the consequences such as pain, reduced quality of life, morbidity, absence from work and premature retirement due to disability place significant burdens on already strained healthcare systems and societal budgets.

DBJIs are less responsive to systemic antibiotics because of poor vascular perfusion in necrotic bone, large bone defects and persistent biofilm-based infection. Emerging bacterial resistance poses a major threat and new innovative treatment modalities are urgently needed to curb its current trajectory.

Systemic antibiotics reduce infection in open fractures. Local delivery of antibiotics can provide higher doses to wounds without toxic systemic effects. This study investigated the effect on infection of combining systemic with local antibiotics via polymethylmethacrylate (PMMA) beads or gel delivery.

An established Staphylococcus aureus contaminated fracture model in rats was used. Wounds were debrided and irrigated six hours after contamination and animals assigned to one of three groups, all of which received systemic antibiotics. One group had local delivery via antibiotic gel, another PMMA beads and the control group received no local antibiotics. After two weeks, bacterial levels were quantified.

Combined local and systemic antibiotics were superior to systemic antibiotics alone at reducing the quantity of bacteria recoverable from each group (p = 0.002 for gel; p = 0.032 for beads). There was no difference in the bacterial counts between bead and gel delivery (p = 0.62).

These results suggest that local antibiotics augment the antimicrobial effect of systemic antibiotics. Although no significant difference was found between vehicles, gel delivery offers technical advantages with its biodegradable nature, ability to conform to wound shape and to deliver increased doses. Further study is required to see if the gel delivery system has a clinical role.

Cite this article: Bone Joint J 2015;97-B:1423–7.

We investigated a new intramedullary locking nail that allows the distal interlocking screws to be locked to the nail. We compared fixation using this new implant with fixation using either a conventional nail or a locking plate in a laboratory simulation of an osteoporotic fracture of the distal femur. A total of 15 human cadaver femora were used to simulate an AO 33-A3 fracture pattern. Paired specimens compared fixation using either a locking or non-locking retrograde nail, and using either a locking retrograde nail or a locking plate. The constructs underwent cyclical loading to simulate single-leg stance up to 125 000 cycles. Axial and torsional stiffness and displacement, cycles to failure and modes of failure were recorded for each specimen. When compared with locking plate constructs, locking nail constructs had significantly longer mean fatigue life (75 800 cycles (sd 33 900) vs 12 800 cycles (sd 6100); p = 0.007) and mean axial stiffness (220 N/mm (sd 80) vs 70 N/mm (sd 18); p = 0.005), but lower mean torsional stiffness (2.5 Nm/° (sd 0.9) vs 5.1 Nm/° (sd 1.5); p = 0.008). In addition, in the nail group the mode of failure was either cut-out of the distal screws or breakage of nails, and in the locking plate group breakage of the plate was always the mode of failure. Locking nail constructs had significantly longer mean fatigue life than non-locking nail constructs (78 900 cycles (sd 25 600) vs 52 400 cycles (sd 22 500); p = 0.04).

The new locking retrograde femoral nail showed better stiffness and fatigue life than locking plates, and superior fatigue life to non-locking nails, which may be advantageous in elderly patients.

Cite this article: Bone Joint J 2014;96-B:114–21.

Objectives

Osteochondral injuries, if not treated adequately, often lead to severe osteoarthritis. Possible treatment options include refixation of the fragment or replacement therapies such as Pridie drilling, microfracture or osteochondral grafts, all of which have certain disadvantages. Only refixation of the fragment can produce a smooth and resilient joint surface. The aim of this study was the evaluation of an ultrasound-activated bioresorbable pin for the refixation of osteochondral fragments under physiological conditions.