We created TiO. 2. nanotubes (TNTs) on the surface of titanium (Ti) implants with subsequential loading with gentamicin and chitosan, acting as a control release agent, by electrophoretic deposition (EPD). We hypothesized femoral implants with TNTs loaded with gentamicin and chitosan would localize antibiotic to the implant and surgical site and prevent PJI in a mouse model. Ti-6Al-4V ELI wires underwent TNT surface modification by two-step anodization. EPD was then used to load gentamicin and chitosan onto the Ti wire with surface TNTs. Control Ti wires contained TNTs with EPD of chitosan only. 12-week-old male C57BL/6J mice underwent received a right femoral intramedullary implant followed by inoculation at the surgical site with 1×10. 3. CFUs of bioluminescent Xen36 Staphylococcus aureus (S. aureus). Mice were randomly divided into two implant groups: 1) Gentamicin + Chitosan Group (n=7; experimental group); 2) Chitosan Group (n=7; control group). Outcomes included: 1) Relative S. aureus abundance by bioluminescence imaging; 2) Quantification of S. aureus at the implant and surrounding tissue by colony forming unit (CFU) analysis; 3) Scanning electron microscopy (SEM) for implant bacterial biofilm; 4) Radiographic signs of PJI. Over 14 days assessment following wire implantation and inoculation with S. aureus, the experimental group had no evidence of infection based on i) no increased Xen36 S. aureus bioluminescence signal and ii) no CFUs present. All control had increased bioluminescence signal, above baseline, at all time-points and presence of CFUs. Ti femoral implants modified with surface TNTs and coated with gentamicin and chitosan through EPD prevented PJI in all mice through 14 days. In comparison, all control mice demonstrated evidence of PJI over 14 days. Implants with TNTs and EPD of gentamicin were highly effective in this mouse PJI model

Introduction. PJI is a devastating complication following total joint arthroplasty. In this study, we explore the efficacy of a bacteriophage-derived lysin, PlySs2, against in-vitro biofilm on titanium implant surfaces and in an acute in-vivo murine debridement antibiotic implant retention (DAIR) model of PJI. Methods. In-vitro: Xen 36 S. aureus biofilm was grown on Ti-6Al-4V mouse tibial implants for 1 day or 5 days and subsequently exposed to growth media, 1000× minimal inhibitory concentration (MIC) Vancomycin, or 5× MIC PlySs2. Implants were sonicated and analyzed for Colony Forming Units (CFU). In-vivo: A Ti-6Al-4V implant was inserted into the proximal tibia of C57BL/6J mice (n=21). All mice received 10. 4. CFU inoculation of Xen 36 S. aureus to the knee joint capsule and the infection was permitted 5 days to progress. On day 5 the mice were separated into three groups (n=7/group): (1) no further surgical intervention (control group), (2) irrigation and debridement (I&D) with saline, (3) I&D with 2mg/mL PlySs2. No implant-exchange was performed to mimic a debridement, antibiotic, and implant retention (DAIR) therapeutic strategy. All mice were sacrificed at day 10. Results. CFU counts for 1-day and 5-day in-vitro grown biofilm on implants demonstrate a >3log-fold reduction with PlySs2 compared to Vancomycin (p=0.01) with no significant difference between Vancomycin and control. In-vivo the addition of PlySs2 to Vancomycin treated mice reduces bacterial load in the periposthetic tissue and implant (p<0.05) with 5 days of treatment. Conclusion. PlySs2 5× MIC exhibits superior anti-microbial effect compared to Vancomycin on implants with 1-day and 5–5day biofilm maturities. The addition of PlySs2 to Vancomycin treatment of an acute established PJI further reduces tissue CFU and implants CFU. For any tables or figures, please contact the authors directly

Introduction. Three-dimensional (3D) printing of porous titanium implants marks a revolution in orthopaedics, promising enhanced bony fixation whilst maintaining design equivalence with conventionally manufactured components. No retrieval study has investigated differences between implants manufactured using these two methods. Our study was the first to compare these two groups using novel non-destructive methods. Materials and methods. We investigated 16 retrieved acetabular cups divided into ‘3D printed’ (n = 6; Delta TT) and ‘conventional’ (n = 10; Pinnacle Porocoat). The groups were matched for age, time to revision, size and gender (Table 1). Reasons for revision included unexplained pain, aseptic loosening, infection and ARMD. Visual inspection was performed to evaluate tissue attachment. Micro-CT was used to assess clinically relevant morphometric features of the porous structure, such as porosity, depth of the porous layer, pore size and strut thickness. Scanning electron microscopy (SEM) was applied to evaluate the surface morphology. Results. Significant differences (p = 0.0002) were found for all morphometric parameters (Table 2). Microscopic analysis revealed uniform beads over the backside of conventional implants, due to the manufacturing technique (Figure 1a). Conversely, beads of random size were found on 3D printed implants, representing a by-product of the manufacturing process, where some starting powder particles are not completely fused together (Figure 1b). The two groups showed similar tissue attachment (3D printed 76.9 ± 27.1%; conventional 73.8 ± 12.2%; p = 0.2635). Conclusion. This was the first study to analyse retrieved 3D printed orthopaedic implants. Differences were found between these and conventional implants, but both literature and registry data do not suggest a short-mid-term clinical issue with 3D printed components. Similar tissue on growth suggested a comparable behaviour with bone in situ. The key difference is the presence of the particles on 3D printed implants, whose clinical significance needs to be investigated. For any figures or tables, please contact the authors directly

We evaluated the accuracy with which a custom-made acetabular component could be positioned at revision arthroplasty of the hip in patients with a Paprosky type 3 acetabular defect. A total of 16 patients with a Paprosky type 3 defect underwent revision surgery using a custom-made trabecular titanium implant. There were four men and 12 women with a median age of 67 years (48 to 79). The planned inclination (INCL), anteversion (AV), rotation and centre of rotation (COR) of the implant were compared with the post-operative position using CT scans. A total of seven implants were malpositioned in one or more parameters: one with respect to INCL, three with respect to AV, four with respect to rotation and five with respect to the COR. To the best of our knowledge, this is the first study in which CT data acquired for the pre-operative planning of a custom-made revision acetabular implant have been compared with CT data on the post-operative position. The results are encouraging. Cite this article: Bone Joint J 2015; 97-B:780–5

Aims

The aims of this study were to develop an in vivo model of periprosthetic joint infection (PJI) in cemented hip hemiarthroplasty, and to monitor infection and biofilm formation in real-time.

Aims

Aseptic loosening is a leading cause of uncemented arthroplasty failure, often accompanied by fibrotic tissue at the bone-implant interface. A biological target, neutrophil extracellular traps (NETs), was investigated as a crucial connection between the innate immune system’s response to injury, fibrotic tissue development, and proper bone healing. Prevalence of NETs in peri-implant fibrotic tissue from aseptic loosening patients was assessed. A murine model of osseointegration failure was used to test the hypothesis that inhibition (through Pad4^-/- mice that display defects in peptidyl arginine deiminase 4 (PAD4), an essential protein required for NETs) or resolution (via DNase 1 treatment, an enzyme that degrades the cytotoxic DNA matrix) of NETs can prevent osseointegration failure and formation of peri-implant fibrotic tissue.

Aims

The aim of this study was to evaluate the performance of first-generation annealed highly cross-linked polyethylene (HXLPE) in cementless total hip arthroplasty (THA).

We have investigated nine patients with cemented Furlong (JRI, London, UK) titanium hip replacements who presented with early pain despite a well-fixed, aseptic prosthesis. All were followed up clinically and radiologically at regular intervals. Pain was located in the thigh and was worse at night. Radiographs showed cortical hypertrophy of the femur around the tip of the stem. Eight of the nine patients subsequently required single-stage revision using an uncemented prosthesis, which relieved the pain. At revision, the pH of the tip of the stem was found to be highly acidic with macroscopic evidence of corrosion consisting of multiple layers of titanium oxides when studied by X-ray dispersive analysis. Cemented titanium implants have a potential for crevice corrosion leading to cortical hypertrophy and intractable pain

Bone ingrowth is desired with uncemented hip implants. Infection is clearly undesirable. We have worked on developing a nanofiber coating for implants that would enhance bone formation while inhibiting infection. Few studies have focused on developing an implant surface nanofiber (NF) coating to prevent infection and enhance osseointegration by local drug release. In this study, coaxial doxycycline (Doxy)-doped polycaprolactone/polyvinyl alcohol (PCL/PVA) Nanofibers were directly deposited on the titanium (Ti) implant surface during electrospinning. The interaction of loaded Doxy with both PVA and PCL NFs was characterized by Raman spectroscopy. The bonding strength of Doxy-doped NF coating on Ti implants was confirmed by a stand single-pass scratch test. The improved implant osseointegration by PCL/PVA NF coatings in vivo was confirmed by scanning electron microscopy, histomorphometry and micro computed tomography at 2, 4 and 8 weeks after implantation. The bone contact surface (%) changes of NF coating group (80%) is significantly higher than that of no NF group (< 5%, p<0.05). Finally, we demonstrated that Doxy-doped NF coating effectively inhibited bacterial infection and enhanced osseointegration in an infected (Staphylococcus aureus) tibia implantation rat model. Doxy released from NF coating inhibited bacterial growth up to 8 weeks in vivo. The maximal push-in force of Doxy-NF coating (38 N) is much higher than that of NF coating group (6.5 N) 8 weeks after implantation (p<0.05), which was further confirmed by quantitative histological analysis and micro computed tomography. These findings indicate that coaxial PCL/PVA NF coating doped with Doxy and/or other drugs have great potential in enhancing implant osseointegration and preventing infection

Introduction. Tantalum trabecular metal components are increasingly used to reconstruct major bone defects in revision arthroplasty surgery. It is known that some metals such as silver have antibacterial properties. Recent reports have raised the question as to whether Tantalum components are protective against infection in revision surgery. This is based on a retrospective, single institution review, of revision cases comparing tantalum with titanium acetabular implants, which reported a lower incidence of subsequent infection in the tantalum group. This laboratory study aimed to establish if tantalum had any intrinsic antibacterial properties against planktonic bacteria or ability to inhibit biofilm formation. Materials and methods. Equal sized pieces of tantalum (Trabecular metal, Zimmer UK) and titanium (Trilogy, Zimmer UK) were sterilised and then incubated with a low dose inoculum of either Staphylococcus aureus or Staphylococcus epidermidis for 24 hours. After serial dilution, colony forming units were quantified on MH agar plates. To establish the ability to inhibit biofilm formation these tantalum and titanium pieces were then washed twice, sonicated and washed again to remove loosely adhered planktonic bacteria. They were then re-incubated for 24 hours prior to quantifying colony forming units. All experiments were performed in triplicate. Results. More than 1×10. 8. cfu/ml were observed in both the titanium and tantalum experiments. After washing and sonication more than 2×10. 7. cfu/ml were observed for both tantalum and titanium groups. The results were the same for both Staph Aureus and Staph Epidermidis. Discussion. Compared with titanium controls tantalum did not demonstrate any intrinsic antibacterial activity or ability to inhibit biofilm formation. The intrinsic properties of tantalum do not account for the previously observed reduction in subsequent infection when tantalum was used in the revision procedure. Conclusion. Tantalum does not have any intrinsic antimicrobial properties or ability to inhibit biofilm formation

Aims

Cementless femoral stems must be correctly sized and well-seated to obtain satisfactory biological fixation. The change in sound that occurs during impaction of the femoral broach is said to indicate good fit, but this has not been widely studied. We set out to find whether the presence or absence of these sound changes could predict correct sizing.

Acetabular bone loss is a challenging problem facing the revision total hip replacement surgeon. Reconstruction of the acetabulum depends on the presence of anterosuperior and posteroinferior pelvic column support for component fixation and stability. The Paprosky classification is most commonly used when determining the location and degree of acetabular bone loss. Augments serve the function of either providing primary construct stability or supplementary fixation.

When a pelvic discontinuity is encountered we advocate the use of an acetabular distraction technique with a jumbo cup and modular porous metal acetabular augments for the treatment of severe acetabular bone loss and associated chronic pelvic discontinuity.

Cite this article: Bone Joint J 2014;96-B(11 Suppl A):36–42.

In 2004 we described the ten-year prospective results of 38 total hip replacements using the Furlong hydroxyapatite-ceramic-coated femoral component in 35 patients < 50 years old. We have now reviewed the surviving 35 arthroplasties in 33 patients at a mean of 16 years (10.3 to 19.9). The mean age of the surviving patients at the time of operation was 41.3 years (26.0 to 49.0). Of these, eight have undergone revision of their acetabular component for aseptic loosening. None of the femoral components has had revision for aseptic loosening giving a survival rate of 100% at 16 years (95% confidence interval 89% to 100%).

The Furlong hydroxyapatite-ceramic-coated femoral component gives excellent long-term survival in young and active patients.

Between 1986 and 1991 we implanted 331 consecutive Furlong hydroxyapatite-coated femoral components of a total hip replacement in 291 patients. A cemented acetabular prosthesis was used in 217 hips and a hydroxyapatite-coated component in 114. We describe the long-term clinical and radiological survival of the femoral component at a mean follow-up of 17.5 years (15 to 21). Only two patients (0.68%) were lost to follow-up. With revision of the femoral component for any reason as the endpoint, the survival at a mean of 17 years was 97.4% (95% confidence interval 94.1 to 99.5), and with revision for aseptic loosening as the endpoint it was 100%. The survival at a maximum of 21 years with revision of the femoral component for any reason as the endpoint was 97.4% (95% confidence interval 81.0 or 99.5). These results compare favourably with the best long-term results of cemented or uncemented femoral components used in total hip replacement.

We describe three cases of fracture of the titanium JRI-Furlong hydroxyapatite-ceramic (HAC)-coated femoral component. We have examined previous case reports of failure of this stem and conclude that fracture may occur in two places, namely at the neck-shoulder junction and at the conical-distal cylindrical junction. These breakages are the result of fatigue in a metallurgically-proven normal femoral component. All the cases of failure of the femoral component have occurred in patients with a body mass index of more than 25 in whom a small component, either size 9 or 10, had been used.

In patients with a body mass index above normal size 9 components should be avoided and the femoral canal should be reamed sufficiently to accept a large femoral component to ensure that there is adequate metaphyseal fixation.

We have reviewed 42 patients who had revision of metal-on-metal resurfacing procedures, mostly because of problems with the acetabular component. The revisions were carried out a mean of 26.2 months (1 to 76) after the initial operation and most of the patients (30) were female.

Malpositioning of the acetabular component resulted in 27 revisions, mostly because of excessive abduction (mean 69.9°; 56° to 98°) or insufficient or excessive anteversion. Seven patients had more than one reason for revision. The mean increase in the diameter of the component was 1.8 mm (0 to 4) when exchange was needed.

Malpositioning of the components was associated with metallosis and a high level of serum ions. The results of revision of the femoral component to a component with a modular head were excellent, but four patients had dislocation after revision and four required a further revision.