To evaluate the ability of different combinations of antibiotic loaded cement to inhibit bacteria growth and biofilm formation. Cement beads were aseptically prepared using Palacos R (plain 40g PMMA cement) or Palacos R+G (40g PMMA cement containing industrially added 0.5g of gentamicin), with or without supplementary antibiotics as follows: Palacos R; Palacos R+G; Palacos R The group 2 cement beads were initially eluted in broth at 37o C for 72hours then transferred to fresh broth containing a known concentration of bacteria. The group 1 samples were not eluted but directly immerse in culture broth containing bacteria. All samples were thereafter incubated at 37oC for 24 hours. After incubation, group 1 samples were visually assessed for bacterial growth, while for the group 2 samples, biofilm formation were quantified using ultrasonication and viable bacteria counting technique. Three proficient biofilm forming Aim
Method
The mini-incision posterior approach may appeal to surgeons comfortable with the standard posterior approach to the hip. We present the first systematic review and meta-analysis of these two approaches. Twelve randomised controlled trials and four non-randomised trials comprising of 1498 total hip arthroplasties were included. The mini-incision posterior approach was associated with an early improvement in Harris hip score of 1.8 points (P < 0.001), reduced operating time (5 minutes, P < 0.001), length of hospital stay (14 hours, P < 0.001), intraoperative and total blood loss (63 ml, P < 0.001 and 119 ml, P < 0.001 respectively). There were no statistically significant differences on the incidence of dislocation, nerve injury, infection or venous thromboembolic events. The minimally invasive posterior approach appears to provide a safe and acceptable alternative to the standard incision posterior approach.
The subvastus approach has potential early advantages over the medial parapatellar approach because it avoids disruption of the quadriceps tendon. We present a systematic review and meta-analysis of the functional outcomes and complications associated with these two approaches. Following an extensive search of prospective trials published in any language before 1st August 2014, studies were screened in duplicate according to pre-defined inclusion and exclusion criteria. Sixteen randomised controlled trials were included in the meta-analysis comprising of 1,711 total knee replacements. Knee society score and range of movement were significantly superior in the subvastus group at early and one-year follow up. The subvastus approach was also associated with a statistically significant reduction in the requirement for intraoperative lateral release, perioperative blood loss, visual analogue score for pain on day 1 post operatively, and the number of days to achieve active straight leg raising. Both tourniquet time and total operative time were increased for the subvastus approach. There was no statistically significant difference in complications such as stiffness requiring MUA, superficial and deep infection and deep vein thrombosis. The subvastus approach confers a functional advantage over the medial parapatellar approach to the knee which lasts for a minimum of one year postoperatively.
The physiological effects of 1,25 vitamin D3 (1,25D) are well known and the previously held dogma was that this was the only active vitamin D metabolite. A number of methods have been employed to demonstrate the effects of 24,25-dihydroxyvitamin D3 (24,25D) on osteoblast maturation responses, in the presence of FHBP, ((3S) 1-Fluoro-3-hydroxy-4-(oleoyloxy)butyl-1-phosphonate), an agonist of lysophosphatidic acid (LPA). These include alkaline phosphatase (ALP) expression and investigation of the role of CYP27B1, which is the enzyme responsible for converting 24,25D to 1,24,25D. Ketoconazole, which inhibits the actions of CYP27B1, as well as an enzyme-linked immunosorbant assay (ELISA) for CYP27B1 were used. The results clearly demonstrate that 24,25D stimulates maturation of MG63 cells when combined with FHBP. It has also been shown that the metabolite is not converted to another active form (for example, 1,24,25D) within osteoblasts, due to the absence of CYP27B1. 24,25D is an active vitamin D metabolite and exerts its effects in a bone fide manner, rather than following conversion to another active metabolite in osteoblasts. Given it is non-calcaemic, this metabolite has the exciting potential of being used in a bone regenerative setting in orthopaedic applications.
Triple-tapered cemented stems were developed in the hope that they would reduce aseptic loosening and prevent calcar bone loss. Between March 2005 and April 2008, a consecutive series of 415 primary C-stem AMT hip arthroplasties in 386 patients were performed under the care of three surgeons at our institution. When all the patients had reached the 5-year anniversary of surgery, functional questionnaires were sent out by mail. In the event of non-response, reminders were sent by post before the patients were contacted by telephone. Postoperative radiographs were also reviewed. Follow-up ranges from 60 to 99 months, with a mean of 76 months. 32 hips (8%) were lost to follow-up. The median OHS was 40, median SF-12 mental component score (MCS) was 50, and median SF-12 physical component score (PCS) was 39. Radiographic review showed that aseptic femoral component loosening has yet to be observed. At 99 months follow up, stem survivorship is 96.9% (95% confidence interval (CI) 82.5 to 99.5). Adverse events such as calcar fracture, greater trochanter fracture and dislocation were rare at <1%. The C-stem AMT demonstrates excellent implant survivorship at 5–8 year follow-up, as well as good midterm functional outcome.
Prosthetic joint infection(PJI) still remains a concern in orthopaedic practice. Antibiotic-loaded acrylic-cement(ALAC) is a proven means of lowering the incidence of PJI. However, increasing antimicrobial resistance has complicated both prophylaxis and treatment, prompting the use of combination antimicrobial therapy, with the addition of vancomycin to gentamicin-containing ALAC commonly used. The new antimicrobial, daptomycin, has better activity than vancomycin and we studied its elution from ALAC in comparison with vancomycin, along with its impact on the co-elution of gentamicin. Cement beads were prepared from PalacosRG containing, 1g/2g daptomycin, 1g/2g vancomycin and without additional antibiotics. Six replicates of each combination were eluted in PBS at 37oC, at timed intervals, for up to 90days, the antibiotic loss was assessed using validated assays. The mean recovery of gentamicin after 90days was 1.1mg with half eluted within the first 6 hours. Recovery was significantly increased by 60% and 40% with addition of 1g&2g of daptomycin(two-tail t-test: p=0.004 and p=0.02), respectively. Although there was a slight increase in gentamicin recovery in vancomycin loaded samples, this was not statistically significant(p>0.05). The significant increases in gentamicin elution from Palacos RG when supplemented with daptomycin, along with a superior activity, may provide a better synergistic effect than PalacosRG supplemented with vancomycin in the management of PJI.
Cyanoacrylate tissue compounds are marketed as a surgical wound dressing with a variety of properties including microbiological impermeability. This study compares the bacteriological impermeability of cyanoacrylates and a commonly used occlusive adhesive dressing using a technique established in several other studies. Cyanoacrylate compound and an occlusive dressing were applied to both CLED and CROM agar plates. S. Aureus and E. Coli was then applied in a range of concentrations. The work demonstrated that cyanoacrylate compound provides as occlusive a barrier to microbiological penetration as adhesive dressings.
Orthopaedic cobalt chromium particles and ions can induce indirect DNA damage and chromosome aberrations in human cells on the other side of a cellular barrier in tissue culture. This occurs by intercellular signalling across the barrier. We now show that the threshold for this effect depends on the metal form and the particle composition. Ionic cobalt and chromium induced single strand breaks at concentrations equivalent to those found in the blood of patients with well functioning metal on metal hip prostheses. However, they only caused double strand breaks if the chromium was present as chromium (VI), and did not induce chromosome aberrations. Nanoparticles of cobalt chromium alloy caused DNA double strand breaks and chromosome aberrations, of which the majority were tetraploidy. Ceramic nanoparticles induced only single strand breaks and/or alkaline labile sites when indirectly exposed to human fibroblasts. The assessment of reproductive risk from maternal exposure to biomaterials, especially those liberated by orthopaedic implants, is not yet possible with epidemiology. Whilst the barrier model used here differs from the in vivo situation in several respects, it may be useful as a framework to evaluate biomaterial induced damage across physiological barriers.
Accelerometer based gait analysis (AGA) is a potential alternative to the more commonly used skin marker based optical motion analysis system(OMAS). The use of gyroscopes in conjunction with accelerometers (i.e. inertial sensors), enables the assessment of position and angular movements of body segments and provides ambulatory kinematic characterisation of gait. We investigated commonly used gait parameters and also a novel parameter, Pelvic obliquity (PO) and whether they can be used as a parameter of physical function and correlate with classic clinical outcome scores Gait was studied in healthy subjects (n=20), in patients with end stage hip OA (n=20) and in patients with end stage knee OA (n=20). Subjects walked 20 metres in an indoor environment along a straight flat corridor at their own preferred speed. A 3D inertial sensor was positioned centrally between the posterior superior iliac spines (PSIS) overlying S1. Comparing gait parameters of end stage hip OA patients with an age and gender matched healthy control group, significantly lower walking speed, longer step duration and shorter step length was observed. After correcting for walking speed between groups, significantly less average range of motion of PO (RoMpo) was observed for patients with end stage hip OA compared to healthy subjects and patients with end stage knee OA. IGA allows objective assessment of physical function for everyday clinical practice and allows assessment of functional parameters beyond time only. IGA measures another dimension of physical function and could be used supplementary to monitor recovery of OA patients after TJR.
Successful osseointegration requires the production of a mechanically competent collagenous matrix, by osteoblasts, at the implant site. Lysophosphatidic acid (LPA) is a bioactive lipid which we discovered interacts with vitamin D3 (D3) to secure human osteoblast (hOB) maturation on both titanium (Ti) and hydroxyapatite. We therefore covalently attached LPA and a related compound, (3S) 1-fluoro-3-hydroxy-4-butyl-1-phosphate (FHBP), to both solid and porous Ti discs and seeded them with hOBs to assess their ability to support D3-induced cell maturation. Solid functionalised discs were washed and reused a further two times, whilst other discs were stored for 6 months. Increased alkaline phosphatase (ALP) activity indicated that both LPA and FHBP-modified Ti serve as superior substrates for securing D3-induced hOB maturation compared to unmodified metal (p < 0.001). Although total ALP activity was less for cells on recycled discs and after storage, enzyme levels were still significantly greater compared to hOBs grown on control Ti. LPA and D3 co-treatment also resulted in an increase in osteocalcin (∼17ng/ml versus 6ng/ml for D3 alone, P < 0.001) and collagen synthesis (∼310pg/ml versus <10pg/ml for D3 alone, P < 0.001). Research is ongoing to evaluate the efficacy of our modified Ti surfaces to secure hOB formation from their stem cell progenitors.
Total Shoulder Resurfacing (TSR) provides a reliable solution for the treatment of glenohumeral arthritis. It confers a number of advantages over traditional joint replacement with stemmed humeral components, in terms of bone preservation and improved joint kinematics. This study aimed to determine if humeral reaming instruments produce a thermal insult to subchondral bone during TSR. This was tested in vivo on 13 patients (8 with rheumatoid arthritis and 5 with osteoarthritis) with a single reaming system and in vitro with three different humeral reaming systems on saw bone models. Real-time infrared thermal video imaging was used to assess the temperatures generated. Synthes Epoca instruments generated average temperatures of 40.7°C (SD 0.9°C) in the rheumatoid group and 56.5°C (SD 0.87°C) in the osteoarthritis group (p = 0.001). Irrigation with room temperature saline cooled the humeral head to 30°C (SD 1.2°C). Saw bone analysis generated temperatures of 58.2°C (SD 0.79°C) in the Synthes (Epoca) 59.9°C (SD 0.81°C) in Biomet (Copeland) and 58.4°C (SD 0.88°C) in the Depuy (CAP) reamers (p=0.12). Humeral reaming with power driven instruments generates considerable temperatures both in vivo and in vitro. This paper demonstrates that a significant thermal effect beyond the 47°C threshold needed to induce osteonecrosis is observed with humeral reamers, with little variation seen between manufacturers. Irrigation with room temperature saline cools the reamed bone to physiological levels, and should be performed regularly during this step in TSR.
