Biomaterial-related infections continue to hamper the success of reconstructive and arthroplasty procedures in orthopaedic surgery. Staphylococci are the most common etiologic agents, with biofilm formation representing a major virulence factor. Biofilms increase bacterial resistance to antimicrobial agents and host immune responses. In staphylococci, production of polysaccharide intercellular adhesin (PIA) by the enzyme products of the icaADBC operon is the best understood mechanism of biofilm development, making the ica genes a potential target for biofilm inhibitors. In this study we report that the antibacterial agent povidone-iodine (PI) also has anti-biofilm activity against Staphylococcus epidermidis and Staphylococcus aureus at sub-inhibitory concentrations (p < 0.001). Inhibition of biofilm by PI correlated with decreased transcription of the icaADBC operon, which in turn correlated with activation of the icaR transcriptional repressor in Staphylococcus epidermidis. These data reveal an additional therapeutic benefit of PI and suggest that studies to evaluate suitability of PI as biomaterial coating agent to reduce device-related infections are merited. Despite improvements in orthopaedic surgery over the last three decades, deep infections continue to hamper the success of reconstructive and arthroplasty procedures. Prosthetic joint infection is associated with significant morbidity and sometimes mortality of the individual. It also represents a tremendous economic burden to healthcare institutions and the general public as a whole.
Expression of the icaADBC-encoded polysaccharide intercellular adhesion by Staphylococcus epidermidis promotes biofilm formation and represents an important virulence factor in biomaterial-related infections following orthopedic surgery. Biofilm development by the pathogen can be viewed as a protective reaction to environmental stressors including osmotic stress, thermal stress, and antimicrobial chemotherapy. Oxidative stress, arising from the release of toxic oxygen radicals by polymorphonuclear cells, is encountered by bacteria entering the body perioperatively. Evasion of this and other cell-mediated immune responses by pathogenic bacteria plays an important role in the development of chronic biomaterial-related infection. Here we investigated the impact of sublethal oxidative stress induced by H 2 O 2 (<18 mM) on S. epidermidis biofilm formation. S. epidermidis grown in brain heart infusion (BHI) media supplemented with 5 mM H 2 O 2 or 10 mM H 2 O 2 formed significantly less biofilm (p < 0.01 and p < 0.001, respectively) than bacteria grown in BHI alone. Consistent with this, using reverse transcription-polymerase chain reaction expression of the ica locus was also shown to be reduced by subinhibitory concentrations of H 2 O 2 . Furthermore, diminished ica operon expression correlated with increased expression of icaR, which encodes a repressor of icaADBC. Thus, these data suggest that mild oxidative stress downregulates biofilm development by S. epidermidis and may have potential in a therapeutic context. ß
PurposeIdentification of anatomical structures that block reduction in developmental dysplasia of the hip (DDH) is important for the management of this challenging condition. Obstacles to reduction seen on arthrogram are well-known. However, despite the increasing use of MRI in the assessment of adequacy of reduction in DDH, the interpretation of MRI patho-anatomy is ill-defined with a lack of relevant literature to guide clinicians.MethodThis is a retrospective analysis of the MRI of patients with DDH treated by closed reduction over a five-year period (between 2009 and 2014). Neuromuscular and genetic disorders were excluded. Each MRI was analysed by two orthopaedic surgeons and a paediatric musculoskeletal radiologist to identify the ligamentum teres, pulvinar, transverse acetabular ligament (TAL), capsule, labrum and acetabular roof cartilage hypertrophy. Inter- and intraobserver reliability was calculated. The minimum follow-up was 12 months.ResultsA total of 29 patients (38 hips) underwent closed reduction for treatment of DDH. Eight hips showed persistent subluxation on post-operative MRI. Only three of these eight hips showed an abnormality on arthrogram. The pulvinar was frequently interpreted as ‘abnormal’ on MRI. The main obstacles identified on MRI were the ligamentum teres (15.8%), labrum (13.1%) and acetabular roof cartilage hypertrophy (13.2%). The inter-rater reliability was good for TAL, capsule and pulvinar; moderate for ligamentum teres and labrum; and poor for hypertrophied cartilage.ConclusionThe labrum, ligamentum teres and acetabular roof cartilage hypertrophy are the most important structures seen on MRI preventing complete reduction of DDH. Focused interpretation of these structures may assist in the management of DDH.
Purpose:This study was undertaken to evaluate the efficacy of a proximal humeral locking plate, and to specifically study the effect of patient age and fracture type on the outcome.Materials and Methods:Thirty-one cases of proximal humeral fractures fixed by using the proximal humeral interlocking (PHILOS) plate were reviewed.Results:Average functional scores (minimum 18 months post operation) per AO / ASIF fracture type were 25.3 for type A, 21.4 for type B, and 22.7 for type C. There was no statistically significant difference between the groups. The functional scores for patients over 65 years of age were significantly inferior (P = 0.03). At a final radiological review (mean 12 months post operation), 30 (96%) of the patients demonstrated fracture union. Seven patients (22.5%) required a second surgical procedure.Conclusion:We obtained both good functional results and bone healing with the PHILOS plate, irrespective of fracture type; the older patients had a poorer outcome. We caution the surgeons on the high potential for reoperations with its use.
Surgical hip dislocation is the gold standard for treatment of femoroacetabular impingement (FAI). It utilizes an intermuscular and internervous approach to the hip. Concerns have been expressed that this approach causes soft tissue trauma resulting in post-operative muscle weakness of patients undergoing this procedure. We therefore asked whether surgical hip dislocation leads to (i) atrophy (decreased muscle diameter or cross-sectional area [CSA]) and (ii) degeneration (fatty infiltration) of 18 evaluated periarticular hip muscles. We retrospectively evaluated 32 patients (34 hips) following surgical hip dislocation for the treatment of FAI using pre and post-operative magnetic resonance (MR) arthrography of the hip. We evaluated muscle diameter, CSA and degree of fatty infiltration according to Goutallier for 18 periarticular hip muscles on axial and sagittal views. The mean interval between pre and post-operative MR was 1.9 ± 1.5 years (range, 0.4–6.1 years). Pre and post-operative muscle diameter and CSA of all 18 evaluated hip muscles did not differ. There was no post-operative change in the Goutallier classification for any of the evaluated 18 muscles. No muscle had post-operative degeneration higher than Grade 1 according to Goutallier. No atrophy or degeneration of periarticular hip muscles could be found following surgical hip dislocation for treatment of FAI. Any raised concerns about the invasiveness and potential muscle trauma for this type of surgery are unfounded. Level III, retrospective comparative study. See guidelines for authors for a complete description of levels of evidence.
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