In vitro testing of a first-in-class tri-alkylnorspermidine-biaryl antibiotic in an anti-biofilm silicone coating.

Biofilm-related infection is among the worst complication to prosthetic joint replacement procedures; once established on the implant surface, biofilms show strong recalcitrance to clinical antibiotic therapy, frequently requiring costly revision procedures and prolonged systemic antibiotics for their removal. A well-designed active release coating might assist host immunity in clearing bacterial contaminants within the narrow perioperative window and ultimately prevent microbial colonization of the joint prosthesis. A first-in-class compound (CZ-01127) was tested as the active release agent in a silicone (Si) coating using an in vitro dynamic flow model of surgical site contamination and compared with analogous coatings containing clinical gold-standard antibiotics vancomycin and gentamicin; the CZ-01127 coating outperformed both vancomycin and gentamicin coatings and was the only to decrease the methicillin-resistant Staphylococcus aureus (MRSA) inocula below detectable limits for the first 3 days. The antimicrobial activity of CZ-01127, and for comparison vancomycin and gentamicin, were characterized against both planktonic and biofilm MRSA using the minimum inhibitory concentration (MIC) assay, serial passages, and serial dilution tests against established biofilms grown with a CBR 90 CDC biofilm reactor. Despite a similar MIC (1 µg/ml) and behavior in a 25-day serial passage analysis, CZ-01127 displayed much greater bactericidal activity against established biofilms and was the only to decrease biofilm colony forming units (CFUs) below detectable limits at the highest concentration tested (500 µg/ml). Coating release profiles were characterized using ATR-FTIR and displayed burst release kinetics within the decisive period of the perioperative window suggesting the silicon carrier is broadly useful for screening antibiotic compound for local delivery applications. STATEMENT OF SIGNIFICANCE: With an aging population, an increasing number of people are undergoing total joint replacement procedures in which diseased joint tissues are replaced with permanent metallic implants. Some of these procedures are burdened by costly and debilitating infections. A promising approach to prevent infections is the use of an antimicrobial coating on the surface of the implant which releases antibiotics into the surgical site to prevent infection. In this study, we tested a new antibiotic compound formulated in a silicone coating. Data showed that this compound was more effective at killing pathogenic methicillin resistant Staphylococcus aureus (MRSA) bacteria than two clinical gold-standard antibiotics-vancomycin and gentamicin-and could be a promising agent for antimicrobial coating technologies.

A prospective comparison of thoracoscopic vs open anterior instrumentation and spinal fusion for idiopathic thoracic scoliosis in children.

BACKGROUND/PURPOSE: The management of scoliosis in children has been evolving. Anterior release, diskectomy, and anterior instrumentation and spinal fusion (AISF) may be of benefit compared with a combined anterior and posterior or a posterior-only approach. Because thoracoscopic AISF (TAISF) has the potential benefit of muscle sparing, superior cosmesis, and less pain, the authors decided to prospectively compare this newer technique with open AISF (OAISF) to evaluate whether the 2 approaches were equivalent. METHODS: All children with idiopathic thoracic scoliosis undergoing AISF at a single center were prospectively examined. One hundred fifty-five children who had a minimum of 1-year follow-up were included in the study. Descriptive statistics are reported as means and SDs. Groups were compared using the independent-samples t test with Levene's test for equality of variances; a 2-tailed P value of .05 or less was considered significant. RESULTS: Open AISF was performed in 114 patients and TAISF was performed in 41; there were 126 girls and 29 boys. Mean age at surgery was similar (14 +/- 3 vs 14.3 +/- 1.5 years; P = .5), as was weight (54.2 +/- 19 vs 54.6 +/- 23 kg; P = .9). There were no differences in preoperative thoracic curves (48.5 degrees +/- 14 degrees vs 49.8 degrees +/- 7 degrees; P = .6) or in the number of vertebral levels instrumented (7.7 +/- 1.3 vs 7.6 +/- 0.7; P = .7). Operative time was shorter with OAISF (383 +/- 65 vs 508 +/- 98 minutes; P < .01), and there was less estimated blood loss (924 +/- 724 vs 1218 +/- 747 mL; P = .03). The OAISF group took longer to extubate (1.4 +/- 1.2 vs 1 +/- 0.3 days; P = .03) and had slightly greater chest tube drainage (1710 +/- 730 vs 1639 +/- 515 mL; P = .5). At the 1-year follow-up, the thoracic curves were similar (17.5 degrees +/- 8 degrees vs 15.2 degrees +/- 7.5 degrees; P = .1) and percentage correction of thoracic curves was also similar (64% vs 69%). CONCLUSIONS: Thoracoscopic AISF is safe and effective in correcting idiopathic childhood scoliosis. Correction of deformity with TAISF is equivalent to OAISF, although it takes longer and has more blood loss. However, it spares cutting muscle, uses smaller skin incisions, and appears to have superior cosmesis.

The biomechanical properties of the finger metacarpophalangeal joints to varus and valgus stress.

PURPOSE: The purpose of this study was to determine the normal biomechanical properties of the passive capsuloligamentous structures about the finger metacarpophalangeal (MCP) joints subjected to dynamic varus/valgus loading and to equate these findings to the clinical situation. METHODS: The finger MCP joints from 9 fresh-frozen cadaver hands were tested in a custom-designed testing apparatus that applied a varus/valgus force in each direction. Testing was performed at 0 degrees, 30 degrees, 60 degrees, and 90 degrees of MCP joint flexion. Load-displacement curves were generated for each specimen. A nonlinear hysteresis curve was apparent on loading and unloading. A region of collateral ligament laxity was identified whereby minimal torque (< 0.5 Nm) caused progressive joint angulation. Subsequently incremental load was required to produce further joint angulation. The slope of this region was used to calculate early and late collateral ligament stiffness. RESULTS: The index and long fingers showed a significant decrease in the region of collateral ligament laxity between 0 degrees and 90 degrees. The long finger collateral ligament laxity also diminished significantly between 30 degrees and 90 degrees. The collateral ligament laxity did not significantly change in the ring and small digits throughout MCP joint flexion. The early or late phase of collateral ligament stiffness was not affected by the amount of MCP joint flexion across any of the digits, except in late radial collateral ligament stiffness of the long finger between 0 degrees and 60 degrees. CONCLUSIONS: The additional stability and clinical observation of tightening of the MCP in flexion appears related to the decreased laxity of the collateral ligaments and not to alterations in the biomechanical properties of the collateral ligaments.

Scaphoid fractures: dorsal versus volar approach.

Twenty-six patients with scaphoid fractures were treated with internal fixation using a cannulated differential pitch compression screw. Sixteen patients underwent a dorsal approach (group 1) 10 patients a volar approach (group 2). Average time from injury to surgery was 6.6 months (range: 0.3-19 months) for group 1 and 8.3 months (range: 0.3-24 months) for group 2. The rate of union, determined by radiographs and clinical examination, was 81% in group 1 and 80% in group 2. No significant differences were noted between the groups for dorsiflexion/palmar flexion, radial deviation, grip strength, and pain level.

Upper extremity limb-length discrepancy in brachial plexus palsy.

Residual limb shortening is common after obstetric brachial plexus palsy. The exact limb-length discrepancy remains undetermined, and the purpose of this paper is to determine the resultant discrepancy. Twenty-two skeletally immature patients with obstetric brachial plexus palsies were examined. Radiographs of both the involved and uninvolved humerii and forearms were obtained with a radiographic ruler placed adjacent to the extremity. Each limb segment was measured and the discrepancy calculated as a percentage compared with the normal side. Twenty-one of the 22 children had some shortening of the limb at both the humerus and forearm level. The involved limb averaged 92% of the uninvolved limb. The humeral length averaged 93% and the forearm length averaged 90%. Children with upper brachial plexus lesions had significantly less forearm and total limb shortening compared with those with global lesions. There was no correlation between age and percentage difference of the humeral, forearm, and total length.