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OBJECTIVE: To establish the lowest effective dose of commercially available nanoparticulate silver (AgNP) for antibacterial activity against Escherichia coli (E coli) and methicillin-resistant Staphylococcus pseudintermedius (MRSP), in vitro, and to establish the effect of incorporating AgNP into carriers for sustained release on this antibacterial activity. SAMPLES: Silver nanoparticle dispersion (0.02 mg/mL) composed of citrate-stabilized, spherical, 10 nm diameter nanoparticles in aqueous buffer. PROCEDURES: E coli and MRSP were treated with 0.01 mg/mL AgNP. The highest concentration of bacteria where growth was inhibited by AgNP was selected for treatment with 0.01 mg/mL AgNP incorporated 3 carriers for sustained release: calcium sulfate hemihydrate (CSH) beads, poloxamer 407 gel, and gelatin sponge, respectively. The antibacterial activity of AgNP and AgNP incorporated into carriers for sustained release was compared with a mixed linear effects model. RESULTS: AgNP inhibited bacterial growth at a concentration of 101 for MRSP and 103 for E coli. For MRSP, the treatment group was associated with bacterial growth (P < .001) while the concentration of bacteria and time were not (P = .292 and P = .289, respectively). For E coli, the treatment group and concentration of bacteria were associated with bacterial growth (P < .001 and = .029, respectively) while time was not (P = .095). Poloxamer 407 gel exerted standalone antibacterial activity against both species of bacteria; sponge and CSH beads did not. CLINICAL RELEVANCE: AgNP has antibacterial activity against E coli and MRSP, which can be reduced when incorporated into carriers for sustained release. Poloxamer 407 gel alone and combined with AgNP exerts antibacterial activity against E coli and MRSP.

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OBJECTIVE: To describe and compare the pattern of fluid dispersal and retrieval in a novel instillation therapy system. STUDY DESIGN: In vitro experimental study. METHODS: A 10 cm2 square model was constructed using plastic sheeting secured to plexiglass, with a wound infusion catheter and Jackson-Pratt (JP) active suction drain positioned in 4 configurations: parallel, perpendicular, diagonal, and opposite. Fluid was instilled using the wound infusion catheter, allowed to dwell for 10 min, and retrieved using the JP drain. Two surface area calculations were made using imaging software: coloration with diluted methylene blue (MB) on photos, and filling with diluted contrast on fluoroscopic images. Fluid retrieval was recorded. Statistical analysis was performed using a mixed-effects linear model (p < .05). RESULTS: Configuration influenced fluid dispersion within the model (p = .0001); the diagonal configuration had the greatest surface area coverage (mean ± SD; 94.5 ± 2.4%) and the parallel configuration had the lowest surface area coverage (60.2 ± 2.9%). A dwell period increased fluid dispersal by an average of 4.0 ± 0.8% (p < .0001). Fluid retrieval exceeded 16.7 ± 1.5 mL (83.5 ± 7.5% volume instilled) for all configurations and was 0.5 ± 0.1 mL (2.5 ± 0.5% volume instilled) greater for MB than contrast agent (p < .0001). CONCLUSION: Perpendicular or diagonal configurations and low-viscosity fluid maximized fluid dispersion and retrieval. CLINICAL SIGNIFICANCE: Wound instillation therapy involves delivering lavage fluid or medications to a closed wound space. This is feasible using a wound-infusion catheter and active suction drain. Configuration should be considered to optimize fluid dispersal and retrieval when planning instillation therapy.

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OBJECTIVE: To determine the influence of continuous and intermittent bolus irrigation on vertebral canal temperature during thoracolumbar hemilaminectomy. STUDY DESIGN: Ex vivo study. SAMPLE POPULATION: Ten canine cadavers. METHODS: Six consecutive thoracolumbar hemilaminectomies starting at T12-13 with alternating left- or right-side selection, and alternating continuous or intermittent bolus irrigation were performed in each dog resulting in 30 hemilaminectomies per irrigation technique. Drilling was performed for 15 s followed by a 10-s pause and resumed until completion of hemilaminectomy. Continuous irrigation consisted of saline delivered at 15 ml/min during drilling. Bolus irrigation consisted of manual delivery of 10 ml saline during the pause. Temperatures were recorded with two sensors placed within the vertebral canal adjacent to target hemilaminectomy site and compared between techniques with a linear mixed model. RESULTS: Intermittent bolus irrigation was associated with lower peak vertebral canal temperatures (mean 15.7°C; range 9.4-23.3°C) than continuous irrigation (mean 16.7°C; range 9.6-27.6°C, p = .003) (mean difference of 1.1°C, p = .006). Similarly, mean vertebral canal temperatures remained lower when hemilaminectomies were performed under intermittent rather than continuous irrigation (mean difference of 0.48°C, p = .006, linear mixed model). CONCLUSION: Lower vertebral canal temperatures were maintained during hemilaminectomy with intermittent bolus rather than continuous irrigation. CLINICAL SIGNIFICANCE: Both intermittent bolus and continuous irrigation are suitable to prevent elevations in canine vertebral canal temperature during hemilaminectomy.

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OBJECTIVE: To evaluate the use of the Leipzig distractor during canine shoulder arthroscopy. STUDY DESIGN: Experimental, ex vivo. SAMPLE POPULATION: Paired shoulder joints from 15 large breed canine cadavers. METHODS: Standard lateral shoulder arthroscopy was performed with or without the use of the Leipzig distractor (n = 15 each). Joint space width, procedure time, and visibility and palpability of the intra-articular structures were assessed during the arthroscopy. After the arthroscopic evaluation, each shoulder joint was disarticulated to assess the area and number of iatrogenic articular cartilage injury (IACI) lesions. Sites around the distraction device were assessed for the presence of iatrogenic injury. RESULTS: With shoulder distraction, median joint space width was 4 mm larger (P = .01), IACI area was 9.5 mm2 lower (P = .003), and there were two fewer total number of IACI lesions (P = .004) compared with nondistracted shoulders. The mean total surgery time was 93 seconds shorter (P = .01) in distracted shoulders. Although distraction was associated with increased visibility of the supraglenoid tubercle (P = .015), no significant differences were found for other intra-articular structures for their visibility and palpability. Unexpected lesions at the sites around the distraction device were not encountered. CONCLUSION: Use of the distraction device decreased the area and incidence of IACI lesions and shortened the arthroscopy time. However, no improvement was found in the visibility or palpability of the intra-articular structures. CLINICAL SIGNIFICANCE: Although additional clinical studies are required to evaluate the effect of the distraction device on pathologic articular conditions and intraoperative manipulation, the use of a shoulder distraction device might improve the outcomes of shoulder arthroscopy by decreasing IACI and arthroscopy time.

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