A novel vacuum assisted closure therapy model for use with percutaneous devices

Influence of negative pressure wound therapy on peri-prosthetic tissue vascularization and inflammation around porous titanium percutaneous devices

Negative Pressure Wound Therapy (NPWT) has been shown to limit downgrowth around percutaneous devices in a guinea pig model. However, the influence of NPWT on peri-prosthetic tissue characteristics leading to limited downgrowth is still unclear. In order to investigate this, 12 CD hairless rats were assigned into two groups, NPWT and Untreated (n = 6/group). Each animal was implanted with a porous coated titanium percutaneous device and was dressed with a gauze and semi-occlusive base dressing. Post-surgery, animals in the NPWT Group received a regimen of NPWT treatment (-70 to -90 mmHg). After 4 weeks, tissue was collected over the device and stained with CD31 and CD68 to quantify blood vessel density and inflammation, respectively. The device with the surrounding tissue was also collected to quantify downgrowth. NPWT treatment led to a 1.6-fold increase in blood vessel densities compared to untreated tissues (p < 0.05). NPWT treatment also resulted in half the downgrowth as the Untreated Group, although not statistically significant (p = 0.19). Additionally, the results showed a trend toward increased CD68 cell densities in the NPWT Group compared to the Untreated Group (p = 0.09). These findings suggest that NPWT may influence wound healing responses in percutaneous devices by increasing blood vessel densities, limiting downgrowth and potentially increasing inflammation. Overall, NPWT may enhance tissue vascularity around percutaneous devices, especially in patients with impaired wound healing. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2091-2101, 2019.

Negative pressure wound therapy limits downgrowth in percutaneous devices

Maintenance of a soft tissue seal around percutaneous devices is challenged by the downgrowth of periprosthetic tissues-a gateway to potential infection. As negative pressure wound therapy (NPWT) is used clinically to facilitate healing of complex soft tissue pathologies, it was hypothesized that NPWT could limit downgrowth of periprosthetic tissues. To test this hypothesis, 20 hairless guinea pigs were randomly assigned into four groups (n = 5/group). Using a One-Stage (Groups 1 and 3) or a Two-Stage (Groups 2 and 4) surgical procedure, each animal was implanted with a titanium-alloy subdermal device porous-coated with commercially pure, medical grade titanium. Each subdermal device had a smooth titanium-alloy percutaneous post. The One-Stage procedure encompassed insertion of a fully assembled device during a single surgery. The Two-Stage procedure involved the implantation of a subdermal device during the first surgery, and then three weeks later, insertion of a percutaneous post. Groups 1 and 2 served as untreated controls and Groups 3 and 4 received NPWT. Four weeks postimplantation of the post, the devices and surrounding tissues were harvested, and histologically evaluated for downgrowth. Within the untreated control groups, the Two-Stage surgical procedure significantly decreased downgrowth (p = 0.027) when compared with the One-Stage procedure. Independent of the surgical procedures performed, NPWT significantly limited downgrowth (p ≤ 0.05) when compared with the untreated controls.