Therapeutic strategies for retention of cranioplasty titanium mesh after mesh exposure.

BACKGROUND: Titanium mesh exposure after cranioplasty is a possible complication and is usually managed by mesh removal and flap transfer, but the advantages of the rigid prosthesis are then lost. This study aimed to present our experience with negative pressure wound therapy combined with soft tissue dilation for retaining the titanium mesh in patients with mesh exposure after cranioplasty. METHODS: This retrospective study included patients treated between 01/2016 and 05/2019 at the Jiangyin Hospital Affiliated to Southeast University School of Medicine. The wound was cleaned, and a cystic space was created for the tissue dilator, which was used with a self-designed negative pressure dressing. After the target dilation was achieved, the repair was conducted while retaining the titanium mesh. RESULTS: Eight patients were included (seven males and one female; 53.6 ± 8.8 (range, 43-65) years of age). The exposed mesh area ranged from 1 × 1 to 4 × 5.5 cm. The thinning scalp area around the exposed mesh ranged from 3.6 × 3.8 to 4 × 5.5 cm. Five patients had positive wound cultures and received sensitive antibiotics. The dilator embedding time was 20-28 days. The time of negative pressure wound therapy was 25-33 days. The hospital stay was 30-41 days. Primary wound healing was achieved in all eight patients. There were no signs of recurrence after 6-18 months of follow-up. The cranial CT scans were unremarkable. CONCLUSIONS: Negative pressure wound therapy combined with soft tissue dilation for exposed titanium mesh after cranioplasty might help retain the titanium mesh.

[Influence of the depth of retained denatured dermis on the survival rate of grafted skin in burn swine with deep partial-thickness burn].

OBJECTIVE: To explore the influence of the thickness of retained denatured dermis on the survival rate of grafted skin in swine with deep partial-thickness burn. METHODS: Four deep partial-thickness wounds were reproduced respectively on both sides of spine in 7 Chinese domestic pigs. The wounds of 6 pigs were divided into 0.25, 0.50, 0.75, and 1.00 mm groups with 12 wounds in each group according to the random number table. Tangential excision and auto-skin grafting were performed. Before the tangential excision, 1 tissue specimen was harvested from the center of each remaining wound for the estimation of the depth of burn, and histological observation was done. After the tangential excision, 1 tissue specimen was harvested from the area near the center of each wound for the measurement of the depth of retained denatured dermis with histological examination. The 8 wounds of one pig were set as the control group, and the operation was done, and then they were treated with exposure treatment after biopsy specimens were taken with above-mentioned method. The general condition of wounds in 5 groups was observed from immediately after injury to post injury month (PIM) 3. On post injury day (PID) 7, the survival rate of grafted skin was observed in 0.25, 0.50, 0.75, and 1.00 mm groups. Wound healing time was recorded. At PIM 3, the specimens were harvested from the wounds of 5 groups, and their ultra microstructures were observed by transmission electron microscope. Data were processed with rank-sum test, one-way analysis of variance, and LSD test. RESULTS: The depth of the burn tissue was (1.120 ± 0.211) mm. The depths of retained denatured dermis in 0.25, 0.50, 0.75, and 1.00 mm groups were respectively (0.830 ± 0.031), (0.701 ± 0.010), (0.382 ± 0.031), and (0.141 ± 0.040) mm. At PID 8, all grafted skin in 0.25 and 0.50 mm groups became necrotic; most grafted skin in 0.75 mm group was necrotic; most grafted skin in 1.00 mm group survived with only a few became necrotic and separated from the wounds. The scabs were gradually separated from the wounds of control group. On PID 15, the grafted skin which did not survive in 0.25, 0.50, and 0.75 mm groups was gradually separated from the wounds with exudate forming scab on the surface in varying degrees, while the wounds in 1.00 mm group were all healed, and the incidence of scabs formation was highest in control group. At PIM 3, scar contraction was found in 0.25, 0.50, 0.75 mm groups and control group, while no obvious scar was observed in 1.00 mm group. There were statistically significant differences in the survival rate of grafted skin in 0.25, 0.50, 0.75, and 1.00 mm groups (χ(2) = 19.421, P < 0.001). The survival rate was the highest in 1.00 mm group [70% (60%, 80%)], while the survival rate was 20% (0, 30%) in 0.75 mm group, and it was in both 0.25 and 0.50 mm groups with non-survival of all the grafted skin. There were statistically significant differences in the wound healing time among 5 groups (F = 41.450, P < 0.001). The wound healing time in 0.25 and 0.50 mm groups were respectively (18.2 ± 1.5), and (18.7 ± 2.3) d, not statistically significant different from that of control group [(18.4 ± 1.7) d, P values both above 0.05]. The wound healing time in 0.75 mm group [(14.9 ± 2.6) d] was significantly different from those of 0.25, 0.50 mm groups and control group (P values all below 0.01). The wound healing time in 1.00 mm group [(9.5 ± 1.2) d] was significantly shorter compared with that of the other 4 groups (P values all below 0.01). Before tangential excision, the zone of infiltration of the inflammatory cells was observed in the deep dermis of wounds in 5 groups. After tangential excision and before auto-skin grafting, the depth from the fault surface to the zone of infiltration of the inflammatory cells varied in 0.25, 0.50, 0.75, and 1.00 mm groups while more inflammatory cells were observed in control group. At PIM 3, many fibroblasts were observed in the dermis of wounds in 1.00 mm group with abundant rough endoplasmic reticulum and basically intact organelles. CONCLUSIONS: Performing autologous skin grafting on deep partial-thickness burn, in which the depth of retained denatured dermis was 0.10 mm, may help regenerate dermal function and alleviate scar formation.