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BACKGROUND Hydrogels are ideal biological carriers in vivo and have been widely used in the treatment of wound healing through loading with or without bioactive substances. Platelet-rich plasma (PRP) is purified from autologous plasma and has known curative efficacy for wound healing. The combined efficacy of shorten poly-N-acetyl glucosamine (sNAG) hydrogels and PRP in the treatment of wound healing has not been previously assessed. MATERIAL AND METHODS The cytotoxic and proliferative effects of PRP on fibroblasts were detected using Cell Counting Kit-8 assays and flow cytometry. The levels of cyclin D1 and cyclin D3 were assessed to evaluate cell proliferation. Protein expression was assessed by western blot analysis. Adenosine levels were assessed by enzyme-linked immunosorbent assay. Cell apoptosis was assessed by flow cytometry and western blot analysis. Rat wound models were performed, and the effects of PRP, single hydrogels, and sNAG hydrogels loaded with PRP were respectively detected through the assessment of wound closure. Hematoxylin eosin staining was used to measure the depth and width of regenerative scars. RESULTS Our results demonstrated that PRP promotes fibroblast proliferation and inhibits apoptosis. PRP contains abundant levels of adenosine, which has a positive role on fibroblast function, whilst the inhibition of adenosine A2A receptors impairs the efficacy of PRP. sNAG hydrogels loaded with PRP showed curative efficacy during wound healing in mice. Mice treated with hydrogels loaded with PRP showed high levels of regeneration with scarless healing. CONCLUSIONS Our results indicate that sNAG hydrogels loaded with PRP promote wound healing. The pro-proliferative, and anti-apoptotic effects of the fibroblasts are mediated by the activating A2A receptor in response to elevated adenosine levels.

Background The aim of this article is to introduce a novel technique of limited dynamic hip screw (LDHS) in the treatment of intertrochanteric fractures and to evaluate its biomechanical effects. Material/Methods Based on the principle of providing both dynamic and static pressure to stabilize the fracture, we improved the dynamic hip screw (DHS) and designed the LDHS. Six fresh cadavers were collected and intertrochanteric fracture models were established, including Evan’s type I fracture (n=3) and type II (n=3). We used the left-to-right comparison in this study. LDHS technique was performed on the left femoral head of each cadaver (LDHS group: n=6), while DHS was performed on the right side (DHS group: n=6). After fixation by either LDHS or DHS, compressive strength, rigidity, shear stress and strain, torsional properties, and ultimate loads were measured and compared in both groups. Results Under the 1200 N pressure, compressive strength, rigidity, shear stress and strain, and ultimate loads of LDHS were better than those of DHS in the 2 groups. All differences were statistically significant. Although LDHS enhanced the torsional properties, there was no significant difference. Conclusions Our study demonstrates that the biomechanical effects of LDHS are superior than those of DHS, and there was no screw failure after implantation. Armed with those better properties, LDHS, as a new internal fixation device, may be a good alternative option in the treatment of intertrochanteric fractures.

BACKGROUND This study aimed to compare the surgical outcomes between open pedicle screw fixation (OPSF) and percutaneous pedicle screw fixation (PPSF) for the treatment of thoracolumbar fractures, which has received scant research attention to date. MATERIAL AND METHODS Eight-four patients with acute and subacute thoracolumbar fractures who were treated with SSPSF from January 2013 to June 2014 at the Changzhou Hospital of Traditional Chinese Medicine (Changzhou, China) were retrospectively reviewed. The patients were divided into 4 groups: the OPSF with 4 basic screws (OPSF-4) group, the OPSF with 4 basic and 2 additional screws (OPSF-6) group, the PPSF with 4 basic screws (PPSF-4) group, and the PPSF with 4 basic and 2 additional screws (PPSF-6) group. The intraoperative, immediate postoperative, and over 1-year follow-up outcomes were evaluated and compared among these groups. RESULTS Blood loss in the PPSF-4 group and the PPSF-6 group was significantly less than in the OPSF-4 group and the OPSF-6 group (P0.05). The OPSF-6 group exhibited significantly higher immediate postoperative correction percentage of anterior column height of fractured vertebra than the other 3 groups (P0.05), and higher correction of sagittal regional Cobb angle and kyphotic angle of injured vertebra than in the PPSF-4 and -6 groups (P0.05). In addition, there was no significant difference in the correction loss of percentage of anterior column height, and loss of sagittal Cobb angle and kyphotic angle of fractured vertebrae at final follow-up among the 4 groups (P0.05). CONCLUSIONS OPSF with 6 screws had an advantage in the correction of injured vertebral height and kyphosis, and PPSF reduced the intraoperative blood loss of patients.