Abstract：
OBJECTIVE: With the ageing population, fragility fractures have become one of the most common conditions. The objective of this study was to investigate whether microbiological outcomes and fracture-healing in osteoporotic bone is worse than normal bone with fracture-related infection (FRI).
METHODS: A total of 120 six-month-old Sprague-Dawley (SD) rats were randomized to six groups: Sham, sham + infection (Sham-Inf), sham with infection + antibiotics (Sham-Inf-A), ovariectomized (OVX), OVX + infection (OVX-Inf), and OVX + infection + antibiotics (OVX-Inf-A). Open femoral diaphysis fractures with Kirschner wire fixation were performed. Staphylococcus aureus at 4 × 104 colony-forming units (CFU)/ml was inoculated. Rats were euthanized at four and eight weeks post-surgery. Radiography, micro-CT, haematoxylin-eosin, mechanical testing, immunohistochemistry (IHC), gram staining, agar plating, crystal violet staining, and scanning electron microscopy were performed.
RESULTS: Agar plating analysis revealed a higher bacterial load in bone (p = 0.002), and gram staining showed higher cortical bone colonization (p = 0.039) in OVX-Inf compared to Sham-Inf. OVX-Inf showed significantly increased callus area (p = 0.013), but decreased high-density bone volume (p = 0.023) compared to Sham-Inf. IHC staining showed a significantly increased expression of TNF-α in OVX-Inf compared to OVX (p = 0.049). Significantly reduced bacterial load on bone (p = 0.001), enhanced ultimate load (p = 0.001), and energy to failure were observed in Sham-Inf-A compared to Sham-Inf (p = 0.028), but not in OVX-Inf-A compared to OVX-Inf.
CONCLUSIONS: In osteoporotic bone with FRI, infection was more severe with more bone lysis and higher bacterial load, and fracture-healing was further delayed. Systemic antibiotics significantly reduced bacterial load and enhanced callus quality and strength in normal bone with FRI, but not in osteoporotic bone. Cite this article: Bone Joint Res 2022;11(2):49-60.
METHODS: A total of 120 six-month-old Sprague-Dawley (SD) rats were randomized to six groups: Sham, sham + infection (Sham-Inf), sham with infection + antibiotics (Sham-Inf-A), ovariectomized (OVX), OVX + infection (OVX-Inf), and OVX + infection + antibiotics (OVX-Inf-A). Open femoral diaphysis fractures with Kirschner wire fixation were performed. Staphylococcus aureus at 4 × 104 colony-forming units (CFU)/ml was inoculated. Rats were euthanized at four and eight weeks post-surgery. Radiography, micro-CT, haematoxylin-eosin, mechanical testing, immunohistochemistry (IHC), gram staining, agar plating, crystal violet staining, and scanning electron microscopy were performed.
RESULTS: Agar plating analysis revealed a higher bacterial load in bone (p = 0.002), and gram staining showed higher cortical bone colonization (p = 0.039) in OVX-Inf compared to Sham-Inf. OVX-Inf showed significantly increased callus area (p = 0.013), but decreased high-density bone volume (p = 0.023) compared to Sham-Inf. IHC staining showed a significantly increased expression of TNF-α in OVX-Inf compared to OVX (p = 0.049). Significantly reduced bacterial load on bone (p = 0.001), enhanced ultimate load (p = 0.001), and energy to failure were observed in Sham-Inf-A compared to Sham-Inf (p = 0.028), but not in OVX-Inf-A compared to OVX-Inf.
CONCLUSIONS: In osteoporotic bone with FRI, infection was more severe with more bone lysis and higher bacterial load, and fracture-healing was further delayed. Systemic antibiotics significantly reduced bacterial load and enhanced callus quality and strength in normal bone with FRI, but not in osteoporotic bone. Cite this article: Bone Joint Res 2022;11(2):49-60.
摘要：
目标：随着人口老龄化，脆性骨折已成为最常见的条件之一。这项研究的目的是调查骨质疏松性骨的微生物学结果和骨折愈合是否比骨折相关感染（FRI）的正常骨更差。
方法：将120只6个月大的Sprague-Dawley（SD）大鼠随机分为6组：假，假+感染(Sham-Inf)，假感染+抗生素（Sham-Inf-A），卵巢切除（OVX），OVX+感染(OVX-Inf),和OVX+感染+抗生素(OVX-Inf-A)。采用克氏针固定治疗开放性股骨干骨折。接种4×104个菌落形成单位(CFU)/ml的金黄色葡萄球菌。在手术后4周和8周对大鼠实施安乐死。射线照相术,Micro-CT,苏木精-伊红,机械测试,免疫组织化学（IHC），革兰氏染色，琼脂平板,结晶紫染色,和扫描电子显微镜。
结果：琼脂平板分析显示骨骼中的细菌负荷较高（p=0.002），和革兰氏染色显示与Sham-Inf相比,OVX-Inf中更高的皮质骨定植(p=0.039)。OVX-Inf显示出愈伤组织面积显著增加(p=0.013),但与Sham-Inf相比，高密度骨体积减少（p=0.023）。IHC染色显示与OVX相比,OVX-Inf中TNF-α的表达显著增加(p=0.049)。骨骼上的细菌负荷显着减少（p=0.001），增强的极限载荷(p=0.001)，与Sham-Inf相比，在Sham-Inf-A中观察到破坏能量（p=0.028），但不在OVX-Inf-A与OVX-Inf相比。
结论：在具有FRI的骨质疏松骨中，随着更多的骨溶解和更高的细菌负荷，感染更严重，骨折愈合进一步延迟。全身抗生素显著降低细菌负荷，增强FRI正常骨的骨痂质量和强度，但不是骨质疏松的骨头。引用这篇文章：骨关节Res2022；11(2)：49-60。
方法：将120只6个月大的Sprague-Dawley（SD）大鼠随机分为6组：假，假+感染(Sham-Inf)，假感染+抗生素（Sham-Inf-A），卵巢切除（OVX），OVX+感染(OVX-Inf),和OVX+感染+抗生素(OVX-Inf-A)。采用克氏针固定治疗开放性股骨干骨折。接种4×104个菌落形成单位(CFU)/ml的金黄色葡萄球菌。在手术后4周和8周对大鼠实施安乐死。射线照相术,Micro-CT,苏木精-伊红,机械测试,免疫组织化学（IHC），革兰氏染色，琼脂平板,结晶紫染色,和扫描电子显微镜。
结果：琼脂平板分析显示骨骼中的细菌负荷较高（p=0.002），和革兰氏染色显示与Sham-Inf相比,OVX-Inf中更高的皮质骨定植(p=0.039)。OVX-Inf显示出愈伤组织面积显著增加(p=0.013),但与Sham-Inf相比，高密度骨体积减少（p=0.023）。IHC染色显示与OVX相比,OVX-Inf中TNF-α的表达显著增加(p=0.049)。骨骼上的细菌负荷显着减少（p=0.001），增强的极限载荷(p=0.001)，与Sham-Inf相比，在Sham-Inf-A中观察到破坏能量（p=0.028），但不在OVX-Inf-A与OVX-Inf相比。
结论：在具有FRI的骨质疏松骨中，随着更多的骨溶解和更高的细菌负荷，感染更严重，骨折愈合进一步延迟。全身抗生素显著降低细菌负荷，增强FRI正常骨的骨痂质量和强度，但不是骨质疏松的骨头。引用这篇文章：骨关节Res2022；11(2)：49-60。
