Orthopedic Surgery Department, Hotel-Dieu de France Hospital, Saint-Joseph University, Beirut, Lebanon.
Faculty of Medicine, Saimt-Joseph University, Beirut, Lebanon.
Int Orthop. 2020 Feb;44(2):391-398. doi: 10.1007/s00264-019-04453-4. Epub 2019 Dec 3.
The Masquelet procedure proved its efficiency in treating infected nonunion filling bony gaps up to 25 cm. Yet the use of local antibiotics is still questionable in the daily practice with lack of evidence regarding its usefulness in controlling infection. An experimental rat model is put in place to study the antibacterial properties of the induced membrane produced during the first stage of Masquelet.
Twenty-three-month-old wistar male rats are inoculated with a 0.5 mL solution of 10^8 CFU/mL MRSA over a critical fracture done on the right femur. Six weeks later, remaining 11 rats exhibiting signs of a chronic infection with a sinus tract and oozing pus along with radiological nonunion are used for a first stage Masquelet procedure. They are randomly divided into two groups with six rats having no local antibiotic in the cement mixture and five rats having 3 g of vancomycin mixed with gentamycin loaded cement. Six weeks later (twelve weeks from baseline), all eleven rats are euthanized and blood samples for C-reactive protein are withdrawn. The induced membrane is identified and resected along with bone fragments and sent for cultures and pathology.
MRSA is isolated in the cultures of all six rats in the first group where no local antibiotic was added. Altered polymorphonuclears with abscess and pus are noted on four of six pathology samples. However in the second group where local antibiotics were added, three out of five rats exhibited eradication of MRSA (p = 0.034) and all samples did not exhibit clear infection signs on pathology. A pyo-epithelioid over a foreign body reaction is seen predominantly in this group demonstrating a regenerative process.
The induced membrane does not have antimicrobial properties capable of overcoming an infected nonunion on its own. When local antibiotics were added during the first stage of the Masquelet procedure, new bone formation occurred indicating the need to control an infection in order for bone union to occur.
Local antibiotics use in adjunction to extensive debridement is advisable during the first stage of a Masquelet procedure for an infected nonunion.
Masquelet 手术已被证明能有效治疗感染性骨不连并填充 25cm 以内的骨缺损。然而，在日常实践中，局部使用抗生素的效果仍存在争议，因为缺乏关于其控制感染效果的证据。本实验建立了大鼠模型，以研究 Masquelet 手术第一阶段产生的诱导膜的抗菌性能。
23 月龄雄性 wistar 大鼠在右侧股骨上造成临界骨折后，于骨折处注入 0.5ml 浓度为 10^8 CFU/ml 的 MRSA 溶液。6 周后，11 只出现慢性感染迹象（窦道和脓性渗出物，伴有放射学骨不连）的大鼠进行第一阶段的 Masquelet 手术。将它们随机分为两组，其中 6 只大鼠的骨水泥混合物中不添加局部抗生素，5 只大鼠的骨水泥混合物中添加 3g 万古霉素和庆大霉素。6 周后（从基线开始 12 周后），所有 11 只大鼠均安乐死，采集血样检测 C 反应蛋白。取出诱导膜和骨碎片进行培养和病理检查。
在第一组（未添加局部抗生素）的 6 只大鼠中，所有大鼠的培养物中均分离出 MRSA。6 个样本中有 4 个的病理样本中可见多核白细胞伴脓肿和脓液。然而，在第二组（添加了局部抗生素）中，5 只大鼠中有 3 只消除了 MRSA（p=0.034），所有样本的病理检查均未见明显感染迹象。这组主要表现为异物反应伴化脓性上皮样细胞，提示存在再生过程。
诱导膜本身没有抗菌性能，无法单独克服感染性骨不连。当在 Masquelet 手术的第一阶段添加局部抗生素时，新骨形成，表明需要控制感染才能发生骨愈合。
对于感染性骨不连，在 Masquelet 手术的第一阶段，建议在广泛清创的基础上使用局部抗生素。
