Model of Induced Leakage of Polymethylmethacrilate Inside Epidural Space and Prevertebral Muscles During Vertebroplasty in Pigs: Clinical, Macroscopical, and Histological Study

Abstract

Study DesignExperimental study in animals.PurposeStudy the clinical behavior of animals after an induced leakage of cement during vertebroplasty in pigs. Study the distribution of polymethylmetacrilate inside the epidural space and prevertebral muscle. Study the histological findings of the spinal cord and muscles, which contact with cement.Overview of LiteratureAlthough vertebroplasty has a low rate of complication, leakage of cement is highly frequent. There is paucity, in how cement is distributed inside the spinal canal and what occurs when soft tissue comes into contact with polymethylmetacrilate.MethodsWe performed vertebroplasty on six pigs. We performed a leakage of cement into the epidural space and into prevertebral muscles. Two weeks later we performed an anatomic evaluation regarding the spreading of polymethylmetacrilate and a histological analysis of soft tissues that came into contact with it.ResultsNo clinical alterations were observed. We observed a laminar distribution of the cement surrounding dura mater, and creating a fusiform cavity inside muscles. Spinal cord was normal in all the animals. In dura mater, we observed: synovialmetaplasia, inflammatory reaction, crystal deposits, and giant-cell-reaction. In muscles, we observed: inflammatory reaction, crystal deposits, giant-cell-reaction, muscular atrophy, fibrosis, and synovial metaplasia.ConclusionsThe spinal cord was normal; it is likely that dura mater and cerebrospinal fluid are responsible to isolate neural structures from cement. Dura mater and muscle showed similar histological changes than other publications. Synovial metaplasia was observed in dura mater and muscles that came into contact with cement. The pulsatile rubbing between the tissue and cement could be responsible of this phenomenon.

Clinical Outcome and Histological Findings After Induced Leakage of PMMA Loaded With Methotrexate and Cisplatin During Vertebroplasty: Experimental Model in Pigs

“…This finding is characteristic of interfaces between tissues and mobile implants. 21 In our previous study, 15 we found similar results, and we concluded then that the laminar distribution summed to the pulsed compression effect by the dural sac could have avoided the focal accumulation of cement so that there was not enough volume to compress the spinal cord. In 2011, the temperatures of bone cement in the spine canal were measured after vertebroplasty with cement inside the vertebral body and leaking into the canal.…”

“…We based our technique on a previously published model of epidural and prevertebral leakage of polymethylmethacrylate for vertebroplasty in pigs. 14,15…”

“…We based our technique on a previously published model of epidural and prevertebral leakage of polymethylmethacrylate for vertebroplasty in pigs. 14,15 We administered preanesthetic sedation in the stall (intramuscular ketamine 10 mg/kg). After that, we transported the animals to the operating room where general anesthesia was administered (intramuscular azaperone 2 mg/kg, atropine 1 mg intramuscularly, intravenous etomidate 3 mg/kg and pancuronium 0.2 mg/kg) followed by orotracheal intubation.…”

Preventative effect of diclofenac sodium and/or diltiazem in rats with epidural fibrosis

“…Non-steroidal anti-infl ammatory drugs (NSAIDs) (5), calcium channel blockers (6), pegaptanid sodium (7), mitomycin-C (2), hemostatic polysaccharide agents have been administered (8). All-trans retinoic acid (9), human amniotic fl uid-sodium hyaluranate (10), poly (D, L-lactic acid-co-glycolic acid)-b-poly (ethylene glycol)-b-poly (D, L-lactic acid-co-glycolic acid) thermogel (11), etarnacept (12), dekorin (13), CMC/PO (14), licofelone (15), temozolamide (16), polymethylmethacrylate (17) and hyperbaric oxygen (18) are examples of other agents that have been studied in the treatment of spinal EF.…”