Model of induced leakage of polymethylmethacrilate inside epidural space and prevertebral muscles during vertebroplasty in pigs: clinical, macroscopical, and histological study.
METHODS
Experimental study in animals.


OBJECTIVE
Study 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.


BACKGROUND
Although 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.


METHODS
We 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.


RESULTS
No 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.


CONCLUSIONS
The 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.
Department of Orthopedic Surgery, University of Navarra, Pamplona, Spain. ; Department of Orthopedic Surgery, German Clinic of Santiago-Universidad del Desarrollo, Santiago, Chile.
Alvaro
A
Silva González
Matías
M
Alfonso Olmos
Carlos
C
Villas Tomé
Marcela Gallegos
MG
Angulo
Histology; Polymethylmethacrylate; Psoas muscles; Spinal cord; Vertebroplasty