MRI study of post-traumatic incompetence of posterior ligamentous complex: importance of the supraspinous ligament. Prospective study of 74 traumatic fractures.
OBJECTIVE
Posterior ligamentous complex (PLC) components have an orderly sequence of rupture. However, it is still unclear how many structures have to be damaged to consider it disrupted. We aim to establish imaging criteria, which can define the complex as competent or incompetent.


METHODS
Prospective study of 74 consecutive vertebral acute traumatic fractures, using X-rays and MRI scan (FS-T2-w/STIR sequences). We analyzed the association between MRI signal (intact, edema, disruption) of each PLC component-facet capsules (FC), interspinous ligaments (ISL), supraspinous ligaments (SSL) and ligamentum flavum (LF)-and the variables: AO/TLICS classification, treatment, surgical findings, interspinous diastasis index (IDI), local kyphosis (LVK) and ISS (TLICS) score. χ2 test and U Mann-Whitney were used for statistics.


RESULTS
MR images of ISL edema correlated surgically with intact ligaments or laxity, and were associated with 87.5% of facet distraction, LVK: 11.6º, IDI: 1.2. Images of ISL, SSL or LF disruptions showed in all cases ruptures under surgical examination. Images of SSL disruption associated with LVK: 14.5º, IDI: 1.8. Images of ISL disruption associated with SSL/LF rupture, LVK: 16º, and IDI: 2; while LF disruption showed LVK: 18º, IDI: 1.9. When comparing "competent PLC" (images of facet distraction and ISL edema) with "incompetent PLC" (images of SSL disruption ± ISL or LF disruption) the latest showed more severe scores in every variable (p < 0.001), except neurologic status.


CONCLUSIONS
Following PLC rupture sequence, ISL edema with facet distraction seems not to be enough to define a posterior tension band incompetence. It is the further step of SSL rupture what gives the key to PLC incompetence.
Spine Unit, Department of Orthopaedic Surgery, Hospital Universitario de Getafe, Carretera de Toledo Km. 12.5, 28905, Madrid, Spain. javierpizones@gmail.com
Javier
J
Pizones
Lorenzo
L
Zúñiga
Felisa
F
Sánchez-Mariscal
Patricia
P
Alvarez
Alejandro
A
Gómez-Rice
Enrique
E
Izquierdo
D000328:Adult; D006801:Humans; D017843:Ligamentum Flavum / Q000293:injuries* / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D012421:Rupture; D016103:Spinal Fractures / Q000473:pathology*