Study design: This study investigated the incidence, predictions, and treatment principles of greenstick lamina fractures in lumbar burst fractures.
Objective: To determine the incidence of dural tears in lumbar burst fracture with greenstick lamina fracture and to find out if any specific clinical and radiographic factors or intraoperative pathologic findings are predictive of dural tears and nerve root entrapment.
Summary of background data: A retrospective review was conducted on 45 patients with 47 lumbar burst fractures treated operatively. Ages ranged from 15 to 70 years (average, 33 years). The duration of follow-up ranged from 32 months to 8 years (average, 52 months).
Methods: All clinical charts and radiologic data of these patients were reviewed. Age, sex, etiology, and all the radiologic parameters were analyzed for their association with greenstick lamina fracture and dural tear. Student's t test and multiple logistic regression analysis were used for statistical analysis.
Results: Greenstick lamina fracture occurred in 20 (42.5%) of 47 burst fractures. Dural tear was detected in 9 (19%) of 47 burst fractures and was predominantly higher in L3 (6 of 9 burst fractures). According to multiple logistic regression analysis of the data, a 20% increase in the interpedicular distance gives a 79% probability of greenstick lamina fracture. The distance between the edges of greenstick lamina fractures was obviously higher in fractures with dural tear. Neurologic status was completely normal before surgery in three of the patients with dural tear and nerve root entrapment.
Conclusions: It is not possible to detect dural tear and nerve root entrapment in greenstick lamina fracture before surgery. Therefore, if there is any suspicion of such an occurrence, it should be the rule to begin with posterior approach and use the open book technique to expose the dura safely before any reduction maneuver.