This study was conducted between the period of May 2009 to 2015. The study was approved by the ethical committee of the center. Inclusion criteria for cases in the study required confirmed thoracolumbar fracture by plain radiographs, computed tomography, and magnetic resonance imaging. Surgical indications included more than 50% loss of vertebral body height, kyphosis progressing 20% or more, more than 50% of canal involvement, posterior ligamentous complex injury.

Twenty-five patients qualified and were reviewed retrospectively in this study. Patients were also graded preoperatively and postoperatively based on the Frankel scale [6]; Plain radiographs were evaluated preoperatively and postoperatively for kyphotic angulations using the traditional Cobb method [7]. [Table/Fig-2] shows how AVH and PVH were measured preoperatively, immediate postoperatively and at 18 months respectively (it was recommended to every patient to undergo removal at 18 month). Average percentage loss of AVH and mid-sagittal height were also calculated on preoperative and postoperative X-rays on follow up.

[Table/Fig-2]:

Demonstrates the measurement of PVH and AVH method.

The first author performed all surgeries in this study. The posterior spinal approach was made one level above and below the fracture. Pedicle screws were placed at one level above and below the fracture site. Fracture level screws were inserted at the same time with the other screws prior to compression/distraction, and were included into the lordosing distracting manoeuvre. Both the fractured pedicles were inserted and care was taken to insert longest possible screws so that they can support subchondral bone and the superior end plate of fractured vertebrae. Kyphosis correction achieved by cantilever forces created by distraction and compression manoeuvre.

[Table/Fig-3] demonstrates an excellent correction done at one-month postoperative interval. Visualization laminectomy performed for confirmation of indirect decompression achieved by distraction manoeuvre when indicated by the presence of compression over neural tissue in MRI. No fusion was performed in all patients so that elective implant removal can be performed after 18 months when the fracture is healed.

[Table/Fig-3]:

Correction of kyphosis at one month postoperative period.

[Table/Fig-4] demonstrates one of the cases for which elective implant removal was performed at 18-months interval after fracture was healed.

[Table/Fig-4]:

An 18 month postoperative implant removal.

Some of the cases which had fractured pedicle or unsafe for insertion of pedicle screws were abandoned and excluded from the study. [Table/Fig-5] demonstrates such one case, in which only single screw was inserted and hence, was excluded from the study.

[Table/Fig-5]:

Postoperative follow up at 16 months of uni-pedicular fixation (Excluded case).

Fourteen men and eleven women with an average age of 42.92 years (range 18 to 74 years) comprised the study. Mean age at the time of operation was 34.5±14.2 years (range 18–74). Male to female ratio of 1.27 the majority of fractures resulted due to fall from height (15 cases {60%}), the remaining cases resulted from car accidents (10 cases 40.0%). Preoperative Frankel grading of patients was done and has been shown in [Table/Fig-6]. Mean operation time was 168±72 (minutes). Average hospitalization time was 9±7 (days). Mean blood loss was 515±485 (ml). There were two cases of postoperative infection and implant failure each [Table/Fig-6].

A mean loss of AVH on postoperative radiograph was 6.12% and maintained 12.4% at the time of review (p<0.001). Similarly, there was 32.8% midsagittal height loss (calculated based on average midsagittal diameter at vertebrae above and below) at the time of injury, which was improved to only 12.6% as compare to initial height loss (p<0.001) [Table/Fig-7].

A mean of 15.2° of kyphosis correction was attained from pre-operation to post-operation (p<0.001). Although there was a 15° average improvement of kyphosis post-fixation, loss of correction over time was nearly 8°, resulting in a 7° mean correction of kyphosis. The postoperative images are shown in [Table/Fig-3,4 and 5].

Burst fractures are the most common type of fracture of the thoracolumbar spine, accounting for greater than 50% of all thoracolumbar trauma [1]. Burst fractures typically involve violation of the inferior and/or superior endplates, and therefore the deformity may progress by gradual settling of the discs into the fractured endplates and vertebral body. Farcy JP et al., proposed that if the sagittal index exceeds 15 degrees [8], the biomechanical environment favors the progression of kyphosis [9].

Traditional pedicle screw instrumentation allowed a correction of kyphosis and an indirect reduction of thoracolumbar burst by distraction and ligamentotaxis. However, due to frequent failure to support the anterior spinal column, there was often a loss of correction leading to a high rate of failure [10-14]. Failure to restore the anterior column support can lead to secondary kyphosis, instability, pain and late onset neurologic deficit, depending primarily on residual load transfer capacity of the fractured vertebral body [15,16].

SSPF is the use of pedicle screw instrumentation one level cephalad to and one level caudal to the fractured vertebra. It has become an increasingly popular method of treatment of thoracolumbar burst fractures, providing the advantage of incorporating fewer motion segments in the fixation [17]. A cadaveric study of short-segment posterior fixation with pedicle fixation at the level of the fracture (short same-segment fixation) showed that short same-segment fixation provides more biomechanical stability than traditional SSPF [3]. However, a review of literature demonstrated that SSPF led to 9%-54% incidence of implant failure and long term loss of kyphosis correction, and up to 50% of patients with implant failure had moderate to severe pain [10,13,18,19].

Failure of SSPF can be attributed to instrumentation failure (i.e., bending and/or breaking of the screws), vertebral factors (i.e., primary osseous collapse or secondary to osteoporosis), or a combination of both [8]. Other possible factors include inadequate fixation points on the vertebrae and insufficient anterior column support [20].

Bi-pedicular fixation works on ligamatotaxis principle and due to which, only early presentations give good results postoperatively. Hence, they were only included. This study also did not compare the significance of using different lengths of the pedicle screws (amongst the longest ones) used during fixation and the sample size was small. Hence, more large scale and multi centric based studies should be conducted.

In this study, we propose SSPF using longest possible screws in both pedicle of fractured vertebra. Bi-pedicular fixation gives significant radiological corrections. A long pedicle screw in bilateral fractured vertebrae supports subchondral bone, superior endplate and allows more correction by cantilever forces created by distraction manoeuvre. This three point fixation also prevents collapse and loss of kyphosis achieved.