Evaluation of the Results of Posterior Decompression , Corpectomy and Instrumentation in Traumatic Unstable Thoraco-Lumbar Burst Fractures

Background: Thoraco-lumbar burst fractures occur as a result of axial load which often causes displacement of the middle column into the vertebral canal. Posterior surgery reduces the morbid outcomes of different other approaches. Objective: To evaluate the clinical and radiological success of posterior corpectomy and instrumentation in the management of traumatic unstable thoraco-lumbar burst fractures. Methods: It is a prospective interventional study carried out in Bangabandhu Sheikh Mujib Medical University and different private hospitals in Dhaka from July 2008 to December 2011. Total 18 patients; 13 male and 05 female within an age range of 21-40 years were selected. Total 09 cases involved L1, 05 cases at D12, 02 cases at D11 and at L2 each. Neurological status was assessed by Frankel‘s grading and pain status by Visual Analogue Score (VAS). Paired t-test was used for statistical analysis. Results: All the patients were followed up for minimum 1 year. Eleven out of 12 patients with Frankel grade-B and 04 patients out of 06 with Frankel grade-C recovered fully and could walk without support (p<0.05). Overall 03 patients ended with some degrees of persistant neurological deficit. The mean postoperative pain improvement and kyphotic angle correction was significant (p<0.05). Conclusion: Decompression through posterior approach by laminectomy, corpectomy and fusion by cage with bone graft and stabilization by pedicle screw and rod significantly improves the clinical and radiological outcome in management of traumatic unstable thoraco-lumbar burst fractures.

Thoraco-lumbar burst fractures should be managed surgically to protect and improve the neurological function, stabilize the spine, early mobilization and rehabilitation as well as minimizing the pain and subsequent deformity. 9pen reduction, arthrodesis, and internal fixation offers the possibilities of immediate stability, correction of deformity, early walking and reduced reliance on orthotic containment, with additional theoretical protection against spinal mal-alignment or neurological injury. 14,15 ifferent operative methods exist with the goals of fracture reduction, fixation and decompressing the neural canal.These stabilization procedures can be divided into anterior, posterior and combined anterior-posterior instrumentation. 4Although removal of the compressing bone fragment from anterior side of spinal cord directly addresses the pathology causing the neurodeficit, 16 the morbidity of the surgery through anterior approach is higher than that of posterior approach. 17So, there has been a tendency for posterior stabilization and instrumentation as the preferred treatment modality for these type of fractures. 8,9 re has been a few study of assessing the outcome of posterior surgery in different literature reviews but in the perspective of our country this approach is new and has not been assessed regarding the outcome.The purpose of this study is to provide a prospective evaluation of patients having traumatic thoracolumbar burst fractures and to assess the clinical and radiological results of patients treated by decompression through posterior approach by laminectomy, corpectomy and fusion by cage with bone graft and stabilization by pedicle screw and rod.The patients operated within 07-39 days (average 27 days) after the incident of trauma.Three patients had associated fractures but none required surgery for those injuries.All the patients were followed up for minimum 1 year.

Methods:
The Inclusion criteria for selection of the study population were -Unstable thoraco-lumbar burst fracture (White and Panjabi scoring >5); ii) incomplete neurological deficit (Frankel grade-B, C, D); iii) progressive neurological deficit; iv) presented within 03 weeks of trauma.Exclusion criteria were as follows: i) stable fractures (White and Panjabi scoring <5); ii) neurologically intact patients (Frankel grade-E); iii) complete neurological deficit (Frankel grade-A); iv) Glasgow coma Scale <14; v) associated fractures requiring operative intervention.The neurological status of all the cases were evaluated both pre and postoperatively and recorded based on Frankel scale showed in table-I & III.The clinical instability was assessed according to the White and Panjabi 18 Scoring as in table-II.Pain severity was assessed by the Visual Analogue Score (VAS) 19 both preoperative and postoperatively.The neural involvement was assessed routinely by MRI in every case and the fracture anatomy was evaluated routinely by X-ray and CT scan as in figure-1(b).
The duration of surgery, intra-operative blood loss and postoperative hospital stay was documented accordingly.All the patients underwent follow-up at 3 months, 6 months and at the end of a year.They were evaluated clinically regarding neurological improvement, functional outcome and complications.The radiological restoration of anatomy and improvement of the kyphotic angle was assessed as in table-III and documented in every followup.The improvement of pain status as well as the restoration of the kyphotic angle was statistically analyzed by the paired t-test.

Operative Procedure:
Posterior approach is faster and technically simple to carry out and is suitable for emergency conditions.The level of vertebra involved was identified preoperatively by a skin marking under radiological guidance to aid the peroperative vertebral level identification as well as planning of the extent of incision.All the patients underwent surgery under general anesthesia and in prone position.A midline incision was made and extended both proximally and distally according to the requirement.The cutaneous bleeding points were secured and the para-spinal muscles were retracted up to the level of the transverse processes.The injured level of vertebra was identified and confirmed by using C-arm or a portable X-ray.
The lamina and the facets were cleared off the soft tissues and any bleeding was secured by proper haemostasis using bipolar diathermy.The pedicles were identified by serially using the pedicle probe and pedicle sound; the integrity of the pedicle walls was checked.The position of the probe was confirmed again by using the C-arm or a portable X-ray.Pedicle screws of adequate length and diameter were inserted minimum two levels above and below the injured segment.The sagittal and coronal angulation for screw insertion was maintained with caution.The screw placement was rechecked by portable X-ray or C-arm.The Titanium rod has been measured, cut and fixed on one side to allow distraction in required situations.We commonly used the 5.5mm diameter screws of 35mm to 45mm length and 5mm diameter rods.
The posterior lamina along with its superior and inferior ligamentum flavum of the injured vertebra was removed and decompression of the neural elements was approached by removing the unilateral pedicle of the side where the bony fracture fragment caused the compression or impingement.Adequate distraction was done by using the distractor.Corpectomy (removal of the vertebral body) was done through this space by using the osteotome with care to the neural elements to avoid injury.Complete removal of the body was confirmed and the decompression was checked.The length of the cage required was measured, cut and packed with autografts.A trial was given before finally placing the cage with bone graft with the cage applicator.The bone grafts were prepared from the bony fragments cut from the spinous process and corpectomy.The position of the cage placement was checked with the image intensifiers (C-arm or a portable X-ray).The lateral gaps around the cage was packed with remaining morcelized autografts and impacted with the bone graft impactor.dural tears were repaired after repositioning the neural elements whenever it has been found to be disrupted.
The Titanium rods were measured; cut, bent and placed.Adequate compression was applied and the screws were tightened.Connector bars were fixed both proximally and distally.The prepared bone grafts were again placed postero-laterally for postero-lateral fusion.Well sized spongostum was cut and placed over the decompressed dural sac.Bleeding points were checked and cauterized.The wound was closed in layers with a drain kept insitu.

Results:
The study comprised of 18 cases during the period of 42 months.Table-II demonstrates the demographic variables depicting that, out of 18 patients, 13(72.30%)were males and 05(27.70%)were females.Most of the patients 12(67.00%)were in 26-30 year age group followed by 06(33.00%) in 21-25 year age group.Male to female ratio was 2.6:1 and the mean age was 32 years.The cause, level of involvement and perioperative outcome of all the patients under study is also elaborated in table-III.Fall was the most common cause of injury 11(62.00%)out of which 07 from trees, 03 fell from roof and 01 from polls.Remaining causes were road traffic accident 07(38.00%).Time between injury and surgery was 07-39 days, mean 27 days.Preoperatively X-ray of the thoraco-lumbar spine was carried out in all patients as well as MRI and CT scan.The most common level of injury involved was L 1 09(50.00%)followed by D 12 05(28.00%)and D 11 and L 2 02(11.00%)each.
All the patients regardless of fracture type were decompressed posteriorly and stabilization was performed in each case by titanium pedicle screws and rods.The pedicles of minimum 2 above segments and 2 lower segments were approached which is showed in figure-I(c).Postoperative X-ray films showed good hardware position in all patients in the study one example of which is showed in figure-I(c),(d).During an average of 14 months (range, 12-36 months) follow-up, no hardware failure was detected.Adequate decompression was achieved in all the cases and no loss of correction was observed.The mean duration of surgery was 03 hours and 14 minutes whereas the mean blood loss was 329 ml.
The mean postoperative hospital stay was 9.8 days (range 05-18 days) and all the patients were mobilized in the 1 st postoperative day.The preoperative and postoperative pain status was assessed by Visual Analogue Score (VAS) 19 .Mean local thoraco-lumbar back pain at the fracture site was 07.22 (range, 6-9) before operation.Postoperatively, the pain score decreased to 01.78 (range, 1-3) at 3 months (p< 0.005), 2.6 (range, 1-4) at 6 months,  The post operative complication occurred in only 01 patient which was a superficial wound infection that was managed conservatively and cured.There were 04 cases where dura was found to be injured before and repaired during the procedure.No dural injury occurred peroperatively.Associated injuries were found in 05 patients having calcaneal fracture, 03 with stable pelvic fracture and 01 Talar dome fracture which was managed non-surgically.

Discussion:
Majority of patients in our study were young.The mean age was around 32 years.It is clear from many studies that young people suffer spinal cord injuries more often than any other age group.Out of 18 cases, 13(72.30%)were male and 05(27.70%)females.Raja 9 showed 86% male patients in his series of 50 patients, similarly in other studies males are supposed to be more exposed to trauma than females. 20,21 all was the most common cause of injury in 11(62.00%)cases which has also been observed in some studies, 9, 20 but Payer 17 showed road traffic accident is the common cause of injury.
Hyperflexion and axial loading was the common mode of injury observed.Most common level involved was L 1 (50.00%)followed by D 12 (28.00%).Raja 9 showed 46% involvement of L 1 and 12% involvement of D 12 , coinciding with our results, other studies Shah et al 22 , Hitchon et al 23 It is also important to note that hospital stay was short which is compatible with other studies. 21Rehabilitation in terms of physiotherapy was started in wards and continued by authors themselves as no proper rehabilitation centers were available to continue the therapy.The average level of discomfort, according to the visual-analog pain scale at the final follow-up evaluation was relatively low as in other studies. 25,26 h the advent of modern design and appliances transpedicular screw fixation by a dorsal approach offers a fast, stable and safe means of achieving stabilization and correcting malalignments. 27In our study all the postoperative follow up X-ray has been evaluated by three different qualified radiologists with an interpretation of good alignment repositioning and restoration of the spinal column and postoperative correction of kyphotic deformity.
We have shown that posterior decompression with posterior pedicle screw instrumentation good restoration of the sagittal curve is possible without loss of correction during the healing of the fracture.The average amount of preoperative kyphosis was 20.44° (range, 10° to 28°) and at 1 year follow-up average kyphosis was 04.94° (range 0°t o 12°).There was average correction of 15.50° (range 10°-25°) at the end of 1 year and we did not observe any significant loss of correction in this period, moreover no correlation was found between the final amount of kyphosis and the degree of pain reported.Essess et al 14 showed 11.30° correction which is comparable to our result.Many other studies also demonstrated the successful repositioning, kyphosis correction, reliable fracture consolidation and neural decompression as well as good neurological recovery achieved via the dorsal approach, 28, 29 although Verlan et al 30 concluded that no treatment is able to restore the morphology of the vertebral segment to normal physiological levels for thoracolumbar spine fractures.
In our study only one case developed superficial wound infection which was managed conservatively.Herck et al 31 33 .
Out of the 18 patients 15(83.00%)had complete recovery within 1 year of follow up.Three (17.00%) patient had partial recovery needing walking aids.Avanzi 34 studied on 15 patients treated within 3-6 weeks of the trauma having thoraco-lumbar fractures found improvement of the neurological picture in 60% of their patients.We must consider that these patients operated within 06 weeks of fracture are more likely to have improved neurological picture than those treated after three months 34,35 .Out of 18 patients of our series 09(50.00%)patients could return to their previous work.Wood et al 32 found 42% patients returning to their previous work and Kraemer 2 found 33% which are almost similar to our studies.
There are limitations of our study as the study population is small and period of follow up of only a year.We also could not determine whether posterior decompression clears the canal adequately as the computed tomography scans were not performed postoperatively.Moreover a long term follow-up is required to assess any sort of loss of correction of kyphosis.Only the functional improvement and radiological alignment were considered and no comorbid factors were evaluated regarding the outcome of the surgery.

Conclusion:
Posterior decompression and instrumentation provides a safe and effective surgical option for management of traumatic thoracolumbar burst fractures.It effectively decompresses the canal and achieves significant correction of kyphotic deformity.Early significant pain relief ensures early mobilization and rapid recovery.

Fig.- 1 :
Fig.-1: Case: 05, A 36 years old young male falling from 30 feet height jackfruit tree presenting with incomplete paraplegia due to burst fracture at L2. Preoperative MRI showing a retropulsion fragment compressing over the neural elements of the spinal canal with reduced diameter of the canal (a), Preoperative CT scan assessment of the spinal canal compromise (b) Postoperative X-ray showing satisfactory placement of pedicle screws and correction of kyphotic deformity (c),(d).
This prospective interventonal study is carried out in Bangabandhu Sheikh Mujib Medical University and different private hospitals in Dhaka city from July 2008 to December 2011.Total 18 patients were selected; 13 male and 05 female within a age range of 21-40 years.Total 09 cases involved L 1 , 05 cases involved at D 12 , 02 cases involved at D 11 and at L 2 each.Six (06) patients presented with Frankel grade-C, 12 patients with Frankel grade-B.

Table - II
Shows White and Panjabi method of diagnosis of clinical instability * A point value total of 5 or more indicates clinical instability.

Table - I
Shows Frankel scale of motor and sensory index

Table - III
24mographic variables, level of involvement, cause, preoperative and postoperative neurological and pain status.McCormack et al24also showed the common level of injury is D 12 -L 1.Most common grade found in these types of fractures was Frankel grade B. It was also noted that more severe the canal compromise, worse the neurological deficit.Gerzbein 20 and Hitchon 23 also showed the similar scenario.
also showed two complications in his series of 30 cases.The complication rate is in agreement with those reported in other studies conducted by McLain et al 21 , Benson et al 32 and Stovall et al