SHORT SEGMENT FIXATION THORACOLUMBAR UNSTABLE BURST FRACTURES USING DC PLATES & PEDICLE SCREWS

STUDY SHORT SEGMENT FIXATION THORACOLUMBAR UNSTABLE BURST FRACTURES USING DC PLATES & PEDICLE SCREWS *Hashem, N.; **A Subai, N. *Faculty of Medicine, Ains Shams University, Egypt ^Department of Orthopedics, Hamad Medical Corp. Doha, Qatar Abstract Materials and Methods Twenty-one patients with unstable burst fractures of the thoracolumbar spine (T-L3) were treated with narrow DC plates and.mm cancellous pedicle screws. The number of levels instrumented in all patients were only one level above and one level below the fracture. Follow-up averaged months (range -4 months). The correction of kyphotic angle in all patients averaged. degrees at follow-up, while in patients with fractures above L level.4 degrees, and in patients with fractures below L level 4 degrees. Twenty one patients with thoracolumbar unstable burst fractures underwent posterior spinal fusion using DC plates and only one level above and one level below the fracture. There were 8 male and 3 female with average follow-up months (range -4 months). The average age of the patients was 3 years (range -48 years). The improvement of vertebral segment height for all patients averaged % of normal atfollow-up, while in patients with fractures above L level 3%, and in patients with fractures below L level % The neurologic improvement averaged.7 Frankel grades (range, -3). The fixation was stable enough to allow early mobilization and rehabilitation. There were no screw breakage of implant failure, and solid fusion was obtained in all patients. Introduction The surgical treatment and internal fixation of unstable spinal injuries has gained increasing favor in recent years. It has been shown not only to decrease length of hospitalization and hence cost, but also to facilitate rehabilitation and earlier return to optimal function (,, 4,, ). Numerous studies have been undertaken to evaluate the efficiency of surgical versus non surgical treatment of these injuries, as well as the relative merits of anterior and posterior surgical stabilization^,7,8,^. This study does not attempt to evaluate critically these considerations. It was designed to attempt to preserve more motion segments by fixing only one level above and one level below the fracture. The study group included patients with unstable burst fractures of thoracolumbar spine treated by DC plates and pedicle screws. The patients were evaluated with regard to correction of deformity, neurologic recovery, and fusion rate. Address for correspondence: Dr. Nasser Al Subai, FACHARCT Department of Orthopedics, Hamad Medical Corporation P.. Box 3, Doha, Qatar 4 All patients were admitted through the Accident and Emergency department and had plain radiographs (antroposterior and lateral views) and CT scan with sagittal reconstruction. Spinal canal compromise was determined and the injuries were classified according to three -columns theory of Denis (4). Patients who had disruption of two or more columns and significant canal encroachment were considered to have unstable fractures and were considered for posterior surgical stabilization. A complete neurologic examination was performed at the time of admission and the neurologic compromise was classified according to the functional system described by Frankel (8). Surgery was undertaken as soon as the patient condition allowed. Surgical intervention was performed within 4 hours in patients, at days in 9 patients, and at days in patients. Surgical Technique The transverse processes and the facets were decorticated and the local bonegrafts from the spinous processes and the harvested laminae were placed over them. The DC plate was bent to conform to the desired configuration. Full threaded. mm cancellous screws of appropriate length were inserted through the contoured plate and tightened. A closed suction drain was placed and the soft tissue was closed in layers. Postoperative antibiotics were continued until the drain was removed, and orthosis was applied. Mobilization was started as soon as possible depending on the neurologic deficit. Physiotherapy started immediately after surgery. Patients were discharged f r o m hospital when they were safely and independently ambulatory. All patients were instructed to wear their brace for 3 months after surgery. Patients were examined in out - patient clinic after discharge from hospital at one month, three months, six months and each year after that. QATAR MEDICAL JOURNAL VOL. 7 / NO. / NOVEMBER 998

Thoracolumbar... A camparative radiographic analysis was performed using Preoperative, postoperative, and months follow-up radiographs. Restoration of vertabral height and sagittal spinal alignment were evaluated. Vertebral Height: was assessed in the lateral films using a Metric ruler. The anterior vertical height of each vertebral body a nd its adjacent discs were measured. In this way, injury to the complete vertebral segment-including the disc space was Measured. Vertebral compression was measured directly at the affected level and reported as a percentage of normal determined by averaging the heights of similar segments above and below the fracture. Kyphotic Angle: was measured via the standarized Cobb Method. The superior end plate of the vertebra above and the mferior end plate of the vertebra below the fracture were used for measurement in all patients so that uniformity was Maintained. The neural function before surgery and at follow-up was given a Frankel grade score. Results This study included patients with unstable burst fractures f the thoracolumbar spine. All fractures were between T and L3. Two patients had fracture two vertebrae, one D-L, a nd the other L-L Vertebra ( I). There were a total of 3 fractures in patients. The distribution of injury levels was s hown in {Table ). The mechanism of injury involved a motor chicle accident in cases, falls from height in 3 cases, and Mjury by a falling object in two cases. Radiologic Assessment The change in kyphotic angle and vertebral segment height from preoperative to postoperative values and from postoperative to month follow-up values were assessed. The preoperative kyphotic angle in all patients averaged 7.8 degrees, corrected to 3.7 degrees postoperatively, and reduced to.7 degrees at follow-up. Thus, postoperatively, kyphosis corrected at an average of 4. degrees, and at follow-up examination loss of kyphosis correction averaged 8. degrees. Thus. degrees of correction was attained at follow-up examination. In patients with fractures above L level the preoperative kyphotic angle averaged 7 degrees, corrected to.8 degrees postoperatively and reduced to. degrees at follow-up.thus postoperativel, kyphosis corrected at an average of. degrees, and at follow-up examination loss of kyphosis correction averaged 9.8 degrees. Thus only.4 degree of correction was attained at follow-up examination. While in patients with fractures below L level, the preoperative kyphotic angle averaged degrees, corrected to lordotic angle of an average of 4 degrees postoperatively, and reduced to lordotic angle of 3 degrees at follow-up. The preoperative vertebral segment height in all patients averaged 7% normal, improved to 9% postoperatively, the height improved at an average of %, and at follow-up examination loss of height averaged %. Thus % improvement was gained at follow-up examination. In patients with fractures above L level, the preoperative height averaged 9%, improved to 9% postoperatively, Thus postoperatively, kyphosis was corrected at an average of degrees, and at follow up examination loss of correction averaged only one degree. Thus 4 degrees of correction was attained at follow-up examination. The preoperative vertebral segment height in all patients averaged 7% of normal, improved to 9% postoperatively and reduced to 7% at follow up. Thus postoperatively, the height Table : Burst Number Level 8 T LI L L3 A Fractures 3 IB : A 8-year old male sustained both LI and L burst fractures with Frankel B neur logic function. A) Preoperative lateral radiograph shows degrees kyphosis and 79% Ver tebral segment height. B) CT scan shows the three column injury and spinal canal encroachment. C) Postoperative reduction and stabilization with DC plates, kyphosis is corrected to e 8rees, vertebral segment height restored to %, and neurologically improved to grade D. QATAR MEDICAL JOURNAL VOL. 7 / NO. / NOVEMBER 998 C

Thoracolumbar. improved at an average of %, and at follow-up examination loss of height improved at an average of %, and follow up examination loss of height averaged %. Thus % improvement was gained at follow-up examination. In patients with fractures above L level, the preoperative height averaged 9%, improved to 9% postoperatively, and reduced to 7% at follow-up. Thus postoperatively the height improved at an average of 3%, and at follow-up examination loss of height averaged %. Thus only 3% improvement was gained at follow-up examination. While in patients with fractures below L level, the preoperative height averaged 7%, improved to 87% postoperatively, and reduced to 83% at follow-up. Thus postoperatively, the height improved at an average of %, and at follow-up examination, loss of height averaged 4%. Thus % improvement was gained at follow-up examination. Neurologic Assessment The preoperative and post operative neurologic function was assessed in all patients according to the functional grading of Frankel (Table ). Six patients 9% were neurologically normal at presentation (Frankel grade E). None of these patients worsened. Fifteen patients 7% had neurologic injury (Frankel grade A). This patient improved to grade C. Two Frankel grade B, one improved to grade E, and one to grade D. Seven Frankel grade C, six improved to grade E and one to grade D. Five Frankel grade D, all improved to Frankel E. The average neurologic improvement was.7% Frankel grades (range, -3 grade). Ambulation was possible in 93% of the neurologically affected patients at follow-up. Table : Pre and Postoperative Frankel Neurologic level Postoperative Preoperative Functional A B C D E Total A B C 7 7 D E 8 Total Complications There were no wound infection, and no iatrogenic neurologic deficit. The two cases with post-traumatic dural tear, CSF leakage from the wounds ceased in two weeks time. The most common problem was catheter-related urinary tract infection in four cases. No cases of bent or broken screws, and solid fusion was obtained in all patients. Discussion In considering the management of patients with unstable injuries to the thoracolumbar spine by posterior instrumentation, a balanced stable spine with optimal neurologic function and fewest number of immobilized spinal segments should be obtained. Among the many advantages cited with pedicle screw implants, the potential for limited fixation has been the most obvious, with the natural assumption that residual intersegmental spinal motion could be maintained in the unaffected segments This advantage becomes increasingly important in the thoracolumbar transition zone, where preservation of motion and restoration of lordosis is necessary. The number of immobilized segments recommended by Roy-Camille for treatment of unstable burst fractures of thoracolumbar spine using his pedicle screw plates were two levels above and two levels below the fracture (7,8). The AO group in their manual of internal fixation, cities the technique of Roy-Camille for performing internal fixation with pedicle screw plating. Instead of using his round-hole plates, however they advocated narrow DC plates ^ l \ Sasso et al, reported on a series of patients with thoracic and lumbar spine fractures treated with internal fixation using DC plates and pedicle screws. The rationale for the number of levels instrumented was similar to that of Roy-Camille. Burst facilities were instumented two levels above and two levels below the fracture (9). In this series of unstable burst thoracolumbar fractures DC plates and pedicle screws were placed only one level above and one level below in an attempt to preserve more motion segments. All patients had significant correction of their deformities after surgery, however at month follow-up patients with fractures above L level did not reveal any significant difference ( ), while in patients with fractures below L level, a significant correction was obtained ( 3). The postoperative significant correction is related to the distraction instrumentation used with the DC plates for reduction of unstable burst fractures. The loss of correction at follow-up essentially occurred above L level where compression forces act more anteriorly, while below L level where the compression forces act more posteriorly a significant correction was obtained at follow-up examination. Also the toggle of the screws within the limits of the screw hole of the DC plates is partially responsible for loss of correction. In Sasso et al series, burst fractures has been also fixed with DC plates and pedicle screws, but they instrumented two levels above and two levels below the fracture. They reported that the preoperative and postoperative values are statistically different however the preoperative and follow-up values are not significantly different as the initial correction was progressively lost after operation such that the initial deformity was QATAR MEDICAL JOURNAL VOL. 7 / NO. / NOVEMBER 998

Thoracolumbar... C D 3A : A 3-year old male sustained LI burst fracture with Frankel C neurologic function. A) Preoperative antroposterior and lateral radiographs shows degrees Kyphosis and 8% vertebral segment height. B) Axial CT scan, and sagittal reconstruction shows the three column injury and spinal canal encroachment. C) Postoperative reduction and stabilization with DC plates, Kyphosis is corrected to degrees and vertebral segment height has been restored to 9% of normal. D) Follow-up radiographs shows that the kyphotic angle is reduced to degrees and vertebral segment height to 8% of normal. However solid fusion is present and neurologic ally improved to grade E. 3C B 3B 3: A 43 year old male sustained L3 burst fracture with Frankel C neurologic function. A) Preoperative antroposterior and lateral radiographs shows degrees kyphosis and 4% vertebral segment height. B) CT scan shows the column injury and spinal canal encroachment. C) Postoperative reduction and stabilization with DC plates, lordosis is 4 degrees and vertebral segement height has been restored to 8% of normal. D) Follow-up radiographs shows that the lordotic angle remained 4 degrees while vertebral segment height is reduced to 78%. Solid fusion is present and neurologically 3D improved to grade E. QATAR MEDICAL JOURNAL VOL. 7 / NO. / NOVEMBER 998 7

Thoracolumbar. approximated 9 ). Thus with using DC plates the loss of correction is not necessarily avoided by increasing the segments that were instrumented. Neurologic injury has been reported to occur in 3 to % of patients with thoracolumbar burst fractures^. Although in many instances the neurologic deficit is likely related to the impact at the time of injury, Hashimoto et al have recently demonstrated a relationship between the amount of traumatic canal stenosis and the neurologic deficit (I). Herndon and Galloway, in their study were not able to show any relationship between preoperative or postoperative neurologic function and canal area or kyphosis(). Evidence, however, has also been presented that surgery may improve the neurologic outcome. Bradford and McBride believe that neurologic recovery is related to the adequacy of surgical spinal decompression^. Gertzbein et al, compared their results in patients with incomplete neurologic injury treated with surgical intervention to those of the literature(9). They found an improvement rate in neurologic function of 83% for patients treated with posterior surgery versus an improvement rate of % for patients treated non surgically. In this series all patients with neurologic deficit had improved in a range of one to three Frankel grade, and ambulation was possible in 93% of them at follow-up. Thus, spinal realignment, decompression, and stabilization improve the potential for Spinal cord recovery. The fusion rate with 'one above - one below' DC plates and pedicle screw fixation in this series was %, while the fusion rate with 'two above - two below' DC plates and pedicle screw fixation was 9.%in Sasso et al series(9). Krag has suggested pedicle fixation two levels above the kyphosis to avoid implant failure (3). Daniaux et al reported a 9% screw breakage rate in the use of pedicle screws and plates(3). In this series no screw breakage or implant failure occurred with the "one above - one below" technique. Conclusion Spinal realignment, decompression, and stabilization improve the potential for spinal cord recovery. The fixation provided with the combination of DC plates and. mm fullthreaded cancellous screws was stable enough to allow early mobilization and rehabilitation. With the "one above - one below" technique, the number of screws is reduced to an absolute minimum. This correspondingly reduces the total risk associated with screw placement, decreases overall operative time and preserve more motion segments. Although fusion rate was high, and no increase in neurologic deficit occurred, the inability to maintain complete postoperative correction was of concern. References: - Aebi M, Etter C, Kehl T, Thalgott J: Stabilization of the lower thoracic and lumbar spine with the internal spinal skeletal fixation system. Spine :44-,987. - Bradford DS, McBride GG: Surgical management of thoracolumbar spine fractures with incomplete neurologic deficit. Clin Orthop 8:-,987. 3- Daniaux H, Seykora P, Genelin A, LangT, Kathrein A: Application of posterior plating and modifications in thoracolumbar spine injuries : Indications, technique and results.spine ::S 33,99 4- Denis F: The three column spine and its significance in the classification of acute thoracolumbar, spinal injuries. Spine 8:87-83,983 - Dick W: The 'Fixateur Interne' as a versatile implant for spine surgery. Spine :88-9, 987 - Dick W, Kluger P, Magerl F, Woersdorfer O, Zach G: A new device for internal fixation of thoracolumbar and lumbar spine fractures. The 'Fixateur Interne', Paraplegia 3: -3, 98 7- Dunn HK: Anterior Spine Stabilization and decompression for thoracolumbar injuries. Orthop Clin North Am 7:3-9, 98. 8- Frankel HL, Hancock DO, Hyslop G, et al: The value of postural reduction in initial management of closed injuries of the spine with paraplegia and tetraplegia: Part. Paraplegia 7:79-9, 99 9- Gertzbein SD, Court - Brown CM, Marks P, et al: The neurological outcome following surgery for spinal fractures. Spine 3:4,988. - Hashimoto T, Kaneda K, Abumi K: Relationship between traumatic spinal canal stenosis and neurologic deficit in thoracolumbar burst fractures. Spine 3: 8-7, 988. -Herndon WA, Galloway D: Neurologic return versus crosssectional area incomplete thoracolumbar spinal cord injuries. J. Trauma 8:8-83, 988 8 - Jelsma RR: Surgical treatment of thoracolumbar spine fractures. Surg Neural 8:-,98 3- Krag MH: Biomechanics of thoracolumbar spinal fixation : A review Spine :S84-99, 99 4- Krompinger WJ, Frederickson BE, Yuan HA : Conservative treatment of fractures of the thoracic and lumbar spine. Orthop Clin North Am 7:-7, 98. - Magerl FP : Stabilization of lower thoracic and lumbar spine with internal skeletal fixation Clin Orthop 89 :-4, 984 - Mullar ME, Allgowar M, Schneider R, Willenegger H : Techniques recommended by the AO group : Manual of internal fixation. Second edition. Berlin. Springer-Verlag, pp 34-3,979 7- Roy - Camille R, Saillant G, Berteaux D, Salgado V: Osteosynthesis of thoracolumbar spine Fractures with metal plates screwed through the vertebral pedicles. Reconstr Surg Traumatol :-,97. 8- Roy - Camille R, Saillant G, Magel C : Internal fixation of lumbar spine with pedicle screw plating. Clin Orthop 3:7-7, 98. 9- Sasso RC, Cotler HB, Reuben JD : Posterior fixation of thoracic and lumbar spine fractures using DC plates and pedicle screws. Spine : S34-39, 99. - Tator CH, Duncan FG, Edmonds VE, Lapczak El, Andrews DF : Comparison of surgical and conservative management in 8 patients with, acute spinal cord injury. Can J Neurol Sci 4:- 9, 987 - Willen J.Anderson J, Toomoka K, Sinczek : The natural history of burst fractures at Thoracolumbar junction. Journal of Spinal Disorders 3:39-4, 99. - Wilmot CB, Hall KM: Evaluation of acute surgical intervention in traumatic paraplegia. Paraplegia 4:7-7,98. QATAR MEDICAL JOURNAL VOL. 7 / NO. / NOVEMBER 998