Orthopedics

The articles prior to January 2012 are part of the back file collection and are not available with a current paid subscription. To access the article, you may purchase it or purchase the complete back file collection here

Trauma 

A COMPARISON STUDY OF TREATMENT OF THORACOLUMBAR FRACTURES USING THE ACE POSTERIOR SEGMENTAL FIXATOR AND COTREL-DUBOUSSET INSTRUMENTATION

David C Markel, MD; Gregory P Graziano, MD

Abstract

ABSTRACT

The results of 26 consecutive thoracolumbar fractures treated with Cotrel-Dubousset instrumentation (CDI) (n = 12) or the ACE Posterior Segmental Fixator (n = 14) with a mean follow up of 20.2 months were analyzed. Preoperatively, no statistically significant difference was noted between the two treatment groups. Postoperatively, no statistically significant difference was noted for improvement of kyphosis (mean: - 6.00° ACE, 1.92° CDI), vertebral body height (mean: 17.86% ACE, 18.83% CDI), vertebral body angle (mean: -6.21° ACE, -5.42° CDI), or estimated blood loss (mean: 1544 cc ACE, 1620 ce CDI). All patients with incomplete paraplegia improved by at least one Frankel grade. Statistically significant differences were noted in operative time (mean: 269 minutes ACE, 357 minutes CDI, P<.0005), and in the number of instrumented levels (mean: 3 ACE, 5.8 CDI). All patients exhibited solid fusion radiographically. Thoracolumbar fractures can be effectively treated by either CDI or the ACE Fixator. The ACE Fixator has the advantage of sparing motion segments and decreased operative time.

Abstract

ABSTRACT

The results of 26 consecutive thoracolumbar fractures treated with Cotrel-Dubousset instrumentation (CDI) (n = 12) or the ACE Posterior Segmental Fixator (n = 14) with a mean follow up of 20.2 months were analyzed. Preoperatively, no statistically significant difference was noted between the two treatment groups. Postoperatively, no statistically significant difference was noted for improvement of kyphosis (mean: - 6.00° ACE, 1.92° CDI), vertebral body height (mean: 17.86% ACE, 18.83% CDI), vertebral body angle (mean: -6.21° ACE, -5.42° CDI), or estimated blood loss (mean: 1544 cc ACE, 1620 ce CDI). All patients with incomplete paraplegia improved by at least one Frankel grade. Statistically significant differences were noted in operative time (mean: 269 minutes ACE, 357 minutes CDI, P<.0005), and in the number of instrumented levels (mean: 3 ACE, 5.8 CDI). All patients exhibited solid fusion radiographically. Thoracolumbar fractures can be effectively treated by either CDI or the ACE Fixator. The ACE Fixator has the advantage of sparing motion segments and decreased operative time.

The primary goals of surgical intervention of thoracolumbar fractures are fracture reduction, canal decompression, stabilization, and early mobilization.1-5 Instrumentation systems were designed to this end and have evolved into the segmental fixation devices of today.

In recent years, Cotrel-Dubousset instrumentation (CDI) (Sofamor-Rang, Du Fliers, France) and pedicle fixation devices have been at the forefront of spinal trauma surgery. CDI has proved strong, versatile, and allows correction in multiple planes.6-10 The disadvantages of CDI are the number of motion segments immobilized by the fixation construct and the complexity in applying the system. The development of the Fixator Interne by Magerl and Dick,8,11,12 and, subsequently, the Posterior Segmental Fixator by Olerud13,14 (Figs IA-B), have allowed pedicle fixation to be exploited in fracture care. The ACE Posterior Segmental Fixator (ACE Medical Company, Los Angeles, Calif) provides strong, stable fixation and involves a minimum number of motion segments. The present study was undertaken to evaluate the effectiveness of the ACE Fixator in comparison to CDI.

Fig 1: Anteroposterior (A) and lateral (B) schematic drawings depicting the ACE Posterior Segmental Fixator. The construct is based on four pedicle screws and two rods. Two screws are joined to a single rod via a gripping device. The relationship of each screw and rod can be changed during reduction maneuvers.

Fig 1: Anteroposterior (A) and lateral (B) schematic drawings depicting the ACE Posterior Segmental Fixator. The construct is based on four pedicle screws and two rods. Two screws are joined to a single rod via a gripping device. The relationship of each screw and rod can be changed during reduction maneuvers.

MATERIALS AND METHODS

All patients with a thoracolumbar fracture treated by the section of Orthopaedic Surgery at the University of Michigan Hospitals during the period of 1989 to 1991 were reviewed. All fractures treated with the ACE fixator were included in the study. All fractures treated by open reduction and internal fixation with CDl were reviewed. Patients wim fractures at the T9 level and below, excluding chance fractures, were included in the study. Fractures above the T9 level and chance fractures were excluded due to licensing limitations and the investigation protocol of me ACE fixator.

The study group included 12 fractures treated by CDI and 15 fractures treated with the ACE Fixator. Only non-chance fractures, fractures below T9, and fractures requiring posterior instrumentation were included. Several CDI patients were excluded due to these criteria (fixation higher than T9, anterior fusion, or more than one fixation device). Two patients in each group had fracture dislocations. All other patients sustained burst fractures.

Through retrospective review of the hospital records, data on preoperative physical findings, operative time, operative blood loss, operative procedures and findings, postoperative physical findings, and Frankel grades were obtained.

Radiographs from the preoperative period and from the most recent outpatient follow up were reviewed. Measurements for preoperative canal compromise were taken from preoperative computed tomography (CT) scans. The anteroposterior (AP) canal diameter was compared to that of the vertebrae above and below the fracture site and a percent of canal compromise obtained. Postoperative CT scans were not available in all patients. Kyphosis around the fracture was measured from the end plates of the vertebrae above and below the fracture. Vertebral body angle was measured from the end plates of the involved vertebra on the plain radiographs. A percent of translation was obtained by comparing the position of the fractured vertebra to that of the unaffected segments above and below the fracture. The vertebral height was obtained by measuring the residual height of the anterior aspect of the affected vertebral body and dividing by the height of the posterior vertebral body.

The radiographic data was analyzed (Tables 1-4). The preoperative homogeneity of the following variables was established: sex (Fisher's Exact Test), kyphosis, vertebral height, vertebral body angle (Student's t test), canal compromise (Mann-Whitney U tests), and Frankel grade (Pearson chi-square test). Intraoperative and postoperative variables were compared. A Student's t test was applied to the following variables: operative time, estimated blood loss, change in kyphosis, change in vertebral height, change in vertebral body angle, and length of follow up. The variance in follow-up time between the two groups was subjected to a Power analysis to confirm the appropriateness of group comparison. The significance of postoperative change in canal compromise was tested using a Mann-Whitney U Test. The significance of postoperative change in Frankel score was tested with the Pearson chi-square test.

Throughout the study, the data were updated as patients presented to me outpatient clinic for routine follow up. Two patients from the ACE group failed to return for follow up, one after initial postoperative evaluation, the other after 4 months. Although phone calls to family members have revealed good functional results, radiographs could not be obtained. These patients were excluded from the postoperative statistical analysis where appropriate. Therefore, the results were based on data obtained from 26 patients. Twelve patients were treated with CDI, and 14 patients were treated with the ACE Fixator. The mean follow-up period was 20.2 months (range: 4 to 39 months).

Table

Table 1PRE- AND POSTOPERATIVE MEASUREMENTS FOR ALL PATIENTS TREATED WITH THE ACE FIXATOR

Table 1

PRE- AND POSTOPERATIVE MEASUREMENTS FOR ALL PATIENTS TREATED WITH THE ACE FIXATOR

Table

Table 2PRE- AND POSTOPERATIVE MEASUREMENTS FOR ALL PATIENTS TREATED WITH COTREL-DUBOUSSET INSTRUMENTATION

Table 2

PRE- AND POSTOPERATIVE MEASUREMENTS FOR ALL PATIENTS TREATED WITH COTREL-DUBOUSSET INSTRUMENTATION

RESULTS

No statistically significant difference was noted between the two preoperative groups. The groups were compared for age (mean: 32.9 ACE, 34.2 CDI, P<.82), kyphosis (mean: 10.2° ACE, 6.6° CDI, P<.31), vertebral body height (mean: 61.7% ACE, 57.1% CDI. P<.50), vertebral body angle (mean: 16.5° ACE, 16.5° CDI, P<.99), canal compromise (mean: 53.7% ACE, 48.8% CDI, P<.82), and Frankel grade (neurologic impairment: 6 points ACE, 4 points, CDI).

Postoperatively, no significant difference was noted for improvement of kyphosis (mean: 6.00° ACE. 1.92° CDI, P<.14), vertebral body height (mean: 17.86% ACE, 18.83% CDI. P<.87), vertebral body angle (mean: -6.2 G ACE, -5.42° CDI, P<.84), or estimated blood loss (mean: 1544 cc ACE, 1620 ce CDI, P<.85). All patients witJi incomplete paraplegia had improvement of at least one Frankel grade.

Table

Table 3PRE- AND POSTOPERATIVE RADIOGRAPHIC DATA OF PATIENTS TREATED WITH THE ACE FIXATOR

Table 3

PRE- AND POSTOPERATIVE RADIOGRAPHIC DATA OF PATIENTS TREATED WITH THE ACE FIXATOR

Table

Table 4PRE- AND POSTOPERATIVE RADIOGRAPHIC DATA OF PATIENTS TREATED WITH COTREL-DUBOUSSET INSTRUMENTATION

Table 4

PRE- AND POSTOPERATIVE RADIOGRAPHIC DATA OF PATIENTS TREATED WITH COTREL-DUBOUSSET INSTRUMENTATION

The analysis revealed significant differences in two areas. Operative time was less when using the ACE device (mean: 269 minutes ACE, 357 minutes CDI, P<.0005). The difference in number of instrumented vertebra levels was also significantly less for me ACE device (mean: 3 ACE, 5.8 CDI).

Time to fusion, postoperative pain, and activity, although not studied specifically, appeared similar in both groups.

DISCUSSION

Historically, conservative treatment was selected for the management of thoracolumbar fractures. This option has been largely discarded due to the morbidity of prolonged bed rest, length of hospital stay, poor rehabilitation potential, and residual spinal deformity.1-5,9

Internal fixation became more popular in the 1970s. Treatment issues began to center around length, method, and surgical approach to the fusion.1-3,5,13,15-21

In the 1980s, the development of CDI changed fixation from a two-dimensional to a three-dimensional concept.6,7,9,22 CDI was revolutionary in its design. Modularity and fourpoint fixation principles could be applied in three different planes.1,6,8,10,22,23 The system could be applied to nearly every fracture or deformity situation due to its versatility.24

Fig 2: The use of the ACE Fixator's reduction handles (A). Fracture reduction via restoration of normal lordosis and ligamentotaxis (indirect reduction) is accomplished. Lateral intraoperative radiograph (B) depicting a reduction technique of the ACE Fixator.

Fig 2: The use of the ACE Fixator's reduction handles (A). Fracture reduction via restoration of normal lordosis and ligamentotaxis (indirect reduction) is accomplished. Lateral intraoperative radiograph (B) depicting a reduction technique of the ACE Fixator.

The recent development of pedicle screw fixation utilizes the strongest part of the vertebrae, the pedicle, for attachment to the spine.12,14,20,25-30 Recently, Magert31 and Dick11,12 have developed the Fixator Interne. The fixator provides two-point rather than four-point fixation in addition to providing a mechanism of fragment reduction.12,15,31,33 The ACE system is similar and utilizes pedicle screws (two-point fixation) to control axial, angular, and rotary deformity, and maintain distraction, compression, or derotation.9,12,14,20,25-31,33-35 Pedicle screws span the entire AP diameter of the vertebrae, and the distractive or compressive forces are transmitted to all three columns.15,26

Fig 3: Preoperative (A) and postoperative (B) computed tomography of a patient treated with the ACE device. The CT scans show marked improvement in canal compromise.

Fig 3: Preoperative (A) and postoperative (B) computed tomography of a patient treated with the ACE device. The CT scans show marked improvement in canal compromise.

Prior lo the development of the ACE Fixator, thoracolumbar fractures were treated primarily with CDI at our institution. We found the Cotrel-Dubousset system versatile, structurally stable, and very applicable to fracture situations.1,8 10.24 We were confident in the system because of its excellent history in the correction of spinal deformity.6,9,24 However, the length of fusion and occasional difficulty associated with insertion of CDI was disconcerting.8,16,23

The ACE Fixator became available in protocol form and was put into use at our institution in 1990. We found the device to be well-suited for thoracolumbar fractures. The design provided ease of application, access for posterior transpedicle decompression, and a means for spine reduction.12-15,25,27,31-33

Fig 4: Preoperative (A) and postoperative (B) radiographs of a patient treated with the ACE device. Preoperative (C) and postoperative (D) radiographs of a patient treated with CDi.

Fig 4: Preoperative (A) and postoperative (B) radiographs of a patient treated with the ACE device. Preoperative (C) and postoperative (D) radiographs of a patient treated with CDi.

The first requirement of any fixation system is the reduction of fracture fragments and improvement of spinal stability.1-5,11,13,15,23,25,27,32-34,36 Neurologic impairment, usually the result of impingement on the spinal cord or nerve roots, should be addressed. Decompression can be performed indirectly, via laminectomy and ligamentotaxis,1,3,9,15,19,25,27,29,32,37 or directly with a transpedicular decompression,5-13,31 at the time of spinal reduction (Figs 2A-B ). The reduction handles create a long, powerful lever arm and increase the reduction forces (Figs IA & 2A). Neurologic improvement was similar for both groups, as was restoration of vertebral body height, body angle, and residual postoperative kyphosis (Figs 3A-B ).

Restoration of lordosis has been a problem in the past with pure hook distraction systems.1,13. 18.24.33.3,16 three-dimensional concept of CDI and the short, strong lever arm of die ACE device allow correction of the fracture deformity and the maintenance of reduction8,12-14.20.22-24.33.35 (pigs 4A.D).

The number of motion segments involved in a construct has been an issue raised when comparing systems employing four-point fixation principles to those utilizing two-point fixationj.2.5.12-14.16.20.25,27.31.34 'There was a significant difference in me number of instrumented levels when comparing the ACE Fixator and CDl. The ACE Fixator only required immobilization of three spinal levels. Theoretically, immobilization of fewer motion segments would allow increased spinal mobility and lessen long-term disability.2,12,38

The rod-long-fuse-short method was an attempt to protect motion segments around an injured area when using long segment fixation devices.3,5 However, biopsy study of the nonfused facet joints revealed degenerative changes.2·39 CDI, with improved applicability,22 did not directly address the issue of motion segment loss.

When pure distraction or compression is required, the minimum three vertebrae can be instrumented with CDI. In general, however, five to six (5.8 in this study) vertebral levels must be instrumented to form a stable CDI construct.6,8-10,16,23 The use of pedicle fixation above and below a fracture and the inherent stability of the ACE construct allows the minimum of three vertebra to be immobilized. 12~ 14.20.35 Jj16 long-term significance of this finding is unknown.2,16

A second significant difference between the ACE group and the CDI group was operative time. Placement of the ACE Fixator required significantly less time than CDI (269 minutes vs 357 minutes), despite extensive experience with CDl application.

We theorize that the difference lies in two factors: First, the ACE Fixator involves fewer vertebrae. There is less hardware to apply, and less exposure is necessary. Second, CDI has an inherent "fiddle factor." The modularity, multiple hook placement sites, rod bending, and distraction technique allow or require adjustment at every stage.23 When instrumenting several levels, the adjustment time tends to accumulate. Surprisingly, estimated blood loss was not influenced by the difference in operative time and was not significantly different between the two groups.

Neither system was without complication. The CDI group had one patient with a broken screw at follow up. There was no sequela. In the ACE series, two patients had broken screws at follow up. One patient was without sequela. The other patient had loss of fixation and a residual kyphosis. The patient remained active, painfree, and without complaint. In all cases of screw failure (CDl and ACE), 5.0 mm screws had been utilized. The use of 5.0 mm screws has been discontinued; 6.0 mm screws are in current use. One ACE patient was noted to have screw penetration of the medial pedicular wall on a postoperative CT scan, and one patient had an unhooked cross-link coupler. Neither patient exhibited adverse sequelae. Two ACE patients underwent hardware removal after the 2-year follow-up period required by Food and Drug Administration protocol.

In conclusion, both CDl and the ACE Posterior Segmental Fixator appear effective in treating thoracolumbar fractures. Although both systems maintain spinal contour, allow decompression, and achieve fusion, segmental fixator devices have the advantage of involving fewer motion segments and shorter operative time.

REFERENCES

1. Errico TJ, Bauer RD. Thoracolumbar spine injuries. In: Errico TJ, ed. Spinal Trauma. Philadelphia, Pa: JB Lippincott; 1991:195-269.

2. Gaines RW. Humphreys WG. A plea for judgment in management of thoracolumbar fractures and fracture dislocations. A reassessment of surgical indications. Clin Orthop 1984; 189:36-42.

3. Jacobs RR. Casey MP. Surgical management of thoracolumbar spinal injuries. General principles and controversial considerations. Clin Orthop. 1984: 189:22-35.

4. McAfee PC, Bohlman HH. Complications following Harrington instrumentation for fractures of the thoracolumbar spine. J Bone Joint Surg. 1985; 67A:672-686.

5. Stauffer ES. Internal fixation of fractures of the Thoracolumbar spine. ./ Bone Joint Surg. 1984; 66A:1136-1138.

6. Coirei Y, Dubousset J. GuiUaumal M. New universal instrumentation in spinal surgery. Clin Orthop. 1988; 227: 10-23.

7. Errico TJ. Kostuik JP. Anterior techniques of stabilization in thoracic and lumbar trauma. In: Errico TJ. ed. Spinai Trauma. Philadelphia. Pa: JB Lippincott; 1991:195-269.

8. Lesoin F, Auiricque A, Villette L, Franz K, Jomin M. Usefulness of Cotrel Dubousset's universal instrumentation in dorsolumbar pathology. Acta Neurochir (Wien). 1987; 89(l-2):80-83. Preliminary report.

9. Leventhal MR. Fractures, dislocations, and fracturedislocations of spine. In: Crenshaw AH, ed. Campbell's Operative Orthopaedics. 8th ed. St Louis, Mo: Mosby-Year Book. Ine: 1992:3553-3582.

10. Ostermann PA, Holt RT. Johnson JR, Henry SL. Treatment of unstable thoracic and lumbar spinal fractures wilh Cotrel-Dubousset instruments. Langenbecks Arch Chir. 1990; 375(3): 161-165.

11. Dick W. Osteosynthesis of severe injuries of the thoracic and lumbar spine with internal fixation. Langenbecks Arch Chir. 1984:364:343-346.

12. Dick W. The "fixateur interne" as a versatile implant for spine surgery. Spine, 1987; 12:882-900.

13. Karlstrom G, Olerud S, Sjostrom L. Transpedicular segmental fixation", description of a new procedure. Orthopedics. 1988; 11:689-700.

14. Olerud S, Karlstrom G, Sjostrom L. Transpedicular fixation of thoracolumbar vertebral fractures. Clin Onhop. 1988;227:44-51.

15. Aebi M, Etter C, Kehl T, Thalgott J. Stabilization of the lower thoracic and lumbar spine with the internal spinal skeletal fixation system. Indications, techniques, and first results of treatment. 6>?<?. 1987; 12:554-551.

16. Bedbrook G. Cotrel-Dubousset rods in spinal fractures. Paraplegia. 1990; 28:342-343. Letter. Comment.

17. Gertzbein SD, Jacobs RR. Stoll J, et al. Results of a locking-hook spinal rod for fractures of the thoracic and lumbar spine, Spine. 1990; 15:275-280.

18. Gertzbein SD, Macmichael D, Tile M. Harrington instrumentation as a method of fixation in fractures of the spine. J Bone Joint Surg. 1 982: 64B:526-529.

19. Jacobs RR, Schlaepfer F. Mathys R Jr, Nachemson A. Perren SM. A locking hook spinal rod system for stabilization of fracture dislocations and correction of deformities of the dorsolumbar spine. A biomechanic evaluation. Clin Orthop 1984; 189:168-177.

20. Krag MH, Beynnon BD, Pope MH, Frymoyer JW. Haugh LD, Weaver DL. An internal fixator for posterior application to short segments of the thoracic, lumbar, or lumbosacral spine. Design and testing. Clin Orthop. 1986; 203:75-98.

21. Luque ER, Cassis N, Ramirez- Wiella G. Segmental spinal instrumentation in the treatment of fractures of the thoracolumbar spine. Spine. 1982; 7(3):312-3I7.

22. Lorenz M, Patwardhan A. Zindrick M. Instability and mechanics of implants and braces for thoracic and lumbar fractures. In: Errico TJ, ed. Spinal TYauma. Philadelphia, Pa: JB Lippincott; 1991:271-280.

23. Richardson AB. Taylor ML, Murphree B. TSRH instrumentation: evolution of a new system. Pan 1. Texas Scottish Rite Hospital. Orthop Nurs. 1990; 9(6): 15-21.

24. Errico TJ. O'Neill J. Standard posterior techniques in the treatment of thoracic and lumbar spine fractures. In: Errico TJ. ed. Spinal Trauma. Philadelphia. Pa: JB Lippincott: 1991:309-334.

25. Esses Sl. The AO spinal internal fixator. Spine. 1989; 14:373-378.

26. Esses SI, Bednar DA. The spinal pedicle screw: techniques and systems. Orthop Rev. 1989; 18:676-682.

27. Esses SL Botsford DJ. Kostuik JP. Evaluation of surgical treatment for burst fractures. Spine. 1990; 15:667-673.

28. Luque ER. Rapp GF. A new semirigid method for interpedicular fixation of the spine. Orthopedics. 1988; 11:1445-1450.

29. Roy-Camille R, Saillant G. Maze! C. Plating of thoracic, dioracolumbar. and lumbar injuries with pedicle screw plates. Orthop Clin North Am. 1 986: 1 7( I ): 147-1 59.

30. Roy-Camille R. Saillant G, Mazel C. Internal fixation of the lumbar spine with pedicle screw plating. CIm Orthop. 1986; 203:7-17.

31. Magerl FP. Stabilization of the lower thoracic and lumbar spine wilh external skeletal fixation. Clin Orthop 1984: 189:124-141.

32. Aebi M. Etter C, Kehl T, Thalgott J. The internal skeletal fixation system. A new treatment of thoracolumbar fractures and other spinal disorders. Clin Orthop 1988; 227:30-43.

33. Pentelenyi T. Zsolczai S. First Hungarian neurosurgical experiences with "Fixateur Interne" in the treatment of thoracolumbar spine injuries. Acta Neurochir (Wien). 1988; 93(3-4): 104-109. Technical note.

34. Levine AM, Edwards CC. Low lumbar burst fractures. Reduction and stabilization using the modular spine fixation system. Orthopedics. 1988; 11:1427-1432.

35. Mann KA, McGowan DP. Fredrickson BE, Falahee M, Yuan HA. A biomechanical investigation of short segment spinal fixation for burst fractures with varying degrees of posterior disruption. Spine. 1990; 15:470-478.

36. Ferguson RL, Allen BL Jr. A mechanistic classification of thoracolumbar spine fractures. Clin Orthop. 1984; 189:77-88.

37. Wenger DR. Carollo JJ. The mechanics of thoracolumbar fractures stabilized by segmental fixation. Clin Orthop. 1984: 189:89-96.

38. Hasday CA, Passoff TL, Perry J. Gait abnormalities arising from iatrogenic loss of lumbar lordosis secondary to Harrington instrumentation in lumbar fractures. Spine. 1983; 8:501-511.

39. Kahanovitz N. Bullough P, Jacobs RR. The effect of internal fixation without arthrodesis on human facet joint cartilage. Clin Orthop 1984; 189:204-208.

Table 1

PRE- AND POSTOPERATIVE MEASUREMENTS FOR ALL PATIENTS TREATED WITH THE ACE FIXATOR

Table 2

PRE- AND POSTOPERATIVE MEASUREMENTS FOR ALL PATIENTS TREATED WITH COTREL-DUBOUSSET INSTRUMENTATION

Table 3

PRE- AND POSTOPERATIVE RADIOGRAPHIC DATA OF PATIENTS TREATED WITH THE ACE FIXATOR

Table 4

PRE- AND POSTOPERATIVE RADIOGRAPHIC DATA OF PATIENTS TREATED WITH COTREL-DUBOUSSET INSTRUMENTATION

10.3928/0147-7447-19950701-17

Sign up to receive

Journal E-contents