| Abstract|| |
Background : Unstable spinal injuries require fixation to provide stability. Various modalities of fixation have been used.
Methods : One hundred and forty seven patients of thoracolumbar spine fractures with neurological deficit were surgically treated using posterior approach. Four different types of posterior instrumentation were used to reduce the fractures and dislocation of thoracolumbar spine and achieve cord decompression - Harrington rod fixation in 55, Hartshill in 19, Steffee in 51 and newer pedicle screw rod systems in 22 patients. Results : The patients were followed up for minimum period of 2 years. Neurological improvement did not vary with type of instrumentation.
Conclusion : Pedicle screw rod-systems are more versatile and technically superior than Harrington and Hartshill systems, in lieu of their ability to gain purchase in all the 3 columns and better reduction of thoraculumbar spine fractures and ability to maintain reduction at the end of 2 years.
Keywords: Thoracolumbar spine; fractures dislocation; posterior spine instrumentation; Harrington; Steffee; Hartshill; Pedicle screw rod systems.
|How to cite this article:|
Pati B N, Krishna L, Chopra R K, Senthil Kumar V A, Bansal M. Thoracolumbar spine injuries-comparison of 4 different posterior spinal instrumentation systems. Indian J Orthop 2004;38:96-9
|How to cite this URL:|
Pati B N, Krishna L, Chopra R K, Senthil Kumar V A, Bansal M. Thoracolumbar spine injuries-comparison of 4 different posterior spinal instrumentation systems. Indian J Orthop [serial online] 2004 [cited 2019 Dec 15];38:96-9. Available from: http://www.ijoonline.com/text.asp?2004/38/2/96/40909
| Introduction|| |
Considerable controversy exists regarding the clinical performance of different instrumentation systems for the surgical treatment of unstable fractures of the thoracolumbar spine. Although the biomechamical performance of different spinal fixation devices has been studied extensively in the laboratory, comparative clinical outcome data are few. This paper compares the versatility/ clinical outcome of different posterior internal fixation devices for thoracolumbar spinal trauma.
The more classic systems of posterior instrumentation, i.e., Harrington, Hartshill and Luque are based on hooks or sublaminar wiring to gain purchase on posterior column structures alone, whereas in pedicle screw fixation all three spinal columns may be controlled directly the pedicle screw rod systems, by virtue of direct fixation through middle and anterior columns, are able to reduce fractures of these columns by ligamentotaxis ,,,,.
Some authors have shown that early operation within 4 days of trauma results in significant reduction in spinal canal encroachment irrespective of instrumentation systems used Harrington or Pedicle screw systems ,,,,,,, . Not many studies have compared pedicle screw systems with Harrington or Hartshill systems in the management of fractures of thoracic and lumber spine ,,,,, . The aim of this study is to compare the efficacy of the classic Harrington, Hartshill and Steffe system and newer pedicle screw rod systems in attainment and maintenance of reduction (i.e., vertebral body height and percentage reduction of horizontal translation) of thoracolumbar spine fractures and also to assess the complication rates and safety of the above systems in the treatment of thoracolumbar spine fractures.
| Materials and Methods|| |
One hundred and forty seven patients of thoracolumbar [T 12 /L 1 ] spine fractures with partial or complete neurological deficit were included in this study. After routine plain X-ray studies, the extent of cord compression and the presence of cord contusion or cord edema or cord transaction was evaluated by MRI. The neurological status was classified according to Frankel's grades. These patients were operated using posterior approach. Harrington rod fixation was performed in 55, Hartshill in 19 patients, Steffee (pedicle screw and plate) in 51 patients and newer pedicle screw rod systems [Moss Miami System and Universal Spine Stabilisation System - AO] in 22 patients. Standard midline posterior approach was used in all patients. In the earlier period of our study we were using Harrington and Steffee instrumentation predominantly. Later Moss-Miami/USS systems was used predominantly. Initially we used fluoroscopy to guide the placement of pedicle screws  , but later with greater experience pedicle screw placement without fluoroscopy could be performed.
Of the 147 patients, 98 were males and 49 were females. Average age was 24 years (range - 16 years to 53 years). The time interval between injury and operative procedure averaged 11 days (range - 3 days to 35 days). We classified the fracture pattern in our patients according to McCormack's load sharing method  for the purpose of evaluating the results [Table 1].
Irrespective of the type of instrumentation used for the fixation of the fracture, the patients with a McCormack's point score of 4 or 5 were mobilized to sitting posture with a thoracolumbar spinal brace after 3rd week postoperatively. Patients with a point score [McCormack] of 8 or 9 week mobilized to sitting posture with a thoracolumbar brace only after 8 to 12 weeks [though the patients were turned on bed for proper back care, surgical stabilization makes nursing easier in these patients], thus making the follow up results comparable irrespective of the type of instrumentation used. Depending on the neurological status of the patients mobilization was done on a wheel chair [Frankel's Grade A or B or C] or with a walker frame of crutches [in Frankel's Grade D or E]. Vigorous preoperative and postoperative chest and lower limb physiotherapy was performed. Thoracolumbar orthosis was continued for 2 years or till radiological evidence of fracture consolidation was seen.
The patients were reviewed at 1 month, 3 months, 6 months, 1 year and 2 years from the date of surgery and the following radiological and clinical parameters were noted in the immediate postoperative period and in the successive visit: reduction achieved, loss of reduction, complication and neurological status.
The preoperative anterior and posterior vertebral heights were measured as a percentage of the mean anterior and posterior body heights of the non-fractured vertebrae immediately above and below. Also, anterior translation of dislocated vertebra was calculated as percentage of anteroposterior diameter of immediately intact vertebra. The above values were compared with the immediate postoperative and values and the measurements in the follow-up x-rays, at the end of one year and 2 years. The neurological status was assessed periodically.
| Results|| |
Initial restoration of anterior vertebral height of fractured vertebrae is much better with pedicle screw systems when compare to Harrington or Hartshill systems [Table 2]. Among these, Harrington shows better reduction than Hartshill System. Similarly maintenance of the achieved reduction is superior and consistent at 1 and 2 years follow- up in pedicle screw and rod systems. The loss of reduction was much higher with Hartshill system. Harrington also showed loss of reduction comparable to Steffeee system, but still they fared better than Hartshill but reduction of translation is comparable with all the four types of posterior instrumentation.
In this study, cases operated upon within 2 weeks of injury showed better reduction compared to those operated upon later than 2 weeks. Complication of implant failure like screw breakage was higher with Steffee system (11.8%) than with Pedicle screw rods system[Table 3]. Wire breakage/ cutout were a high 21% with Hartshill system and hook cut through (10.9%) ws a common comlication with Harrington. Deep infection necessitating implant removal was commoner with Harrington system.
Neurologically, majority or our patients were in Frankel's A and B grades. None of our patients were in Frankel's E Grade [Table 4]. Almost all the patients in Frankel's Grade A did not show improvement. There was improvement by one or two grades in many of the patients with Frankel's Grade B and Grade C, irrespective of the instrumentation system used. Only an occasional patient showed neurological worsening by one grade [Table 5].
| Discussion|| |
Pedicle screw devices have shown better reduction than Harrington rods and Hartshill system ,,, . The advantage of pedicle screws is its capability of holding all the 3 colums of spine where as Harrington and Hartshill systems get a purchase over the posterior column structures alone. Therefore the efficacy of reduction of anterior column fractures is better with pedicle screw systems and maintenance of reduction in one and 2 years follow-up is superior with pedicle screw compared to Harrington and Hartshill systems ,,,,. Whether combining an anterior procedure is necessary, is beyond the scope of this study.
Vornanen et al have shown better reduction with Harrington rods when compared to pedicle screw systems  .It is important to take into consideration the results of Shonoet al  who have shown in their experimental study that posterior distractive reduction maneuver generates anterior and middle spinal column defects, leading to significant mechanical instabilities particularly in axial compressive loading. This had prompted us to use thoracolumbar spinal brace for 2 years or till radiological evidence of fracture consolidation is evident.
Pedicle screw fracture occurred in 7.8% of our patients which is comparable to published literature  . Wire breakage with Hartshill instrumentation was 10.5% in our study in compared to 8.3% in reports4. Pedicle or lamina fracture varied between 3.65 to 5.9% with the different instrumentation's, when compared to the reports in literature of 1.4% to 2.6% 2,4.
In our study, cases operated within 2 weeks of injury showed better reduction when compared to cases operated after 2 weeks, though Vornanen et al observed that early operation with 4 days after injury is essential to achieve significant reduction  . Neurological outcome analysis showed that cases who fell in Frankel's Grade A did not show improvement, similar to Dickman's observation4. Neurological improvement was not affected by the type of instrumentation used.
We conclude that in our country where resources are limited, using the easier and the less demanding posterior approach, and indirect reduction techniques are the best surgical options for injuries of T 12 and L 1 . The newer pedicle screw rod system are more versatile and technically superior to classic Harrington, Hartshill systems, in fixation of thoracolumbar spine injuries because pedicle screw rod systems achieve 3 column fixation causing efficient distraction and translation and because of their ability to maintain the reduction at 2 years, follow up.
Fewer complications (like screw breakage), compared to the Steffee system make the pedicle screw rod systems, the posterior instrumentation of choice. At the same time the authors emphasize the fact that insertion of pedicle screws needs technical expertise and experience of high order to minimize complications of nerve root injury and pedicle fracture. The time at which postoperative mobilization to erect posture is started, should strictly take note of the fracture pattern.
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B N Pati
303, Sector – III, RK Puram, New Delhi
Source of Support: None, Conflict of Interest: None
[Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5]