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TB SPINE : ROLE OF INSTRUMENTATION
YOGESH PITHWA*, GANESH CHAUHAN**,SANJAY DHAR***, PRASHANT WELING****
*Chief Resident; **Registrar; ***Associate Professor and Unit Chief; ****Lecturer, BYL Nair Hospital, Mumbai 8.
31 patients of TB spine lesions were studied. The study groups were divided into two; A : un-instrumented group and B : instrumented group. Patients with more than two contiguous vertebral involvements or with bone grafts spanning more than two disc spaces were instrumented. Posterior instrumentation (Group BI) was used in five patients with higher thoracic lesions and anterior instrumentation (Group BII) was used in three patients with lower thoracic and lumbar lesions.
The average blood loss was 400 ml, 800 ml and 450 ml and the average surgery time was 3, 6 and 4 1/2 hours in Groups A, BI and BII, respectively. The average pre-operative kyphoses were 27 and 20 degrees in Group A and B, respectively. Over an average follow-up of 2.7 years post-operatively (ranging from 6 months to 11 years), the average kyphoses were 30 and 10 degrees in Groups A and B, respectively; i.e. an average deterioration of 11% and an average correction of 50%, respectively.
Thus, we concluded that instrumentation should be used in cases involving more than two contiguous vertebral bodies, or bone grafts spanning more than 2 disc spaces, particularly in the thoracic and junctional regions. Also, whenever possible, it is advantageous to prefer anterior instrumentation to posterior instrumentation in view of lesser intra-operative blood loss and total surgical time.
INTRODUCTION
From the time that Sir Percival Pott (1779) first associated spinal deformity and paralysis to tuberculosis; the treatment perspectives have gradually evolved from "reducing the mortality" to "reducing the morbidity" to "reducing the deformity". With the advent of effective combination chemotherapy in the early 1950s, the mortality rate among patients with spinal tuberculosis decreased from approximately 1% to 3%. The concept of radical debridement and anterior fusion was propelled by the paper published by Hodgson and Stock in 1960.[3,4] The first trial of the Medical Research Council of England [9-16] has shown that the rate of favourable results (defined as full physical activity, clinical and radiographic evidence of quiescence of the disease, no CNS involvement, no residual sinuses or abscesses) that was obtained at 5 years by chemotherapy alone, compared favourably with the rate that was obtained by radical surgical treatment combined with chemotherapy. The only advantage of anterior spinal arthrodesis was the decreased tendency for progression of the deformity.
The review of literature on anterior debridement with anterior spinal arthrodesis, however, fails to justify this as an isolated procedure to prevent deformity progression; more so, for lesions in the thoracic spine with more than 2 contiguous vertebral body involvement. Clinically, the unsightly residual kyphosis at the end of treatment has been a problem for clinicians and patients. Furthermore, trying to correct an established kyphosis poses much more technically demanding procedure than trying to prevent one.
Based on this groundwork, a study was conducted to convey the merit and demerits of anterior spinal arthrodeses alone versus anterior spinal arthrodeses with posterior instrumentation versus anterior spinal arthrodesis with anterior instrumentation. The study was conducted to indicate certain trends and impressions, which appear to justify a particular type of treatment that might best, suit these patients. Any new method, which involves the patient in a major and potentially dangerous procedure, should clearly show better results than those obtained by well-tried conventional methods.
MATERIAL AND METHODS
Patients included in the study had active spinal tuberculosis, excepting one case that had presented as late onset paraparesis secondary to internal gibbus. These patients had lesions in thoracic, thoracolumbar and lumbar spines and warranted surgery on the lines of "Middlepath Regime" as advocated by Tuli et al in 1975.[20,21] None of the patients had draining sinuses before surgery. There were 31 patients, 14 males and 17 females; with age ranging from 1.5 to 52 years (Table 1).
TABLE 1
Data analysis (31 patients)Male 14 Female 17 Age (Range) 1.5 years - 52 years Adults 25 Children 6
For all the patients, chemotherapy was started immediately after tuberculosis of the spine was diagnosed. A combination of isoniazid, rifampicin, ethambutol and pyrazinamide was used for the first three months followed by isoniazid and rifampicin for another nine months. In children, ethambutol was not used. Specific criteria were used to detect the need for instrumentation (Table 2).
TABLE 2
Criteria for instrumentationPre-operative MRI changes suggestive of more than two contiguous vertebral involvement at the thoracic or junctional level. Intra-operative Bone graft spanning more than two disc spaces in the thoracic spine.
Anterior instrumentation (rod-screw construct) was used in the lower thoracic (T9 downwards), thoracolumbar and lumbar spines (Figs. 1A and 1B). Posterior instrumentation in the form of Hartshill rectangles with sub-laminar steel wiring was done in the upper thoracic spines (Figs. 2A and 2B). A total of eight patients out of the 31 met with the above criteria for instrumentation and were treated accordingly; 5 of them being instrumented posteriorly and 3 anteriorly.
No neurological complications were encountered in any patient. After surgery, patients were allowed to sit up and walk around with appropriate spinal orthoses, most commonly Taylor’s brace; after twelve weeks in Group A and after seven days in Group B. All patients were tracked for a follow-up of over 2.7 years on an average (range : 6 months-11 years). Chronological changes of kyphosis on X-rays were measured to check the effectiveness of the surgical intervention.
A diagnosis of successful fusion was made if there was (a) no significant loss of correction, (b) no graft resorption, (c) no graft bed resorption and (d) visible graft remodeling such as trabecular re-arrangement between the graft bed and the graft.
Fig.1A: Per-op MRI coronal section showing complete involvement of L4 and L5 vertebral bodies.
Fig1B: Anterior instrumentation with anterior arthrodesis spanning L3 to L5.
Fig.2A: D10-11 TB spine showing kyphus angle of 29 degrees.
Fig. 2B: Post-op x-ray showing reduction of deformity to 12 degrees.
RESULTS
Bony fusion in the patients with grafts spanning 2 vertebral bodies was obtained in 4.2 months in adults and 3.3 months in children, on an average. For grafts spanning more than 2 vertebral bodies, fusion was obtained in 6.1 months in adults and 6.4 months in children.
In adults, average pre-operative kyphosis was 27 degrees in Group a and 20 degrees in Group B (Table 3). Average kyphosis in the immediate post-operative period was 24 degrees in Group A and 3 degrees in Group B. Average kyphosis at final follow-up at an average of 2.7 years was 30 degrees in Group A and 10 degrees in Group B, on an average.
TABLE 3 Group a : Uninstrumented Cases Pre-operative Immediate Final follow-up Kyphosis post-op kyphosis kyphosis 27 degrees 24 degrees 30 degrees Group b: Instrumented Cases Pre-operative Immediate post-op Final follow-up kyphosis kyphosis kyphosis 20 degrees 3 degrees 10 degrees
Thus, working within the criteria for selection of instrumentation as stated above, we were able to significantly correct the kyphosis and maintain it as well. Two patients were lost to follow-up; however, in the remaining 29 patients there was no evidence of any graft failure or resorption. There was no instrument failure. One patient developed superficial wound dehiscence, which was appropriately and adequately treated.
DISCUSSION
Kyphosis has been a common complication in patients treated with chemotherapy alone, although the British Medical Research Council Working Party [9-16] reported encouraging results from this type of therapy. Since Hodgson and Stock’s report in 1960, [ 3,4] anterior arthrodeses has been advocated as the treatment of choice for tuberculosis of the spine. For successful anterior radical surgery, they showed that surgical extirpation of the tuberculosis focus and its replacement with a bone graft or grafts in structurally sound position were the key to effectiveness. In 1968, Lee and Hahn reported that immediately after anterior radical surgery in 120 adult patients, they obtained 29.9% correction of initial kyphosis, and at six months after surgery, there was 12.8% correction. In 1993, Kim et al reported that immediately after radical surgery in 140 patients, they obtained 55.1% correction of initial kyphosis, and at 2 years after surgery, there had been 7.5% correction of the initial angle. In addition, Rajasekaran and Soundarapandian19 reported that a stable anterior graft provided structural support in only 41% of patients, and that graft failure with residual kyphosis occurred in 59%. They stated that the graft failed most often in patients in whom it spanned more than 2 disc spaces. In 1973, Kemp et al5 and in 1966, Oheneba [18 ] also advocated secondary posterior fusion for lesions involving more than 2 contiguous vertebral bodies.
Now, with this background, to take a quick look at the average number of vertebrae involved in Koch’s spine, the literature review is as follows:
No. of vertebrae involved As reported by 1. Average 3 Hodgson and Stock (JBJS, 1960) [3,4] 2. 3.3 to 3.6 Martin, (JBJS 1970) [7,8] 3. 2.1 Lifeso et al (JBJS, 1985).[6]
Thus, we concluded that it is unwise to rely solely on the anterior strut graft to prevent vertebral collapse, more so when more than 2 contiguous thoracic vertebrae were involved or when the graft spanned more than 2 disc spaces (Figs. 3A, 3B and 3C). Myung-Song Moon et al also drew a similar conclusion in 1995; they advocated posterior instrumentation followed by inter-body fusion either in the same or separate sitting for all cases. As regards the mode of instrumentation, we however, feel that whenever possible anterior debridement, decompression and strut grafting should be combined with anterior instrumentation, which would be more advantageous than posterior instrumentation as;
1.both, instrumentation and grafting done as a single stage surgery through the same incision, minimizing the total blood loss and the surgery time (Table 4).
2.no risk of graft slipping out on turning the patient for posterior instrumentation
3.decreased length to fusion.
Furthermore, Oga M, and Sugioka Y in 1993 [17] conducted a study evaluating the risk of instrumentation as a foreign body in spinal tuberculosis. They found no adherence of mycobacterium to stainless steel discs, whereas discs inoculated with Staph. epidermidis demonstrated definite adherence.
Remarkable intra-operative correction of kyphosis was obtained. No resorption/subsidence of the graft was noticed. The spinal stability was also well-maintained by the instrumentation. There was no evidence of re-activation or relapse. No fatal complication as related to any vessel perforation was ever encountered by us during either the intra-operative or post-operative period.
The problems that we faced were:
1.Lack of adequate space anteriorly to put in the anterior implants in the thoracic vertebrae particularly above T9 of small stature patients.
2.Possible problem of prominent hardware impaling the great vessels, particularly in the thoracic spine.
These problems that we have faced could very well be labeled as "teething stage" problems, which can be solved by appropriately modifying the implants or by using smaller sized implants.
Fig 3A. Pre-op x-ray showing kyphus of 14 degrees.
Fig 3B. Immediate post-op x-ray, following anterior arthrodesis without instrumentation showing correction of kyphus to 11 degrees.
Fig 3C. 1 year post-op x-ray showing deterioration of kyphus to 27 degrees.
TABLE 4 Group A Group BI Group BII Average blood loss 400 ml 800 ml 450 ml Average surgery time 3 hours 6 hours 4 1/2 hours
CONCLUSION
It is distressing, both to the patients and the treating surgeon, to see an unsightly hunchback deformity in a case of Koch’s spine. Hence, we feel that every attempt should be made to minimize this deformity with some form of instrumentation wherever indicated, and preferably anteriorly.
REFERENCES
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2.Fountain SS, Hsu LC, Yau AC, et al. Progressive kyphosis following solid anterior fusion in children with tuberculosis of the spine : A long term study. J Bone and Joint Surg 1975; 57A : 1104-7.
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16.Medical Research Council Working Party on Tuberculosis of the Spine; a ten year assessment of a controlled trial comparing debridement and anterior spinal fusion in the management of tuberculosis of the spine in patients on standard chemotherapy in Hong Kong. J Bone and Joint Surg (Br) 1982; 64-B : 393-98.
17.Oga M, Sugioka Y. Evaluation of the risk of instrumentation as a foreign body in spinal tuberculosis. Clinical and biological study. Spine 1993; 18 : 1890-94.
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21.Tuli SM. Results of treatment of spinal tuberculosis by "Middle Path" Regime. J Bone and Joint Surg 1975; 57-B : 13-23.
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