Surgical Treatment of Dorsolumbar Spine Tuberculosis by Posterior Decompression , Stabilization with Transpedicular Screws and Rods and Fusion

Background: Spinal tuberculosis is a medical disease and antitubercular drugs play the main role in the recovery of patients. However, with proper indication, surgical procedures are superior in the prevention of neurological deterioration, maintenance of stability, early recovery and early mobilization. Modern method of surgical intervention of dorsolumbar tuberculosis is posterior decompression, stabilization with transpedicular screws and rods and fusion. Objective: To evaluate the efficacy of posterior decompression, stabilization by transpedicular screws and rods and fusion in patients with spinal TB in thoracic and lumbar region. Materials and method: This is a prospective interventional study carried out at National Institute of Traumatology & Orthopaedic Rehabilitation (NITOR), Dhaka, Bangladesh and different private hospitals in Dhaka from October, 2012 to December, 2014. Total number of patients was 12; among them 7 were male and 5 were female, age ranged from 21-60 years with a follow up period of 12 months to 18 months. Results: More common site of tubercular lesion was at dorsal spines (58.73%). In this study the patients were preoperatively classified according to American Spinal Injury Association (ASIA) Impairment Scale and among the patients 1 was ASIAA, 2 were ASIA-B, 5 were ASIA-C, 3 were ASIA-D, and 1 was ASIA-E. In postoperative state 1 patient was ASIA-B, 3 patients were ASIA-D and 8 were ASIA-E. Maximum patients (75%) had bony fusion grade 1. More than 80% subjects had good outcome. Conclusion: Posterior decompression, stabilization with transpedicular screws and rods and fusion is a satisfactory surgical modality of treatment of dorsolumbar spinal tuberculosis.


Introduction
Vertebral tuberculosis (TB) is the commonest form of skeletal tuberculosis and it constitutes about 50% of all cases of tuberculosis of bone and joints. 1 Bone and joint tuberculosis accounts approximately 15% to 38% of extra pulmonary form of the disease and 1% to 5% of all the cases of TB.Spinal TB can affect any segment of the lower thoracic and the lumbar vertebrae. 2inal tuberculosis was initially described by Sir Percival Pott (1779) as a painful kyphotic deformity of the spine associated with paraplegia. 3he disease spreads to the spine from primary focus either directly or through blood i.e. intercostal arteries and Batson's venous plexus. 4lood borne infection usually settles in a vertebral body adjacent to the intervertebral disc.Bone destruction and caseation follow, with infection spreading to the disc space and to the adjacent vertebrae. 4As the vertebrae collapse into each other, a sharp angulation is formed which produces kyphosis.Caseation and cold abscess formation may extend to neighboring vertebrae or escape into the paravertebral soft tissue.There is a major risk of cord damage due to pressure by the abscess or displaced bone or ischaemia from spinal artery thrombosis. 4y part of spinal column may be affected by tuberculosis but it is most commonly found in the lower thoracic and thoracolumbar region.The order of frequency has been dorsal (42%), lumbar (26%), dorsolumbar (12%), cervical (12%) and sacral (3%). 1 Spinal TB is a medical disease and antitubercular drugs play the main role in the recovery of patients. 5If there is no complication and if the lesion is limited to the vertebrae, antitubercular chemotherapy can treat TB. 2 However, with proper indication, surgical procedures are superior in the prevention of neurological deterioration, maintenance of stability, early recovery and early mobilization. 2The most popular protocol for anti TB chemotherapy is to use rifampicin, isoniazid, ethambutol and pyrazinamide for initial two months followed by a maintenance phase of rifampicin and isoniazid for six, nine, twelve or eighteen months. 6e principle of surgical intervention of spinal TB is to decompress the spinal cord by removing the necrotic tissue and draining of any pus and devitalized tissue followed by immobilization.Yet the infected vertebrae are prone to collapse and they require mechanical support to prevent progressive deformity. 7A history of TB, a positive skin test and an elevated ESR are useful in the diagnosis of spinal TB.Radiology remains also essential in providing precious information for diagnosis and prognosis of spinal TB.Plain radiograph may show involvement of adjacent vertebrae with erosion of end plates.There may be significant kyphosis and paraspinal shadow, occasionally with involvement of posterior elements.

Indications of Surgical
MRI is also useful in diagnosis of spinal TB in early and doubtful cases.MRI shows soft tissue including the spinal cord and its distortion by epidural collection.It may also show asymptomatic skip lesion away from the main disease.
CT scan is useful for appreciation of bone destruction and for needle aspiration or biopsy.CT guided biopsy and abscess drainage also aid in making the diagnosis.The use of DNA amplification technique (polymerase chain reaction or PCR) facilitates rapid and accurate diagnosis of the disease.Culturing the organisms is slow.Nevertheless, it is still a precious diagnostic method in order to recognize the causative organism.

Materials and method
This is a prospective interventional study carried out at National Institute of Traumatology & Orthopaedic Rehabilitation (NITOR), Dhaka, Bangladesh and different private hospitals in Dhaka, Bangladesh from October 2012 to December 2014.Total number of patients were 12 having spinal tuberculosis in thoracic and lumbar region.They underwent posterior decompression, stabilization by transpedicular screws and rods and fusion.Among them 7 were male and 5 were female, age ranged from 21-60 years with a follow up period of 12 months to 18 months.Patients were selected on the basis of history, physical examination, hematological, radiological, MRI findings and in some cases CT guided FNAC.Patients were recruited on the basis of inclusion and exclusion criteria.In this study the patients were preoperatively classified according to American Spinal Injury Association (ASIA) Impairment Scale 10 and among the 12 patients 1 was ASIA-A, 2 were ASIA-B, 5 were ASIA-C, 3 were ASIA-D, and 1 was ASIA-E.In postoperative state 1 patient was ASIA-B, 3 patients were ASIA-D and 8 were ASIA-E.Postoperative clinical outcome was evaluated by Modified Macnab criteria. 12Among 12 patients 7 (58.33%)cases were excellent, 3 (25%) cases were good, 1 (8.33%) case was fair and 1 (8.33%) case was poor.The overall result was analyzed by categorizing satisfactory (excellent and good) 10 (83.33%) case and unsatisfactory 2 (16.67%) cases (Table V).

Follow up
The detail follow up schedule for evaluation was selected to be conducted monthly for 3 months, then at 6 months, 9 months, 12 months and 18 months after surgery.The evaluation included clinical, haematological and radiological investigations.The clinical evaluation included functional assessment, local pain status, stability and mobility of spine, level of deformity of spine, motor score as motor strength of lower limb, walking ability, walking speed of lower limb, bowel and bladder and sensory improvement.Plain x-rayof dorsal and lumbar spine (AP & lateralview) was done to see successful fusion and deformity correction.Hematological evaluations (ESR, CRP) were measured to determine the presence of active disease.

Discussion
The purpose of surgically treating dorsolumbar spine tuberculosis is to evacuate the abscess, excise the diseased tissue, and decompress neural tissue, maintenance of stability, early recovery and early rehabilitation.Regarding the subjective assessment of this series, it was observed that (58.33%) patients had excellent functional outcome, 3 (25%) patients had good, 1 (8.33%) patient had fair and 1 (8.33%) patient had poor functional outcome.
In this study overall a satisfactory (excellent and good) result was found in 10 (83.33%) patients and unsatisfactory (fair and poor) resultin3 (16.66%) patients.

Conclusion
If patients have milder form of spinal TB and are diagnosed earlier, conservative management consisting of Anti TB chemotherapy and orthosis is the treatment of choice.In those where conservative management has failed and the patient is developing progressive kyphotic deformity and/or progressive neurological deficit and/or progressive instability, surgical intervention is indicated.Based on the result shown above it can be concluded that surgical procedure specially posterior decompression, stabilization by transpedicular screws and rods and fusion is an effective, safe and acceptable procedure for patients with spinal TB in thoracic and lumbar region.Posterior approach is a minimum surgical intervention and easy approach that encourages neurological recovery, good correction of kyphosis and prevention of further progressive kyphosis.
Spinal tuberculosis is common in 1st three decades. 7In this study age of the patients varied from 20-60 years maximum was within 21-30 years.Here 58.33% cases were male and 41.67% cases were female.This finding is consistent with the study of Khoo et al. 13 In this study most of the common clinical presentation was pain (83.33%) followed by gibbus (58.33%), paraplegia (50%), weight loss (33.33%), difficulty to working (16.67%) and spinal deformity (8.33%).Siddiqui et al. 14 showed majority (53.3%) patients had complaints of back pain while weakness in 17.8%.In a study done by Polly & Dunn 15 53% subjects had complaints of back pain.Garg et al. 8 reported clinical features of spinal TB that includes local pain, local tenderness, stiffness and spasm of muscles, cold abscess, gibbus and prominent spinal deformity.
Regarding distribution of lesion 58.33% were dorsal, 25% were lumbar and 16.67% were dorsolumbar.Study by Godlwana et al. 16 showed that thoracic spine was involved in 42% of cases, lumbar spine in 30% of cases and dorsolumbar in 10% cases.
In this study the kyphotic angle at preoperative state was compared with that at postoperative follow up.All patients showed a decrease in kyphotic angle in final follow up.This finding is consistent with the study of Jain et. al. 17 In this study 8.33% patients were ASIA grade A, 16.67% were ASIA grade B, 41.67% were ASIA grade C, 25% were ASIA grade D and 8.33% were ASIA grade E in preoperative state.On the other hand in postoperative state 8.33% were ASIA grade B, 25% were ASIA grade D and 66.67% were ASIA grade E. This difference was statistically significant.Study done by Gupta et al. 18 showed that before starting treatment, 2.08% patients were in ASIA A, 4.16% were in ASIA B, 18.75% were in ASIA C, 75% were in ASIA D and 20% were in ASIA E. After 6 months of therapy 90% patients were in ASIA D and 55.5% in ASIA

Table III : Distribution of age, sex, occupation, clinical presentation, lesion & level of involvement (N=12)
No motor or sensory function is preserved in the sacral segments S4, S5.Incomplete sensory but not motor function is preserved below the neurological level and includes the sacral segments S4, S5.Incomplete motor function is preserved below the neurological level and more than half of a key muscle below the neurological level has a muscle grade less than 3. Incomplete motor function is preserved below the neurological level and at least half of key muscles below the neurological level have a musclegrade of 3 or more.Normal.Motor and sensory functional are normal.