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ANTERIOR SURGERY IN THORACIC SPINE TUBERCULOSIS ALD V/S TRANSTHORACIC DECOMPRESSION : Analysis in 40 Cases
Nikhil M Bhuskute, Purshottam Gholve
Consulting Orthopaedic Surgeons. Santacruz,Mumbai - 400 054.
We produce retrospective study of forty cases of tuberculous spine involving thoracic region treated medically as well as surgically. Our study shows that transthoracic has added advantage of anterior instrumentation possibly preventing posterior surgery.
INTRODUCTION
This study is retrospective analysis of 40 cases of tuberculous spine involving thoracic region treated with anti-TB drugs and surgery in form of anterolateral decompression or transthoracic anterior decompression. In our series average time of fusion was 7.66 months in ALD and nine months in transthoracic approach, while failure of fusion was 11% and 5% respectively. Both transthoracic and ALD allowed adequate decompression and neurological recovery, but ALD was choice of operation in cases of late onset paraplegia while with transthoracic decompression rate of fusion and correction of kyphosis was better than ALD. Bone graft for fusion mandatory in both approaches. Also transthoracic has added advantage of anterior instrumentation possibly preventing posterior surgery.
MATERIAL AND METHODS
We carried out a study of 40 cases of TB of thoracic spine. The cases considered were mostly treated at our hospital. Patients were divided in two groups :
1.Transthoracic approach with bone grafting (strut/cancellous chips/both) = 20 cases.
2.(i) ALD with bone grafting (strut / cancellous chips / both) = 18 cases
(ii) ALD without bone grafting = 2 casesAll these cases were selected randomly without any bias.
The data regarding these patients was noted in the following manner.
1.Preliminary data consisting of name, age, sex.
2.Detailed history regarding the symptoms of pain, time since neurological symptomatology and whether any initial treatment was taken elsewhere.
3.Detailed neurological examination was carried out.
Neurological function was classified according to Kumar and Tuli classification of paraplegia. Duration of paraplegia / paraparesis was considered in the study. Most had acute onset paraplegia. Radiological assessment followed clinical assessment. The level was decided using AP and lateral projections. Tc99m bone scan was done in two patients. Both showed an increased uptake. Myelogram was done in two patients where it showed a complete block. There was dry tap in one patient; MRI was done in 15 patients. MRI helped in following ways :
1.The disc status.
2.Amount of collapse and deformity.
3.Epidural abscess / granulation tissue.
4.Cord oedema / ischaemia.
5.Pre / paravertebral abscess.
6.Involvement of posterior elements.
In this study there were 18 males and 22 females. The age range was from 9-60 with an average of 34.6 years.
The surgery was performed as early as possible. The major indications for surgery were decided as follows :
1.Progressive neurodeficit.
2.Paraplegia on admission.
3.Progressive and unstable kyphosis.
In our study all cases were bone grafted except two patients in ALD who presented with internal gibbus following late onset paraplegia. The aims of bone grafting were :
1.Stability
2.Enhanced fusion.
3.Prevent the progression of kyphosis.
The different grafting techniques that were used were strut grafting using rib (more often) and iliac strut, cancellous chips and combined.
The decision of which type of bone grafting technique to be used was decided intraoperatively after assessing the void created instability and correction achieved after extension of spine.
The results of grafting with correction achieved were as follows :
1. Excellent - Consolidation with correction
2. Good - Consolidation with no correction
3. Fair - Consolidation with increase in angle.
4. Poor - Consolidation with severe increase in angle.
5. Failure - No consolidation
The purpose of this study is to evaluate;
1.Usefulness of anterior surgery in TB of thoracic spine.
2.Correction / Prevention of deformity.
3.Surgical difficulties as encountered during anterior approaches.
4.Common and rare complications that occurred.
5.Search for the causes, where improvement did not occur inspite of proper early surgery / anti TB drugs.
SURGICAL TECHNIQUE
Senior orthopaedic surgeons who had experience of spinal surgeries operated all cases.
1. Anterolateral Decompression
The approach followed was as that described by Alexander and Dott. A posterior curved (C-shaped) incision was taken starting in the midline 7.5 cm proximal to the gibbus gently curved laterally for 7.5 cm and return to midline 7.5 cm distal to the gibbus. Muscle incised and ribs exposed subperiosteally. Costotransverse junction was dissected and rib excised from angle and removed enmass from the transverse process. In most of surgeries excision of three ribs was required. Intercostal vessels were identified and ligated. Intercostal nerves were sacrificed. Usually three in most cases of surgeries. The intercostal vessels along with pleura was retracted medially. The nerve root was traced to its origin upto the intervertebral foramina. Now the transverse process was nibbled and the pedicle lying above the nerve root was nibbled from above downward. After excision of 2 transverse processes and pedicles the cords surrounded with granulation tissue was exposed. Anteriorly the collapsed body with internal gibbus was visible. Under visualisation of dura the affected body and posterior parts were debrided and bone graft was packed in the void after correction.
Precautions
1.Pedicle was always nibbled from above downwards to avoid damaging the cord / dural tear.
2.Posteriorly the lamina / facets was not excised (except involvement of posterior elements).
3.Pleura was gently retracted avoiding tear in pleura.
Because of adhesion we violated pleura in three of our cases where we inserted ICD post surgery.
Difficulties Encountered
1.Orienting with pathological anatomy was difficult.
2.Debridement on the farther (opposite lateral side) was difficult.
3.Placement of strut grafts was difficult and preventing its intraspinal displacement.
Advantages
1.Direct visualisation of cord.
2.Very easy to remove the hard internal gibbus. Adequacy of decompression better judged.
3.Removal of posterior elements very easy.
4.Circumferential decompression possible.
2. Transthoracic DecompressionWe used transthoracic approach for lesions from T2 and T12 in our series. We had limited exposure in upper and lower thoracic vertebrae. Most of the times it was left side thoracotomy with sand bag beneath the right lateral portion corresponding to the deformity. Always the incision was taken one or two intercostal spaces above the affected level. Transverse incision over the rib, extending anteriorly, 5 cm anterior to the anterior axillary line and posteriorly midway between the spine and medial border of scapula. The incision was extended as per requirements during the surgery. Ribs were excised subperiosteally with rib shear along with anterior and posterior limits of incision. Parietal pleura were cut after deflating the lung and lung retracted anteriorly.
The affected vertebral body identified by presence of a prevertebral abscess or by the concavity present. Segmental arteries were cauterised and the vertebral body and disc space was exposed. Aorta retracted anteriorly then the body was debrided, scooped and bone graft was packed after correction of deformity. ICD was inserted and kept till the thoracic cavity drained usually 4-5 days in most of our cases. In one of our cases we did anterior instrumentation for additional stability. But unfortunately we don’t have long term follow-up on it.
Precautions
1.While opening parietal pleura lung to be deflated.
2.In exposing D12-L1 diaphragm 2.5 cm away from its insertion and reclosure of diaphragm is equally important.
3.Identify aorta and retract it properly in right sided approach preventing inferior vena cava or azygos vein as per the level.
4.While hammering the strut graft prevent injury posteriorly to the cord.
Difficulties Encountered
1.Cord not visualised easily so intraspinal debridement not easy.
2.Adequacy of decompression cannot be judged properly.
3.Breakage of strut graft while hammering in a small void.
Advantages
1.Wide exposure.
2.Radical debridement possible, avoiding cord injury.
3.Anterior instrumentation for maintaining correction of kyphosis and support for the graft.
RESULTS
TABLE 1 :
Age distribution of patientsAge Group (years) Total Number Percentage
0-10 1 2.5% 11-20 4 10% 21-30 8 20% 31-40 10 25% 41-50 12 30% 51-60 4 10% > 60 1 2.5% Total 40
TABLE 2 :
Sex distribution of the patientsSex Number Percentage Male 18 48% Female 22 52% Total 40
TABLE 3 :
Level of tubercular infectionLevel Total Number Percentage D1-D3 9 21% D4-D8 11 29% D9-D12 20 50%
TABLE 4 :
Type of surgery doneType Number Percentage Transthoracic + BG 20 50% ALD + BG 18 46% ALD (for internal gibbus) 2 4%
TABLE 5 :
Preoperative grade of paraplegia / paresisALD seriesGrade Number Percentage I 2 10% II 6 30% III 8 40% IV 4 20% Transthoracic seriesGrade Number Percentage I 2 10% II 7 35% III 7 35% IV 4 20%
TABLE 6 :
Recovery assessmentALD series Number Percentage Full recovery (A) 9 45% Able to work (B) 5 25% Some recovery (C) 2 10% No recovery (D) 4 20% Transthoracic series Number Percentage Full recovery (A) 8 40% Able to work (B) 6 30% Some recovery (C) 4 20% No recovery (D) 2 10%
DISCUSSION
Transthoracic and anterolateral approaches have been used over last 50 years in the treatment of thoracic spine TB. Though both have their own indications, there is an overlap in certain cases where the choice of technique remains debatable. In the middle of last century WH Kirkaldy and TG Thomas compared series of these two approaches. They had come to a conclusion that average time for fusion was little longer in transthoracic approach, but the failure rate was very low as compared to anterolateral approach. Seddon had come out with 1st series on ALD stating the usefulness of ALD and had given reoperation rate of ALD in 11%. AR Hodgson and Stock presented his detailed work advocating a radical anterior debridement with bone grafting to achieve good results. Bony fusion is considered to be the evidence of elimination of the disease. Time test has shown iliac graft to give good results, however Kemp et al also observed that in patients who had rib graft alone, rate of union was slow and graft often failed to incorporate.
TABLE 7 :
Recovery assessment gradewiseALD Series Preop Grade Total Number Recovery A B C D I 2 2 — — — II 6 4 2 — — III 8 4 2 2 — IV 4
1 — — 3
Transthoracic series Grade Total Number Recovery A B C D I 2 2 — — — II 7 4 3 — — III 7 2 3 2 — IV 4
— 1 1 2
TABLE 8
ComplicationsALD series 1 Dislocation of spine 1 2 Initial improvements with relapse 2 3 Postop no improvement followed up with deterioration 2 4 Death (Systemic complication) 2 5 Wound gap 3 6 Violation of pleura 3 7 Infection 1 Transthoracic series 1 Lung infection 3 2 Relapse 1 3 Would gap 1 4 Vascular injury 1 5 Death (Systemic complication) 1
TABLE 9
Relation of recovery to the level of affectionA B C D D1-D3 2 3 — 2 D4-D8 3 1 — 4 D9-D12 10 6 4 —
In our study of 40 patients the results of transthoracic had proved better than of ALD considering the fusion rate was high. In two of our patients where internal gibbus was the offending factor ALD gave us the best results. At the very beginning we have mentioned the usefulness of MRI’s. It’s now fact that with introduction of CPA MRI has become almost a mandatory investigation for all TB spines with or without neurological deficit. MRI gave us idea about the planning and execution of our approach.
Neurological recovery was considered one step in the ladder for combating TB spine. Both groups of patients had equal rate of improvement. It was with ALD we came across initial improvement and relapse after one and half years. There were other two cases in ALD which showed no improvement post surgery and came 6-8 weeks post surgery with increased neurological deficit and bladder bowel involvement. In one of the cases MRI was done and the cause was defined as persistence of the granulation tissue and pus without any correction of kyphosis. Both these patients underwent a thorough transthoracic decompression with bone grafting but never recorded. One of our earlier cases that presented one and half years after ALD showed greater improvement with transthoracic bone grafting with anterior instrumentation.
The thoracotomy had its own disadvantage though we had no patients coming back with relapses. There were three bad infections, which were very difficult to treat. One of the patients succumbed to systemic sepsis.
One case required special discussion, case number eight in ALD series, this was twenty year old female with D3-D4 Koch’s spine with grade III paraplegia. ALD was done for her. Postoperatively she was in bed for eight weeks. She had good recovery and was able to walk with brace. After discharge within one week she came back with D3-D4 dislocated spine with grade IV paraplegia. She was treated with posterior decompression with fusion with HartShill with sublaminar wiring. MRI in her case showed compression of cord with instability. Post surgery she never recovered.
In literature it has been mentioned by AR Guiguis (JBJS, 1967), Campbel and by Dr. SK Gupta (Indian journal of radiology 1973). In one of references in spine volume 14 we have example of lateral translation of spine with paraplegia following anterior surgery without posterior fusion the patients at risks were :
1.The patients were children with anterior and posterior element destruction.
2. In centres where ambulant chemotherapy of tuberculous spondylitis is usually practised without proper brace.
3. Where anterior decompression and strut graft are to be performed. Preliminary posterior stabilisation is necessary with both anterior and posterior involvement.
If the excision of pedicles goes posteriorly into facets and then into lamina spinal instability causing pain, slow healing dislocation can arise. This has been called vertebral shift (Griffith et al 1957).
Regarding the correction / maintenance of kyphosis we had good results with transthoracic, some common complications occurred in both sets of patients. In transthoracic 80% of patients had excellent or good results where as it was only 50% in ALD, whereas the rate of failure was 10% and 22.5% respectively.
In literature we have some conflicting reports. In study presented by MK Goel (JBJS 1967) he had studied for TB thoracic spine. He concluded that an early surgical decompression was required in form of ALD, but fusion using bone graft was not required. In his 48 patients, 45 without bone grafting recovered and healed. He also claimed that no instability occurred and fusion was unnecessary.
However in our study bone grafting has been used routinely and still a case of instability occurred in form of dislocation. Since we were studying transthoracic approach lately we did one case of anterior instrumentation for case of D8-D9 Koch’s spine with Grade III paraplegia. This was an old case of Koch’s spine operated with ALD one and half year back and had relapse. Regarding results she had got immediate post-op complete recovery and the latest follow up at 12th week there was no collapse and bone graft was consolidating. We don’t have a longer follow-up in this case but intra operative there was good opening out of the kyphus and after graft was in place the rod was compressed again.
In our series time of fusion was 7.66 months in ALD and nine months in transthoracic approach, while failure of fusion was 11% and 5% respectively. Both transthoracic and ALD allowed adequate decompression and neurological recovery, but ALD was choice of operation in cases of late onset paraplegia while with transthoracic rate of fusion and correction of kyphosis was better than ALD. Bone graft for fusion mandatory in both approaches. Also transthoracic has added advantage of anterior instrumentation possibly preventing posterior surgery.
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