Abstract
Introduction
Classification systems allow categorization of radiological similar lesions. Evaluation of differing clinical treatment modalities, helps formulate protocols. However no classification systems exists for dorso-lumbar (DL) tuberculous lesions, though surgeons continue to debate treatment strategies.
Material and Methods
270 dorso-lumbar tuberculous lesions were surgically treated between 2001–2011. Pre-operative radiology included X-rays (D1-S1), MRI and CT scan in all patients. Cervico-dorsal lesions were excluded. Categorization was based on anatomical location, extent of anterior osseous disease (AD), posterior element disease (PD) and site and matching of epidural disease (ED). Anatomical location: 1. Dorsal between D1 and D12 (117); 2. Lumbar between L1 and L5 (46); 3. Sacral: S1-S4 (6); 4. Cross over lesions: (DL 48, LD 29, LS 15, SL 9). If major AD was in L1 and lesser in D12 the lesions were called “Lumbo-Dorsal” cross over and vice versa. The terminology changed accordingly at Lumbo-sacral junction. Extent of Anterior Destruction: Distance between proximal and distal normal bone gave estimate of anterior defect (AAD) that requires reconstruction. There was statistically significant increase in AAD from Type 1 to 3. Type 1 (n = 37): Paradiscal erosion cavitation restricted to less than 50% of body-height. AAD was 2.7cms (1.8–3.2). Type 2 (n = 33): Central osseous destruction with cavitation reaching both end plates. AAD was 3.34cms (2.8–4.0). Type 3 A (n = 82): Less than 50% destruction in one and more than 50% in the other body. Significant cavitation reaching far end plate. Less than 50% circumference available for reconstruction. AAD 3.69cms (2.9 – 4.2). Type 3 B (n = 79): More than 50% destruction in both bodies. AAD 4.98cms (4.0 to 6.2 cms). Type 4 (n = 28): This includes types 1,2 and 3 with PD. Type 5 (n = 11): AD affecting more than 2 bodies in continuity. PD may or may not be present. AAD varies with each case and should be studied on the CT scan picture. Site of ED: This was predominantly anterior (152), posterior (21), hemispherical (42), circumferential (30) or mixed pattern (25). Matching ED with AD: Matched ED (n = 227) meant that the site of ED was adjacent to osseous destruction; Un-matched ED (n = 43); Anterior unmatched compression (38). Anterior ED extended proximal or distal to AD; Posterior un-matched compression (6). ED was posterior when the lesion was anteriorly located.
Results
Inter-observer variability. 25 radiology sets were distributed to 4 authors. All recorded type 1,2,4 and 5 correctly on X-ray and MRI. Statistically significant variation was recorded between types 3A and B (7/15 type 3). CT scan, reduced variation significantly (2/15) Better delineation of AD aided decision-making. Variation in noting ED was insignificant. Four most common patterns were: 1. Dorsal, Type 3 A, anterior matched ED (42); 2. Dorsal, Type 3 B, anterior matched ED (30); 3. Dorso-Lumbar, Type 2, matched anterior ED (22); 4. Lumbo-Dorsal, Type 4, anterior matched ED (18).
Conclusion
Classification allows categorization of lesions and comparison of treatment outcomes. Improvisation in posterior surgery has intensified the on-going debate between anterior and posterior surgical approaches. Irrespective of approach, classification defines AD and PD that allows the surgeon to plan an approach that would provide a adequate spinal cord decompression and stable construct. The author's recommendations are: 1. Type 1, 2, 3A: anterior decompression and reconstruction; 2. Type 3 B and type 4 anterior reconstruction and posterior stabilization. CT scan is a useful to assess AD and planning reconstruction. The new classification is the first of its kind that promises comparison of radiological data.