Ganga Medical Centre & Hospitals Pvt Ltd

A validated 3-D Finite Element Model (FEM) of the paediatric spine was built with the expertise available at the Rush-Presbyterian-St. Lukes Medical center, Chicago, Illinois, USA. The data obtained from the FEM study will be correlated with the data available from the 15-year longitudinal clinico-radiological study that has been completed in Ganga Hospital, Coimbatore. Finite element model allows investigations on the relationship between the extent of vertebral destruction, the location and level of lesion and the resulting deformity of the spine. The mechanical basis of deformity initiation and progression will be ascertained. The data obtained from this study will be used to propose treatment guidelines and define surgical indications to prevent progressive deformity.

	Finite element model of the spine demonstrating the “buckling collapse” of the spine due to the vertebral body loss from tuberculous disease process.
	Dr. Gunnar Anderson and Dr. Raghu Natarajan of Rush University, Illinois, Chicago with Dr. S Rajasekaran. The research team consists of Dr J Naresh Babu, Dr S.Rajasekaran, Dr Raghu Natarajan, Dr Gunnar Anderson

A study of effect of mechanical forces on endplates of lumbar vertebrae “Scoliotic disc as a biological model”

Yves Cotrel Research Foundation (Paris) Award 2004

The effect of mechanical stress on the integrity and function of endplate is of great interest to spine surgeons. Scoliosis represents an ideal clinical situation where this phenomenon can be studied as the endplate on the concave side are under severe stress and those on the convex side are devoid of such severe stress. We conducted an invivo study of the endplates diffusion studies by contrast MRI. Serial coronal section MRI of adolescent idiopathic scoliosis patients from anterior to posterior demonstrating various grades of endplate breaks and disc degeneration at all levels.


0hrs	10mins	2hrs	6hrs	12hrs

The flow of the contrast medium across these endplates is studied by injecting Inj Gadodiamide and taking serial MRI at 0hrs, 10mins, 2hrs, 6hrs and 12hrs.

50 intervertebral discs (45 scoliotic and 5 normal) from subjects (one control and ten adolescent idiopathic scoliosis) during Oct 2004 to Oct 2005 were studied. The patients underwent radiographic study, plain MRI study and serial post-contrast MRI study to analyse the effect of the abnormal mechanical stresses on the disc degeneration.

Endplate Damage In Lumbar Discs Can Be Identified In-vivo By Post-Contrast MRI Studies

ISSLS Prize for Best Lumbar Spine Research 2004

Site-specific endplate damages have been documented to occur from early age in cadaveric studies. Although postulated as an important mechanism for disc degeneration, no method has been described so far to identify such breaks in vivo.

T1-weighted images were obtained pre and post-contrast with Gadodiamide at 5, 10mts, 2, 4, 6, 12 & 24hours. Diffusion was calculated by measuring signal intensity values in vertebral body (VB), subchondral bone (SCB), endplate, center (CNP) and periphery (PNP) of nucleus pulposus (NP). Enhancement percentage (EP) for each time period, Peak enhancement percentage (PEP) and time taken to achieve PEP (Tmax) were used to study diffusion characteristics of each region.

Serial post-contrast MRI study depicting an endplate break by virtue of the absence of endplate delay and diffusion march. The dye directly enters the nucleus pulposus within 10mins of injection.

Intact endplate was identified in pre-contrast images as a distinct zone hypo-intense to SCB and NP by at least 75 units. Post-contrast, the normal pattern was that there was a sequential achievement of PEP from VB to CNP (Diffusion march) with a delay (endplate delay) at the endplate (Tmax for VB & SCB was 10min, Endplate was 2hrs and NP was 6hrs). Endplate breaks were identified as patchy areas, where there was simultaneous enhancement of SCB, endplate and PNP at 10 min (absence of endplate delay and Diffusion march).

Pharmacological modulation of disc diffusion by Nimodipine -A prospective in-vivo human study

Histological studies have documented that Calcium channel antagonist Nimodipine increases vascularity of end plates in rats. However, there is no corresponding data for humans and whether endplate hypervascularity leads to increase in diffusion. This prospective study in human volunteers reports for the first time in literature an increase in diffusion following Nimodipine by serial post contrast MRI study.

Forty lumbar end plates of four young healthy male volunteers formed the study material. The pre-drug diffusion levels were studied by pre and post contrast MRI (0.3 mmol/kg of gadodiamide) at 10 minutes, two, four, six, 12 and 24 hours. After a gadodiamide wash out period of 10 days, a plain MR examination was performed to ensure return of signal intensity values to the base line.

Bar diagrams depicting the enhancement of dignal intensity at all the stages of disc
diffusion namely the subchondral bone, endplate and nucleus pulposus.
(Blue - precontrast, Red - Postcontrast)

Oral Nimodipine was administered (30 mgs QID) for five days following which diffusion studies were performed by a similar MRI sequence. Paired sample t-test and area under curve (AUC) measurements were performed to compare the pre and post-drug signal intensities. This is the first study to document an increase in diffusion of human lumbar discs by oral nimodipine and poses interesting possibility of pharmacological enhancement of lumbar disc diffusion.

Collaborators:
Ganga Hospital, Coimbatore,
Microbiological Laboratories, Coimbatore.
Christian Medical College, Vellore ,
Central Leather Research Institute, Chennai

The biology of the cells of the annulus fibrosus and nucleus pulposus are heavily influenced by the mechanical forces they are subjected to.

Electron Microscopic examination of the intervertebral discs of adolescent idiopathic scoliosis showing increased cell death and debris surrounded by reactive matrix formation on the concave side and normal cell and fibrous long structural collagen on the convex side.

Scoliosis is a perfect human biological model where the effects of the mechanical forces can be studied. Most of the studies on scoliosis so far have concentrated on the annulus fibrosus and nucleus pulposus but not on the endplate. But the endplate influences the diffusion which is the only source of nutrition of the disc. But no firm data is available on the pattern of diffusion and disc composition in the scoliotic discs. An in-depth study of MR imaging of endplate, nucleus pulposus, and annulus fibrosus on concave and convex sides of varying severity of scoliotic curve at different levels is being done and correlated to the cell and matrix characteristics of the disc.


Non viable and viable disc cells stained for cell counting using Aqueous Haematoxyllin stain exclusion	Haematoxyllin and Eosin staining showing cartilage cracks and clustering of disc cells on concave side

End plate damage score and correlation to disc degeneration
Lumbar degenerative disc disease is the commonest cause of low back pain. The inter-vertebral disc gets its nutrition from the end plate by a process of diffusion. Decreased diffusion of nutrients leads to degeneration of the disc and hence End plate damage (EPD) plays a crucial role in degenerative disc disease (DDD).
Biological treatment of DDD is underway, but may not succeed when diffusion is altered due to EPD. Quantification of EPD and its correlation to altered diffusion patterns and DDD has
not been done invivo.
A serial post-contrast MRI study was performed to identify various types of EPD and a scoring system was devised. This End plate score provides guidelines in planning the management of DDD.

Altered diffusion patterns in inter-vertebral discs can identify healthy, ageing and
degenerated discs - an in vivo serial post contrast diffusion study in 365 human lumbar discs.

Degenerative disc disease (DDD) causes significant low back pain. However, objective methods to differentiate healthy from ageing and degenerated discs invivo is still not available. This information is important for proper understanding of DDD and strategizing prevention and treatment. We conducted a Contrast MRI study in 73 adults and have identified distinct patterns of diffusion that identify structural and functional changes in the disc which help to differentiate between healthy, aged and degenerated discs. This information provides an objective method based on which degenerated discs can be identified and also to develop

Four types of diffusion curves in healthy, ageing , degenerating and degenerated discs

Computer navigated spine surgery
The emergence of highly sophisticated, Iso-C3D C-arm based computer navigation system has revolutionized the way spine surgery is performed. The institute has been performing Iso-C navigation guided surgeries since 2004 and our team is involved in various studies being conducted to evaluate the utility of this technology in complex spinal procedures.

Navigation in Spine tumour excision. The accuracy of cervical pedicle screw fixation under navigation

We have used computer navigation for the excision of benign tumors of the spine through a minimally invasive approach. The advantages are accurate localization, complete excision of the tumor, minimal damage to the normal bone and a small surgical scar. This implies safer surgery, shorter rehabilitation and early return to normal activity. Our series of osteoid osteoma excision using Iso C-3D based computer navigation has been published.

CT scan images of an osteoid osteoma in the vertebrae. Computer navigation accurately localises the tumor
and aids complete excision of the tumor with minimal normal bone removal.

The accuracy of cervical pedicle screw fixation under navigation

Although pedicle screw fixation has superior biomechanical advantages compared to any
other form of fixation in the cervical spine, it has also got the disadvantages of increased
complication rate due to the peculiar anatomy and the presence of important neuro vascular
structures. The complexity of fixation is increased in the presence of instability or congenital
anatomical variations. We are studying the application and accuracy of navigated cervical
pedicle screws under such challenging circumstances.

9 year old girl with Klippel feil's syndrome and C1-C2 instability with various congenital anomalies. Intra-operative navigation picture showing trajectory. Post-operative Radiographs and CT
scan showing accurate placement of pedicle screws