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Orthopaedic Proceedings
Vol. 106-B, Issue SUPP_15 | Pages 32 - 32
7 Aug 2024
Raftery K Tavana S Newell N
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Introduction

Vertebral compression fractures are the most common type of osteoporotic fracture. Though 89% of clinical fractures occur anteriorly, it is challenging to replicate these ex vivo with the underlying intervertebral discs (IVDs) present. Furthermore, the role of disc degeneration in this mechanism is poorly understood. Understanding how disc morphology alters vertebral strain distributions may lead to the utilisation of IVD metrics in fracture prediction, or inform surgical decision-making regarding instrumentation type and placement.

Aim

To determine the effect of disc degeneration on the vertebral trabecular bone strain distributions in axial compression and flexion loading.


Orthopaedic Proceedings
Vol. 104-B, Issue SUPP_9 | Pages 24 - 24
1 Oct 2022
Tavana S Leong J Freedman B Newell N
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Background

In vivo evaluation of IVD strains is crucial to better understand normal and pathological IVD mechanics, and to evaluate the effectiveness of treatments. This study aimed to 1) develop a novel in vivo technique based on 3T MRI and digital volume correlation (DVC) to measure strains within IVDs and 2) to use this technique to resolve 3D strains within IVDs of healthy volunteers during extension.

Methods

This study included 40 lumbar IVDs from eight healthy subjects. The optimal MR sequence to minimise DVC uncertainties was identified by scanning one subject with four different sequences: CISS, T1VIBE, T2SPACE, and T2TSE. To assess the repeatability of the strain measurements in spines with different anatomical and morphological variations four subjects were scanned with the optimal sequence, and uncertainties of the strain measurements were quantified. Additionally, to calculate 3D strains during extension, MRIs were acquired from six subjects in both the neutral position and after full extension.


Orthopaedic Proceedings
Vol. 104-B, Issue SUPP_9 | Pages 9 - 9
1 Oct 2022
Rahman T Baxan N Murray R Tavana S Schaer T Smith N Bull J Newell N
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Introduction

Nucleus replacement surgery has the potential to be an early treatment option for chronic lower back pain. The surgery involves removal (nuclectomy) and replacement of the native degenerated nucleus with a material designed to restore the disc's physiological properties. Multiple techniques have been considered to perform a nuclectomy, however the advantages and disadvantages of each are not well understood. The aim of this study was to quantitatively compare three nuclectomy techniques: automated-shaver, rongeurs, and laser.

Methods and results

Fifteen human vertebra-disc-vertebra lumbar specimens were split into three groups. Before and after nuclectomy axial mechanical tests were performed and T2-weighted 9.4T MRIs were acquired for each specimen. Using the automated-shaver and rongeur similar volumes of disc material were removed (2.51±1.10% and 2.76±1.39% of the total disc volume, respectively), whilst considerably less material was removed when using the laser (0.12±0.07%). Using the automated-shaver and rongeur significantly reduced the toe-region stiffness, while the linear region stiffness was significantly reduced only in the rongeur group. From the MRIs, more homogeneous cavities were seen in the center of the disc when using the automated shaver compared to rongeur, whilst laser ablation resulted in small, localized cavities.