Title : Intra-discal high-frequency ultrasound for degenerative disc disease: A seamless sequential ex vivo and in vivo study
Abstract:
Background: InterVertebral Disc (IVD) herniation remains a leading cause of spinal morbidity. Traditional surgical decompression has clear efficacy, but at the cost of invasiveness and longer recovery time. The search for a minimally invasive method in treating IVD herniation is of paramount importance.
Objectives: This study explores a minimally invasive energy-based strategy to reduce the disc bulging and restores the IVD height in a porcine using seamless ex vivo and in vivo model.
Study Design & Methods: Hyper-acute disc prolapses were induced biomechanically and surgically, ex vivo through a freshly harvested spinal functional unit (SFU) of a porcine (less than half an hour post mortem), to determine the dosing, frequency, and duration of HF-US application. Seamlessly, adopting the data collected and validated from ex vivo, in vivo study conducted using 1.5 MHz, pulsed, and with medium power applied on L4/L5 and L5/L6 IVD with L1-L3 as control. Baseline IVD height was measured, and intra-discal ICG (indocyanine green) was injected in IVD L1-L6 to visualize the bulging of the disc and quantify the IVD height, before and after treatment, respectively. (Image J software was used for accurate measurement). Disc bulging and annular tear were observed in L4/L5 and L5/L6. Post treatment, IVD height and reduction of disc bulging were quantified. P-value, standard deviation (SD), and standard error of the mean (SEM) were calculated using a paired t-test.
Results: The mean of IVD height was 4.12 mm and 5.64 mm for the treatment and control groups, respectively. Post intra-discal HF-US application, the treatment discs increased to 6mm and >25% disc bulging reduction, observed with an ICG-compatible camera, while controls remained unchanged (5.62 mm). Statistical analysis showed a significant difference between the treatment group vs the control group (P~0.03%, SD of treatment: 0.058,
Control: 0.040mm, SEM treatment group: 0.041mm)
Conclusions: Intra-discal HF-US application produces measurable decompression in acutely herniated porcine discs, restoring IVD height, and sealing the annular tears without open decompression. This minimally invasive strategy warrants further chronic in vivo study to assess the durability and biological response, followed by a first-in-human study.
