Nucleus replacement could get a new chance with annulus closure.

Area of Science:

• Spinal biomechanics
• Biomaterials science
• Orthopedic surgery

Background:

• Herniated discs often require nucleotomy, potentially leading to disc height reduction, decreased intradiscal pressure, and increased range of motion.
• These changes can accelerate spinal degeneration.
• Nucleus replacement implants aim to restore disc biomechanics but carry extrusion risks.

Purpose of the Study:

• To evaluate the biomechanical stability and safety of a novel collagen-based nucleus replacement implant combined with an annulus closure device after simulated disc herniation and nucleotomy.
• To assess the implant's ability to restore disc height, intradiscal pressure, and range of motion.
• To determine the risk of implant or nucleus material extrusion after cyclic loading.

Main Methods:

• Six human lumbar spinal segments underwent induced disc prolapse and nucleotomy.
• A collagen-based nucleus implant was inserted, and the annulus defect was sealed.
• Biomechanical parameters (range of motion, neutral zone, intradiscal pressure, disc height) were measured before and after interventions, including 100,000 cycles of loading.
• Implant and nucleus material extrusion was macroscopically evaluated.

Main Results:

• Disc prolapse decreased disc height; subsequent nucleotomy significantly altered biomechanical parameters.
• Nucleus implantation with annulus closure successfully restored the measured parameters to levels comparable to the intact state.
• No macroscopic extrusion or migration of the implant or nucleus material was observed after cyclic loading.

Conclusions:

• Simulated disc herniation and nucleotomy lead to biomechanical destabilization.
• Combining nucleus replacement with annulus closure effectively restores spinal biomechanics and stability.
• This approach shows promise for treating disc herniations, mitigating risks associated with traditional treatments and implants.