Synthetic Neurovascular Tissue has a functional lifespan of 8-12 years. After this period, the cellular components of the SNT layer begin to senesce. Vascular channels narrow. Neural bridge conductivity degrades. Structural anchoring weakens.

This is by design.

SNT-7, like every generation before it, is engineered with a predetermined cellular lifespan. The cells divide a set number of times, then stop. The tissue ages, degrades, and eventually fails. When it fails, the implant it bonded loses integration. Function degrades. Pain increases. The patient requires SNT replacement surgery — a procedure that costs 60-80% of the original implantation.

This is the Maintenance Trap: once you have augmented yourself with SNT-bonded cyberware, you are committed to periodic replacement of the bonding layer for as long as you want the implant to function. Stop paying and the implant becomes a piece of dead metal attached to dying tissue.

A standard cybernetic arm costs approximately Φ800,000 to install (implant + SNT + surgery). SNT replacement every 10 years costs Φ500,000. Over a 40-year lifespan with the implant, total SNT costs exceed Φ2 million — two and a half times the original implant cost.

The three SNT manufacturers have been asked repeatedly whether a longer-lasting formulation is possible. Their responses are consistent: 'Current cellular engineering limitations prevent indefinite SNT viability.' Internal documents leaked in 2219 from Cortex Dynamics suggest otherwise. A research team achieved 25-year SNT viability in laboratory conditions in 2217. The project was cancelled by executive order. The memo cited 'insufficient market demand for extended-lifespan product variants.'

The market demand is enormous. The profit from replacement cycles is larger.