Silent degradation: when software, sensors and alarms fail quietly
The dangerous device failures announce nothing — a sensor drifting inside its displayed range, an alarm that never triggers, a software state nobody tested. What the design and surveillance records show.
The volatile evidence inside active clinical equipment
Event logs, alarm history, power state and the settings as found are the strongest record of what an infusion pump or ventilator did. Routine ward turnover and biomedical servicing erase most of it within days.
Use error, device error, and what the design record anticipated
Calling a device event operator error settles nothing. Usability engineering treats a mistake at the interface as evidence about the design, and the manufacturer's own file records which mistakes were foreseen.
Corrosion at modular junctions and the alloy question
A modular junction is a crevice with micromotion in it. Reading the degradation means examining the surfaces before cleaning, verifying the alloy, and addressing assembly and patient factors explicitly.
The operating theatre is where implant evidence is lost
Most of what an explanted implant could prove is decided in theatre, not in the laboratory. Cleaning, fixation and sterilisation remove the surface record before anyone identifies it as evidence.
Wear debris and the host response are two findings
A worn implant surface and the tissue around it answer different questions. Reading the wear mode, characterising the debris, and establishing the host reaction are separate acts of evidence.
Mechanism consistency and the limits of "consistent with"
Reconstructing body kinematics from interior marks, restraint evidence and recorded data constrains what loading a body saw. A finding of inconsistency is strong; a finding of consistency excludes very little.
Where injury tolerance numbers actually come from
Tolerance criteria descend from cadaveric testing, sub-injurious volunteer work and statistical scaling. They describe a population under a defined loading condition, and no individual is that population.
Where the biomechanical opinion ends and medicine begins
A biomechanist establishes loading direction, magnitude and rate, and compares it against tolerance data. Diagnosis, timeline and baseline belong to medicine. Most challenges live on that boundary.
The construct, not the component: working length, screw count and stress concentration
A plate that meets every applicable standard can still be part of a construct that fails. Working length, screw placement, junctions and mixed metals are assembly properties, not device properties.
Serial radiographs and the explant: two records that decay differently
Follow-up imaging is a load history written in instalments, and the removed hardware is the physical half of the same record. Theatre routine destroys one of them within hours.
When a fixation plate breaks: fatigue life against healing time
Trauma fixation hardware has a finite fatigue life and is meant to be relieved of load by healing bone. When it breaks, the fracture surface usually says more about union than about metal.
How medical tubing ages out before its expiry date
Plasticiser migration, drug and lipid interaction, disinfectants and sterilisation can leave a set unfit long before its labelled shelf life ends — and the device is usually cut, flushed or discarded first.
When a wrong connection should be physically impossible
Small-bore connector standards were written so that incompatible routes cannot mate. Connector matters usually turn on which generation of hardware was in service and what the design record shows.
Reading the break in a separated catheter
A catheter that comes out in two pieces can have separated half a dozen ways. The fracture surface, the dimensions and the retained fragment narrow the list — if nobody trims the specimen first.