Noticed your buddy's situation but modern motion sensors don't just isolate a single joint anymore, that's the whole point of having multiple sensors. They track your ankle, hip, and knee together to see how movement at one impacts the others. Overpronation would show up clearly in the ankle data and the software would link it to the resulting knee stress. The visualization would literally draw a line from the ankle collapse to the knee hyperextension, lol. The podiatrist might have identified the root cause without the tech, but the sensor data would visually confirm the chain reaction.