If you were the child who could fold into positions that made other people wince, who was called clumsy, who got lightheaded standing up too fast, and who was later assessed for autism or ADHD, you may have wondered whether any of it was connected.

If you have ever felt pain running from your buttock down the back of your thigh getting out of a low car seat, rolling over in bed, climbing stairs, or sitting through a long drive, you know how hard it is to point at where the trouble is.

If you have ever pushed off hard for a wide forehand, felt your foot roll under you as you turned, and taken your shoe off two hours later to find the outside of your ankle puffed up, you have had a tennis ankle sprain.

If you have ever woken up, reached for your phone before your feet touched the floor, read a two-digit number, and let it decide whether today would be a good day or a careful one, you know how quickly a wearable starts running your morning.

If you have ever felt a catch reaching into an overhead cupboard, an ache lifting a kettle, soreness fastening a seatbelt, a twinge reaching across for a mug, or pins and needles running from your neck into your hand, you already know the awkward part of shoulder pain: it rarely stays in one tidy place.

If your child wins the flexibility test at every practice and has now started saying a knee feels wobbly or a shoulder slipped, this is worth understanding rather than panicking about.

If your teenager has stood up and had to grab the doorframe, gone gray in a hot shower, or told you the classroom went swimmy—you have probably already been told it is growth, or dehydration, or exam stress.

Lunging for a ball that was never quite reachable. Pushing off hard to change direction. Stopping dead at the kitchen line. Then a sharp catch in the back of the lower leg, and the certainty that somebody behind you kicked it—except nobody is behind you.

Getting out of a low armchair. Climbing the stairs to your own bedroom. Stepping over the lip of your shower. These are the movements that decide whether a joint replacement feels like a success—and every single one of them happens at home.

If you have ever gripped the banister a little harder than usual coming down the stairs, caught your toe on the edge of a rug, put a hand on the kitchen counter to steady yourself while reaching for a high shelf, or felt the room tilt for a second when you stood up from the couch—you have had a near-miss.

If you have ever been woken by an ache on the outside of your hip after rolling onto that side, felt it standing at the kitchen counter with your weight sunk onto one leg, or getting out of a low car seat, you already know the particular nuisance of outside hip pain.

If you have ever felt an ache at the front of your knee walking down stairs, getting out of the car after a long drive, sitting through a whole movie, or easing down a hill in the last miles of a long run, you may have experienced runner's knee.