A growth plate is the layer of cartilage near the ends of long bones where new bone is added during growth. Growth plates start to close in late adolescence and are typically fully closed by the early 20s. While they are open, they are biologically distinct from the surrounding bone, and they handle stress differently.
There are two types of growth plate that matter for sports injuries:
Physes — the growth plates at the ends of long bones (near joints). These are responsible for length growth and are vulnerable to fractures, especially after acute injuries. The Salter-Harris classification describes the patterns these fractures can take. A growth-plate fracture in a young athlete can look superficially like an ankle sprain or a wrist sprain, which is why we recommend that any acute joint injury in someone under 16 gets a closer look than the same injury in an adult.
Apophyses — sites where tendons attach to bone (different from physes). These can become irritated when a tendon is repeatedly loaded faster than the apophysis can handle. Common examples: Osgood-Schlatter at the tibial tubercle (anterior knee), Sever's at the calcaneus (heel), Little League elbow at the medial epicondyle.
Apophysitis (irritation of an apophysis) is usually self-limiting — the pattern resolves as growth completes. The treatment is patience, load reduction, and sometimes physical therapy. It does not usually require imaging or aggressive treatment.
The reason OrthoConnect weights growth-plate-aware patterns higher in its scoring is not because these injuries are catastrophic — most are not. It is because they deserve a slightly earlier conversation with a clinician than the same symptoms would in an adult, and because they are easy to miss if you are thinking only in adult terms.