The growth plate is the weak link
In an adult, a tendon attaches to hard, mature bone, and that junction is stronger than the muscle pulling on it. In a growing child the same tendon attaches to an apophysis, an area of growth cartilage that is still turning into bone. It is the weakest part of the chain, so when the system is overloaded, that is where symptoms appear.
This explains a pattern that puzzles a lot of parents. Adults tear muscles and strain tendons. Children tend to get sore attachment points instead. The mechanism is the same overload; the tissue that complains is different.
Why growth spurts make it worse
Bones lengthen first. Muscles and tendons then have to catch up, adapting to the new distance between attachment points. For a period of months during a rapid spurt, the calf and quadriceps are effectively working at a longer length than they are adapted to, which increases resting tension and the pull on the growth plates.
Coordination temporarily suffers at the same time. Limb lengths change faster than the nervous system's map of the body updates, so landing mechanics and control get a little clumsier, which adds impact exactly when the tissue is least tolerant.
Why the knee and heel specifically
- The heel takes the whole Achilles pull with every stride, sprint and jump, hence Sever's disease.
- The shin bump below the kneecap takes the quadriceps pull with every kick, jump and deceleration, hence Osgood-Schlatter.
- The bottom tip of the kneecap takes the same chain a little higher up, hence Sinding-Larsen-Johansson.
- The kneecap joint itself is sensitive to hip and thigh strength, which lags during growth, hence adolescent patellofemoral pain.
What raises the risk
- Rapid growth, roughly the 6–12 months around peak height velocity.
- Jumps in weekly training volume, particularly at the start of a season or after a break.
- Playing one sport year-round with no meaningful off-season.
- Multiple teams: school, club, county and district all training the same body.
- Hard surfaces and worn or unsupportive footwear.
- Limited lower-limb strength, especially calves, quadriceps and glutes.
What parents should actually do
The instinct is to look for something to fix - a stretch, an insole, a supplement. The evidence points somewhere less exciting but more effective: manage the weekly dose of impact, and systematically build the strength of the muscles pulling on the sore area.
Practically, that means counting sessions across all teams rather than looking at each in isolation, holding volume steady rather than progressing it during a spurt, keeping two short strength sessions a week all year round, and using the 24-hour symptom response to judge whether the current dose is right.
Is it something to worry about?
Growth-related knee and heel pain does not cause long-term joint damage and does not lead to arthritis. It is genuinely painful, it can disrupt a season, and it deserves proper management, but it is not something that harms the joint over time.
Get it assessed if pain is present at rest or at night, if the joint swells, if there was a specific injury, if the child is unwell, or if there is no improvement after six weeks of sensible management.