Growth plates: how young fingers grow, and how they break
Finger bones grow from a soft layer of cartilage near each joint. Until it turns to bone, that layer is the weakest part of a young climber's finger, and repeated hard crimping can crack it.
In plain words
Children's bones get longer because of growth plates: thin layers of cartilage near the ends of each bone, where new bone is made. Cartilage is softer than bone, and softer than the tendons and pulleys around it. So in a growing finger, hard crimping stresses the growth plate at the back of the middle finger joint, not the pulleys. Small damage can build up session after session, sometimes without pain, until the bone cracks: a stress fracture. Once growth stops, around the late teens for fingers, the plate turns into bone and this weak point is gone.
Memory hookGrowing fingers break at the plate: pain at the back of the middle joint means stop.
How a growth plate works, and how it fails
Watch it
Part 1 shows a finger bone growing and then fusing. In part 2, pick a grip, add hard sessions, and add rest days. Compare a growing finger with an adult one.
Why the middle finger joint
In a crimp the middle joint bends to about 90° while the fingertip pushes on the edge. That squeezes and shears the base of the middle bone, on its back (dorsal) side. The back part of the growth plate is the last part to fuse, so it stays weak the longest. The middle and ring fingers are the longest, and they are most often affected.
Who is at risk, and when
Mostly during the pubertal growth spurt. The AOSSM sheet gives about 11–14 for girls and 12–16 for boys; injuries can occur up to about 18.
Repeated hard crimping, especially sideways or dynamic moves onto crimps. Campus board work and added weight are named risk factors.
Often a gradual ache at the back of the middle finger joint, swelling, stiffness, or a finger that bends less than the others. Some injuries give no earlier warning.
What helps
a young climber with finger pain should stop and see a doctor, not climb through it.
the AOSSM sheet says no double-dyno campusing until 18 or until the growth plates close, and no added weight.
avoid full crimps where possible, and avoid dynamic moves onto crimps.
good feet take weight off the fingers.
different styles and holds, not hours on small edges.
The evidence
- Measured Finger growth-plate stress injuries are the most frequent sport-specific injury in adolescent climbers. In a four-year clinic series of 27 young climbers with 37 injuries (mean age 14.7, SD 1.5; 19 male, 8 female; two-thirds competing), 28 injuries were Salter-Harris type III fractures, running through the growth plate into the joint. Schöffl et al. 2022. Am J Sports Med 50(1):229–237.
- Measured Growth-plate stress fractures are the most common injury in youth climbers, and campus board training is a known risk factor. Meyers et al. 2020, a review. Curr Sports Med Rep 19(11):457–462.
- Measured The AOSSM STOP Sports Injuries climbing sheet (reviewed September 2025) names growth-plate stress fractures of the fingers as the most common injury in youth climbers. It gives growth-spurt ages of about 11–14 for girls and 12–16 for boys, and advises no double-dyno campusing until 18 and no added weight. It recommends seeing a professional for finger pain lasting more than 24 hours, or recurring for more than a week. sportsmed.org/rock-climbing.
- Measured The British Mountaineering Council guide says growth plates are weaker than the surrounding tendons and ligaments. It adds that fingers finish growing around age 17, the middle joint (PIP) is most often affected, X-rays can look normal when an MRI shows the fracture, and typical time off is 6–8 weeks. BMC growth plate guide, v1.0, February 2024.
- Model The animation is a drawing, not a simulation of real forces: the "micro-damage" bar has no units and no measured timing.
- Coaching practice Teach open-hand and half-crimp grips early, and keep young climbers off campus boards.
None of the adult numbers elsewhere on this site (critical force, half-times, grip forces) apply to children.
What the animation simplifies
- Bone growth is shown as one smooth process. Real growth comes in spurts and differs a lot between children.
- The stress circle shows where load concentrates, not how big it is. Each "hard session" adds a fixed amount of damage scaled by grip; each "rest day" removes a fixed amount. Real repair is slower and varies.
- The adult finger has no growth plate, so the same load shows up at the A2 pulley, the usual adult weak point.
- Real injuries can appear without warning, and pain is not a reliable early alarm.
Try it
Common mistakes
the weak point is different, and so are the warning signs.
growth-plate injuries usually build up quietly. A dull ache at the back of the middle joint is the warning.
campus boards and added weight are named risk factors for growing climbers.
ask for an experienced review; an MRI may be needed.