Time course of epiphyseal growth plate fusion in rat tibiae.
Level 5 - mechanism / opinion, no new human data
Animal study with no human data
PubMed 12667553 · doi:10.1016/s8756-3282(02)00983-3
What was done
Researchers evaluated epiphyseal growth plate fusion in proximal tibiae from male (n = 19) and female (n = 15) rats aged 2 to 25 months. Bones were imaged using 3D microcomputed X-ray tomography at voxel resolutions ranging from (5.7 µm)³ to (11 µm)³. Growth plate fusion was quantified by measuring the number and volume of cancellous bone bridges crossing the growth plate.
What was found
Growth plate fusion followed a sigmoidal pattern: - 10% of maximum bridge formation occurred by 3.9 months in males and 5.8 months in females. - 50% occurred by 5.6 months in males and 5.9 months in females. - 90% occurred by 7.4 months in males and 6.5 months in females. - Total bridge volume when the maximum number of bridges first formed (~360 bridges in males, ~290 in females) was 0.99 mm³/tibia in males and 0.40 mm³/tibia in females. - Total bridge volume continued to increase for an additional 7.0 months in males and 17.0 months in females, reaching peak values of ~1.5 mm³/tibia in males and ~2.2 mm³/tibia in females.
Why it matters
These findings define the time course of rat proximal tibial growth plate fusion, providing reference data to select appropriately aged animals when modeling post-fusion adult bone disorders like osteoporosis.
Limits
This is an animal study without direct human clinical data. The total sample size is small (34 animals spanning a 2- to 25-month age range), leaving few animals per time point. Only the proximal tibia was assessed, which may not represent growth plate fusion dynamics at other anatomical sites.
Cited by
- supports Unlike humans whose growth plateaus in early adulthood, rodents continue to grow throughout the course of their life.