At what age do growth plates typically close in a healthy boy?

Growth Plate Closure in Boys

Growth plates in boys typically close completely around age 19, approximately 2 years later than in girls, with most plates achieving complete fusion between ages 17-19 years. 1

Timeline of Growth Plate Closure

The distal femur and proximal tibia growth plates close around age 16 in boys, with approximately 90% of growth occurring at these sites by this age. 2 Complete fusion follows a predictable ascending pattern from foot to wrist, with the calcaneus, distal tibia, proximal tibia, femur, and radius closing sequentially. 1

Age-Specific Closure Patterns

• By age 17: Most lower extremity growth plates show advanced closure, though not yet complete 1
• By age 19: Complete growth plate fusion occurs in 90%, 97%, 95%, 97%, and 98% of boys at the radius, femur, proximal tibia, distal tibia, and calcaneus, respectively 1
• Around age 14: The epiphyseal plates close in the context of acute compartment syndrome risk assessment, though this represents a clinical threshold rather than complete fusion 3

Factors Influencing Closure Timing

Pubertal development is the strongest predictor of growth plate closure (correlation coefficient ρ = 0.514-0.598), more so than chronological age alone. 1 Boys with higher BMI demonstrate accelerated growth plate fusion, with obese or overweight boys showing 1.71-4.03 times increased odds of earlier closure compared to normal-weight boys. 1

Physical activity level does not significantly influence the timing of growth plate closure. 1

Clinical Implications

When annual height velocity slows to <1.5 cm per year, radiography should be performed to confirm growth plate status, as this indicates impending closure. 3 During puberty, radiographic assessment every 1-2 years is recommended to monitor growth plate status in boys receiving growth-promoting therapies. 3

Important Caveats

• Bone age assessments should be interpreted with caution in boys with skeletal dysplasias or chronic conditions, as these may not accurately reflect growth potential 3
• The 2-year sex difference in closure timing (girls at ~17 years, boys at ~19 years) is consistent across multiple growth plate sites 1
• MRI using cartilage sequences provides superior reliability for assessing growth plate closure compared to T1-weighted sequences or plain radiographs, particularly when evaluated by pediatric radiologists 4