My 13-year old son was just diagnosed with slipped capital femoral disease. He is nearly 100 pounds overweight, which is a problem but it seems like anything that happens to him is blamed on his weight. What's the connection here?

Slipped capital femoral epiphysis (SCFE) occurs most often between the ages of eight or nine and 18. It's during this time that the physeal (growth) plate is still open in the femur (thigh bone).

Obesity increases the shear stress across the physeal plate. Over time this area is traumatized enough it eventually leads to separation of the bone from the cartilage and growth plate at the top of the femur. Some doctors say on X-ray it looks like the top of an ice cream cone has fallen off the cone.

A recent study from New York City showed that obesity (measured by Body Mass Index or BMI) is clearly linked with SCFE. Children who are in the normal weight range rarely get SCFE. If they do, it's more likely caused by an underlying endocrine problem.