Limb length differences of under 1.5-2 centimeters are tolerable for most, requiring either no intervention at all or mild fixes such as shoe lifts, says Claire Shannon, a Johns Hopkins pediatric orthopaedic surgeon. However, patients with larger differences—which Shannon can estimate using measurements and algorithms that calculate growth—often require surgical intervention to avoid pain and functional mobility limitations.

When patients come to see Shannon for the first time, she starts by performing a comprehensive physical exam of all the limbs as well as other areas of anatomy that might give a tip-off for undiagnosed genetic syndromes. She also works with colleagues in radiology to collect imaging that can help characterize a patient’s deformity.

For smaller limb differences, she often recommends epiphysiodesis to introduce scar tissue in the growth plate of the unaffected limb to halt its growth, allowing the affected limb to catch up as it continues to grow longer. For those with more severe limb differences, she recommends lengthening procedures with an external frame for patients whose growth plates are still active. For those whose growth plates are closed, she recommends an internal rod controlled by magnets.

Each of these lengthening procedures can take up to several months to complete. Patients with congenital deformities often require multiple procedures every few years as they grow. Close follow-up over time allows Shannon to get to know her patients and families, and to celebrate their successes.

For example, five-year-old Eva Ricano-Medina was born with Ollier’s disease, which caused benign cartilaginous tumors at the growth plates in her left leg, bowing the leg and restricting its growth. After a comprehensive physical exam, Shannon used an external frame as part of Eva’s treatment. 

“When she first met me, she said that all she wanted to do was play soccer. But she just couldn’t keep up with the other kids,” says Shannon. Now, “Every time Eva comes in, she wants to tell me how much straighter and stronger her leg is becoming. It’s great to hear.”

Many length discrepancies stem from congenital or genetic causes, like Eva’s; others develop after trauma, such as an injury to the growth plate of a bone. Shannon specializes in correcting limb length discrepancies and is one of a small group of experts in this field nationally and internationally.