Instability of the hip — hip dysplasia — occurs to some degree in approximately 15%, or 1 in 6 infants, but only 2-3 per thousand need treatment, according to the International Hip Dysplasia Institute. When they do need treatment, however, one of the issues can be leg length discrepancy, a condition that can also result from bone growth abnormalities.
Standard treatments for leg length discrepancy use external cages that surround the leg. The leg is cut through and held in a stable position while natural bone healing and bone growth fills in the gap, with the hoped for eventual result of equal leg length after 6-9 months. The external cage structure is held in place by pins that attach to the cage and the bone, piercing the skin. The cage, also called a “fixator”, adjusts to gradually increase the space between the pieces of leg bone. The cages and pins are awkward and uncomfortable at any age but for children the discomfort can be worse. While there are internal solutions for adults, so far no internal leg bone lengthening process has been used due to potential complications with children’s bone growth plate.
Physician’s at Carnegie Mellon University and Texas Tech University Health Sciences Center El Paso have applied for a patent on internal bone-lengthening technology for use with children. The new technology is an expandable rod attached directly beside the leg bone, bridging the cut through the bone. A smartphone app controlled by the patient controls the gradual lengthening of the rod. As with the fixator, it pullsthe bone pieces further apart to allow new bone growth. The hope is that this much less awkward solution will be easier for getting dressed and moving about, have less associated pain and discomfort, and be less prone to infection because there are no pins piercing the skin.
The bone-lengthening device is still in development with no announced testing or release dates, but the promise of less painful and awkward help for children with leg length discrepancies.