A crucial question in upper and lower extremity limb lengthening in children is the physeal response to lengthening. Damage to the growth plate must be avoided to prevent subsequent loss of length gained. This animal study evaluated the affect of lengthening on the hind limb growth plate. While the rate of lengthening was consistent, the amount of lengthening varied. Growth was measured using an oxytetracycline labeling technique and the histomorphological changes of the growth plate were evaluated. In the group of animals lengthened by 20%, there was no difference between the growth plates on the lengthened and control limbs. Lengthening by 30% or more resulted in growth plate abnormalities. Closure of the physis was prevalent in lengthening of 45%.
The Heuter-Volmann Law indicates that the growth plate is responsive to an applied load. Distraction osteogenesis induces large forces across the growth plate. The typical lengthening procedure attempts to achieve “as much as possible” length to minimize sequential lengthenings and to achieve maximum patient satisfaction. This study suggests possible induction of premature closure with 30% or more of limb lengthening. Although extrapolation the human situation is questionable, this study reinforces the need for caution in young children being considered for large degrees of lengthening.
Journal of Pediatric Orthopaedics