Review Question - QID 210225

This patient has an estimated 3 years of growth remaining. An epiphysiodesis of the proximal tibia and distal femur for 3 years would achieve the most equal limb lengths.

Limb leg discrepancies (LLD) are broadly divided into static and progressive discrepancies. Static LLDs are commonly a result of extra-physeal trauma and lead to a length discrepancy that does not change over time. Progressive LLDs result from physeal injury or congenital abnormalities. It is estimated that boys reach skeletal maturity at age 16 and girls at age 14. The patient in this question has 3 years of growth remaining. In the lower extremity, the estimated growth at each of the physes near skeletal maturity are: proximal femur 0.3cm/year, distal femur 0.9cm/year, proximal tibia 0.6cm/year, and distal tibia 0.5cm/year. Performing an epiphysiodesis of the distal femur and proximal tibia results in 1.5cm/year growth loss on the operative extremity per year. In this case, doing this for 3 years would result in an estimated near equalization of the limb lengths with a starting LLD of 4.6cm.

Menelaus described an arithmetic method of LLD correction by epiphysiodesis using only the chronological age. He notes that this method works best in patients near skeletal maturity and should not be used for children under the age of 8.

Little et al. reviewed 71 epiphysiodeses performed for LLD. They compared three different prediction methods to determine their accuracy: Anderson and Green, Menelaus, and Moseley. They determined that all of the methods were equally accurate and that there is a proportion of patients that have unpredictable results. They advocated for the use of the Menelaus method, which is based only on chronologic age, as it was most the simple to use and resulted in equivalent prediction accuracy.

Illustration A is a chart showing the growth prediction per year of the most active physes in the lower extremity.

Incorrect Answers:
Answer 1: This girl has minimal or no growth remaining on average.
Answer 2: This would result in over-shortening of the operative limb by an estimated 1.4cm (estimated correction being 6cm [1.5cm x 4 years]).
Answer 3: This would result in an estimated 3cm correction and a 1.6cm LLD would remain (operative limb being longer).
Answer 5: This would result in an estimated 1.5cm correction and a 1.6cm LLD would remain (operative limb being longer).