Review Question - QID 3626

The clinical presentation is consistent with a leg length discrepancy in a male who is one month after the onset of puberty with a chronologic and skeletal age of 13 years. Because his final projected LLD will be 4.0cm, epiphysiodesis of the femur AND tibia at approximately 13 yrs 6 months of age is the most appropriate treatment.

Menelaus stated growth ceases at a chronological age of 16 years in boys and 14 years in girls, thus calculating 3 years of growth from the onset of puberty. The assumption is that the distal femur grows at 0.9 cm/year and the proximal tibia 0.6 cm/year. Using these numbers for calculation and assuming 3 yrs of growth remaining, we would expect a total of 4.5 cm of growth correction if we performed the epiphysiodesis at 13 yrs of age. In order to not overshoot the measured discrepancy of 4 cm, one would need 2yrs at 15 mm/yr and then 0.67 (15 mmm) or (12 months)= 10 mm or 8 months, for a total time of growth restriction of 2 yrs and 8 months. Therefore, one would do the epiphysiodesis at 13 yrs and 4 months of age using the Menelaus method.

Little et al. present Level 4 evidence of their 71 patients with leg length discrepancies. They evaluated different methods of discrepancy calculation including the Anderson and Green, Menelaus, and Moseley methods. They found no difference between the different methods for accuracy in predicting ultimate discrepancy.

Dimeglio calculates growth at the knee as 2 cm/year, 1.1 cm from the femur and 0.9 cm from the tibia. Time for growth is 2.5 years, growth ceasing by bone age of 15 years and 6 months for boys and 13 years 6 months for girls. Using the Dimeglio method, we would need to stop growth at 2 cm x 2 yrs.=4 cm. Therefore, 15yrs 6 mo - 2 years is 13 yrs and 6 mo. as the time for epiphysiodesis.

Therefore, one would need to initiate the epiphysiodesis between 13 yrs 4mo to 13 yrs 6 months, depending on the method used.