Menelaus developed a simple calculation for timing epiphysial arrest in adolescents with limb length discrepancy. The author is from Royal Children's Hospital in Melbourne, Australia.
Gender |
Age at Growth Arrest |
female |
14 |
male |
16 |
years left of growth =
= (age at growth arrest in years) – (current age)
where:
• Current age is based on chronological age rather than skeletal age.
Epiphysis |
Growth per Year |
distal femur |
3/8 inch (0.375) |
proximal tibia |
1/4 inch (0.25) |
both |
5/8 inch (0.625) |
Measurements:
(1) current limb length discrepancy
(2) annual increase in discrepancy (assuming constant growth)
discrepancy at normal growth arrest =
= (current discrepancy) + ((years left of growth) * (annual increase in discrepancy))
decrease in growth of normal limb if fuse epiphysis of distal femur =
= (0.375 * (years left of growth))
decrease in growth of normal limb if fuse epiphysis of proximal tibia =
= (0.25 * (years left of growth))
decrease in growth of normal limb if fuse both epiphyses =
= (0.625 * (years left of growth))
The target discrepancy is between 0.5 and 0.75 inches. The authors found that paralyzed patients function best with such a residual discrepancy, while a non-paralyzed patient usually tolerated this level.
Specialty: Surgery, orthopedic