Dimensions of the anterior cruciate ligament and thickness of the distal femoral growth plate in children: a MRI-based study.

BACKGROUND

When determining the dimensions of an anterior cruciate ligament (ACL) graft in children, bone age should be considered in addition to the patient's age, gender, and body height.

OBJECTIVES

We aimed to determine the relationship between age, gender, and ACL dimensions as well as thickness of growth plate cartilage of the distal femur during puberty.

METHODS

We retrospectively analyzed MRI scans of the knee in 131 children (82 girls, 49 boys) aged 6-18 years (mean age: 14.9 ± 2.6 years). ACL length and width as well as thickness of the growth plate cartilage at the distal femoral epiphysis were measured.

RESULTS

Mean ACL length increased linearly up to the age of 12 years in females and 14 years in males; thereafter, mean ACL length remained constant. Mean ACL length was largest at the age of 12 to < 13 years (38.18 mm) in females and at 15 to < 16 years (39.38 mm) in males. Mean ACL width increased up to the age of 12 years in girls and 13 years in boys. After the age of 12 years, both the ACL length and width were significantly larger in boys than girls (p = 0.002 and p = 0.045, respectively). Mean thickness of the growth plate cartilage of the distal femur remained stable up to the age of 12 years in girls and 14 years in boys. Thickness of the growth plate cartilage changed most markedly between the age intervals of 11 to < 12 years and 12 to < 13 years in girls and between the age intervals of 13 to < 14 years and 14 to < 15 years in boys.

CONCLUSIONS

ACL dimensions depended on both age and gender during the growth period. Measurement of cartilage thickness of the femoral distal growth plate proved to be an objective parameter to assess the maturation stage of local bone. This may be useful for the planning and timing of orthopedic ACL procedures.

LEVEL OF EVIDENCE: III-retrospective cohort study.