Deceleration in maturation of bone during adolescent age in achondroplasia--a retrospective study using RUS scoring system.

OBJECTIVES: Knowledge of bone age in achondroplasia is required for the prediction of adult height, timings of limb lengthening, and epiphysiodesis procedures. The purpose of this investigation was to determine the differences in skeletal age in achondroplasia and a control population with the Tanner-Whitehouse 3 method using the RUS score and to determine the right age for the interventional procedure for limb lengthening procedure or deformity correction in these patients.

MATERIALS AND METHODS: Left hand radiographs of 34 patients (age range, 5-18 years) with achondroplasia were evaluated for skeletal age using the RUS scoring system, which were compared with the left hand radiographs of 41 patients (age range, 5-18 years) without achondroplasia measuring skeletal age. The difference in chronological age and RUS bone age were evaluated statistically according to gender and age group.

RESULTS: In the achondroplasia group, chronological age were 10.5 +/- 4.3 years for males and 10.1 +/- 3.6 years for females and RUS bone age were 9.2 +/- 4.0 years for males and 8.9 +/- 3.4 years for females, which showed statistically significantly difference (males p = 0.0003 and females p < 0.0001), while in the control group, chronological age were 11.1 +/- 2.9 years for males and 10.7 +/- 3.4 years for females and RUS bone age were 11.2 +/- 3.4 years for males and 10.7 +/- 3.3 years for females, which did not show statistically significantly difference (males p = 0.54 and females p = 0.76). Our finding suggested a delay of 1.4 years for males and 1.2 years for females in the maturation of bone in achondroplasia patients. Difference between chronological age and RUS bone age was 0.9 +/- 1.1 for <10 years and 1.6 +/- 0.9 for >10 years in the study group, while 0.1 +/- 1.1 for <10 years and -0.2 +/- 0.6 for >10 years in the control group, which also showed >statistically significant difference (<10 years p = 0.04 and >10 years p < 0.0001). These differences indicate that there was a delay in the maturation of bones by 1 year in the group <10 years and 1.8 years in the group >10 years in achondroplasia patients compared to nonachondroplasia patients.

CONCLUSION: We recommend the use of the Tanner-Whitehouse 3 method especially the radius, ulna, short bone score to measure the skeletal age and to wait for a longer time before interventional procedures in achondroplasia patients.