Predicting ambulatory function at skeletal maturity in children with moderate to severe osteogenesis imperfecta

Maximizing ambulation is a key treatment aim in moderate to severe osteogenesis imperfecta (OI). Here we investigated which early clinical characteristics predicted ambulation function at skeletal maturity. We assessed Bleck ambulation scores in 88 individuals with OI at 5 to 6 years of age and again at final height (at 15 to 24 years of age). At 5 to 6 years of age, 33 (38%) children were non-ambulators, 32 (36%) were fully independent ambulators, and 23 (26%) had intermediate ambulation skills. At skeletal maturity, 58% of the study participants had the same mobility level as at first assessment. The ability to ambulate independently at skeletal maturity was predicted by independent ambulation at 5 to 6 years (odds ratio [OR] 22.6, 95% confidence interval [CI] 4.9–105; P < 0.001), height z score at 5 to 6 years (OR 3.1, CI 1.6–6.3; P = 0.001) and weight z score at 5 to 6 years (OR 0.44, CI 0.19–0.99; P = 0.04).

Conclusion: Independent ambulation at 5 to 6 years was the main determinant of independent ambulation at skeletal maturity. This highlights the importance of maximizing ambulation in children below 5 years of age.