The disclosure features methods for treating hypophosphatasia (HPP) in a patient (e.g., a child or an adolescent having HPP) exhibiting gait impairments or decreased walking ability by administering a soluble alkaline phosphatase (sALP) to the patient and assessing improvement in the gait impairment using a modified Performance-Oriented Mobility Assessment-Gait (mPOMA-G) analysis and score.
