Slightly literary.
步态 (bùtài) is 'gait' and
蹒跚 (pánshān) is 'staggering' - both
足 (foot) radicals. In casual speech you'd just say
走路一摇一晃 (zǒulù yī yáo yī huàng, 'walk swaying around') or
走得不稳 (zǒu de bù wěn, 'walk unsteadily').
步态蹒跚 has a clinical-or-poetic flavour, used in medical writing about Parkinson's-type symptoms and in literary descriptions of the elderly.
