The Pneumatic Post-Amputation Mobility Aid (PAMM Aid) is a device used for training amputees how to walk with a prosthesis. It has the benefit of allowing amputees to walk soon after their amputation and is easy to fit.
From the PPAM Aid website:
PPAM Aid (Pneumatic Post-Amputation Mobility Aid) is a device designed for partial weight bearing in post amputation rehabilitation. PPAM Aid is used to aid the reduction of residual limb oedema, prepare the residual limb for wearing a prosthesis and allow the re-education of postural reactions, balance and gait. The appliance is suitable for below knee, knee disarticulation and long above-the-knee amputees and can be used over soft dressing, bandaging or a plaster cast.