Stiff ankle joint and Medical
There can be a multiplicity of reasons for stiffness of this joint , from "normal" wear and tear to tightness of opposing muscle groups to abnormal biomechanical actions of the lower limb. Many of these causes are relatively amenable to treatment which may be able to bring about an increase in range of movement of said joint. It may be as simple as a course of excersises or the wearing of an orthosis (Insole ) in the shoe. In any event your acquaintance should consult a Physiotherapist or Podiatrist with a specialist interest in this field. This should at the very least provide a firm diagnosis of the problem and some treatment options. Hope this is of some help
Regs Iain