Preface 1: This question is about flappies → flipflops/sandals/clogs and other similar footwear that is flat and that probably was made of a foamy-plastic liquid that have become solidified but whatever the material is, is too flat and maladjusted to human feet anyway.
Preface 2: I don't ask this question about a personal problem I currently suffer from → in the past, while using flappies generally daily, I did generally daily suffered from a mild right neck pain that was irradiated to the right shoulder and accompanied with popping joints from their area (especially from the shoulder), but after I stopped using flappies generally, 99% of the time, and started to go anywhere with new shoes or barefotted instead, than, humbly, that problem was gone - I no longer suffer from it.
While flappies does give some protection from walking hazards, I get the impression they can cause various bodily damages, including neck damage.
From searching accessible information on this footwear and plausible effects I found inconsistency in the naming of the footwear itself and little accessible data on possible problems; in between I found these:
- Bad posture or support:1 Flappies' surface is usually maladjusted all foot arch types (normal and not) resulting in foot pain, leg pain, lower back pain and increase of pressure on spines in general
- Bad Shock Absorbance2 likely resulting in heel sprain, knee pain and lower back pain
- Plantar fascia development, due to either of the above
- Tendon pressure3 that might result in tendonitis.
- It can be very hard, if sometimes at all possible to use adjusted shoe inserts with flappies, which naturally raises the chance for problems by proper positioning and fixing (splinting) of the shoe insert to the flappy.
What neck damage might be caused by general usage of flappies?