“Keeps reopening” can describe two different situations, and they are not the same problem. One is a wound that was closed and then came apart. The other is a wound that healed completely and later returned. What lies behind each one differs, and so does what helps.
Wound dehiscence is the term for the first. StatPearls, a clinical reference available through NCBI Bookshelf, defines it as a partial or total separation of previously approximated wound edges, caused by a failure of proper wound healing. For surgical wounds, it describes this as typically occurring five to eight days after surgery, while healing is still in its early stages.
The same reference lists what makes dehiscence more likely: ischemia, infection, increased abdominal pressure, diabetes, malnutrition, smoking and obesity. Its broader list of risk factors for abnormal healing also includes necrotic tissue, glucocorticoid use and radiation exposure.
The second situation is recurrence: the wound healed, and then came back. The European Wound Management Association, in its patient Q&A, states that if you have had a venous leg ulcer you are at risk of developing another one. It describes the major risk factors for a pressure ulcer as pressure with reduced mobility, and for diabetic foot ulcers as poor blood supply, lack of sensation or trauma.
That distinction matters because what helps differs by wound. For venous leg ulcers, EWMA describes continuing therapeutic compression as the most important action to prevent an ulcer. For pressure ulcers it advises altering position frequently in bed and when in a chair or wheelchair, with regular inspection and care of the skin. For diabetic foot ulcers it advises inspecting your feet daily, and footwear that fits well and does not cause friction or extra heat.
There is also a reason a wound can look finished before it is. As EWMA puts it, a wound may be closed on the outside while it takes months before the inside is completely healed.
None of this identifies which of the two is happening with any particular wound. MedlinePlus describes wound care centers as places that treat wounds which are not healing, where the team examines and measures the wound, checks the blood flow in the area around it, and works out why it is not healing. That assessment is what separates a wound that came apart from one that has returned.