Wound healing
Most people ask at some point before, during or after surgery – How long does it take to heal up? And can I damage the wound healing?
The post operation leaflet describes the rudimentary principles of returning to activity, but sometimes it is easier to follow advice if you have a clearer understanding of what is happening. This page aims to explain wound healing as we understand it.
Most of the scientific data used in understanding healing comes from a couple of large studies made in the last 80-100 years. This means our understanding has withstood the test of time. There is always more to learn, but the structure and principle of what happens seems solid. It takes up to 1-2 years to fully mature a scar. Be patient!
Let us start with the 4 phases of wound healing post hernia surgery:
Phase 1. Bleeding:
Stopping bleeding or sealing the leaky edges of the wound. When platelet cells from the blood encounter collagen fibres it sets off a coagulation cascade – The bodies emergency response to tissue injury (a surgical wound). This clot forms a stable plug of cells by depositing fibrin.
Phase 2. Inflammatory:
Once the plug is stable the small capillary blood vessels open bringing more oxygenated fluid to the wound. Chemicals in the stable plug attract white cells (neutrophils) to the scene which mature into macrophages.
These clean up the wound, removing damaged dead cells and cleaning out any contaminants. The wound is filled with oxygenated fluid and cells, becoming swollen, red, warm, and painful.
The cells brought in start to proliferate and mature into more specialised functions. The fibrin used to make the plug stable attracts fibroblasts. Fibroblasts secrete procollagen, a peptide organised to bridge the gap between sides of a wound.
The procollagen joins together to make peptides which change their name to be called collagen fibrils that are short and laid down in a haphazard fashion filling in the gap.
These fibrils are building blocks that, joined together, will form long collagen fibres. Shorter fibrils are easier to remodel. Joining them together as the scar matures into long collagen fibres allows the body greater flexibility to organise them optimally in response to mechanical forces applied as the scar models over time.
Other specialised cells arising from fibroblasts called myofibroblasts help to contract this scarring tissue and form elastic cross-bridges making the scar neater, finer, and stronger still. There is less elastin too. Elastin is a protein that allows collagen to recoil and feel more pliable. There is little elastin in scar tissue.
These phases are overlapping. Each phase can be delayed or sped up by maximising the conditions it exists in. For example:
If you take blood thinning medication again too soon after surgery, it can dissolve the clot and take it longer to organise enough fibrin to become a stable plug. Once the clot is stabilised by fibrin it will not dissolve.
If you have a medical condition that reduces oxygen supply such as: smoking, obesity, diabetes, lung disease or peripheral vascular disease, then the inflammation and proliferation phases are slowed down.
Bacterial infection, wound contamination, excess fatty cells, etc. take longer to clear away, making the inflammatory phase last longer and slowing down progression to the next step. Being older and frailer also makes these latter phases take longer.
Wound strength over time:
A 2013 systematic review published in Plastic and Reconstructive Surgery GO (doi:10.1097/GOX.0b013e31828ff9f4) showed it takes 6-8 weeks to get to about 80% of wound strength. The final wound does not get much stronger than this. The wounds shape and colour alter as wound healing progresses through the 4 phases.
So, what is this telling us?
It says be careful in the first 6-8 weeks as you can disrupt the wound healing by lifting too much. However, phases 2, 3 & 4 also need movement and mechanical force to encourage deposition of collagen and to ‘show’ the body what direction the collagen fibres need to be laid down to provide a strong wound.
So do not become still or scared of causing damage. Listen to your body. If it hurts do not do it yet. We also know that healing wounds need more oxygen and so tire more quickly. They will need rest as well as activity. The less they are worked hard, the longer they will last.
Using the hernia pants or support belts we recommend in hernia surgery provide that support, so the operated area tires less quickly, allowing you to do more and be more active during your recovery.
Other interesting points to note are:
Scar tissue has less elastin in it than non-scarred tissue. This makes final wound strength a little less than 100% of what it was before.
Increased age also reduces elastin content due to more UV light exposure with passing time and smoking also inhibits elastin formation.
There is a genetic determinant as well.
Elastin makes our scars and tissues stronger and more pliable. Adhesions from scar tissue become more noticeable as elastin content reduces. Scar tissue also does not observe normal tissue planes reducing pliability.
This is why we encourage massaging wounds and stretching exercises to use mechanical force to encourage more laxity that can reduce the sensation of tugging. If you’d like to understand more about how your wound heals please see our “Wound Healing” page.
All patients are encourage to read our post surgery care leaflet
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