Oedema is the first and most easily observed reaction of tissues to injury. In between cells in healthy tissues there is iterstitial fluid. This fluid is very similar to blood plasma, containing water molecules, nutrients, electrolytes and cellular waste. Proteins generally are unable to pass through the capillary walls, however some small amounts do get trapped.
The lymphatic system supports the venous system by transporting the cellular waste products and accumulated proteins back to the blood supply.
Any changes in the capillary permeability or capillary pressure will change the rate of filtration and absorption through the interstitial fluid.
The increased fluid in the intercellular space is known as oedema or swelling.
Oedema Through Tissue Healing Stages
Inflammatory Phase: Normal acute inflammation results in increased interstitial fluid as it releases histamine and bradykinin which increases the capillary permeability.
The oedema at this stage is easy to mobilize and reduce. It feels soft and liquid and is non-pitting. The fluid consists of mostly water and dissolved electrolytes. The major concern of oedema at the inflammatory phase is physical restriction of joint movement.
Therapists will work to reduce and control oedema as soon as possible in the inflammatory phase to prevent it from continuing into the next stage of healing and creating further complications.
Proliferative Phase: The oedema in this stage is more of a concern. The higher protein content in this fluid causes it to be more viscous, making it very difficult for the lymphatic system to remove the cell waste and consequently flooding the area with nutrient poor fluid. The protein rich fluid causes thickening of tissues and subsequently shortens ligaments and tendons. The viscous oedema deposits itself between the tissue layers causing adhesions and as the fluid continues to move into the area it is replaced by dense fibrous tissue.
On palpation this fluid has started to feel thick. It can feel ‘spongy’ and will be pitting. The severity of the pitting and the firmness of the fluid are very good indicators for the severity of the oedema.
The longer this state continues and the more extensive the swelling, the more extensive the scarring, pain, disfigurement and disability will be.
In other words, the longer and worse the swelling is, the stiffer the joints will be. It will also result in delayed healing due to decreased nutrition and increased inelasticity.
Maturation Phase: Oedema that continues into the final stage of healing is very worrisome to the physician and therapist alike. This oedema will be fibrotic and brawny on palpation. The fluid at this stage can impair the metabolic circulation, cell nutrition and arterial flow and can result in tissue necrosis. At the very least oedema at this stage will cause stiffness, disfigurement and reduced function.
- Rehabiliation of the Hand & Upper Extremity 2011