The stability of a suture is what enables it to withstand the forces connected with the healing process, and is better known as its “tensile strength”.
This corresponds to the strain, in kilograms, that the suture can withstand before breaking. The suture material must have and must maintain a tensile strength that is suitable for its specific use. [1]
In view of the fact that a suture usually breaks at its weakest point – for example, at the knot or at an area that has been accidentally damaged – the knot tensile strength is very important for the surgeon.
The knot tensile strength is usually 30 to 50% less than the linear tensile strength of a suture. The suture material and diameter are key factors concerning tensile strength.
The loss of tensile strength should not be confused with resorption see Resorption >> of the suture material. A suture is only as functional as its tensile strength permits.
After healing has taken place, the stitch is of no more use and effectively becomes a foreign body. So, once healing is completed, it is best for the thread to be absorbed and disappear, or for it to be removed. While they may have the same decimal designation, suture threads differ in terms of how long they last depending on their composition and structure.
An absorbable suture should be chosen by ensuring that its decrease in strength is proportional to the increase in strength of the wound. See Healing >>

Cross-matching of suture strength and tissue strength during healing

Our immune system considers all suture threads to be foreign bodies and the inflammatory response that occurs is similar to the reaction against any foreign body. The severity and duration of the reaction depend on the type of thread, its texture, the degree of tissue trauma sustained, and the length of time the suture is in place. The inflammatory reaction is in accordance with the amount of material and therefore with the number and size of the knots.
One of the principles of surgical suturing, therefore, is to combine suture security with minimal amount of material. If the inflammatory response is intense, the suture may weaken or the surrounding tissues may become compromised. A certain amount of inflammation is necessary in normal healing. However, a suture that causes a severe, prolonged inflammatory reaction can delay healing and leave the wound open to infection.  

[1]  Hochberg J, Meyer KM, Marion MD.; Suture Choice and Other Methods on Skin Closure; Surg Clin North Am. 2009 Jun;89(3):627-41.