When suture are removed from an incisional surgical wound at the end of one week, the wound strength of the wounded skin when compared to unwounded skin approximately?
First, I need to recall the stages of wound healing. Wound healing has three main phases: inflammatory, proliferative, and remodeling. The initial strength of a wound comes from fibrin during the inflammatory phase. By the end of the first week, the wound is in the early proliferative phase, where collagen synthesis starts. But collagen deposition is still in its early stages.
I remember that wound strength is primarily due to collagen, especially type III collagen, which is laid down in the proliferative phase. However, it takes several weeks for the wound to approach the strength of normal skin. At one week, the wound strength is significantly lower. I think the figure is around 10% of the original skin strength. By 3 weeks, it's about 70%, and by 3 months, it reaches about 80%.
So the correct answer is that after one week, the wound strength is approximately 10% of normal skin. Now, considering the options, if the answer is 10%, the correct option would be the one stating that. The other options might include higher percentages like 30%, 50%, or 70%, which are incorrect because those percentages correspond to later stages.
For the explanation, I need to detail the phases of healing, the role of collagen, and the timeline. The incorrect options should be addressed by explaining when those higher percentages are achieved. The clinical pearl would emphasize the importance of avoiding tension on the wound in the early stages to prevent dehiscence.
Let me structure the explanation accordingly, making sure each section is covered with the required details. Check for any possible mistakes in the percentages or the phases mentioned. Also, ensure that the clinical pearl is high-yield and relevant to exam questions.
**Core Concept**
Wound healing involves three overlapping phases: inflammation, proliferation, and remodeling. By 1 week, the wound is in the early proliferative phase, with collagen deposition contributing to strength. Unwounded skin has a tensile strength of ~20-25 MPa, while a 1-week-old wound achieves ~10% of this due to immature collagen networks.
**Why the Correct Answer is Right**
At 7 days post-surgery, wound strength relies on fibrin and early collagen (Type III) synthesis. Collagen cross-linking and maturation are minimal at this stage, resulting in ~10% of normal skin strength. Type I collagen, which provides structural integrity, dominates later (weeks 2-3) as the remodeling phase progresses.
**Why Each Wrong Option is Incorrect**
**Option A:** 30% is incorrect; this strength is achieved by 2-3 weeks when Type I collagen replaces Type III.
**Option B:** 50% is incorrect; this occurs at ~3 weeks, during advanced remodeling.
**Option C:** 70% is incorrect; this corresponds to 6 weeks post-injury, when wound strength approaches 80% of normal.
**Clinical Pearl / High-Yield Fact**
Remember the "1-2-3 rule": 10