A 45-year-old man undergoes primary closure of a traumatic laceration to the forearm. On postoperative day 10, the wound is noted to have separated at the suture line with exposure of subcutaneous tissue, but no purulent drainage or signs of infection. The patient reports no comorbidities and has normal nutritional status. Which phase of wound healing has been disrupted, and what is the most likely cause?

Explanation

## Wound Dehiscence — Timing and Pathophysiology **Key Point:** Wound dehiscence on **POD 10** indicates failure of the **proliferative phase** (POD 5–21), specifically inadequate collagen deposition and tensile strength at the wound edges. ### Wound Dehiscence: Timing Correlates with Healing Phase: | Timing | Phase | Mechanism | Typical Cause | |--------|-------|-----------|---------------| | **POD 0–5** | Inflammatory | Hemostatic failure, early infection | Bleeding disorder, SSI | | **POD 5–14** | Proliferative | ↓ Collagen synthesis, ↓ tensile strength | Malnutrition, ↓ blood flow, tension | | **POD 14+** | Remodeling | ↑ MMP activity, collagen remodeling | Chronic infection, excessive motion | **Clinical Pearl:** Tensile strength of a wound: - **POD 5:** ~5% of final strength (depends on fibrin clot and early collagen) - **POD 10:** ~10–15% of final strength (early collagen I deposition) - **POD 21:** ~50–60% of final strength (robust collagen matrix) - **POD 60:** ~80% of final strength At POD 10, the wound relies primarily on **early collagen deposition**. Dehiscence at this point reflects inadequate collagen synthesis or premature loss of sutures before sufficient collagen cross-linking. **High-Yield:** In a healthy, well-nourished patient with no infection, POD 10 dehiscence = **inadequate collagen deposition** (proliferative phase failure), often due to: - Excessive wound tension - Suture technique (too few, too loose) - Local ischemia - Rarely: unrecognized malnutrition or deficiency (vitamin C, zinc, protein) **Mnemonic:** **DEHIS** for dehiscence risk: **D**iabetes, **E**xcessive tension, **H**ypoproteinemia, **I**nfection, **S**uture technique.