A 38-year-old woman with poorly controlled diabetes mellitus (HbA1c 10.2%) undergoes open reduction and internal fixation of a femoral fracture. At 3 weeks postoperatively, the surgical wound shows delayed healing with minimal granulation tissue formation and poor epithelialization. The surgeon suspects impaired wound healing due to hyperglycemia and wants to assess the degree of collagen deposition and neovascularization in the wound. Which investigation best evaluates the histological status of wound healing at this stage?

Explanation

## Histological Assessment of Impaired Wound Healing **Key Point:** Wound biopsy with histopathological examination is the gold standard investigation for directly assessing the histological status of wound healing, including collagen deposition, neovascularization, inflammatory cell infiltration, and epithelialization. ### Why Wound Biopsy is Correct **High-Yield:** Histopathology provides direct visualization of: 1. **Collagen architecture** — quantity and organization of collagen deposition (critical in proliferative phase) 2. **Neovascularization** — capillary formation and angiogenesis status 3. **Inflammatory response** — presence and type of inflammatory cells 4. **Epithelialization** — degree of re-epithelialization and basement membrane reformation 5. **Fibroblast activity** — assessment of fibroblast proliferation and function **Clinical Pearl:** In hyperglycemia, histology typically shows: - Reduced collagen cross-linking (impaired lysyl oxidase activity) - Decreased neovascularization (impaired VEGF signaling) - Prolonged inflammatory phase with altered macrophage function - Delayed epithelialization ### Why Other Investigations Are Indirect or Insufficient | Investigation | What It Measures | Limitation | | --- | --- | --- | | **Serum albumin/prealbumin** | Nutritional status | Indirect marker; does not assess wound histology directly | | **TcPO₂ measurement** | Tissue oxygen tension | Assesses perfusion but not collagen deposition or cellular architecture | | **Doppler ultrasound** | Blood flow velocity | Evaluates vascular perfusion but not histological wound maturation | **Mnemonic:** **BENCH** for wound healing assessment — **B**iopsy for histology, **E**xudates for infection, **N**utrition labs (albumin) for systemic status, **C**linical exam for gross appearance, **H**emodynamics (Doppler) for perfusion. **Warning:** Do not confuse **functional assessments** (TcPO₂, Doppler) with **structural assessments** (biopsy). At 3 weeks, the question specifically asks about collagen and neovascularization — both require histological examination. [cite:Robbins and Cotran Pathologic Basis of Disease 10e Ch 3]