# Pressure Injury Reconstruction

## Introduction
Pressure injuries (formerly pressure ulcers or decubitus ulcers) result from sustained pressure and shear forces on soft tissue overlying bony prominences. Affect 2.5 million patients annually in the United States; prevalence 10-18% in acute care and up to 28% in long-term care. Most common in spinal cord injury (SCI) patients, the elderly, and critically ill or immobilized patients. Surgical reconstruction is reserved for advanced (Stage III-IV) pressure injuries that fail conservative management. Recurrence rates remain high (30-60%); success depends on addressing underlying risk factors and patient education.

## Pathophysiology
**Sustained pressure** exceeding capillary closing pressure (~32 mmHg) causes tissue ischemia. Muscle is most susceptible to ischemia, followed by subcutaneous fat, then skin (injury propagates from deep to superficial — "iceberg" phenomenon). **Shear forces**: tangential forces (e.g., patient sliding in bed) cause kinking and thrombosis of perforating vessels; amplify pressure injury. **Friction**: abrasion of the epidermis; contributes to superficial injury.

**Moisture** (incontinence, perspiration): macerates skin, increases friction coefficient, and predisposes to bacterial colonization. **Reperfusion injury**: paradoxical tissue damage upon restoration of blood flow after ischemic period; reactive oxygen species generation.

### Risk Factors
**Intrinsic**: spinal cord injury (most significant), advanced age, malnutrition, diabetes, vascular disease, anemia, incontinence, cognitive impairment, spasticity. **Extrinsic**: sustained pressure, shear, friction, moisture, immobility. **Braden Scale**: validated risk assessment tool (sensory perception, moisture, activity, mobility, nutrition, friction/shear); score <12 indicates high risk.

## Classification (National Pressure Injury Advisory Panel — NPIAP)
**Stage 1**: intact skin with non-blanchable erythema; skin may be warm, firm, or painful. **Stage 2**: partial-thickness skin loss involving epidermis and/or dermis; presents as shallow open ulcer or blister. **Stage 3**: full-thickness skin loss extending into subcutaneous fat; bone, tendon, and muscle NOT exposed; may include undermining and tunneling. **Stage 4**: full-thickness tissue loss with exposed bone, tendon, muscle, or joint capsule; often includes undermining, tunneling, and osteomyelitis.

**Unstageable**: obscured by eschar or slough; true depth cannot be determined until debrided. **Deep tissue injury (DTI)**: intact skin with localized area of persistent non-blanchable deep red, maroon, or purple discoloration; represents deep tissue damage that may evolve rapidly.

## Common Locations
**Sacrum/coccyx**: most common (35-40%); supine positioning. **Ischial tuberosity**: second most common (25-30%); seated positioning (wheelchair-bound patients). **Greater trochanter**: lateral positioning (15-20%). **Heel**: supine positioning. **Occiput**: common in pediatric and ICU populations.

## Non-Operative Management
**Prevention is the cornerstone**: pressure redistribution (specialty mattresses, turning every 2 hours), moisture management, nutritional optimization, skin inspection. **Wound care**: debridement of necrotic tissue (sharp, enzymatic, autolytic), moist wound healing environment, negative pressure wound therapy. **Nutritional optimization**: protein intake 1.25-1.5 g/kg/day, caloric supplementation, vitamin C and zinc supplementation. **Incontinence management**: bowel and bladder programs, barrier creams, catheterization when appropriate. **Spasticity management**: baclofen, botulinum toxin, intrathecal baclofen pump.

## Preoperative Evaluation for Surgical Reconstruction
Surgery is indicated for **Stage III and IV** pressure injuries that fail conservative management. **Patient selection is critical**: patient must be medically optimized, nutritionally replete (albumin >3.0, prealbumin >15), infection-free, and committed to postoperative pressure relief. Assess for **osteomyelitis**: MRI is the most sensitive and specific imaging modality; bone biopsy is the gold standard for diagnosis. Probe-to-bone test: if a probe reaches bone through the wound, positive predictive value for osteomyelitis is ~89%.

Address spasticity before or concurrent with reconstruction. Rule out malignant transformation (**Marjolin ulcer**): chronic wounds >10 years; biopsy suspicious areas. Smoking cessation, diabetes optimization (HbA1c <8%). Social assessment: wheelchair setup, home environment, caregiver support, patient motivation.

## Surgical Principles
**Radical debridement**: excise the ulcer, surrounding scar (bursa), and any infected or necrotic bone. **Ostectomy**: remove prominent bony prominence to reduce future pressure concentration; avoid excessive bone removal (shifts pressure to adjacent areas or contralateral side, and shortens femoral lever arm in ischial cases). **Flap coverage**: provide well-vascularized tissue to fill dead space and cover the bony prominence. **Design flaps to preserve future options**: pressure injuries recur frequently; plan flap design to allow re-advancement or use of alternative flaps for future reconstruction.

**Suction drains**: place to prevent seroma and hematoma; remove when output <30 mL/day. **Tension-free closure**: primary closure of donor site; avoid tension on suture line over bony prominence.

## Flap Options by Location

| Location | Workhorse Flap | Alternatives |
|----------|---------------|--------------|
| Sacrum | Gluteus maximus V-Y advancement or rotation | SGAP flap, lumbar artery perforator flap |
| Ischium | Posterior thigh V-Y (hamstring) advancement | Gluteus maximus, IGAP, gracilis, TFL |
| Greater trochanter | TFL V-Y advancement or transposition | Vastus lateralis, rectus femoris, ALT (pedicled) |

### Sacral Pressure Injuries
**Gluteus maximus myocutaneous flap**: most common; rotation or V-Y advancement. V-Y advancement: preserves muscle function; can be re-advanced for recurrence. Rotation flap: provides greater reach; more tissue bulk. Bilateral flaps for large or midline defects.

**Superior gluteal artery perforator (SGAP) flap**: preserves gluteus maximus muscle function; fasciocutaneous flap based on perforators. **Lumbar artery perforator flap**: alternative fasciocutaneous option for upper sacral defects.

### Ischial Pressure Injuries
**Posterior thigh V-Y advancement flap (hamstring)**: biceps femoris or combined hamstring muscles; provides bulk to fill the dead space. Large arc of advancement; re-advanceable for recurrence. Preserves gluteus maximus for sacral reconstruction if needed in the future. **Gluteus maximus V-Y advancement or rotation**: provides excellent bulk; sacrifices ambulatory potential.

**Inferior gluteal artery perforator flap**: fasciocutaneous flap preserving muscle. **Gracilis myocutaneous flap**: based on the medial circumflex femoral artery; useful for medial ischial defects; relatively thin. **Tensor fasciae latae (TFL) flap**: reaches the ischium with a long skin paddle but may have distal tip necrosis.

### Trochanteric Pressure Injuries
**TFL flap**: workhorse for trochanteric defects; based on the ascending branch of the lateral circumflex femoral artery. V-Y advancement or transposition. Reliable blood supply; adequate bulk for moderate defects. **Vastus lateralis flap**: provides excellent bulk for deep defects; can include skin paddle.

**Rectus femoris flap**: alternative option; donor site weakness in knee extension. **ALT flap (pedicled)**: provides large skin paddle and adequate bulk.

<image>Illustration showing flap options for the three most common pressure injury locations. The figure shows a posterior view of a patient in prone position with three anatomic sites highlighted. At the sacrum, a bilateral gluteus maximus V-Y advancement flap is shown: two large myocutaneous flaps designed symmetrically on each side of the sacral defect with V-shaped incisions, with arrows showing the direction of advancement toward the midline, and the inferior and superior gluteal artery pedicles labeled. At the ischial tuberosity, a posterior thigh V-Y hamstring advancement flap is shown: a large flap based on the biceps femoris and semimembranosus muscles, with the inferior gluteal artery perforators labeled, and an arrow showing advancement superiorly to cover the ischial defect. At the greater trochanter, a tensor fasciae latae V-Y advancement flap is shown: a long flap designed along the lateral thigh with the lateral circumflex femoral artery ascending branch labeled, and an arrow showing advancement medially and superiorly to cover the trochanteric defect. Each flap design is shown with dashed lines for the incision and solid colored shading for the skin paddle.</image>

## Postoperative Management
**Air-fluidized bed** (Clinitron) or low-air-loss mattress for minimum 4-6 weeks; avoids all pressure on the reconstruction. Gradual sitting protocol for ischial reconstructions: begin at 2-4 weeks with 15-minute intervals, increase by 15 minutes every 3 days as tolerated. Drain management: remove when output <30 mL/day. Nutritional support continued postoperatively.

Physical therapy for wheelchair seating evaluation, transfers, and pressure relief techniques. Long-term: pressure-redistributing wheelchair cushion, regular skin checks, turning schedule.

## Complications and Recurrence
**Recurrence**: 30-60% overall; most significant challenge in pressure injury reconstruction. Risk factors for recurrence: noncompliance with pressure relief, persistent spasticity, malnutrition, smoking, incontinence. **Wound dehiscence**: 10-20%; often from premature sitting or inadequate pressure relief. **Infection**: wound infection, osteomyelitis recurrence; treat with debridement and antibiotics.

**Hematoma/seroma**: prevented with closed suction drains. **Flap necrosis**: partial or complete; usually from tension or inadequate blood supply.

<image>Postoperative care protocol timeline for pressure injury flap reconstruction. A horizontal timeline spanning 0 to 12 weeks after surgery. At week 0, the patient is shown on an air-fluidized bed in a specific position avoiding the surgical site. From weeks 0-2, strict bedrest with no pressure on the flap is indicated, with drain management and wound monitoring. At week 2, drains are typically removed. From weeks 2-4, gradual prone-to-lateral positioning is introduced. At weeks 4-6, a graduated sitting protocol begins for ischial reconstructions with 15-minute sessions increasing by 15 minutes every 3 days. A pressure-mapping wheelchair cushion evaluation is shown at this stage. From weeks 6-12, progressive mobility and full sitting tolerance is achieved. Along the bottom, continuous items are shown: nutritional supplementation throughout, pressure redistribution surfaces throughout, and physical therapy beginning at week 2.</image>

## Key Clinical Pearls
Patient selection is the most important determinant of surgical success; patients who cannot or will not comply with postoperative pressure relief protocols have unacceptable recurrence rates, and surgery should be deferred until modifiable risk factors are addressed. Always design flaps to preserve future reconstructive options; pressure injuries recur frequently, and the initial flap choice should not preclude re-advancement or use of alternative flaps at the same site. Ostectomy of the bony prominence is an essential part of the procedure, but excessive bone removal must be avoided; overly aggressive ischial ostectomy transfers pressure to the contralateral ischium or perineum. Osteomyelitis must be ruled out or treated before definitive flap coverage; MRI is the most sensitive imaging study, but bone biopsy with culture remains the gold standard for diagnosis. An air-fluidized bed for minimum 4-6 weeks postoperatively is non-negotiable; premature sitting or pressure on the reconstruction is the most common cause of early failure.

## References
- Rubayi S, Chandrasekhar BS. Trunk, abdomen, and pressure sore reconstruction. Plast Reconstr Surg. 2011;128(3):201e-215e.
- Yamamoto Y, Tsutsumida A, Murazumi M, Sugihara T. Long-term outcome of pressure sores treated with flap coverage. Plast Reconstr Surg. 1997;100(5):1153-1160.
- Keys KA, Daniali LN, Warner KJ, Mathes DW. Multivariate predictors of failure after flap coverage of pressure ulcers. Plast Reconstr Surg. 2010;125(6):1725-1734.
- Sameem M, Au M, Wood T, Farrokhyar F, Mahoney J. A systematic review of complication and recurrence rates of musculocutaneous, fasciocutaneous, and perforator-based flaps for treatment of pressure sores. Plast Reconstr Surg. 2012;130(1):67e-77e.