Is it safe to use a wound vacuum (Negative Pressure Wound Therapy - NPWT) on a wound with exposed tendon?

Using Wound VAC on Wounds with Exposed Tendon

Negative pressure wound therapy (NPWT) can be safely and effectively used on wounds with exposed tendon, but only after complete surgical debridement of all necrotic tissue and infection, with mandatory use of a non-adherent protective interface layer directly over the tendon.

Critical Prerequisites Before Application

Complete debridement is absolutely mandatory before applying NPWT to any wound with exposed tendon. 1 You must surgically remove all necrotic tissue, continuing into healthy-appearing tissue, before considering NPWT application. 1 This is non-negotiable—applying NPWT to wounds with residual necrotic tissue will lead to complications including potential fistula formation and treatment failure. 2

For infected wounds with exposed tendon, perform thorough surgical debridement and lavage first. 3 NPWT should never be applied until complete surgical removal of necrosis has been accomplished. 1

Mandatory Technical Requirements

Interface Layer Protection

You must use a large, fenestrated non-adherent interface layer placed directly over the exposed tendon. 2 This is a good practice point that prevents catastrophic complications:

• Failure to apply this protective layer exposes the patient to significant risk of tendon damage during dressing changes 2
• The interface layer prevents adhesions between the tendon and surrounding tissues 2
• Place the layer as widely as possible, extending beyond the immediate wound margins 2

Pressure Settings

Use continuous pressure of 75-80 mmHg rather than the standard 125 mmHg for wounds with exposed tendon. 4 Standard pressures may be too aggressive and cause desiccation of the tendon surface. 4 Never use intermittent or variable pressure settings, as these severely compromise the splinting effect and therapeutic benefits. 2, 5

Foam Selection

Use specialized commercial foam-based NPWT dressing kits rather than improvised "vac-pack" methods with surgical towels. 2 The polyurethane foam compresses under negative pressure, providing constant medial traction and preventing lateral retraction that could compromise healing. 2

Clinical Evidence Supporting Use

Multiple studies demonstrate successful outcomes with NPWT on exposed tendons:

• In 75 patients with lower-extremity wounds and exposed tendon/bone, NPWT produced profuse granulation tissue that rapidly covered the exposed structures, with successful coverage in 71 of 75 patients (95%). 6
• For infected Achilles tendons after surgical repair, NPWT achieved complete wound closure in all 5 treated patients without impairing tendon function. 7
• In 16 patients with foot/ankle wounds and exposed tendon, NPWT successfully covered exposed structures with healthy granulation tissue in 15 of 16 cases (94%). 8
• For late deep infections after Achilles tendon reconstruction, NPWT combined with debridement showed no re-infection at mean 29.9-month follow-up. 3

Treatment Protocol

Dressing change frequency: Every 2-3 days to allow frequent wound assessment and prevent progressive drying. 4 The average number of dressing changes required is 3-5 before achieving adequate granulation for definitive closure. 3

Duration of therapy: Expect 13-18 days of NPWT on average before the wound is ready for definitive closure. 3, 8

Monitoring at each change: Inspect the wound bed for signs of desiccation (dry appearance, lack of moisture, tissue adherence to foam). 4 If desiccation occurs, reduce pressure settings further and ensure the interface layer is properly positioned. 4

Physiologic Benefits in This Context

NPWT provides multiple mechanisms that support healing over exposed tendon:

• Increases local blood flow and tissue perfusion, enhancing oxygen and nutrient delivery to the bradytrophic tendon tissue 1, 7
• Removes wound exudates and inflammatory fluids, reducing bacterial load and edema 1
• Stimulates granulation tissue formation through mechanical forces independent of drainage 5
• Prevents secondary bacterial contamination through the sealed dressing system 5

Definitive Closure Options

After adequate granulation tissue formation (typically covering the exposed tendon):

• Split-thickness skin grafting is the most common definitive closure method 3, 8
• NPWT can be continued over the skin graft for the first 5 days to support graft take 3
• Primary closure may be possible if wound contraction has been adequate 6
• Free flap coverage is reserved for cases where NPWT fails to generate adequate granulation 8

Absolute Contraindications

Do not use NPWT if:

• Purulence is present in the wound—debride first 2
• Necrotic tissue remains—complete debridement first 1
• The wound is a non-surgical diabetic foot ulcer with exposed tendon—evidence does not support NPWT in this specific scenario 1

Common Pitfalls to Avoid

• Never apply foam directly to exposed tendon without the protective interface layer 2
• Never use standard 125 mmHg pressure on exposed tendons—reduce to 75-80 mmHg 4
• Never reapply NPWT at the same settings that caused initial desiccation 4
• Do not extend dressing change intervals beyond 3 days, as this increases risk of complications 4