What is the preferred graft type, split thickness (STSG) or full thickness (FTSG), for a plantar surface wound?

Split Thickness vs Full Thickness Skin Grafts for Plantar Surface Wounds

Full thickness skin grafts (FTSG) are preferred over split thickness skin grafts (STSG) for plantar surface wounds due to their superior durability, better resistance to weight-bearing forces, and improved long-term outcomes.

Rationale for Graft Selection

Anatomical Considerations

• Plantar surface wounds present unique challenges due to:
  • High mechanical stress from weight-bearing
  • Shear forces during ambulation
  • Need for durable coverage that can withstand these forces

Evidence for Full Thickness Grafts

Full thickness grafts provide several advantages for plantar wounds:

• Greater durability: FTSG contains the complete dermis, providing better resistance to mechanical forces
• Better functional outcomes: The thicker dermis helps prevent contracture and provides better padding
• Improved cosmetic results: More closely matches the specialized thick skin naturally present on plantar surfaces
• Lower recurrence rates: More resistant to breakdown under pressure and shear forces

Clinical Decision Algorithm

1. Assess wound characteristics:

   • Size and depth of the wound
   • Location on plantar surface (weight-bearing vs. non-weight-bearing)
   • Presence of infection or necrotic tissue
   • Vascular status of the foot

2. Consider patient factors:

   • Mobility status and expected activity level
   • Presence of neuropathy (especially in diabetic patients)
   • Overall health status and healing capacity

3. Select graft type based on location:

   • For weight-bearing areas (heel, metatarsal heads): FTSG strongly preferred
   • For non-weight-bearing areas: FTSG still preferred but STSG may be considered

Surgical Considerations

For Full Thickness Grafts:

• Harvest from non-weight-bearing areas with similar skin characteristics
• Ensure complete removal of subcutaneous fat from the graft
• Secure with non-absorbable sutures to prevent displacement
• Consider negative pressure wound therapy post-operatively to improve graft take 1

For Split Thickness Grafts (when used):

• Harvest at greater thickness (0.014-0.018 inches) than typical STSG
• Consider harvesting from plantar arch area for better match 2
• May require more aggressive immobilization post-operatively

Post-Operative Management

1. Immobilization:

   • Non-removable knee-high offloading device for 1-2 weeks to protect graft 1
   • When non-removable devices are contraindicated, use removable offloading devices

2. Wound care:

   • First dressing change typically at 5-7 days
   • Assess for graft take and signs of infection
   • Avoid soaking as it can induce skin maceration 3

3. Long-term considerations:

   • Custom footwear modifications after healing
   • Regular follow-up to assess for breakdown
   • Patient education on foot care and inspection

Special Considerations for Diabetic Plantar Wounds

For diabetic foot ulcers, additional factors must be considered:

• Vascular assessment is critical:

  • If ankle pressure <50 mmHg or ABI <0.5, consider revascularization before grafting 3
  • For ulcers not healing within 6 weeks despite optimal management, consider revascularization 3

• Infection management:

  • Complete debridement of all necrotic tissue before grafting
  • Appropriate antibiotic therapy for any infection 1

Outcomes and Expectations

Research has shown that while STSG can achieve wound coverage, they have limitations for plantar surfaces:

• A study by Choi et al. (2020) found that plantar surface STSG had significantly lower healing rates at 60,90, and 365 days compared to non-plantar STSG 4
• While STSG can provide coverage, they are more prone to breakdown under the mechanical stresses of weight-bearing

Potential Pitfalls and Caveats

1. Donor site selection:

   • For FTSG, choose donor sites carefully to minimize donor site morbidity
   • Consider non-weight-bearing areas of the foot or redundant skin areas

2. Graft failure risks:

   • Inadequate debridement of the recipient bed
   • Poor immobilization post-operatively
   • Unrecognized vascular insufficiency
   • Continued pressure on the graft site

3. Alternative considerations:

   • For large defects where FTSG may not be feasible, consider local flaps or free tissue transfer
   • For infected wounds, consider negative pressure wound therapy to prepare the wound bed before grafting 1

By selecting full thickness grafts for plantar surface wounds and following proper surgical and post-operative protocols, clinicians can achieve better long-term outcomes with lower recurrence rates and improved patient quality of life.