Overview
Definition:
Skin Tension and Subcutaneous Grafting (STSG) over an exposed tendon, often augmented with a dermal substitute, is a reconstructive surgical technique designed to cover vital structures that have lost their protective soft tissue envelope
This technique is crucial for preserving tendon function and viability in complex wounds where primary closure or traditional skin grafts alone are insufficient.
Epidemiology:
The incidence is directly related to trauma mechanisms involving significant soft tissue loss, such as high-energy industrial accidents, road traffic accidents, crush injuries, and military combat wounds
It is also indicated in iatrogenic exposures following complex oncological resections or infections leading to tissue dehiscence.
Clinical Significance:
Failure to adequately cover exposed tendons can lead to desiccation, infection, adhesion formation, and ultimately, loss of joint function and potential limb amputation
STSG with dermal substitutes provides a robust, well-vascularized bed that promotes graft take and restores a protective barrier, significantly improving functional outcomes and reducing morbidity.
Indications
Absolute Indications:
Exposed tendon (flexor or extensor) without viable periosteum or paratenon
inability to achieve primary closure
absence of active infection at the wound site
adequate vascularity of the recipient bed.
Relative Indications:
Large soft tissue defects over vital structures
chronic wounds with poor healing potential
radiation-damaged tissues requiring neovascularization
post-debridement defects in oncologic or infective scenarios.
Contraindications:
Active uncontrolled infection
severe peripheral vascular disease affecting the recipient bed
exposed bone without periosteum (unless bone grafting is simultaneously performed)
patient refusal or poor medical condition for surgery.
Diagnostic Approach
History Taking:
Detailed mechanism of injury
time elapsed since injury
previous surgical interventions
comorbidities (diabetes, peripheral vascular disease, immunosuppression)
medications (anticoagulants, steroids)
tetanus immunization status
presence of pain, sensation, and active/passive motion distal to the injury.
Physical Examination:
Thorough assessment of the wound bed for exposed tendon viability (color, turgor, absence of purulence)
assessment of surrounding soft tissue envelope availability
evaluation of distal neurovascular status (pulses, capillary refill, sensation, motor function)
palpation for crepitus or foreign bodies
examination of adjacent joints for range of motion and stability.
Investigations:
Complete Blood Count (CBC) to assess for infection and anemia
Erythrocyte Sedimentation Rate (ESR) and C-Reactive Protein (CRP) if infection is suspected
Blood glucose levels and HbA1c in diabetic patients
Wound cultures if purulence is present
Doppler ultrasound or angiography to assess peripheral vascularity if compromised
Plain radiographs to rule out associated fractures or foreign bodies.
Differential Diagnosis:
Exposed bone
exposed neurovascular bundle
exposed joint capsule or cartilage
soft tissue defect with intact fascia.
Management
Preoperative Preparation:
Wound debridement to remove all non-viable tissue, foreign material, and contaminants
meticulous hemostasis
initial wound coverage with temporary dressings (e.g., saline-moistened gauze, negative pressure wound therapy)
administration of broad-spectrum antibiotics based on wound contamination and local resistance patterns
tetanus prophylaxis if indicated
consultation with plastic/reconstructive surgeon.
Surgical Technique Stsg Dermal Substitute:
Harvesting of split-thickness skin graft (STSG) from a suitable donor site
preparation of the recipient bed, ensuring adequate vascularity and hemostasis
placement of the dermal substitute (e.g., Integra®, Alloderm®) over the exposed tendon, allowing it to conform and establish vascular ingrowth
securing the dermal substitute with sutures or staples
meshing of the STSG if necessary for expansion and drainage
applying the STSG over the dermal substitute, ensuring intimate contact
applying a bolster dressing to maintain graft contact and prevent shearing forces.
Postoperative Care:
Elevation of the affected limb to minimize venous congestion and edema
meticulous dressing care, avoiding tension or shearing
immobilization of the grafted area to promote graft adherence
monitoring for signs of graft failure (ischemia, infection, hematoma, seroma)
gradual progression of mobilization as dictated by graft take and tendon healing
initiation of physical therapy to restore range of motion and function.
Dermal Substitutes
Types And Mechanisms:
Dermal substitutes are typically acellular matrices that serve as a scaffold for host cell infiltration and neovascularization
Examples include: Integra® (a bilayered product with silicone outer layer and collagen-glycosaminoglycan inner layer) which promotes neovascularization and dermal regeneration, followed by a later STSG
Alloderm® (an acellular human cadaveric dermal matrix) which acts as a scaffold for host cells
These provide a vascularized bed that enhances STSG survival.
Advantages:
Improved graft take rate compared to direct STSG on tendon
reduced risk of graft contracture
better cosmetic and functional outcome
potential for restoration of some dermal appendages
provides a thicker soft tissue coverage.
Disadvantages:
Increased complexity and cost
requires careful patient selection and surgical technique
potential for infection or extrusion of the substitute
often requires a staged procedure (e.g., with Integra®).
Complications
Early Complications:
Graft loss (partial or complete) due to ischemia, hematoma, seroma, or infection
wound dehiscence
donor site morbidity (pain, infection, scarring)
compartment syndrome
osteomyelitis if underlying bone is involved.
Late Complications:
Graft contraction and scarring leading to functional limitations
chronic pain
adhesion formation
nerve entrapment
secondary wound breakdown
unfavorable cosmetic outcome
delayed infection.
Prevention Strategies:
Aggressive debridement of non-viable tissue
meticulous hemostasis
appropriate antibiotic prophylaxis
judicious use of dermal substitutes
meticulous surgical technique to ensure graft adherence and avoid shearing
proper postoperative immobilization and wound care
early recognition and management of complications.
Prognosis
Factors Affecting Prognosis:
Viability of the exposed tendon
extent of associated soft tissue and bony injury
presence and control of infection
quality of the recipient bed vascularity
patient's overall health and comorbidities (especially diabetes and peripheral vascular disease)
adherence to postoperative protocols
skill of the surgical team.
Outcomes:
Successful STSG over dermal substitute can restore protective coverage, promote tendon healing, and preserve or restore functional limb use
Outcomes range from good to excellent with proper management
Delayed or failed coverage can lead to significant functional deficits, chronic pain, and potential limb loss.
Follow Up:
Close monitoring for at least 6-12 months
Regular wound checks, assessment of graft viability and maturation, range of motion exercises, and functional rehabilitation
Long-term follow-up may be necessary to address any late complications or functional deficits
Patients should be educated on long-term graft care and potential issues.
Key Points
Exam Focus:
Understanding the indications for STSG with dermal substitutes in exposed tendon injuries is paramount
Know the different types of dermal substitutes, their mechanisms of action, and advantages/disadvantages
Be familiar with the staged approach often required for certain substitutes.
Clinical Pearls:
Adequate debridement is the cornerstone of success
Ensure meticulous hemostasis
If using a staged approach like Integra®, ensure proper adherence and allow sufficient time for vascularization before STSG
Negative pressure wound therapy can be invaluable as a temporary measure
Early mobilization is crucial once graft take is confirmed.
Common Mistakes:
Inadequate debridement leading to graft failure or infection
Failure to achieve meticulous hemostasis
Inappropriate selection of dermal substitute or graft type
Premature or aggressive mobilization leading to graft shearing
Overlooking distal neurovascular status
Not considering comorbidities that affect wound healing.