Fracture Blisters: Symptoms, Causes, and Treatment Options

 Imagine you’re in the emergency room, your ankle throbbing after a bad fall. The doctor confirms it: you’ve broken a bone. But then, a few days later, you notice something strange—blisters forming on your skin, right over the fracture site. You’re confused, maybe even a little worried. What are these blisters, and why are they there? 

(A Proximal Leg Fracture with Fracture Blister developed over it)

What Are Fracture Blisters?

Fracture blisters are fluid-filled vesicles or bullae that form on the skin overlying a fractured bone. They are a sign of significant soft-tissue injury and occur in approximately 2.9% of all fractures requiring hospitalization (Verywell Health). These blisters are most commonly seen in areas where the skin adheres tightly to the bone with little subcutaneous fat, such as the ankle, wrist, elbow, foot, and distal tibia. They resemble second-degree burns in appearance but are caused by mechanical trauma rather than heat.

Fracture blisters can be single or multiple and may appear directly over the fracture or at a distance, depending on the injury’s impact on surrounding tissues. They are more likely to occur in high-energy injuries, such as motor vehicle accidents or falls from significant heights, but can also develop in low-energy trauma, like a moderate ankle sprain, in up to 25% of cases.

Pathophysiology: How Do Fracture Blisters Form?

The exact cause of fracture blisters remains partially elusive, but research suggests that damage to the dermal-epidermal junction—the interface between the skin’s outer (epidermis) and inner (dermis) layers—plays a central role. When a bone fractures, particularly with significant force, the skin experiences shearing stresses that can separate these layers, creating a potential space for fluid accumulation.

A 1995 biomechanical study by Giordano et al. demonstrated that the tension induced by fracture deformation causes this dermal-epidermal separation in cadaveric ankle skin specimens. The study highlighted that the differing elasticity and viscoelastic properties of the dermis and epidermis lead to layer splitting when critical strain is reached. Post-traumatic edema (swelling) increases interstitial pressure, reducing cohesion between epidermal cells and promoting fluid transfer into the blister cavity (PMC Article).

Additionally, damage to local blood vessels and lymphatics contributes to venous stasis and tissue hypoxia, which can lead to epidermal necrosis. This combination of mechanical stress, swelling, and reduced oxygen supply creates the perfect storm for blister formation. Histologically, a 1993 study by Varela et al. confirmed a typical dermo-epidermal junction split with re-epithelialization, noting that intact blisters are sterile but become colonized with pathogens like Staphylococcus aureus and Staphylococcus epidermidis upon rupture.

Types of Fracture Blisters

Fracture blisters are classified into two clinical and histological types:

Type	Location of Cleavage	Characteristics	Healing Time	Complications
Clear Fluid-Filled (Subcorneal)	Within the epidermis, above the granular layer	Contains clear, gel-like serum; minimal dermal damage; heals without scarring	~13 days	Lower risk
Blood-Filled (Subepidermal)	Between epidermis and dermis	Contains blood from damaged papillary dermal vasculature; may scar or alter pigmentation	~16 days	Higher risk

Both types indicate a cleavage injury at the dermal-epidermal interface, but blood-filled blisters are associated with more severe tissue disruption, increasing the likelihood of complications like infection or wound dehiscence.

Where and When Do Fracture Blisters Occur?

Fracture blisters are most frequently observed over fractures of the ankle and proximal tibia, followed by the wrist, elbow, and foot. These areas are prone due to their thin skin, minimal subcutaneous fat, and lack of cushioning muscle or tissue. For example, the ankle has few hair follicles, sweat glands, or deep veins, making the skin particularly vulnerable (DermNet NZ).

Timing is variable:

• Typical Onset: 24–48 hours post-injury, with an average of 2.5 days.
• Range: As early as 6 hours or as late as three weeks.
• Post-Surgical: Can occur after elective foot and ankle surgery.

Blisters may not always form directly over the fracture site; they can appear at a distance due to the injury’s broader impact on soft tissues. Curiously, areas like the wrist, elbow, and foot, despite having similar skin characteristics, are less commonly affected, possibly due to differences in injury patterns or tissue dynamics.

Risk Factors

Fracture blisters are more likely in:

• High-Energy Injuries: Falls from heights (~18 feet), motor vehicle accidents, or Gustilo Anderson Grade I/II open tibia fractures.
• Low-Energy Trauma: Up to 25% of cases, such as ankle sprains or moderate blunt trauma.
• Predisposing Conditions: Diabetes mellitus, peripheral vascular disease, collagen vascular disease, hypertension, smoking, alcoholism, and lymphatic obstruction, all of which impair wound healing.

Notably, age, sex, race, overall health status, concurrent injuries, or initial fracture treatment do not appear to influence blister formation.

Diagnosing Fracture Blisters

Diagnosis is primarily clinical, based on the appearance of tense, fluid-filled vesicles or bullae on swollen skin overlying a fracture. Healthcare providers should document:

• Number of blisters
• Location
• Size
• Type (clear or blood-filled)

No specific diagnostic tests are required, though imaging (e.g., X-rays, CT scans) is used to assess the underlying fracture. The blisters are generally painless, similar to friction blisters or second-degree burns, but their presence can be daunting for patients and inexperienced clinicians.

Managing Fracture Blisters

The management of fracture blisters is a complex and controversial topic, with no universal consensus in the medical literature. The primary challenge is balancing the need for timely fracture stabilization with the protection of compromised skin to minimize complications.

General Principles

• Intact Blisters:

• Should be left undisturbed, as the blister roof serves as a sterile biological dressing, reducing infection risk (Healthline).
• Gentle, non-adherent dressings (e.g., Aquacel, gauze) can be applied to protect the area.

• Ruptured Blisters:

• Require cleaning and dressing with moist, non-occlusive dressings to promote healing.
• Topical agents like silver sulfadiazine (Silvadene) are commonly used to prevent infection and aid re-epithelialization, particularly in non-diabetic patients (PubMed Study).
• Silver-coated dressings may reduce pain and shorten healing time.

Surgical Considerations

• Delaying Surgery:

• Most experts recommend delaying surgical fixation until blisters resolve, typically 7–10 days, to reduce the risk of wound complications (PMC Article).
• Average delays vary by fracture type:

Fracture Type	Average Delay (Days)
Ankle	6
Tibial Plateau	11
Tibial Shaft	3.5
Calcaneal	12
Pilon	6.75
Mean	7.7

• Early Surgery:

• In high-energy trauma, surgery within 24–48 hours may stabilize the fracture and reduce further soft-tissue damage, potentially preventing blister formation.
• Incisions should avoid blister beds, as crossing them can double the risk of infection and wound dehiscence.

• Alternative Approaches:

• If surgery is urgent, incisions can be made through the blister bed (less preferred) or planned to avoid blisters entirely.
• The AO Foundation recommends waiting 7–10 days for non-urgent surgeries if blisters are present.

Advanced Techniques

• Negative Pressure Wound Therapy (NPWT):

• Also known as a “wound vac,” NPWT may accelerate blister healing, allowing earlier surgical intervention (Verywell Health).

• Blister Aspiration or Deroofing:

• Some studies support aspirating or deroofing blisters and treating the bed with antimicrobials, but this should be done cautiously due to infection risks (EFORT Open Reviews).
• A 2025 systematic review found evidence supporting this approach in controlled settings.

Patient-Specific Factors

Patients with comorbidities like diabetes or vascular disease require close monitoring and may need hospital admission if blisters develop. Early recognition and tailored wound care are critical in these high-risk groups.

Potential Complications

Fracture blisters can significantly complicate fracture management:

• Infection: Ruptured blisters or incisions through blister beds increase the risk of bacterial colonization and surgical site infections.
• Wound Dehiscence: Surgical wounds may fail to heal properly, leading to prolonged recovery.
• Delayed Healing: Both the fracture and skin may take longer to heal, extending hospital stays.
• Chronic Ulcers: Rare but possible in severe cases.
• Scarring and Pigmentation Changes: More common with blood-filled blisters due to deeper tissue damage.

A study by Strauss et al. reported a 13% prevalence of wound complications in 45 patients with lower extremity fracture blisters. Blood-filled blisters are particularly concerning, with six out of seven skin complications in one study requiring split-thickness skin grafting.

Preventing Fracture Blisters

While not always preventable, early surgical stabilization within 24 hours of injury may reduce blister formation by minimizing ongoing soft-tissue trauma. This is particularly relevant for high-energy injuries. Additionally, careful monitoring of high-risk patients and prompt wound care can mitigate complications.

Fracture blisters are a fascinating yet challenging aspect of orthopedic trauma. They highlight the intricate relationship between bone and soft tissue in the healing process. For patients, understanding fracture blisters can demystify a potentially alarming complication, while for healthcare providers, it underscores the need for careful, individualized management. By respecting the blisters’ role as a natural barrier, avoiding unnecessary interventions, and prioritizing wound care, we can optimize outcomes for patients with fractures.

Whether you’re a patient navigating recovery or a clinician managing complex cases, fracture blisters remind us that even the smallest details—like a blister on the skin—can have a big impact on healing.