Overview
Morel-Lavallée lesions are uncommon but important traumatic injuries in which the skin and subcutaneous tissue are forcefully separated from the underlying fascia. This creates a closed pocket that can fill with blood, lymphatic fluid, fat, and debris. Because the injury is “closed” rather than an open wound, it can be missed early, yet it may later cause swelling, pain, skin breakdown, infection, and delayed healing.
Although many lesions are treated without surgery at first, operative management is often needed for larger, persistent, or complicated cases. Until now, however, there has been limited high-quality information on what happens after surgery and which patients are most likely to develop postoperative wound problems. This multicenter study from 15 trauma centers helps fill that gap.
Why Morel-Lavallée lesions matter
These injuries usually occur after high-energy trauma such as motor vehicle collisions, falls, or crush injuries. The shearing force damages small blood vessels and lymphatics, creating a dead space under the skin. Over time, this space can collect fluid and become organized into a chronic cavity or pseudocapsule.
Treatment depends on lesion size, location, chronicity, and associated injuries. Conservative care may include compression, observation, or drainage in selected cases. When these measures are insufficient, surgery may involve evacuation of the fluid collection, debridement of devitalized tissue, and closure of the dead space. Surgeons may use quilting sutures, drains, or negative-pressure wound therapy to reduce recurrence and promote healing.
Even after surgery, wound complications remain a major concern because the surrounding skin may already be injured, blood supply can be compromised, and contamination or tissue death may occur.
Study design
This was a prospective, multicenter, observational study conducted from 2021 to 2024 at 15 trauma centers. Adult patients with a Morel-Lavallée lesion who underwent operative treatment were included.
The main outcome was the development of a postoperative wound complication. The study defined wound complications as:
cellulitis,
deep wound infection,
skin necrosis,
necrotizing soft tissue infection,
and organized hematoma.
The researchers also used multivariable logistic regression to identify independent predictors of wound complications while accounting for other possible risk factors such as closure of dead space, current tobacco use, and diabetes.
Key findings
A total of 134 patients underwent surgery for Morel-Lavallée lesions. Of these, 27 patients, or 20.1%, developed at least one postoperative wound complication. In other words, about 1 in 5 patients experienced a problem after surgery.
The most common complications were:
skin necrosis in 10 patients (7.5%),
deep wound infection in 9 patients (6.7%),
cellulitis in 7 patients (5.2%),
organized hematoma in 7 patients (5.2%),
and necrotizing soft tissue infection in 3 patients (2.2%).
These results show that postoperative morbidity is not rare, even in specialized trauma centers.
Injury patterns linked to higher complication rates
When the researchers compared patients who developed wound complications with those who did not, two injury mechanisms appeared more common among the complication group:
bicycle collision: 14.8% vs. 1.9%, P = .004
pedestrian struck by motor vehicle: 37.0% vs. 15.0%, P = .010
These differences suggest that the mechanism and energy of injury may influence postoperative recovery. Bicycle and pedestrian-vs-vehicle collisions can produce extensive shearing injury, soft tissue crush, and skin compromise, all of which may make healing more difficult.
Independent predictor of wound complications
After adjusting for other factors, only one variable remained an independent predictor of postoperative wound complications: being a pedestrian struck by a motor vehicle.
The odds ratio was 3.44, with a 95% confidence interval of 1.29 to 9.17, and the result was statistically significant (P = .014). This means that, in this study population, patients injured as pedestrians hit by vehicles had more than three times the odds of developing a wound complication compared with other mechanisms, even when controlling for closure of dead space, tobacco use, and diabetes.
Interestingly, other commonly suspected contributors, including dead-space closure, tobacco use, and diabetes, were not identified as independent predictors in this analysis. That does not mean they are unimportant in general wound care; rather, within this study, they did not independently explain the risk once the injury mechanism was taken into account.
What the results mean for patients and surgeons
These findings are clinically useful for counseling, planning, and postoperative monitoring. Patients with Morel-Lavallée lesions should be informed that surgery can be effective but is not risk-free. The overall wound complication rate of 20.1% is substantial and should be discussed before operative treatment.
For patients injured as pedestrians by motor vehicles, surgeons may want to maintain a higher index of suspicion for postoperative wound problems. These patients may benefit from closer follow-up, careful skin assessment, aggressive wound surveillance, and early intervention if signs of infection or necrosis appear.
The study also reinforces a broader surgical principle: soft tissue injury severity is often driven by the mechanism of trauma. A lesion that looks similar on imaging may behave very differently depending on how the injury occurred and how much devitalized tissue surrounds it.
Clinical context and practical considerations
Morel-Lavallée lesions are frequently challenging because they sit at the intersection of trauma surgery, orthopedics, and plastic surgery. Successful management often requires individualized treatment.
Common operative strategies may include:
fluid evacuation and debridement,
removal of the capsule in chronic lesions,
closure of dead space using quilting sutures or layered closure,
drain placement,
negative-pressure wound therapy when appropriate,
and staged reconstruction in severe soft tissue injuries.
The goal is not only to remove the fluid collection but also to restore tissue apposition and prevent re-accumulation. When tissue viability is poor, repeated procedures may be needed.
Because wound complications can include infection and tissue necrosis, early recognition is essential. Warning signs after surgery may include increasing redness, warmth, drainage, fever, worsening pain, foul odor, blackened skin, or recurrent swelling. Prompt reassessment can reduce the risk of deeper infection or further tissue loss.
Strengths and limitations of the study
A major strength of this research is its prospective multicenter design, which improves the relevance of the findings across different trauma settings. The study also included a relatively large operative cohort for an uncommon injury.
There are, however, some important limitations. As an observational study, it can identify associations but cannot prove causation. Surgical techniques may have varied across centers and surgeons. The study focused on patients who underwent operative management, so the results may not apply to all Morel-Lavallée lesions, especially those treated nonoperatively. In addition, some potentially relevant factors, such as lesion size, exact anatomical location, and timing from injury to surgery, may influence outcomes but were not highlighted in the abstract.
Bottom line
In this multicenter study, more than 20% of patients who underwent surgery for Morel-Lavallée lesions developed a postoperative wound complication. The only independent predictor was a pedestrian struck by motor vehicle mechanism of injury.
These findings suggest that trauma mechanism matters greatly when estimating postoperative risk. They also support careful patient counseling and close postoperative follow-up, especially in patients with high-energy crush or shearing injuries.