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The Law of Laplace: Application in Wound Care

How Physics Guides Safe, Ethical, and Patient-Specific Bandaging Decisions

By Saturn Dagwase, DPT, CWS, CLT-LANA, FACCWS, DAPWCA

External compression is one of the most powerful and evidence-based interventions in wound care, particularly in the management of venous leg ulcers, lymphedema, mixed venous–lymphatic disease, and chronic lower-extremity edema. Clinical evidence demonstrates that compression therapy improves healing rates and reduces recurrence by addressing venous hypertension and chronic tissue congestion rather than focusing solely on the wound surface (Atkin & Tickle, 2016; O’Meara et al., 2012).

By reducing interstitial fluid accumulation, enhancing venous and lymphatic return, and improving microcirculatory perfusion, compression directly targets the underlying pathophysiology that impairs wound healing. Despite its proven benefits, compression applies sustained mechanical force to living tissue that may be fragile, ischemic, or insensate. When applied without understanding pressure behavior across the limb, compression may result in pain, skin breakdown, or ischemic compromise. One of the most important principles governing safe compression is the Law of Laplace.

IMPORTANCE OF EXTERNAL COMPRESSION

 

External compression plays a central role in wound care because it directly modifies the hemodynamic and interstitial forces that impair healing in venous and lymphatic disease. Chronic venous insufficiency and lymphedema are associated with impaired outflow, persistent edema, inflammation, and reduced oxygen diffusion to the wound bed. Without correcting these conditions, topical wound care alone is often insufficient to achieve durable healing (Moffatt et al., 2018; Partsch & Mortimer, 2015).

By applying controlled circumferential pressure, compression reduces venous hypertension, promotes venous return, and facilitates lymphatic drainage. This reduction in edema improves capillary perfusion and lowers inflammatory mediator concentration within the tissue (Lawrence & Kakkar, 1980). Compression also enhances the efficiency of the calf muscle pump during ambulation and stabilizes surrounding tissue, reducing shear forces at wound margins. For these reasons, compression is not merely adjunctive—it is often the cornerstone of wound care.

LAW OF LAPLACE DEFINITION

 

The Law of Laplace is a fundamental physical principle describing the relationship between pressure, tension, and radius in curved structures. In its most clinically relevant form, it states that the pressure exerted on the wall of a cylindrical or spherical structure is directly proportional to the applied tension and inversely proportional to the radius of that structure.

As radius decreases, pressure increases for a given amount of tension, even when the applied force remains unchanged. Conversely, larger radii result in lower pressure for the same applied tension. Although derived from physics, the Law of Laplace is deeply embedded in physiology and clinical medicine and provides a framework for understanding how mechanical forces interact with biological tissue.

LAW OF LAPLACE IN MEDICINE

Across medical disciplines, the Law of Laplace explains how pressure and wall stress influence organ function and injury risk. In cardiovascular medicine, it explains why dilated cardiac chambers experience increased myocardial workload and why hypertrophy develops as a compensatory mechanism. It also explains aneurysm progression as vessel radius increases and wall tension escalates.

In pulmonary medicine, the Law of Laplace explains why smaller alveoli are more prone to collapse and why pulmonary surfactant is necessary to stabilize alveoli of different sizes. More broadly, this principle informs understanding of pressure behavior in blood vessels, hollow organs, and capillary beds.

TRANSLATING LAPLACE TO COMPRESSION

 

Although many medical applications of the Law of Laplace focus on internal pressure, the same principle applies when external circumferential forces are applied through compression bandages or wraps. In wound care, bandage tension represents the applied force, limb radius substitutes for organ radius, and interface pressure represents the pressure exerted on skin and underlying tissues.

Compression pressure is therefore inherently non-uniform, even when application technique appears uniform. Because limb radius varies along the length of the extremity, the same bandage tension produces different pressures at different locations. Understanding this relationship allows clinicians to anticipate pressure behavior and modify compression proactively.

APPLICATION IN WOUND CARE

In wound care, the Law of Laplace governs how compression systems interact with edematous and compromised tissue. Distal limb segments such as the ankle have a smaller radius than proximal segments like the calf. As a result, the same bandage tension generates higher interface pressure distally and lower pressure proximally (Partsch & Mortimer, 2015).

Compression pressure is dynamic. As edema resolves and limb circumference decreases, effective limb radius becomes smaller, resulting in increased interface pressure. Irregular limb geometry further concentrates pressure at predictable high-risk zones. Padding increases effective limb radius and redistributes pressure, improving both safety and therapeutic effectiveness (Moffatt et al., 2018).

RISKS & SAFETY

When compression therapy is applied without consideration of the Law of Laplace, adverse outcomes may occur even when compression is otherwise clinically indicated. These complications are often caused by uneven pressure distribution due to limb geometry, inadequate padding, or inappropriate tension adjustment (Lawrence & Kakkar, 1980).

Documented risks include compression-induced neuropathy, pain, treatment intolerance, worsening edema due to proximal fluid trapping, skin injury, ischemia, and avoidable surgical escalation. Patients with diabetes or preexisting neuropathy are at particularly high risk due to diminished protective sensation (Atkin & Tickle, 2016; Moffatt et al., 2018).

CASE STUDY

A 68-year-old patient with chronic venous insufficiency and mixed venous–lymphatic edema developed ankle pain and burning within hours of compression application. Examination revealed focal tenderness at the malleolar region. Applying the Law of Laplace, excessive distal pressure due to small limb radius and irregular geometry was identified.

Targeted padding was added around the ankle and distal tension was reduced while maintaining proximal support. The patient experienced immediate symptom relief and continued edema reduction without skin breakdown, illustrating the value of Laplace-guided compression.

CONCLUSION

The Law of Laplace provides a foundational framework for understanding how external compression behaves across limbs of varying size and shape. Effective compression is not defined by the product alone, but by the clinician’s understanding of the forces applied to living tissue.

In wound care, compression failure is often not a failure of compression therapy itself, but a failure of pressure management. Mastery of Laplace-based principles improves safety, tolerance, and clinical outcomes.