RICE Protocol: Acute Ankle Sprain Edema Simulator

RICE Treatment

Compression bandage 0 mmHg

Elevation angle 0°

Simulation speed 1.0×

Live Readouts

Grade: —

Interstitial fluid

0.0 mL

Elapsed time

0.0 h

Net filtration rate J_v

0.0 mL/h

How it works

An acute ankle sprain tears capillaries and raises local capillary pressure, so fluid leaks into the tissue faster than the lymphatics can remove it — that's swelling (edema). Net capillary filtration follows the Starling equation:

Jv = Kf · [ (Pc − Pi) − σ·(πc − πi) ]
dV/dt = Jv − Lclear·V

Pc — capillary hydrostatic pressure (elevated by injury, inflammation)
Pi — interstitial hydrostatic pressure (rises with V and with compression)
πc, πi — plasma / interstitial oncotic (protein) pressure, σ = reflection coefficient
Kf — capillary filtration coefficient (permeability × surface area)
Lclear — first-order lymphatic clearance rate of the swollen fluid

Each element of RICE changes a term in this system:

Ice — cold-induced vasoconstriction cuts Kf and lowers Pc, slamming the filtration tap almost shut.
Compression — external bandage pressure raises Pi directly, opposing further filtration, and the rhythmic tissue pressure boosts lymphatic pumping (Lclear).
Elevation — raising the limb above heart level lowers the hydrostatic column feeding Pc and improves venous/lymphatic return, adding to Lclear.
Rest — not modeled numerically here, but avoiding muscle-pump loading prevents re-injury that would reset Pc upward.

The injury grade shown is a simplified clinical proxy from swelling volume: Grade I (mild, <12 mL) is a stretch with minimal fiber tearing; Grade II (moderate, 12–28 mL) is partial ligament tearing with instability; Grade III (severe, >28 mL) is complete rupture. Watch how aggressive Ice + Compression + Elevation flattens the swelling curve compared to no treatment.

Interstitial fluid (edema) Ice pack Compression wrap

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