How To Apply a Posterior Ankle Splint VIDEO How To Apply a Sugar Tong Ankle Splint VIDEO Other treatment depends on severity of the sprain: Mild (eg, 1st-degree) sprains: PRICE and weight bearing and mobilization as soon as it can be tolerated (usually within a few days) Moderate (eg, 2nd-degree) sprains: PRICE, including immobilization of the ankle in a neutral position with a posterior splint or a commercially available boot, followed by mobilization and physical therapy Severe (eg, 3rd-degree) sprains: Immobilization (possibly with a cast), possibly surgical repair, and physical therapy High ankle sprains usually require a cast for several weeks.