BACKGROUNDDistal tibial physeal fractures are common injuries that can frequently be treated nonoperatively. Most commonly, long leg cast immobilization is recommended after closed reduction. The purpose of this study was to compare outcomes between long leg cast (LLC) and short leg cast (SLC) immobilization after closed reduction of Salter-Harris II (SH-II) distal tibial fractures. METOHDSA retrospective, multicenter comparative study was performed evaluating skeletally immature patients treated with closed reduction of a displaced SH-II distal tibia fracture at three Level I Pediatric Trauma Centers between 2012 and 2018. Radiographs after casting were compared to those at the time of cast removal to assess for the primary study outcome of loss of reduction (LOR). Secondary outcomes included the length of casting, premature physeal closure, time to weight-bearing, and time to release to activities. RESULTSA total of 148 patients with a median age of 12.7 years (IQR 11.2-13.7) met inclusion criteria. LLC were utilized in 110 cases while 38 patients received a SLC. Loss of reduction occurred in 10 patients (6.8%), nine with a LLC and one in a SLC (p=0.454). Those treated in SLC had a shorter length of casting (p=0.030) and quicker release to activities (p=0.004) than those with LLC. CONCLUSIONSFindings of this retrospective, multi-center study show similar rates of loss of reduction between SLC and LLC immobilization for SH-II distal tibial fractures after closed reduction. Patients received less total casting and returned to sports quicker after SLC immobilization. KEYWORDS CONCEPTS•Salter-Harris II distal tibia fractures can be treated with closed reduction and short leg casting without an increased rate of displacement•Distal tibial physeal fractures treated in a short leg cast can possibly return to sports quicker•The rate of interval displacement of a SH-II distal tibia fracture after closed reduction is approximately 6.7%. LEVEL OF EVIDENCELevel III Retrospective Comparative Study