Arthroscopic-assisted reduction is one recommended technique for pediatric distal tibial epiphyseal fractures. A 15-year-old male patient with a triplane distal tibial epiphyseal fracture (Tillaux type) was scheduled for arthroscopic reduction and pinning, which failed to provide adequate fracture reduction. Open surgery was subsequently performed, which revealed a capsular interposition in the fracture line attributable to an anterior capsular tear of the ankle. The possibility of capsular interposition should always be taken into consideration when problems such as those described in this case presentation are encountered in such patients. This is precisely why direct visualization either through arthroscopy or open arthrotomy is sometimes necessary.