Seventy-one fractures of the tibial shaft were treated with interlocking intramedullary nails. None of the fractures were treated with static locking of the intramedullary nails. These 71 fractures were studied to determine whether certain fracture patterns are prone to loss of alignment when static interlocking is not used. Loss of alignment was defined as shortening of 1 cm or more and/or change in angulation of at least 5°. Loss of alignment occurred in eight of the 71 (11%) fractures. Shortening and/or angulation occurred in seven of 22 spiral and short oblique fractures, and in none of 27 transverse fracture patterns. It was concluded that the dynamically locked and nonlocked modes of intramedullary nailing should not be used in the stabilization of spiral and oblique fractures of the tibial shaft.