RADIOGRAPHIC ANALYSIS OF TIBIAL FRACTURE MALALIGNMENT FOLLOWING INTRAMEDULLARY NAILING

Intramedullary nailing of the tibia was performed on 145 tibiae (137 p atients) for fracture or nonunion from 1985 to 1992. There were 133 ca ses available for radiographic analysis of postoperative tibial alignm ent. Of the 133 nailings, 16 (12%) were malaligned (12 acute fractures and 4 nonunion-malunions). Malalignment was defined as 5 degrees angu latory deformity in any plane. Malalignment was seen in 58% of proxima l third fractures, 7% of middle third fractures, and 8% of distal thir d fractures. Of the malaligned fractures, 83% were either segmental or comminuted. Thirteen percent of the reamed tibiae were malaligned as compared with 9% of the unreamed tibiae. There was no relationship bet ween nail insertion site and degree of angulation. The medial entrance angle averaged 9.5 degrees and contributed to a valgus deformity in 4 proximal third tibial fractures. The average anterior bow deformity o f 5 proximal third fractures was 7 degrees (range, 5 degrees-12 degree s). Careful attention to operative technique and entrance angle, parti cularly with proximal third or comminuted fractures, is recommended to prevent angular deformity and malunion after tibial nailing. Proximal third tibial fractures may require a neutral or slightly lateral entr ance angle to ensure a more anatomic reduction and centromedullary nai l orientation to offset the tendency for valgus angulation.