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Saturday, March 18, 2000

Rotational malalignment in tibia is subject of study

A retrospective study of 40 patients with healed unilateral tibial shaft fractures treated with intramedullary nailing who were evaluated for malrotation found five of the patients (12.5 percent) were aware of a rotational difference after healing occurred.

Rotational malalignment after femoral nailing has been discussed in the literature, however this has not been documented in the tibia, say researchers of the study in poster exhibit 453.

Each of the 40 patients underwent clinical gait evaluation. Ink tracings were made for 12 steps. Foot progression angles measured. Each patient was questioned about perceived rotational differences between both legs. All patients underwent Axial CT scans of both tibias at the level of the knee and ankle in order to precisely assess rotational differences. Radiographs were evaluated for fracture pattern and location according to AO classification system.

Of the five 40 patients who were aware of a rotational difference, three noted external rotation deformity and two complained of internal rotation. The two patients (5 percent) with internal rotation believed the rotational difference adversely affected their ability to ambulate. One of these patients underwent corrective osteotomy. The other three believed the problem was not significant enough to undergo further treatment.

The clinical rotational difference in foot progression angle for these five patients averaged 20.8 degrees (range: 18-25). Four other patients were noted to have differences in foot progression angles on gait evaluation, however, they were unaware of this. The foot progression angle differences averaged 8.5 degrees (range: 3-10). Four of the five patients who noted a difference had fractures involving the distal one-third tibia with associated fibula fracture at the same level. Three of these four also had undergone fibular plating at the time of tibial nail

The researchers noted that they documented a 12.5 percent incidence of perceived malrotation and only 5 percent of the patients have developed symptomatic malrotation. This data also suggests that rotational differences of 18 degrees or greater may lead to symptomatic gait patterns. Rotation less than this may be compensated for during gait.

Radiographically, fractures involving the distal one-third tibial shaft with associated fibual at the same level may be unstable and prone to rotational malalignment, the researchers said. Plating the fibula may not be beneficial in controlling.

Co-authors of the study, both of Medical College of Ohio, Toledo, Ohio, are Gregory Georgiadis, MD, associate professor, orthopaedic surgery, and Thomas A. Olexa, MD, chief resident.

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Last modified 06/March/2000 by IS