Reduced lengthening index by use of bifocal osteotomy in the tibia: comparison of monofocal and bifocal procedures with the Ilizarov external fixator.

We lengthened 63 tibial segments in 49 patients, performing a monofocal osteotomy on 31 segments and a bifocal osteotomy on 32 segments. In the monofocal osteotomy group, the average lengthening was 4.8 (2.4-7.1) cm with a lengthening index (LI) of 1.7 (0.9-4.4) months/cm. In the bifocal osteotomy group, the average lengthening was 7.4 (4.9-10.0) cm and with a LI of 1.0 (0.7-2.1) months/cm. The difference in LI between the groups was statistically significant, but more major complications, like persistent ankle joint contracture and pseudarthrosis in the callotasis lengthening zone, occurred with bifocal lengthening.