Comparative study of callus progression in limb lengthening with or without intramedullary nail with reference to the pixel value ratio and the Ru Li's classification.

Introduction: Callus progression is a great concern during limb lengthening. In this study, we investigated the difference in callus progression between tibial lengthenings with and without intramedullary nail.

Method: Seventy tibiae in 38 patients with an average age of 24 years were lengthened with Ilizarov external fixator and nail; 56 tibiae in 40 patients with an average age of 28.6 years were lengthened with the same Ilizarov external fixator but without nail. The callus progression was compared with reference to pixel value ratio (PVR) and Ru Li's classification. Statistical analysis was performed to compare the variation trend of PVR and incidence of various callus pathways (particular patterns of callus progression as outlined in Ru Li's classification) and shapes of each aspect of callus between the two groups.

Results: The trend of PVR was not statistically different in posterior, lateral and medial aspects of the callus between the two groups, but averagely lower in the anterior aspect in the group without nail than that with nail. The group without nail presented less incidence of homogeneous pathway, greater incidence of heterogeneous pathway; also greater incidence of fusiform callus, less incidence of cylindrical callus.

Conclusion: It was concluded that with nail, the callus underwent a more favorable progression and even longer lengthening could be allowed.