Long bone lengthening surgery using progressive surgical methods has been the source of frequent complications. Some authors have classified these complications either descriptively, according to the date of onset after the operation, or based on their severity. The Caton classification (1985) has had the virtue of contributing the notion of the treatment contract stipulating the objective to reach in treatment. Within the context of the preoperative information delivered to patients and their family, this contract can be improved by adding a notion of maximum treatment duration. The objective of this study was therefore to propose a classification that includes honoring a triple contract associating the planned gain in bone length, the duration of treatment, and the occurrence of sequelae.

The classification of complications proposed includes four grades: grade I: triple contract honored, including a few treatments without general anesthesia; grade II: triple contract fulfilled, but with unplanned interventions under general anesthesia; grade III: the time stipulated was not honored because the time to obtain bone union was too long or because the program was interrupted; grade IV: sequelae are present. This classification was assessed based on a consecutive series of 34 surgical procedures in 32 patients (two patients underwent two lengthening procedures during this period) at 43 bone segments associating progressive lengthening with external fixation or with nail lengthening. The grade of each complication was determined by each of the authors according to the classification proposed and other classifications reported in the literature (Caton, Paley, Popkov, and Donnan).

Approximately one-third (10) of the 34 lengthening procedures did not present any complications. Two-thirds (24) presented 30 complications. Consensus was obtained between all the authors on the grades proposed for our classification and the Caton classification, but consensus was not reached with the other classifications in which part of the interpretation was subjective (Paley, Popkov, and Donnan).

The classification proposed required respecting predetermined objectives during limb lengthening surgery based on a triple contract: gain, duration, and function. It is reliable and reproducible by different operators because the criteria are objective. It can also be applied to diverse surgical techniques, whether with external fixation and/or internal osteosynthesis.

Level IV: retrospective study or historical series.