Study to Assess the Pain, Satisfaction, and Quality of Life of Patients With FITBONE® Lengthening Nail

Inclusion Criteria: * Patients aged ≥12 years old, with congenital or acquired lower limb discrepancy greater than 30mm, undergoing femoral or tibia bone lengthening with FITBONE * Patients with a regular indication for a surgical intervention with FITBONE according to manufacturer IFU * The patient (or his/her legally acceptable representative) is capable of understanding the content of the Informed Consent Form (ICF) * The informed consent form is correctly obtained Exclusion Criteria: * Patients with a medical condition that is contraindicated according to the FITBONE instruction for use. * Patients with any conditions that, in the Investigator's opinion, may interfere with the study execution, including those likely to be lost to follow-up. * Patients who have any conditions or medical condition that, in the investigator's opinion, may interfere with the study's execution or in which the patient should not participate for safety reasons. * Patients requiring the application of or have already in-situ concomitant devices that cannot be safely removed (except for permitted concomitant devices). * Patients participating in other clinical or have taken part in any clinical study in the last 3 months.