A Review of Precice Intramedullary Limb Lengthening (IMLL) System for Limb Lengthening Procedures in Children.

Inclusion Criteria: * All potential index surgeries must meet the inclusion criteria below in order to be considered for enrollment: 1. Patient was 12 years of age or younger at the time of the index surgery. 2. Diagnosis of femoral or tibial limb length discrepancy greater than or equal to 2.0 cm. 3. Limb length discrepancy secondary to congenital or acquired etiologies. 4. Patients received limb lengthening treatment of the femur or tibia with the Precice IMLL System or an external fixator limb lengthening device. 5. Minimum medullary canal diameter ≥6 mm in the treated bone - Precice IMLL System treatment group only. 6. Closed or nonfunctioning physeal growth plates in the treated bone - Precice IMLL System treatment group only. 7. Minimum of 12 months of follow-up. 8. Available medical and radiographic records preoperatively through consolidation. Exclusion Criteria: * Index surgeries will be excluded from consideration for the study if they meet any of the following criteria: 1. Patients with unresolved limb lengthening-related adjacent joint contractures (loss of range of motion), subluxation, or dislocation prior to the index surgical procedure. 2. Patients with uncorrected coronal or sagittal plane angular malalignment following the index surgical procedure. 3. Patients with unresolved complications related to previous limb lengthening on the index or different limbs, including unhealed pin sites and/or residual bone infection (from external fixator devices) on the index limb. 4. Patients with femoral head osteonecrosis from a previous implantation of a femoral nail prior to the index surgical procedure. 5. Patients with a previous implantation of a femoral or tibial nail across an open physeal growth plate prior to the index surgical procedure.