Journal of Pediatric Orthopaedics - 2026-03-02 - Journal Article
Quantifying Proximal Tibial Physeal Injury in Rigid Intramedullary Nailing in Adolescent Patients.
Kha ST, Johnston M, Ryan JR, Farnsworth CL, Schmitz MR, Jackson ME, Souder CD
Topics
Key Takeaway
Computer simulation of rigid intramedullary nailing in adolescents aged 10–13 shows proximal tibial physeal injury volumes of 2.26–5.15% across reamer sizes 9.75–12.0 mm, remaining below the classically described 7% threshold of concern.
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Summary
This study quantified proximal tibial physeal injury volume during simulated rigid intramedullary nailing using 3D Boolean intersection modeling of 16 pediatric knee CTs (ages 10–13) across three reamer diameters and three tibial tubercle ossification stages. Physeal injury ranged from 2.26% (12.0 mm reamer, TTOS 2) to 5.15% (12.0 mm reamer, TTOS 0), all below the 7% threshold historically associated with growth disturbance. A 10-degree more vertical sagittal trajectory increased physeal violation by 1.09× in the TTOS 1 group, with minimal effect in TTOS 0 and TTOS 2.
Key Limitation
The 7% physeal injury threshold cited as the safety benchmark is derived from animal and indirect clinical data, not validated in the proximal tibial physis of adolescents undergoing RIMN, making the clinical significance of staying below this threshold uncertain.
Original Abstract
BACKGROUND
Rigid intramedullary nailing (RIMN) is increasingly used to treat tibia fractures in skeletally immature patients; however, the volume of injury to the proximal tibial physis and subsequent risk of abnormal growth is unknown. This study aimed to determine volume of proximal tibial physeal injury during RIMN of the tibia in skeletally immature adolescents.
METHODS
The volume of injury to the proximal tibial physis was measured through computer simulation modeling of RIMN using three-dimensional (3D) models. Sixteen normal pediatric knee CT scans (ages 10 to 13 y) with open physes were reconstructed and tibial tubercle ossification stage (TTOS) determined. Opening reamers of 9.75 mm, 11.0 mm, and 12.0 mm diameters were virtually simulated from a standardized suprapatellar starting point and trajectory. Boolean intersection modeling quantified the reamed physeal volume as a percentage of the total physis. A secondary analysis simulated ±10 degrees sagittal trajectory variation for reamer insertion.
RESULTS
Simulated reaming demonstrated increasing physeal injury with larger reamer diameters. The average percentage of total physeal volume injury simulated by the 9.75 mm, 11.0 mm, and 12.0 mm reamers, respectively, was 3.32%, 4.26%, and 5.15% in the TTOS 0 group; 3.17%, 3.99%, and 4.73% in the TTOS 1 group; and 2.26%, 2.89%, and 3.46% in the TTOS 2 group. Trajectory variation demonstrated that a 10-degree more vertical reamer trajectory change in the sagittal plane increased the volume of physeal injury 1.09 times more than the standard reference trajectory in the TTOS 1 group, while trajectory variations in the TTOS 0 and TTOS 2 groups resulted in minimal volume changes.
CONCLUSIONS
Computer simulation modeling can quantify the volume of injury to the proximal tibial physis during RIMN in skeletally immature patients. The volume of physeal injury appears to remain below the classically described level of concern of 7%. These findings provide a foundation for further investigation into physeal injury thresholds and growth modulation.
CLINICAL RELEVANCE
This simulation study informs surgical decision-making and provides insights on growth plate violation when using RIMN to treat skeletally immature tibia fractures.