The Schöttle point needs to be used with care for paediatric knees: A cross-sectional radiological study
Chaofan Liao1, Peidong Liu1, Rongtao Yang1
1Sports Medicine Center, Honghui Hospital, Xi'an Jiaotong University, Xi'an, Shaanxi Province, China.
Purpose:
The "Schöttle point" is an important anatomical landmark in medial patellofemoral ligament (MPFL) reconstruction. This study aimed to observe the relationship of Schöttle point and distal femoral physis (DFP) using three-dimensionl (3D) computed tomography (CT), given the existing controversy and potential risks of physeal injury during surgery.
Methods:
A retrospective analysis of 118 knee CT scans from 88 patients (aged 6-16 years) was conducted. Using RadiAnt Viewer, the two-dimensional (2D) Digitally Radiograph (DR) and 3D renderings were reconstructed. The Schöttle point was identified, and its position relative to the DFP was assessed on both 2D and 3D images. Key distances, including the vertical Schöttle point-to-DFP distance, were measured on 3D reconstructions. Statistical analyses included correlation and reliability tests.
Results:
A critical discrepancy was found: on 3D renderings, the Schöttle point was consistently distal to the DFP in all knees. Conversely, 2D-DR showed its position as proximal or at the physis in 100% of cases. The mean vertical distance from Schöttle point to DFP on 3D renderings was 6.1 ± 1.9 mm, showing a strong positive correlation with patient age (p < 0.01) that plateaued after 12 years. Notably, the methods of the Schöttle point do not seem to fit all five knees from patients under 8-year-old. Measurements demonstrated excellent reliability (ICC > 0.75).
Conclusion:
The Schöttle point's cortical position is consistently distal to the DFP in paediatric knees on 3D assessment, a relationship often different from 2D radiographs. Crucially, surgeons must respect the U-shaped 3D morphology of the physis when planning tunnel trajectory to avoid physeal damage. The distance from Schöttle point to the DFP increases with age. Intraoperatively, the position can be controlled using fluoroscopic 2D images combined with palpation of bony landmarks, though 3D planning is recommended for precision during paediatric MPFL reconstruction. Level of Evidence Level III, cross-sectional study.
