I'm Joe Featherall, and I'd like to thank my co-authors and AOSSM for allowing me to present this work. In introduction, patella dislocation is most common in the 10 to 17-year-old population, and recurrent dislocations are commonly treated with success with medial patellofemoral ligament reconstruction. A key technical challenge of this procedure is anatomic femoral tunnel placement without fiseal injury, adding a unique dimension to this procedure in comparison to MPFL reconstruction in the adult population. There are a number of reported femoral tunnel technical failures, proximal anchor migration due to proximal anchor placement, sagittal deformity due to fiseal injury, either posterior or anterior to the mid-sagittal plane, and coronal plane deformity due to fiseal injury either medial or lateral to the mid-coronal plane. And finally, patella overload and graft failure due to unfavorable anisometry of the graft. There have been a number of important studies that have investigated the medial patellofemoral ligament insertion, and these studies have provided some conflicting data regarding whether the MPFL inserts either proximal, distal, or having a variable relationship to the distal femoral fices. Although these studies have provided great insight into the femoral insertion, these have been largely based on anatomic landmarks and have not been correlated with the major radiographic landmarks that are used for intraoperative technique. Also these studies have some limitations in terms of sample size due to specimen availability. So in summary, optimal femoral tunnel positioning and surgical technique in pediatric MPFL reconstruction are not yet clearly defined. Our research question was, what is the position of Schottel's point relative to the medial distal femoral fices and its reliability as a landmark for femoral tunnel reaming in MPFL reconstruction? To answer this question, we did a query of two institutions' PAC systems and extracted pediatric knee CTs. We imported this data into a three-dimensional image computing platform known as 3D Slicer, which has been multiply validated and is an NIH-funded open-source image computing platform. We transformed the data into a perfect lateral position to mimic intraoperative technique and then used a ray casting algorithm to create our digitally reconstructed radiographs and then analyzed both the 3D data and the DRRs using fiducial markers. So regarding our distance measurements, the fiducial marker was placed at Schottel's point on the lateral digitally reconstructed radiograph. This was then overlaid onto the CT data and measurements were made relative to the medial fices and measurements were also validated on the 3D volume renderings. So, regarding our results, I'd like to bring your attention to the highlights here where the appearance of Schottel's point on the lateral radiograph appears proximal to the fices, and again, this is its appearance relative to the projection, is proximal to the fices in about 45% of cases and at the fices in another 45% of cases. When you correspond these fiducial markers to the three-dimensional data, you find that Schottel's point in actuality is distal to the fices in 100% of the knees within our cohort. So in conclusion, Schottel's point is consistently distal to the medial distal femoral fices within all knees within our cohort study. Schottel's point is a consistent and reliable radiographic landmark for pediatric MPFL reconstruction with the caveat that compensation may be needed in a small number of cases for the diameter of the reamer. These are our references and thank you for your time and attention.

optimal femoral tunnel positioning

pediatric medial patellofemoral ligament reconstruction

Schottel's point

medial distal femoral fices

reliable radiographic landmark