A Cadaveric Study of the Sagittal Patellar Insertion of the Medial Patellofemoral Ligament in Children: Implications for Reconstruction.

Abstract

Background: Patellofemoral instability is a common problem, and medial patellofemoral ligament (MPFL) reconstruction is a standard treatment approach for recurrent instability. The accurate restoration of anatomy in MPFL reconstruction is essential. While coronal-plane anatomy of the MPFL patellar insertion has been previously reported, sagittal-plane anatomy has not been widely studied.

Purpose: To evaluate the sagittal patellar insertion of the MPFL in pediatric specimens to guide future anatomic reconstruction.

Study design: Descriptive laboratory study.

Methods: A total of 11 pediatric cadaveric knee specimens were dissected. The patella and sagittal MPFL insertion were evaluated. The maximal anterior-posterior patellar width, distance from the posterior patella to the posterior MPFL insertion, distance from the medial patellar articular cartilage edge to the MPFL insertion, maximal MPFL thickness, and distance from the anterior MPFL insertion to the anterior patella were measured. The proportion of patellar coverage by the sagittal MPFL insertion footprint was calculated.

Results: The pediatric knee specimens had a mean age of 9.3 ± 1.4 years (range, 6-11 years). The mean maximal transverse patellar width was 19.0 ± 2.7 mm (range, 13.7-22.7 mm). The mean posterior patella-to-posterior MPFL distance was 10.5 ± 1.6 mm (range, 7.7-12.6 mm). The mean patellar articular cartilage edge-to-MPFL distance was 2.3 ± 0.6 mm (range, 1.5-3.5 mm). The mean maximal MPFL thickness was 4.0 ± 0.9 mm (range, 2.6-5.5 mm). The mean anterior MPFL-to-anterior patella distance was 4.4 ± 1.1 mm (range, 2.6-5.8 mm). The sagittal MPFL insertion footprint spanned a mean of 21.0% (range, 16.1%-29.7%) of the medial patella.

Conclusion: This study, utilizing skeletally immature cadaveric specimens, demonstrated that the sagittal MPFL insertion consistently resided in the anterior third of the patella, averaging 21% of the total sagittal patellar width. Additionally, the distance from the MPFL insertion to the medial patellar articular cartilage edge showed minimal variation, representing a consistent intraoperative landmark for MPFL graft placement.

Clinical relevance: This research characterized MPFL insertion anatomy on the medial patella in the sagittal plane. This knowledge provides a clear target area for anatomic graft placement during MPFL reconstruction.