The relationship of the medial patellofemoral ligament attachment to the distal femoral physis

Background: No published study has ever described the relationship of the medial patellofemoral ligament (MPFL) attachment to the distal femoral physis in skeletally immature cadaveric specimens. As such, there continues to be much confusion about this relationship, which is important when considering MPFL reconstruction in the skeletally immature patient.

Hypothesis: The MPFL footprint is distal to the medial border of the distal femoral physis.

Study design: Descriptive laboratory study.

Methods: Sixteen skeletally immature cadaveric specimens were used for this study. The average age of the specimens was 12 years (range, 10-15 years). The MPFL femoral attachment, adductor tubercle, and medial epicondyle were identified in all specimens, and the topography of the distal femoral physis was carefully described. Measurements were then taken of the distance from the medial aspect of the distal femoral physis to the MPFL femoral attachment and the horizontal distance from the MPFL femoral attachment to the point where a femoral tunnel would intersect the undulating femoral physis. All measurements were made with digital calipers.

Results: The MPFL attachment was distal to the medial aspect of the femoral physis in all specimens. The MPFL attachment was an average of 8.5 mm distal to the medial aspect of the distal femoral physis. In the coronal plane, the undulating physis was 10.5 mm medial to the MPFL attachment. In all specimens, the undulations of the medial physis were concave directly posterior and lateral to the MPFL attachment and convex anterior to the MPFL attachment. Both the adductor tubercle and the medial epicondyle were also distal to the femoral physis in all specimens.

Conclusion: This study has confirmed the findings of others, who have shown that the MPFL femoral attachment lies distal to the medial aspect of the distal femoral physis. In addition, the study findings show that the MPFL femoral attachment is in very close proximity to the distal femoral physis.

Clinical relevance: To facilitate anatomic MPFL reconstruction, Schottle et al described a radiographic method to identify the MPFL femoral attachment on lateral radiographs in skeletally mature patients. Because of the complex physeal anatomy, much confusion exists concerning whether an MPFL femoral tunnel can be placed safely in the pediatric patient. The findings of this study suggest that anatomic MPFL reconstruction may be accomplished with a tunnel angled distally and anteriorly to avoid injury to the distal femoral physis.