Background

ACL reconstruction has the highest failure rate in under age 18, and recent research suggests that combining Iliotibial band (ITB) lateral extra-articular tenodesis (LET) and ACL reconstruction may lower the rates of ACL tear in skeletally mature patients. The anatomy of the anterolateral ligament (ALL) has been controversial, with modern studies varying in their description of the precise origin and insertion, as well as relation to surrounding structures on the lateral femur and anterolateral tibia. No pediatric cadaveric study to date has clearly identified the locations of the known surrounding structures of the anterolateral ligamentous complex and their relationship to the physis.

Purpose

To quantitatively assess the anatomy of the pediatric lateral collateral ligament (LCL) origin, the popliteus origin, relationships to the physis, and in the tibial insertion of the iliotibial band (ITB) at Gerdy’s tubercle to guide reconstruction.

Methods

Nine (9) pediatric cadaveric knee specimens were dissected to identify the ligamentous femoral origin of the LCL, popliteus, and ITB tibial insertion (age range 0.2-10 yrs). Marking pins were used to localize the central footprint of these structures, followed by CT scans. Measurements were made on digital CT images (9 coronal, 7 sagittal images) to include: Dimensions of Footprint of ITB insertion at Gerdy’s Tubercle; Distance of Gerdy’s Tubercle to Physis and to Joint Line; Distances of LCL and Popliteus origins to Physis and to Joint Line.

Results

The area of Gerdy's tubercle is 28.65 +/- 17.86 mm2. The distance of Gerdy's tubercle to the physis is 1.55 +/- 3.06 mm and to the joint line is 9.55 +/- 3.65 mm. The distance of the LCL origin to the physis is -4.44 +/- 2.87 mm and to the joint line is 12.53 +/- 4.54 mm. The distance of the popliteus origin to the physis is -8.15 +/- 3.23 mm and to the joint line is 8.21 +/- 3.98 mm.

Conclusions

The relationship of the Popliteus to LCL (anterior, distal) is consistent with prior studies in adults. A Variable relationship exists between position of ITB insertion at Gerdy’s Tubercle and the physis. This study illustrates quantitative anatomy for structures on the lateral/anterolateral knee to aid in development of LET reconstruction techniques to optimize knee stability while avoiding physeal injury.