The relationship of lateral anatomic structures to exiting guide pins during femoral tunnel preparation utilizing an accessory medial portal

Abstract

Anatomic reconstruction of the anterior cruciate ligament through an accessory medial portal has become increasingly popular. The purpose of this study is to describe the relationship of guide pin exit points to the lateral anatomic structures when preparing the anterior cruciate ligament femoral tunnel through an accessory medial portal. We utilized seven fresh frozen cadaveric knees. Utilizing an anteromedial approach, a guide wire was placed into the center of each bundle's footprint. Each guide wire was advanced through the lateral femoral cortex. The guide pins were passed at 90, 110, and 130 degrees of knee flexion. The distances from each guide pin to the closest relevant structures on the lateral side of the knee were measured. At 90 degrees the posterolateral bundle guide pin was closest to the lateral condyle articular cartilage (mean 5.4 +/- 2.2 mm) and gastrocnemius tendon (mean 5.7 +/- 2.1 mm). At 110 degrees the posterolateral bundle pin was closest to the gastrocnemius tendon (mean 4.5 +/- 3.4 mm). At 130 degrees the posterolateral bundle pin was closest to the gastrocnemius tendon (mean 7.2 +/- 5.5 mm) and lateral collateral ligament (mean 6.8 +/- 2.1 mm). At 90 degrees the anteromedial bundle guide pin was closest to the articular cartilage (mean 2.0 +/- 2.0 mm). At 110 degrees the anteromedial bundle pin was closest to the articular cartilage (mean 7.4 +/- 3.5 mm) and gastrocnemius tendon (mean 12.3 +/- 3.1 mm). At 130 degrees the AM bundle pin was closest to the gastrocnemius tendon (mean 8.2 +/- 3.2 mm) and LCL (mean 15.1 +/- 2.9 mm). Neither guide pin (anteromedial or posterolateral bundle) put the peroneal nerve at risk at any knee flexion angle. At low knee flexion angles the anteromedial and posterolateral bundle guide pins closely approximated multiple lateral structures when using an accessory medial arthroscopic portal. Utilizing higher flexion angles increases the margin of error when preparing both femoral tunnels. During preparation of the anterior cruciate ligament femoral tunnel through an accessory anteromedial portal the tunnels should be drilled in at least 110 degrees of knee flexion in order to move guide pin exit points away from important lateral knee structures.

Riscos e consequências do uso da técnica transportal na reconstrução do ligamento cruzado anterior: relação entre o túnel femoral, a artéria genicular lateral superior e o epicôndilo lateral do côndilo femoral

“…The data suggest that more than 100,000 reconstructions are performed annually in the United States (4,21) . However, there is little documentation of vascular complications in the literature.…”

“…Farrow and Parker (21) evaluated the risk of injury to these structures, except for the genicular artery, in cadavers, and drilled the femoral tunnel by means of knee arthrotomy, using bone structures as the reference points for standardized placement of guidewires with the knee flexed at 90 degrees, in a position that was slightly lateral to the medial femoral condyle and slightly above the anterior cornu of the medial meniscus. They concluded that the femoral tunnel should be drilled with the knee flexed at a minimum of 110 degrees, in order to diminish the risk of injury to lateral structures.…”

“…Horizontalization of the femoral tunnel resulting from the transportal anatomical technique (20) exposes the guidewire of the femoral tunnel to an anatomical region of the lateral femoral condyle that is usually not approached (21) . This region contains the main artery feeding the lateral femoral condyle and one of the main vascular branches of the popliteal artery: the lateral superior genicular artery (22,23) .…”

The Sagittal Plane Angle and Tunnel-Related Complications in Double-Bundle Anterior Cruciate Ligament Reconstruction Using the Transportal Technique: An In Vivo Imaging Study

“…Many studies on the complications of double-bundle ACL reconstruction using the transportal technique have been reported. [20][21][22][23][24][25] A high flexion angle of the knee joint is usually recommended to avoid transportal techniqueerelated complications. 21 Most studies have reported on the relation between knee flexion angle and risk incidence and have indicated that a lower flexion angle increases the incidence of lateral anatomic structure and cartilage damage.…”

“…21 Most studies have reported on the relation between knee flexion angle and risk incidence and have indicated that a lower flexion angle increases the incidence of lateral anatomic structure and cartilage damage. 20,21,[23][24][25] These studies used cadavers and Sawbones models (Sawbones, Malmo, Sweden). However, no in vivo study has analyzed the relation of sagittal plane tunnel positions to complications related to ACL reconstruction using the transportal technique.…”