2015 ISAKOS Biennial Congress ePoster #1240

Evaluation of the Accuracy of Tibial Tunnel Positioning During Reconstruction of the Anterior Cruciate Ligament Between Navigation System and Fluoroscopic Imaging

Takeshi Oshima, MD, PhD, Sydney, NSW AUSTRALIA
Junsuke Nakase, MD, PhD, Kanazawa, Ishikawa JAPAN
Yoshinori Ohashi, MD, Kanazawa, Ishikawa JAPAN
Hitoaki Numata, MD, Kanazawa, Ishikawa JAPAN
Hiroyuki Tsuchiya, Kanazawa, Ishikawa JAPAN

Kanazawa University Hospital, Kanazawa, Ishikawa, JAPAN

FDA Status Cleared

Summary: We evaluated the accuracy of tibial tunnel positioning during anatomic single-bundle anterior cruciate ligament reconstruction when using a navigation system or fluoroscopic imaging. The tibial tunnel position tends to vary in the medial-lateral direction when using the navigation system. When using fluoroscopic imaging, it varies in the anterior-posterior direction

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Abstract:

Introduction

In anterior cruciate ligament (ACL) reconstruction, femoral tunnel placement is guided by landmarks such as the “resident’s ridge” and the position which is 4 mm anterior to the posterior articular cartilage. Therefore it is relatively easy to identify the femoral footprint.
For accurate tibial tunnel placement, intra-articular landmarks are used. Tibial landmarks may change due to chronic ACL injury or revision ACL reconstruction. Therefore, intra-articular landmarks of the tibia are difficult to identify intraoperatively, especially in cases of remnant preservation in ACL reconstruction.
To improve the accuracy of anatomical tunnel positioning, the use of navigation systems and fluoroscopic imaging was introduced in ACL reconstruction. Many studies have suggested the effectiveness of these support procedures in ACL reconstruction; however, their accuracy remains controversial.

Purpose

This study evaluated the accuracy of tibial tunnel positioning during anatomic single-bundle ACL reconstruction using a navigation system or fluoroscopic imaging.

Materials And Methods

Our study included 30 patients who underwent anatomic single-bundle ACL reconstruction. The tibial tunnel position had been assessed using an intraoperative navigation system, fluoroscopic imaging, and postoperative computed tomography (CT).
We determined the tibial tunnel position by referring to the location of the lateral meniscus and ACL remnant. After inserting the guide pin, we recorded the position of the pin using the navigation system (N-position) and fluoroscopic imaging (F-position).
The exact tibial tunnel position was determined and the accuracy of the N -position and F-position was assessed using postoperative CT (C-position). We calculated the ratio of the tibial tunnel position to the anterior-posterior (AP) and medial-lateral (ML) directions.

Results

In the AP direction, the F-position (38.0% ± 4.9% from the anterior edge) was significantly anterior compared to the C-position (43.0% ± 4.1%, p = 0.005).
In the ML direction, the N-position (47.1% ± 3.9% from the medial edge) was significantly lateral compared to the C-position (43.3% ± 2.7%, p = 0.001).

Discussion And Conclusion

On fluoroscopic imaging, the position varied in the AP direction. This result was caused by tibial rotation during lateral imaging. Tibial rotation makes the AP length appear longer, thus making the F-position vary in the AP direction.
On using the navigation system, the position varied in the ML direction. In navigation systems, the horizontal axis of the tibia is identified by registering the spine of the medial tubercle and the medial and lateral points of the tibial plateau edge. We marked the points of the tibial plateau on the skin so that the axis could be changed. The ML length was longer than the AP length, which could cause an error in the ML direction.
The navigation system and fluoroscopic imaging were useful methods for tibial tunnel placement. However, the tunnel position tends to vary in the ML plane when using the navigation system and in the AP plane when using fluoroscopic imaging. Therefore, careful registration of the position when using the navigation system and obtaining an exact lateral image when using fluoroscopic imaging are important.