Original Article
Comparison Between Rigid and Flexible Systems for Drilling the Femoral Tunnel Through an Anteromedial Portal in Anterior Cruciate Ligament Reconstruction

https://doi.org/10.1016/j.arthro.2009.10.012Get rights and content

Purpose

The purpose of this study was to compare the differences in femoral tunnel length and distance to the lateral anatomic structures when using standard and flexible guide pins for anterior cruciate ligament (ACL) femoral tunnel drilling through a medial portal.

Methods

Using a medial arthroscopic portal in 10 cadaveric knees, we sequentially drilled straight and flexible guide pins into the center of the ACL femoral footprint using the same starting point. We recorded the interosseous length and distances to the peroneal nerve and the femoral origin of the lateral collateral ligament (LCL) for each pin.

Results

The mean interosseous length was 43.5 mm for the flexible pin and 37.1 mm for the straight pin (P = .01). The mean distance to the peroneal nerve was 42.3 mm for the flexible pin and 37.8 mm for the straight pin (P = .33). The mean distance to the femoral origin of the LCL was 26.1 mm for the flexible pin and 13.4 mm for the straight pin (P = .003).

Conclusions

The use of commercially available flexible reamers and 42° femoral guides results in longer femoral interosseous tunnel length than can be achieved with a straight guide pin. Femoral interosseous length consistently of 40 mm can be achieved with this technique and cannot be replicated with a rigid straight pin. This is advantageous for femoral tunnel drilling in an anatomic ACL reconstruction that uses suspensory fixation devices. There is minimal risk to the peroneal nerve and the femoral origin of the LCL unless lateral femoral wall blowout occurs.

Clinical Relevance

Flexible pins allow longer femoral tunnels and safer distances from the LCL by use of a medial portal technique.

Section snippets

Methods

Ten ethylene glycol–preserved cadaveric knee specimens were obtained from the Department of Anatomy. Each specimen was kept at room temperature throughout the study. There were 9 female specimens and 1 male specimen. The mean age of the specimens was 82 years (range, 67 to 97 years). There were 5 left and 5 right knees. Each specimen was mounted to simulate the standard arthroscopic position of 90° of knee flexion. A 30° arthroscope was placed by use of a trans–patellar tendon portal at the

Results

The data are summarized in Fig 2. The femoral interosseous distance of the flexible guide pins was longer than that of the straight guide pins (P = .01). This was because of the more proximal exit point on the lateral femoral cortex for the flexible guide pins (Fig 3). The mean interosseous distance was 37.1 mm (range, 34 to 42 mm) and 43.5 mm (range, 35 to 52 mm) for the straight and flexible guide pins, respectively. This difference was significant (P = .01). For the straight pin, 8 of 10

Discussion

This study examined the differences in ACL femoral tunnel drilling with a straight guide pin compared with a flexible guide pin drilled through a medial portal. The interosseous length of the tunnels drilled with the flexible guide pin were on average more than 6 mm longer than those drilled with a rigid straight pin. This allows for longer femoral sockets and is indicative of a more proximally directed femoral socket to allow a suspensory fixation device to be secured to the thicker lateral

Conclusions

The use of commercially available flexible reamers and 42° femoral guides results in longer femoral interosseous tunnel length than can be achieved with a straight guide pin. Femoral interosseous length consistently of 40 mm can be achieved with this technique and cannot be replicated with a rigid straight pin. This is advantageous for femoral tunnel drilling in an anatomic ACL reconstruction that uses suspensory fixation devices. There is minimal risk to the peroneal nerve and the femoral

Acknowledgment

The authors thank Margaret H. Cooper, Ph.D., Gregory S. Smith, Ph.D., and the staff of the Saint Louis University Center for Anatomical Science and Education for the use of their practical anatomy laboratory and their resources. They also thank Heidi A. Israel, Ph.D., for her help with the statistical analysis.

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    The authors report no conflict of interest.

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