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Am J Sports Med. 2011 Jun;39(6):1306-15. doi: 10.1177/0363546510397170. Epub 2011 Feb 18.

Anterior cruciate ligament reconstruction: can anatomic femoral placement be achieved with a transtibial technique?

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  • 1OrthoCarolina, Sports and Complex Knee Center, Charlotte, NC 28207, USA. dana.piasecki@orthocarolina.com

Abstract

BACKGROUND:

Recent reports have suggested that a traditional transtibial technique cannot practically accomplish an anatomic anterior cruciate ligament (ACL) reconstruction.

HYPOTHESIS:

The degree to which a transtibial technique can anatomically position both tibial and femoral tunnels is highly dependent on tibial tunnel starting position.

STUDY DESIGN:

Descriptive laboratory study.

METHODS:

Eight fresh-frozen adult knee specimens were fixed at 90° of flexion and then dissected to expose the femoral and tibial ACL footprints. After the central third patellar tendon length was measured for each specimen, computer-assisted navigation was used to identify 2 idealized tibial tunnel starting points, optimizing alignment with the native ligament in the coronal plane but distal enough on the tibia to provide manageable bone-tendon-bone autograft-tibial tunnel mismatch (point A = 10-mm mismatch; point B = 0-mm mismatch). Tibial tunnels were then reamed to the center of the tibial insertion using point A in half of the knees and point B in the other half. Guide pin positioning on the femoral side was then assessed before and after tibial tunnel reaming, after beveling the posterolateral tibial tunnel rim, and after performing a standard notchplasty. After the femoral tunnel was reamed, the digitized contours of the native insertions were compared with those of both tibial and femoral tunnels to calculate percentage overlap.

RESULTS:

Starting points A and B occurred 15.9 ± 4.5 mm and 33.0 ± 3.3 mm distal to the joint line, respectively, and 9.8 ± 2.4 mm and 8.3 ± 4.0 mm from the medial edge of the tibial tubercle, respectively. The anterior and posterior aspects of both tibial tunnels' intra-articular exits were within a few millimeters of the native insertion's respective boundaries. After the tibial tunnel was reamed from the more proximal point A, a transtibial guide pin was positioned within 2.1 ± 1.6 mm of the femoral insertion's center (vs 9.3 ± 1.9 mm for point B; P = .02). After beveling a mean 2.6 mm from the back of the point A tibial tunnels, positioning improved to within 0.3 ± 0.7 mm from the center of the femoral insertion (vs 4.2 ± 1.1 mm for the point B tibial tunnels; P = .008). Compared with the more distal starting point, use of point A provided significantly greater insertional overlap (tibial: 97.9% ± 1.4% vs 71.1% ± 15.1%, P = .03; femoral: 87.9% ± 9.2% overlap vs 59.6% ± 8.5%, P = .008). No significant posterior femoral or tibial plateau breakthrough occurred in any specimen.

CONCLUSION:

Tibial and femoral tunnels can be positioned in a highly anatomic manner using a transtibial technique but require careful choice of a proximal tibial starting position and a resulting tibial tunnel that is at the limits of practical. Traditional tibial tunnel starting points will likely result in less anatomic femoral tunnels.

CLINICAL RELEVANCE:

A transtibial single-bundle technique can accomplish a highly anatomic reconstruction but does require meticulous positioning of the tibial tunnel with little margin for error and some degree of graft-tunnel mismatch.

PMID:
21335345
[PubMed - indexed for MEDLINE]
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