Surgical and Anatomic Considerations in ACL Reconstruction
There is clear evidence to support that transtibial drilling does not fully restore the anatomic femoral footprint of the ACL. This section will discuss the most recent literature on this debate. Bedi et al. evaluated 10 cadaver specimens that underwent ACL reconstruction with transtibial and anteromedial portal technique. They showed that the guidewire was positioned in the center of the ACL femoral footprint in all cases with anteromedial portal drilling, and with transtibial reaming the femoral tunnel was positioned a mean distance of 1.94 mm anterior and 3.26 mm superior to the center of the femoral footprint. In addition, their biomechanical evaluation showed that the anteromedial portal ACL reconstruction controlled tibial translation significantly more than the transtibial reconstruction with anterior drawer, Lachman, and pivot shift examinations of knee stability. Strauss et al. performed a cadaver studying using transtibial drilling with an over-the-top guide to drill the femoral tunnel. Their results showed that the mean overlap of the femoral tunnel was 30% of the native femoral insertion, and was 7.6 mm from the center of the native ACL femoral insertion. They concluded that the transtibial technique resulted in a nonanatomic femoral tunnel that is posterior and superior to the native femoral insertion. Tompkins et al. evaluated 10 cadaveric knees that had either transtibial or anteromedial ACL reconstruction. Preoperative and postoperative CT scans were performed. Their results showed that the anteromedial technique placed 97.7% of the tunnel with the native femoral footprint, significantly more than 61.2% for the transtibial technique. In addition, anteromedial drilling placed the center of the femoral tunnel 3.2 mm from the native center of the femoral ACL footprint compared with 6.0 mm with the transtibial technique. Gadikota et al. evaluated femoral tunnel drilling with the transtibial, anteromedial, and outside-in technique in cadaver specimens and used three-dimensional software to analyze the reconstructions. They showed that on average 27% of the transtibial tunnel was outside the ACL footprint. This was significantly larger compared with 13.6% with the anteromedial technique and 10.8% with the outside-in technique. Larson et al. compared four techniques of femoral tunnel drilling including: transtibial, anteromedial drilling over a rigid guidewire, anteromedial drilling over a flexible guidewire, and outside-in reaming. The results were analyzed with three-dimensional CT scans. They concluded that drilling using the transtibial technique produces the most vertical and longest tunnels. Independent drilling techniques produced the most anatomic tunnels but at the expense of tunnel length. Robert et al. evaluated coverage of the ACL femoral footprint using transtibial, anteromedial, and outside-in drilling in ACL reconstruction of cadaver knees. The results showed the average distance to the native ACL femoral footprint was 6.8 mm for the transtibial technique, 2.84 mm for the anteromedial technique, and 2.56 mm for the outside-in technique. The average percentage of ACL footprint coverage was 32%, 76%, and 78% with the transtibial, anteromedial, and outside-in technique, respectively.
Three recent studies examined in vivo results of femoral tunnel placement rather than using cadaver specimens. Koopf et al. evaluated 58 patients with three-dimensional CT scans after transtibial ACL reconstruction. They used the quadrant method and the anterior-to-posterior and proximal-to-distal measurements and compared these to previously established anatomic tunnel positions. They concluded that traditional ACL reconstruction by the transtibial technique fails to accurately position both the femoral and the tibial tunnels within the native ACL insertion site. Ahn et al. obtained three-dimensional CT scans in 69 patients who had either two-incision outside-in ACL reconstruction, or transtibial ACL reconstruction. They concluded that after single-bundle ACL reconstruction, three-dimensional CT showed that the outside-in technique allows for the placement of the graft closer to the anatomic tunnel position when compared to the traditional transtibial technique. Takeda et al. performed a randomized study evaluating 50 patients, with 25 having ACL reconstruction using the transtibial technique and the other half anteromedial drilling. Both groups had double-bundle reconstruction. Three-dimensional CT scans were performed postoperatively. They concluded that the anteromedial and posterolateral femoral tunnels were placed significantly deeper, lower, and closer to the femoral footprint reported in previous cadaver studies in the anteromedial portal technique than in the transtibial technique. However, femoral tunnel length was significantly shorter in the anteromedial portal group than in the transtibial group.
Only one study was located showing that the tibial and femoral footprints of an ACL reconstruction could be placed in a highly anatomic position using the transtibial technique. Piasecki et al. performed ACL reconstruction on cadaver specimens. They noted with careful tibial pin placement and beveling of the tibial tunnel that they could reproduce native femoral tunnel placement more reliably than traditional tibial tunnel placement. However, even with their modified transtibial technique, only 87% overlap of the native femoral ACL footprint was achieved. In summary, the only way to ensure that the drill hole is within the native footprint is to either drill from the medial portal or outside-in in a two-incision technique.
Can Transtibial Drilling Recreate the Anatomic Femoral Footprint of the ACL?
There is clear evidence to support that transtibial drilling does not fully restore the anatomic femoral footprint of the ACL. This section will discuss the most recent literature on this debate. Bedi et al. evaluated 10 cadaver specimens that underwent ACL reconstruction with transtibial and anteromedial portal technique. They showed that the guidewire was positioned in the center of the ACL femoral footprint in all cases with anteromedial portal drilling, and with transtibial reaming the femoral tunnel was positioned a mean distance of 1.94 mm anterior and 3.26 mm superior to the center of the femoral footprint. In addition, their biomechanical evaluation showed that the anteromedial portal ACL reconstruction controlled tibial translation significantly more than the transtibial reconstruction with anterior drawer, Lachman, and pivot shift examinations of knee stability. Strauss et al. performed a cadaver studying using transtibial drilling with an over-the-top guide to drill the femoral tunnel. Their results showed that the mean overlap of the femoral tunnel was 30% of the native femoral insertion, and was 7.6 mm from the center of the native ACL femoral insertion. They concluded that the transtibial technique resulted in a nonanatomic femoral tunnel that is posterior and superior to the native femoral insertion. Tompkins et al. evaluated 10 cadaveric knees that had either transtibial or anteromedial ACL reconstruction. Preoperative and postoperative CT scans were performed. Their results showed that the anteromedial technique placed 97.7% of the tunnel with the native femoral footprint, significantly more than 61.2% for the transtibial technique. In addition, anteromedial drilling placed the center of the femoral tunnel 3.2 mm from the native center of the femoral ACL footprint compared with 6.0 mm with the transtibial technique. Gadikota et al. evaluated femoral tunnel drilling with the transtibial, anteromedial, and outside-in technique in cadaver specimens and used three-dimensional software to analyze the reconstructions. They showed that on average 27% of the transtibial tunnel was outside the ACL footprint. This was significantly larger compared with 13.6% with the anteromedial technique and 10.8% with the outside-in technique. Larson et al. compared four techniques of femoral tunnel drilling including: transtibial, anteromedial drilling over a rigid guidewire, anteromedial drilling over a flexible guidewire, and outside-in reaming. The results were analyzed with three-dimensional CT scans. They concluded that drilling using the transtibial technique produces the most vertical and longest tunnels. Independent drilling techniques produced the most anatomic tunnels but at the expense of tunnel length. Robert et al. evaluated coverage of the ACL femoral footprint using transtibial, anteromedial, and outside-in drilling in ACL reconstruction of cadaver knees. The results showed the average distance to the native ACL femoral footprint was 6.8 mm for the transtibial technique, 2.84 mm for the anteromedial technique, and 2.56 mm for the outside-in technique. The average percentage of ACL footprint coverage was 32%, 76%, and 78% with the transtibial, anteromedial, and outside-in technique, respectively.
Three recent studies examined in vivo results of femoral tunnel placement rather than using cadaver specimens. Koopf et al. evaluated 58 patients with three-dimensional CT scans after transtibial ACL reconstruction. They used the quadrant method and the anterior-to-posterior and proximal-to-distal measurements and compared these to previously established anatomic tunnel positions. They concluded that traditional ACL reconstruction by the transtibial technique fails to accurately position both the femoral and the tibial tunnels within the native ACL insertion site. Ahn et al. obtained three-dimensional CT scans in 69 patients who had either two-incision outside-in ACL reconstruction, or transtibial ACL reconstruction. They concluded that after single-bundle ACL reconstruction, three-dimensional CT showed that the outside-in technique allows for the placement of the graft closer to the anatomic tunnel position when compared to the traditional transtibial technique. Takeda et al. performed a randomized study evaluating 50 patients, with 25 having ACL reconstruction using the transtibial technique and the other half anteromedial drilling. Both groups had double-bundle reconstruction. Three-dimensional CT scans were performed postoperatively. They concluded that the anteromedial and posterolateral femoral tunnels were placed significantly deeper, lower, and closer to the femoral footprint reported in previous cadaver studies in the anteromedial portal technique than in the transtibial technique. However, femoral tunnel length was significantly shorter in the anteromedial portal group than in the transtibial group.
Only one study was located showing that the tibial and femoral footprints of an ACL reconstruction could be placed in a highly anatomic position using the transtibial technique. Piasecki et al. performed ACL reconstruction on cadaver specimens. They noted with careful tibial pin placement and beveling of the tibial tunnel that they could reproduce native femoral tunnel placement more reliably than traditional tibial tunnel placement. However, even with their modified transtibial technique, only 87% overlap of the native femoral ACL footprint was achieved. In summary, the only way to ensure that the drill hole is within the native footprint is to either drill from the medial portal or outside-in in a two-incision technique.
SHARE
