Tunneling position

Pettinger et al. observed a TERS spectrum of monolayer-thick brilliant cresyl blue (BCB) adsorbed on a smooth Au film surface by using a Ag tip, while no STM image of the adsorbed surface was shovm [23]. The Raman intensity increased when the tip was in the tunneling position, meaning that the tip-surface distance was around 1 nm. They calculated the field enhancement factor by the method described by... 

In addition to sulphate, selenate (J. M. Bigham, unpubl.) and chromate (S. Regen-spurg unpubl.) can also be incorporated in the tunnels of synthetic schwertmannite. Whether or not two different Se-O distances (based on EXAFS) attributable to surface and tunnel selenate, respectively, exist in the Se-form is still under discussion (Waychunas et al., 1995, 1995 a). The Cr form has the bulk composition Fei6Oi6(OH)i0.23(CrO4)2.gg. In fact, synthetic schwertmannite formed in the sul-phate/arsenate system tolerates arsenate only up to a As/(As-rS) mole ratio of ca. 0.5, and it is likely that most of this arsenate is surface-bound. Above this ratio, a new, very poorly ordered Fe-hydroxy arsenate with two broad XRD peaks at ca. 0.31 and 0.16 nm and BhfS at 4.2K and ca. 1.5 K of 41.6 and 47.3T, respectively, forms (Carlson et al. 2002). From this one may conclude that, whereas the tetrahedral oxyanions with hexavalent central cations (S Se Cr) can be accomodated in the tunnel positions, the pentavalent cations can not, or not as easily. Schwertmannite from acid mine water contained between 6 and 70 g kg As (Carlson et al. 2002). 

Further candidates for the tunnel position in the schwertmannite structure is selenate. It seems that the oxyanions of hexavalent elements (S, Se, Cr) can be accomodated in the akaganeite structure whereas tliose of pentavalent ones (P, As) may only adsorb on the surface (Waychunas et al. 1995). 

Zantop T, Wellmann M, Fu FH, Petersen W (2008) Tunnel positioning of anteromedial and posterolateral bundles in anatomic anterior cruciate ligament reconstruction. Am J Sports Med 36(l) 65-72... 

Ziegler CG, Pietrini SD, Westerhaus BD, Anderson CJ, Wijdicks CA, Johansen S, Engebretsen L, LaPrade RF (2011) Arthroscopically pertinent landmarks for tunnel positioning in single-bundle and double-bundle anterior cruciate ligament reconstructions. Am J Sports Med 39(4) 743-752... 

Fig. 3.6 Actual femoral bone tunnel position during ACL reconstruction in arthroscopy...

Fig. 4.6 Ideal tunnel position for (a) single-bundle reconstruction, (b) double-btmdle reconstruction from our results. White dot line, L-shaped ridge red line, attachment of anterior horn of lateral meniscus blue dot line, anterior margin of the medial and lateral intercondylar tubercle yellow circle, tibial tunnel for single-bundle ACL reconstruction red circle, tibial tunnel of anteromedial bundle for double-bundle ACL reconstruction blue circle, tibial tunnel of posterolateral bundle for double-bundle ACL reconstruction...

The debate in terms of the morphology and stmcture of the ACL has continued to this day. The choice of graft material and tunnel position of ACL reconstmction is dependent on how various evidences from the current anatomical literature are interpreted. Our proposed method for tibial tunnel creation is greatly simplified, and we believe that our results and method for tibial tunnel creation can be usefully applied to any reconstmction technique furthermore, we strongly believe that accurate reproducibility of tibial tunnel creation can be achieved by its standardization. 

The second aim of this chapter is to answer the following question Can the clinically available transtibial procedure for anatomic DB reconstruction really obtain significantly better knee stability in comparison with the conventional SB reconstruction procedure This question must be asked because the previous biomechanical studies, which reported that the former procedure can obtain significantly better knee stability than the latter procedure [11-13], widely exposed the knee joint and directly identify the anatomic attachments. Clinically, however, the authors have used an arthroscopic transtibial procedure for femoral tuimel creation. Therefore, there is a possibility that the femoral tunnel positions in the clinical are not identical to the ideal tuimel locations created in the previous biomechanical studies. To answer the following question, the authors performed the arthroscopic transtibial procedure of anatomic DB reconstruction, which had been performed in the authors clinical practice, in cadaver specimens, and compared the results with those of the conventional SB reconstruction procedure [11]. 

Giron F, Cuomo P, Edwards A, Bull AM, Amis AA, Aglietti P (2007) Double-bundle anatomic anterior cruciate ligament reconstruction a cadaveric study of tunnel positioning with a transtibial technique. Arthroscopy 23(1) 7-13... 

Neven E, D Hooghe P, Bellemans J (2008) Double-bundle anterior cruciate ligament reconstruction a cadaveric study on the posterolateral tunnel position and safety of the lateral structures. Arthroscopy 24(4) 436-440... 

V shows the transverse ligament. The 2.4-mm guide wire for the AM tunnel should be inserted just posterior to the transverse ligament at 90° knee flexion. The AM tunnel position must not be too anterior to the ACL tibial attachment. It is important to maintain 90° knee flexion to avoid misplacement caused by changing the position of the transverse ligament... 

The relationship between femoral and tibial tunnel positions is important to avoid causing impingement. During ACL reconstruction, the transverse ligament and Parsons knob are useful as anterior landmarks, the medial intercondylar ridge is... 

This is a reconstructed AM graft of the ACL from the anterolateral portal. The synovial cover is evaluated as excellent, tension is evaluated as taut, and there is no tear of the AM graft. This view of second-look arthroscopy shows that this tunnel position does not cause roof impingement... 

Bedi A, Maak T, Musahl V, Citak M, O Loughlin PF, Choi D, Pearle AD (2011) Effect of tibial tunnel position on stability of the knee after anterior cmciate ligament reconstruction is the tibial tunnel positimi most important Am J Sports Med 39(2) 366-373. doi 10.1177/ 0363546510388157... 

As mentioned, in traditional single-bundle reconstmction using the transtibial technique, the femoral tunnel was made at the isometric point on the lateral wall of the intercondylar notch. This traditional femoral tunnel position was higher and more anterior to the anatomic ACL footprint therefore, various types of ACL graft impingement have been reported in this technique. 

Fig. 22.1 A case with residual instability after nonanatomic single-bundle ACL reconstruction, without graft tear by obvious reinjury. (a, b) Femoral tunnel position (a, white arrow) and tibial tunnel position (b, black arrow) in three-dimensional computed tomography, (c) Magnetic resonance imaging (sagittal view). The femoral tunnel was made at the high noon position on the lateral wall of the intercondylar notch. Tibial tunnel was placed posteriorly to avoid graft impingement. However, normal restoration of the knee kinematics and stability would be impaired with such a vertical graft placement ...

When it comes to the tibial tunnel position, the risk of roof impingement might be higher in anatomic reconstmction, as the tibial tunnel of the AMB in anatomic... 

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