Summary

Drilling a femoral tunnel for the fixation of the TA with 30° of ventral inclination, we avoid a collision with the femoral ACL tunnel and we maintain a bone bridge between the two tunnels of at least 5 mm.

Abstract

Objectives: Some anterolateral tenodesis reconstructions suggest the use of the central third of the iliotibial band fixed proximally drilling a femoral tunnel. It has not yet been analysed the possibility of collision between this tunnel and the one of the Anterior Cruciate Ligament (ACL). It has not been described the best angle for a safe drilling of the tunnel of the tenodesis to avoid this collision. The aim of this study is to analyse postoperative CT of patients underwent consensual reconstruction of ACL and Anterolateral Tenodesis (AT).
The hypothesis was: drilling the tunnel of the tenodesis with an inclination angle of 30° ventrally from the transepicondylar axis there is no collision and between the tunnels there is a residual bone bridge of at least 5 mm.

Methods

Was analysed a prospective series of 33 postoperative CT scan of patients underwent consensual reconstruction of ACL and AT. ACL were reconstructed with an anatomic femoral tunnel and AT were performed with the central third of iliotibial band fixed via interference screw in a femoral tunnel starting 5 mm proximally and 5 mm ventrally from the lateral femoral epicondyle and with a 30° ventral inclination from the transepicondylar axis (TA)
The following parameters were evaluated:
- collisions between the tunnels
- the residual bone bridge between the tunnels evaluated at the level of the lateral condylar cortex and at a distance of 10 mm more deeply
The following measurements were carried out:
- the inclination of the tenodesis angle with respect to the transepicondylar axis both in axial and coronal plane. Positive values were considered when the inclination of the tunnel was in the proximal or ventral direction from TA, negative when the direction was distal or dorsal.
- simulated drilling of the TA's tunnels in the axial plane with the same starting point of the real tunnels but whit a 30° of standard ventral inclination were carried out. Subsequently any collision was evaluated.
All the measurements were carried out by one orthopedic surgeon and one radiologist, the latter blind to the aim of the study. For each case the measurements were taken twice, keeping the result of the first measurement blind. Ultimately, a statistical analysis was performed in order to analyze inter and intra-rater reliability.

Results

We found 7 cases (21.21%) of femoral tunnels collision. In 8 cases (24.24%), the observed bone bridge between the 2 tunnels was less than 5 mm; 2 cases (6.06%) at the cortical level and 6 cases (18.18%) 10 mm more deeply.
In all collisions' cases, the inclination in the axial plane was in a range of +8.28°/+19°, the one in the coronary plane results in a range of - 10.42°/+26°
In cases where the bone bridge between the tunnels was less than 5 mm the inclination in the axial plane was in a range of +16.02°/ +24.58°, the inclination in the coronal plane was in a range -14.39°/26°.
In 18 cases (54,54%) no collisions were observed and at least 5 mm of bone bridge between the 2 tunnels was maintained. In these cases, the inclination in the axial plane was in the range of +23.15°/+27.09°, the inclination in the coronal plane was in a range of - 15.34°/+28.38°.
No collision was detected when the simulated drilling was carried out with 30° of ventral inclination in the axial view.

Conclusions

Drilling a femoral tunnel for the fixation of the TA with 30° of ventral inclination, we avoid a collision with the femoral ACL tunnel and we maintain a bone bridge between the two tunnels of at least 5 mm.
The inclination of the tunnel in the proximal or distal direction does not appear to affect the possibility of conflict if the starting point is 5 mm ventrally and 5 mm proximally from the lateral femoral epicondyle.