Importance of anatomically locating the infrapatellar branch of the saphenous nerve in reconstructing the anterior cruciate ligament using flexor tendons.

Objective: To describe the path of the infrapatellar branch of the saphenous nerve (IBSN) using the medial joint line, anterior tibial tuberosity (ATT), tibial collateral ligament and a horizontal line parallel to the medial joint line that passes over the ATT, as reference points, in order to help surgeons to diminish the likelihood of injuring this nerve branch during reconstruction of the anterior cruciate ligament (ACL) using flexor tendons.
Methods: Ten frozen knees that originated from amputations were examined. Through anatomical dissection performed with the specimens flexed, we sought to find the IBSN, from its most medial and proximal portion to its most lateral and distal portion. Following this, the anatomical specimens were photographed and, using the ImageJ software, we determined the distance from the IBSN to the medial joint line and to a lower horizontal line going through the ATT and parallel to the first line. We also measured the angle of the direction of the path of the nerve branch in relation to this lower line.
Results: The mean angle of the path of the nerve branch in relation to the lower horizontal line was 17.50 ± 6.17°. The mean distance from the IBSN to the medial joint line was 2.61 ± 0.59 cm and from the IBSN to the lower horizontal line, 1.44 ± 0.51 cm.
Conclusion: The IBSN was found in all the knees studied. In three knees, we found a second branch proximal to the first one. The direction of its path was always from proximal and medial to distal and lateral. The IBSN was always proximal and medial to the ATT and distal to the medial joint line. The medial angle between its direction and a horizontal line going through the ATT was 17.50 ± 6.17°.