Injury to the infrapatellar branch of the saphenous nerve in ACL reconstruction with the hamstrings technique: clinical and electrophysiological study.

The incidence of IBSN injury to the infrapatellar branch of the saphenous nerve (IBSN) in ACL surgery using the hamstrings technique has been reported to be between 30 and 59%. The purpose of this study was to evaluate the incidence of IBSN injury in ACL surgery with the hamstrings technique through clinical and electrophysiological evaluation, and also to evaluate potential risk factors of IBSN injury related to the surgical incision. Between November 2003-September 2004, 21 consecutive patients (22 knees) with an acute ACL rupture suitable for reconstruction were included. Patients with previous surgeries or scars around the knee and those with any degree of osteoarthritis were excluded. Clinical and electrophysiological evaluations were performed in all the cases. Hypoesthesia of the IBSN territory was found in 17 knees (77%) with an average area of 36 cm(2) (1-120 cm(2)). Injury to the IBSN was electrophysiologically detected in 15 knees (68%). Two patients also had an injury to the saphenous nerve (9%). The presence of sensory loss associated with damage to the IBSN did not correlate with the size of the incision or the distance to the tibial tubercle. This injury probably occurs during tendon harvesting as found by an injury to the saphenous nerve in two of our patients. However the sensory loss does not impair normal daily activities in these patients.