Injury of the Infrapatellar Branch of the Saphenous Nerve During Hamstring Graft Harvest

PURPOSE Sensory disturbance around the surgical incision due to injury of the infrapatellar branch of the saphenous nerve can be seen in the anterior cruciate ligament reconstruction. In this research, we aimed to compare the incidence, extent of sensory loss, its clinical effect, and natural course caused by two different skin incisions used for hamstring graft harvest. METHODS Vertical incision for 36 patients and oblique incision for 42 patients used for graft harvest were included in this study. Sensory loss areas were documented at 6th week, 3rd month and 6th month. Pin prick examination is used to detect the change in sensation. Digital photographs of hypaesthesia were taken and analysed by computer for area detection. The length of incision and subjective complain of sensory loss were also noted. RESULTS At 6th month, 77% (28/36) of the vertical incisions were associated with persistent sensory loss when compared to the oblique incision (45%, 19/42). The measured area of hypaesthesia was significantly higher in vertical incision (42.4 ± 22.3 cm2) than that in oblique incision (9.3 ± 15.3 cm2) at 6th month. The area of hypaesthesia gradually shrunk in size from distal to proximal in direction. Also, subjective cutaneous anaesthesia was higher in vertical incision (15/36, 41%) than oblique incision (6/41, 14%) at 6th month. CONCLUSION Oblique incision with less risk of nerve damage is better for graft harvesting. Area of hypaesthesia gradually reduces with time and even recover totally. As a possible complication, nerve injury and its benign prognosis should be explained to the patient before surgery.