Relationship between different skin incisions and the injury of the infrapatellar branch of the saphenous nerve during anterior cruciate ligament reconstruction.

BACKGROUND: After anterior cruciate ligament (ACL) reconstruction, some patients suffered from sensory disturbance around the surgical incision of the leg. This research was aimed to investigate the relationship between the different skin incisions and the injury of the infrapatellar branch of the saphenous nerve (IPBSN) post ACL reconstruction.

METHODS: ACL reconstructions were performed with quadruple hamstring tendon for 60 patients. Sensory disturbance around the skin incision was followed up at an average of 14.5 +/- 4.7 months post operation. Among the 60 patients, vertical incision for 35 patients and oblique incision for 25 patients were used for graft taking during ACL reconstruction. The lengths of the incisions were measured. The patients were asked to mark the sensory disturbance zone at follow up time, and then the marked area was measured. The IPBSN of 15 cadaver knees were anatomized. The distance between the IPBSN and the upper edge of the pes anserinus tendon at the middle point of the incision was measured. Independent-samples t-test, chi-square and Mann-Whitney tests were used for statistical analyses.

RESULTS: The patients' age (P = 0.329), the follow-up time (P = 0.681), and the incision length (P = 0.732) between the two groups had no significant difference. Twenty-three patients (65.7%) in the vertical incision group had IPBSN injury compared with 6 patients (24.0%) in oblique incision group (P = 0.002). The average sensory disturbance area in vertical incision group ((48.0 +/- 75.3) cm(2)) was significantly larger (P = 0.004) than that in the oblique group ((8.4 +/- 19.4) cm(2)). The anatomy measurement showed the average distance between IPBSN and the upper edge of the pes anserinus tendon was 0.6 cm at the incision.

CONCLUSIONS: Oblique incision with less risk of damage for IPBSN may be better for graft harvesting in ACL reconstruction. As the IPBSN is so near and parallel to the hamstring tendons, damage to the IPBSN is one of the potential complications for graft harvesting, regardless of the incision used. That's why even in the oblique incision group, 24% patients also had sensory disturbance complication.