The 'sentinel' vessel: an anatomical landmark to identify the pes anserinus during hamstrings harvest for ACL reconstruction.

Hamstrings identification and subsequent graft harvest can be made difficult by body habitus and variability in tendon anatomy. We describe a 'sentinel' blood vessel near the insertions of gracilis and semitendinosus to facilitate identification. A prospective study of 100 patients (100 knees) undergoing primary arthroscopic ACL reconstruction (via the anterior approach) with hamstrings graft was conducted. We searched for a 'sentinel' vessel and studied its position, orientation and perpendicular distance from the pes tendons. The 'sentinel' vessel was present in 98/100 knees. It passed from the superficial fascia to the periosteum at the pes insertion at a mean perpendicular distance of 8 mm from the upper border of the pes tendons. The 'sentinel' vessel was a consistent anatomical finding and served as a reliable guide in determining the pes insertion. Identifying this anatomical landmark allowed a small skin incision with limited wound dissection minimising risk of injury to the infra-patellar branch of the saphenous nerve.