An anatomical study to determine the safest posterior arthroscopic approach to the human hip

Abstract

The human hip (acetabulofemoral joint) is amongst the most complex joints for arthroscopic surgery. This is due to the many inviolable structures that are in direct contact, proximity, or surround the hip joint, notably: the femoral neurovascular bundle, anteriorly; the lateral cutaneous nerve of the thigh, in the anterolateral aspect; and gluteal vessels and the sciatic nerve (SN) in the posterior region. Arthroscopic access of the hip joint involves the opening of cutaneous entry portals. We here discuss the posterior portal (PP), placed at 1cm proximal and 1cm posterior to the palpable apex of the great trochanter, where its anterior and posterior edges merge superiorly, in neutral position or slight interior rotation of the hip (Aprato et al. Muscles, Ligaments and Tendons Journal. 2016). The PP offers a good view of the posterior aspect of the articular capsule of hip, but involves risk of injury to the SN and anatomical variations should be considered. This study evaluates the types of anatomic variations of the SN and assesses the risk of nerve injury by measuring the distance between the nerve and the PP in 40 cadaveric hip joints (17 males and 3 females). We used a millimeter caliper to obtained the measurements and the standard Beaton's and Anson's criteria (Anat Rec. 1937) as a reference to classify the anatomic variations. From our sample, 35 specimens presented with variation type I: SN emerging below the piriformis muscle (PM) in a single bundle; and 5 specimens presented with variation type II, common peroneal nerve running through the PM and the tibial nerve emerging below the PM. The average distance from the sciatic nerve to the PP was 3.06cm for type I variation group, 2.46cm for the type II variation group (p<0.05, Wilcoxon and t test). In the cases presenting with type II variation, the SN is closer to the region of access via PP and the risk of injury is higher. We recommend a careful analysis of the MRI, prior to the surgery, with attention to the anatomical variations of the SN, and a maximum distance of 2.0cm from the cutaneous PP in order to increase the surgical safety of posterior arthroscopic approaches of the human hip joint.Support or Funding InformationIn conjunction with the Building Bridges initiativesThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.