Morphological study and relations of the fascia vasto-adductoria

The precise description of the fascia vasto-adductoria (FVA) has become an issue of great surgical and clinical importance. Neurovascular entrapment within the adductor canal (AC) may simulate many clinical conditions for cases presented with medial knee or leg pain and ischemic manifestations of the leg. The aim of the present work is to describe the morphological features of the FVA and to elucidate its neurovascular relations. Forty thigh specimens, pertaining to 15 embalmed and five fresh adult human cadavers, were dissected in pursuit of this aim. The FVA was a continuous subsartorial fascia, roofing the whole length of AC and extended between two points lying at a mean distance of 25.6 and 7 cm proximal to the base of patella. It was subdivided into two parts; proximal thin quadrangular (proximal part of FVA) and distal thick pentagonal (vastoadductor membrane; VAM) and the subsartorial space was observed superficial to it. The mean length of its proximal and distal parts was 7.8 and 7.9 cm, respectively. The proximal part of FVA, while stretched across the vastus medialis (VM) and the adductor longus (AL) muscles, became attached to the wall of the femoral artery and overlaid the femoral vessels, the saphenous nerve (SN), and an arterial pedicle for VM muscle. It was constantly pierced by two arterial pedicles arising from the femoral artery to the sartorius muscle and occasionally (50%) by a communicating nerve branch arising from the SN to join the medial femoral cutaneous nerve. The VAM stretched across the VM muscle and both the AL and adductor magnus (AM) muscles and overlaid the SN, its subsartorial and lower medial femoral cutaneous branches, femoral vessels, 1–3 arterial pedicles for the sartorius and descending genicular vessels. The VAM originated from the tendinous fibres of the AM tendon and constantly spread anterolaterally. It was constantly pierced by 1–3 arterial pedicles to sartorius muscle and both the lower medial femoral cutaneous branch and the subsartorial branches of the SN. An arterial pedicle to the VM muscle and perforating veins between the superficial veins and the femoral vein proved to pierce it in 8/40 specimens. Entrapment of the SN at the distal narrow aperture of the AC, or one of its cutaneous branches at the piercing sites of the FVA, should be remembered when diagnosing cases presented with medial knee or leg pain. The attachment of the proximal part of the FVA to the wall of the femoral artery could add to the mechanism of its potential compression. True AC block should be done deep to the FVA to ensure effective SN analgesia. Its site is recommended to be at the distal one cm of the proximal part of the AC which is at a distance of 16–17 cm proximal to the base of patella. The VAM, being an anatomical connection between the VM and AM muscles, is theorized to increase the mechanical efficiency of the VM oblique muscle to maintain the knee extensor mechanism.