Great Saphenous Vein Cutdown-The Great Saphenous Vein in Coronary Bypass Surgery

Great Saphenous Vein Cutdown

Exposure of the great saphenous vein through a skin incision (a“cutdown”) is usually performed at the ankle. This site has the disadvantage that phlebitis (inflammation of the vein wall) is a potential complication. The great saphenous vein also can be entered at the groin in the femoral triangle, where phlebitis is relatively rare; the larger diameter of the vein at this site permits the use of large-diameter catheters and the rapid infusion of large volumes of fluids

Anatomy of Ankle Vein Cutdown

The procedure is as follows:

1. The sensory nerve supply to the skin immediately in front of the medial malleolus of the tibia is from branches of the saphenous nerve, a branch of the femoral nerve.

The saphenous nerve branches are blocked with local anesthetic.

2. A transverse incision is made through the skin and subcutaneous tissue across the long axis of the vein just anterior and superior to the medial malleolus. Although the vein may not be visible through the skin, it is constantly found at this site.

3. The vein is easily identified, and the saphenous nerve should be recognized; the nerve usually lies just anterior to the vein

Anatomy of Groin Vein Cutdown

1. The area of thigh skin below and lateral to the scrotum or labium majus is supplied by branches of the ilioinguinal nerve and the intermediate cutaneous nerve of the thigh. The branches of these nerves are blocked with local anesthetic.

2. A transverse incision is made through the skin and subcutaneous tissue centered on a point about 1.5 in. (4 cm) below and lateral to the pubic tubercle . If the femoral pulse can be felt (may be absent in patients with severe shock), the incision is carried medially just medial to the pulse.

3. The great saphenous vein lies in the subcutaneous fat and passes posteriorly through the saphenous opening in the deep fascia to join the femoral vein about 1.5 in. (4 cm), or two fingerbreadths below and lateral to the pubic tubercle. It is important to understand that the great saphenous vein passes through the saphenous opening to gain entrance to the femoral vein. However, the size and shape of the opening are subject to variation.

The Great Saphenous Vein in Coronary Bypass Surgery

In patients with occlusive coronary disease caused by atherosclerosis, the diseased arterial segment can be bypassed by inserting a graft consisting of a portion of the great saphenous vein. The venous segment is reversed so that its valves do not obstruct the arterial flow. Following removal of the great saphenous vein at the donor site, the superficial venous blood ascends the lower limb by passing through perforating veins and entering the deep veins.

The great saphenous vein can also be used to bypass obstructions of the brachial or femoral arteries.

Venous Pump of the Lower Limb-Varicose Veins

Venous Pump of the Lower Limb

Within the closed fascial compartments of the lower limb, the thinwalled, valved venae comitantes are subjected to intermittent pressure at rest and during exercise. The pulsations of the adjacent arteries help move the blood up the limb. However, the contractions of the large muscles within the compartments during exercise compress these deeply placed veins and force the blood up the limb.

The superficial saphenous veins, except near their termination, lie within the superficial fascia and are not subject to these compression forces. The valves in the perforating veins prevent the high-pressure venous blood from being forced outward into the low-pressure superficial veins. Moreover, as the muscles within the closed fascial compartments relax, venous blood is sucked from the superficial into the deep veins.

Varicose Veins

A varicosed vein is one that has a larger diameter than normal and is elongated and tortuous. Varicosity of the esophageal and rectal veins is described elsewhere.

This condition commonly occurs in the superficial veins of the lower limb and, although not life threatening, is responsible for considerable discomfort and pain.

Varicosed veins have many causes, including hereditary weakness of the vein walls and incompetent valves; elevated intraabdominal pressure as a result of multiple pregnancies or abdominal tumors; and thrombophlebitis of the deep veins, which results in the superficial veins becoming the main venous pathway for the lower limb. It is easy to understand how this condition can be produced by incompetence of a valve in a perforating vein. Every time the patient exercises, high-pressure venous blood escapes from the deep veins into the superficial veins and produces a varicosity, which might be localized to begin with but becomes more extensive later. The successful operative treatment of varicosed veins depends on the ligation and division of all the main tributaries of the great or small saphenous veins, to prevent a collateral venous circulation from developing, and the ligation and division of all the perforating veins responsible for the leakage of highpressure blood from the deep to the superficial veins. It is now common practice to remove or strip the superficial veins in addition.

Needless to say, it is imperative to ascertain that the deep veins are patent before operative measures are taken.

Arteries of the Gluteal Region-Superior Gluteal Artery-Inferior Gluteal Artery-The- Trochanteric Anastomosis

Arteries of the Gluteal Region

Superior Gluteal Artery

The superior gluteal artery is a branch from the internal iliac artery and enters the gluteal region through the upper part of the greater sciatic foramen above the piriformis. It divides into branches that are distributed throughout the gluteal region.

 

Inferior Gluteal Artery

The inferior gluteal artery is a branch of the internal iliac artery and enters the gluteal region through the lower part of the greater sciatic foramen, below the piriformis. It divides into numerous branches that are distributed throughout the gluteal region.

The Trochanteric Anastomosis

The trochanteric anastomosis provides the main blood supply to the head of the femur. The nutrient arteries pass along the femoral neck beneath the capsule. The following arteries take part in the anastomosis: the superior gluteal artery, the inferior gluteal artery, the medial femoral circumflex artery, and the lateral femoral circumflex artery.

The Cruciate Anastomosis

The cruciate anastomosis is situated at the level of the lesser trochanter of the femur and, together with the trochanteric anastomosis, provides a connection between the internal iliac and the femoral arteries. The following arteries take part in the anastomosis: the inferior gluteal artery, the medial femoral circumflex artery, the lateral femoral circumflex artery, and the first perforating artery, a branch of the profunda artery.

Veins of the Lower Limb

The veins of the lower limb can be divided into three groups: superficial, deep, and perforating. The superficial veins consist of the great and small saphenous veins and their tributaries, which are situated beneath the skin in the superficial fascia.

The constant position of the great saphenous vein in front of the medial malleolus should be remembered for patients requiring emergency blood transfusion. The deep veins are the venae comitantes to the anterior and posterior tibial arteries, the popliteal vein, and the femoral veins and their tributaries. The perforating veins are communicating vessels that run between the superficial and deep veins. Many of these veins are found particularly in the region of the ankle and the medial side of the lower part of the leg. They possess valves that are arranged to prevent the flow of blood from the deep to the superficial veins.

Ligaments of the Gluteal Region-Sacrotuberous Ligament-Sacrospinous Ligament-Greater Sciatic Foramen-Foramina of the Gluteal Region-Lesser Sciatic Foramen-Muscles of the Gluteal Region-

Ligaments of the Gluteal Region

The two important ligaments in the gluteal region are the sacrotuberous and sacrospinous ligaments. The function of these ligaments is to stabilize the sacrum and prevent its rotation at the sacroiliac joint by the weight of the vertebral column.

Sacrotuberous Ligament

The sacrotuberous ligament connects the back of the sacrum to the ischial tuberosity.

Sacrospinous Ligament

The sacrospinous ligament connects the back of the sacrum to the spine of the ischium.

Foramina of the Gluteal Region

The two important foramina in the gluteal region are the greater sciatic foramen and the lesser sciatic foramen.

Greater Sciatic Foramen

The greater sciatic foramen is formed by the greater sciatic notch of the hip bone and the sacrotuberous and sacrospinous ligaments. It provides an exit from the pelvis into the gluteal region.

The following structures exit the foramen:

■■ Piriformis

■■ Sciatic nerve

■■ Posterior cutaneous nerve of the thigh

■■ Superior and inferior gluteal nerves

■■ Nerves to the obturator internus and quadratus femoris

■■ Pudendal nerve

■■ Superior and inferior gluteal arteries and veins

■■ Internal pudendal artery and vein

Lesser Sciatic Foramen

The lesser sciatic foramen is formed by the lesser sciatic notch of the hip bone and the sacrotuberous and sacrospinous ligaments. It provides an entrance into the perineum from the gluteal region. Its presence enables nerves and blood vessels that have left the pelvis through the greater sciatic foramen above the pelvic floor to enter the perineum below the pelvic floor.

The following structures pass through the foramen

■■ Tendon of obturator internus muscle

■■ Nerve to obturator internus

■■ Pudendal nerve

■■ Internal pudendal artery and vein

Muscles of the Gluteal Region

The muscles of the gluteal region include the gluteus maximus, the gluteus medius, the gluteus minimus, the tensor fasciae latae, the piriformis, the obturator internus, the superior and inferior gemelli, and the quadratus femoris.

Note the following:

■■ The gluteus maximus is the largest muscle in the body. It lies superficial in the gluteal region and is largely responsible for the prominence of the buttock.

■■ The tensor fasciae latae runs downward and backward to its insertion in the iliotibial tract and thus assists the gluteus maximus muscle in maintaining the knee in the extended position.

 

Fractures of the Femur-

Fractures of the Femur

Fractures of the neck of the femur are common and are of two types, subcapital and trochanteric. The subcapital fracture occurs in the elderly and is usually produced by a minor trip or stumble. Subcapital femoral neck fractures are particularly common in women after menopause. This gender predisposition is because of a thinning of the cortical and trabecular bone caused by estrogen deficiency. Avascular necrosis of the head is a common complication. If the fragments are not impacted, considerable displacement occurs. The strong muscles of the thigh, including the rectus femoris, the adductor muscles, and the hamstring muscles, pull the distal fragment upward, so that the leg is shortened (as measured from the anterior superior iliac spine to the adductor tubercle or medial malleolus). The gluteus maximus, the piriformis, the obturator internus, the gemelli, and the quadratus femoris rotate the distal fragment laterally, as seen by the toes pointing laterally.

Trochanteric fractures commonly occur in the young and middle aged as a result of direct trauma. The fracture line is extracapsular, and both fragments have a profuse blood supply. If the bone fragments are not impacted, the pull of the strong muscles will produce shortening and lateral rotation of the leg, as previously explained.

Fractures of the shaft of the femur usually occur in young and healthy persons. In fractures of the upper third of the shaft of the femur, the proximal fragment is flexed by the iliopsoas; abducted by the gluteus medius and minimus; and laterally rotated by the gluteus maximus, the piriformis, the obturator internus, the gemelli, and the quadratus femoris. The lower fragment is adducted by the adductor muscles, pulled upward by the hamstrings and quadriceps, and laterally rotated by the adductors and the weight of the foot.

In fractures of the middle third of the shaft of the femur, the distal fragment is pulled upward by the hamstrings and the quadriceps , resulting in considerable shortening. The distal fragment is also rotated backward by the pull of the two heads of the gastrocnemius. In fractures of the distal third of the shaft of the femur, the same displacement of the distal fragment occurs as seen in fractures of the middle third of the shaft. However, the distal fragment is smaller and is rotated backward by the gastrocnemius muscle to a greater degree and may exert pressure on the popliteal artery and interfere with the blood flow through the leg and foot.

From these accounts, it is clear that knowledge of the different actions of the muscles of the leg is necessary to understand the displacement of the fragments of a fractured femur.

Considerable traction on the distal fragment is usually required to overcome the powerful muscles and restore the limb to its correct length before manipulation and operative therapy to bring the proximal and distal fragments into correct alignment