Clinical Cases - Anterior & Medial Thigh
B.L., a 65-year-old woman, submitted to cardiac catheterization in order to measure the pressures in the chambers of her heart. A catheter was inserted in her right femoral vein in the femoral triangle and floated through the iliac veins and the inferior vena cava to the right heart, where diagnostic procedures were performed without incident. Four hours after completion of the procedure, however, B.L. began to complain of a painful throbbing in her right groin. Over the course of the next hour, the pain worsened and she began to experience numbness and tingling in her right anteromedial thigh and leg. On examination, her right leg felt cool and a mass was observed in the right groin. No distal pulses could be felt in the leg. B.L. was immediately taken up to surgery for exploration of the groin region.
Questions to consider:
- Given what you know about the anatomy of the inguinal region and the anteromedial thigh, what are the risks associated with catheterization in the groin region?The risks of catheterization include damage to the femoral artery or vein leading to an internal hemorrhage, injury to the femoral nerve, needle introduction into the peritoneal cavity, and formation of an arteriovenous fistula.
- What do you think caused the mass in the patient's groin?The mass in the patient's groin was due to the formation of a hematoma. The hematoma could result from failure of the wound in the femoral vein to close, or more likely, due to a laceration of the femoral artery that occurred at some point during the procedure.
- How would you explain the numbness and absence of distal pulses?The numbness and lack of distal pulses are most likely due to the compression of the neurovascular structures of the femoral triangle (femoral a., v., and n.) by the hematoma.
- Why would the femoral vein be used for catheterization instead of vessels closer to the heart, like the external jugular, for instance?The femoral vessels have a couple of advantages over other possible locations for many procedures involving catheterization. First, the femoral vessels tend to be much larger than vessels in the arm or neck and allow a larger catheter. Second, they do not present the same risks as catheterization of the neck. For example, an aberrant needle in the neck could enter the pleural space and cause a pneumothorax, and, in the case of the carotid arteries, there is also the risk of thrombosis or atheroembolism caused by the puncture and manipulation of the arteries, leading to a stroke. As a result, femoral catheterization is typically used for procedures requiring access to the arterial circulation around the heart and the arch of the aorta (including the cranial circulation) and for procedures in the abdomen (venous and arterial); however, the trend in recent years, as physicians become more skilled in the techniques, has been to use more proximal locations for certain venous procedures (i.e. internal jugular or subclavian venous catheterization). In addition, much of limb angiography is carried out in local vascular trees, rather than through central catheters, because local injection of contrast media reduces the amount of contrast medium that needs to be introduced to the body, thus reducing the likelihood and severity of adverse reactions.
- What other procedures might carry similar risks to structures in the femoral triangle?Other procedures (than the one described above) that present risks to the integrity of structures in the femoral triangle include any procedure involving puncture of the vessels (blood sampling, angioplasty, angiography, placement of vena caval filters, and other catheterizations), as well as surgical procedures in or near the inguinal region, including hernia repair, lymphadenectomy, and hip replacement surgery.
A 24-year-old man was referred to a surgeon with a suspected intramuscular lipoma in his right upper thigh. On examination, a prominent lump was visible in the upper medial portion of the right thigh and a soft mass could be palpated. Distal to the mass, the surgeon noted a shallow triangular defect apparently in the musculature lateral to the gracilis muscle and medial to the sartorius muscle. When the patient adducted the leg against resistance, the mass became more round and firm. Computed tomography (CT) indicated that the mass was muscular and not adipose, as initially suspected. Upon questioning, the patient indicated that he had sustained an injury to the medial thigh about 1 year earlier. He had been kicking a soccer ball with the medial aspect of his foot at the same time that an opponent was attempting to kick the ball in the opposite direction. He had felt a sharp pain immediately, but after several days, the pain subsided, so he thought he had strained a muscle. He did not become concerned until the mass had started to grow in his right thigh. A needle biopsy showed that the mass was normal muscle tissue, and since the patient experienced no discomfort, the surgeon told him that no treatment was required.
Questions to consider:
- What do you think that the mass was?The mass was one of the adductor muscles of the medial thigh, and based on the location of the mass and the associated defect, it was probably the adductor longus muscle.
- What do you suspect happened to cause the mass in the first place, and why was it growing?The mass resulted when the tendon of the adductor longus muscle avulsed near the bone from the soccer trauma described by the patient. This avulsed tendon allowed the muscle to retract, forming an abnormal bulge in the upper medial thigh. As the injury healed, the muscle likely reattached to the femur at a more proximal location, resulting in a loss of mechanical advantage, which in turn led to hypertrophy of the adductor longus to compensate. This hypertrophy resulted in the growth of the mass in the medial thigh.
- How can a radiologist differentiate between muscle tissue and adipose tissue on a CT scan?Tissues can be differentiated on CT scans based on their relative densities. Bone typically appears white, whereas muscle tissue is usually a medium gray and adipose tissue is dark gray to almost black. Thus the composition of the mass could be determined based on its density when compared with surrounding muscle and subcutaneous fat.
- What was the defect the surgeon noticed below the mass?The defect palpated by the surgeon was the space left behind when the adductor longus retracted following the soccer injury. The presence of this sort of defect in the location described above is a clue that indicates that the adductor longus muscle had ruptured previously.
- What other things might present as a swelling in the medial thigh?Femoral and obturator hernias may present as swellings in the medial thigh, as well as lymph nodes from the superficial inguinal group. Other possibilities to consider when observing a swelling in the medial thigh include a hematoma, or a soft tissue tumor like the intramuscular lipoma indicated above.
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