Neonatal Compartment Syndrome

There are only a few cases of compartment in the neonate. This can be a difficult diagnosis. Compartment syndrome in the neonate does not present itself with the classic “P’s” as seen in adult patients. Compartment syndrome in the neonate does not present itself with the classic “P’s” as seen in adult patients. There are 5 P’s: pain/swelling, paresthesia, pulselessness, pallor, and paralysis. Diagnosis in neonate is usually made retrospectively after the patient has complications. The condition of compartment syndrome usually occurs within the first 24 hours of birth. It usually occurs in the forearm, is usually unilateral and occurs more in the dorsal aspect of the forearm. Risk factors are the mother may be diabetic, some hypercoagulable state (like polycythemia), and prematurity. The actual cause is not known, however it can be a combination of extrinsic compression and hypercoagulable state. Make sure to avoid missing the diagnosis of compartment syndrome. The infant will have a swollen, tense forearm associated with skin lesions on the forearm. The skin may have erythema, bullae, and edema. The skin lesions will be present at birth and usually at the forearm. The patient may also have pseudoparalysis, may lack spontaneous limb movement, and there might be some nerve injury involved also. The clinical diagnosis of compartment syndrome will be made after exclusion of other conditions such as infection, vascular injury, and amniotic band syndrome. The clinical diagnosis of compartment syndrome will be made after exclusion of other conditions such as infection, vascular injury, and amniotic band syndrome. Infection could be cellulitis or can be necrotizing fasciitis. Both should be excluded! Treatment of neonatal compartment syndrome of the forearm should be early diagnosis and immediate fasciotomy. Ischemic muscle contracture will develop from missing the diagnosis and delaying the treatment.

Anatomy of the Acetabulum

The column principle divides the acetabulum into an anterior and posterior column which becomes important when considering acetabular fractures and their management. The anterior column is composed of the anterior ilium, the anterior wall and dome of the acetabulum and the superior pubic ramus. The posterior column extends from the obturator foramen through the posterior aspect of the weight bearing dome of the acetabulum and then obliquely through the greater sciatic notch. The ischiopubic ramus is a complex structure that consists of the inferior pubic ramus and the inferior ramus of the ischium. It forms the inferior border of the obturator foramen. The pelvis is oriented to form an inverted “Y” shape. The obturator artery is a branch of the anterior division of the internal iliac artery. It arises in the pelvis and it enters the obturator canal. The obturator artery the divides into two branches: the anterior and posterior branches of the obturator artery form a vascular circle around the outer surface of the obturator membrane. An acetabular branch reaches the hip joint and joins the ligamentum teres to supply the head of the femur. It usually supplies a small portion of the head of the femur. Corona mortis is a connection between the internal iliac branch (obturator) and the external iliac or its branch, the inferior epigastric. Corona mortis is predominantly a venus connection and the arterial connection is much less. Its location on the superior pubic ramus is variable. It is about 3-7 cm from the symphysis pubis. It is located behind and on top of the superior pubic ramus and one must be careful with lateral dissection of the superior pubic ramus. The Corona Mortis is susceptible to injury in pelvic trauma and in pelvic surgery especially during the ilioinguinal approach.  Be aware that the sciatic nerve can be split, and this can be a normal variant. Keep the knee flexed and the hip extended during posterior approach to the acetabulum. This will protect the sciatic nerve. The sciatic nerve is posterior to the obturator internus muscle and anterior to the piriformis muscle. When using the sciatic nerve retractor in the lesser sciatic notch, the muscle and tendon of the obturator internus protects the sciatic nerve. It acts as a buffer layer between the retractor and the nerve, because the nerve is posterior to the muscle. Sliding trochanteric osteotomy allows exposure of the dome and the superior aspect of the acetabulum. This type of osteotomy keeps the muscles intact and this will balance its pulling forces. There will be less of a chance of displacement of the greater trochanter this way. The superior gluteal nerve is close to the superior gluteal artery at the greater sciatic notch. The superior gluteal nerve can be injured from approaches that involve more than 5 cm above the acetabulum. Excessive traction or attempt to control the bleeding from the superior gluteal artery at the greater sciatic notch, may injure the nerve by a suture or by a vascular clip that may entangle the nerve. Injury to this nerve may affect the gluteus minimus. Injury to this nerve affects the abductors of the hip joint and the patient may end up with Trendelenburg Gait. The inferior gluteal nerve may also be injured. It innervates the gluteus maximus muscle. The Lateral Femoral Cutaneous Nerve can become injured during the ilioinguinal approach for acetabular fixation. The Lateral Femoral Cutaneous Nerve usually passes under the ilioinguinal medial to the anterior superior iliac spine (ASIS).

Injury to the Corona mortis may lead to significant hemorrhage which may be difficult to control. The superior gluteal artery passes through the greater sciatic notch. Injury to the superior gluteal artery can be associated with acetabular fractures, especially fractures that involve the posterior column of the acetabulum. The superior gluteal artery cam ne damaged by aggressive retraction of the abductor muscles during posterior approach to the hip. The Medial Femoral Circumflex Artery (MFCA) can be damaged due to dislocation of the femoral head or from taking down the quadratus femoris from the femur instead of the ischium. You need to leave a tag of 1 cm for the piriformis and the obturator internus from the greater trochanter to preserve the deep branch of the medial circumflex artery. If you detach these two tendons too close to the trochanter, this could injure the deep branch of the medial femoral circumflex artery. The medial femoral circumflex is the main blood supply to the femoral head. The sciatic nerve is close to the acetabulum and can be injured. In fact, sciatic nerve injury is the most common traumatic and iatrogenic nerve injury connected to the acetabulum. Sciatic nerve injury can be approximately 10% with hip dislocation. The incidence may be higher with posterior acetabular fractures. When you examine a patient with an acetabular fracture, always check the sciatic nerve function. Check dorsiflexion of the ankle and the toes. It is peroneal division of the sciatic nerve that will be affected. Check for numbness on the top of the foot. Repeat the exam again just before surgery. Partial sciatic nerve injury can get worse from acetabular surgery. The sciatic nerve anatomy is variable but well described. There may be variations in its anatomy. These diagrams show the incidence of the most common patterns of the relationship between the sciatic nerve and the piriformis muscle.

Anatomy of the Adductor Longus Muscle

The adductor longus muscle is one of the adductor muscles of the hip located within the thigh. There are six adductor muscles for the hip and here is a diagram showing the arrangement of these adductor muscles. The adductor longus muscle arises from the anterior surface of the superior pubic ramus, just lateral to pubic symphysis. It is inserted into the middle third of the medial lip of the linea aspera on the posterior surface of the shaft of the femur. The adductor longus muscle is innervated by the obturator nerve which arises from the L2, L3, and L4 ventral rami of the lumbar plexus. Outside the obturator foramen in the proximal part of the thigh, the obturator nerve divides into anterior and posterior divisions. It is the anterior division of the obturator nerve which supplies the adductor longus muscle. The adductor longus muscle adducts and flexes the thigh, and helps to laterally rotate the hip joint. Adductor strains may occur in hockey players or soccer players. It is sometimes called a “pulled groin.” Adductor strains usually involve the adductor muscles, especially the adductor longus muscle. It occurs due to eccentric contraction of the muscle. The injury occurs due to external rotation of an abducted leg. The patient will have groining pain and pain at the site of the injury, usually near the pubic ramus. The patient will also have weak adduction. It may be difficult to differentiate an adductor strain from a sport hernia. X-rays are usually normal. MRI will show avulsion of the adductor muscles from the pubic ramus. Adductor strain treatment includes: ice, rest, protected weight bearing, and patient will go through a rehabilitation program. Surgery is rarely done and the role of surgery is not well defined.

Anatomy of Coracobrachialis Muscle

The brachialis muscle is a muscle in the upper arm that flexes the forearm at the elbow joint. The brachialis muscle originates from the lower half of the anterior humerus, near the insertion of the deltoid muscle. The brachialis muscle is located underneath of the biceps brachii muscle.
It is inserted into the tuberosity on the anterior surface of the coronoid process of the ulna.
The function of the brachialis is that it flexes the forearm at the elbow joint. It doesn’t aid in pronation or supination. The biceps muscle is a strong supinator. There is dual innervation of the brachialis muscle. The musculocutaneous nerve arises from the lateral cord of the brachial plexus. It is the primary nerve supply to the brachialis muscle as well as the coracobrachialis and biceps muscles. The musculocutaneous nerve lies underneath the biceps muscle and on top of the brachialis muscle. Part of the brachialis is also innervated by the radial nerve. The dual innervation of the brachialis allows it to be split during anterior approached to the humeral shaft. The medial part lies in the flexor compartment with the musculocutaneous nerve. As the limb develops, rotation of the lateral brachialis to become flexor and the lateral part brings with it the radial nerve supply. Structures of the cubital fossa located around the brachialis muscle.

The cubital fossa is a triangular hollow area on the anterior surface of the elbow. The brachialis muscle makes up part of the floor of the cubital fossa region. The cubital fossa makes up four main structures from lateral to medial. Radial nerve, biceps brachii tendon, brachial artery, and median nerve. Anterior approach to the humerus (splitting the brachialis):  curved incision is made from the tip of the coracoid process along the anterolateral aspect of the humerus. During part of this procedure, the brachialis is split in the middle after retraction of the biceps muscle. How to approach the radial nerve on the distal humerus? The lower part of the humeral shaft is approached between the brachialis and the brachioradialis muscle with the brachialis retracted medially and the brachioradialis retracted laterally. The radial nerve is identified and protected. Because there is a dual innervation for the muscle, the brachialis is not denervated. When the brachialis is retracted, this may endanger the nerve supply to the lateral brachialis. Coronoid process fractures are usually associated with elbow dislocations and can occur from hyperflexion with avulsion of the brachialis tendon insertion or shearing off of the trochlea.

Femoral Triangle

The femoral triangle is a superficial triangular space located on the anterior aspect of the thigh just inferior to the inguinal ligament. The boundaries of the femoral triangle include the lateral border, medial border, and base. The lateral border is formed by the medial border of the Sartorius M. The Sartorius muscle is a thin, small muscle going that goes from lateral to medial. The Sartorius muscle inserts on the medial side of the proximal tibia. The medial border of the femoral triangle is formed by the medial border of the adductor longus M. The adductor longus muscle goes from medial to lateral direction. The base of the femoral triangle is formed by the inguinal ligament. The floor of the triangle is formed by the iliacus M., psoas major M., pectineus M., and the adductor longus M. The roof of the femoral triangle is covered by skin, superficial and deep fascia. The femoral triangle contains three important structures. From lateral to medial, it is the femoral nerve, femoral artery, and femoral vein, which contains deep inguinal lymph nodes. The femoral nerve lies within the groove between the iliacus and psoas major muscles. Two other nerves are located within the femoral triangle, and they are the lateral cutaneous nerve on the thigh and the femoral branch of the genitofemoral nerve.

The lateral cutaneous nerve of the thigh crosses the lateral corner of the triangle. It supplies the skin on the lateral part of the thigh. The femoral branch of the genitofemoral nerve runs in the lateral compartment of the femoral sheath. It supplies the majority of the skin over the femoral triangle. The femoral triangle also contains the femoral sheath which is a funnel shaped sleeve of fascia enclosing the upper 4 cm of the femoral vessels. The neurovascular bundle is medial to the sartorius muscle. Therefore, in the anterior approach to the hip, it is always safe to go lateral to the sartorius muscle in order to avoid the important structures within the femoral triangle. Do not go medial to the sartorius muscle. You will injure the structures if you go medial to the sartorius muscle. It is important to remember when performing this approach to avoid the lateral cutaneous nerve of the thigh. The sartorius muscle is almost like the teres minor muscle in the shoulder. Do not go inferior to the teres minor muscle in the shoulder, you will injure the axillary nerve and the posterior circumflex artery.