psoas Abscess infection, A Diagnostic Dilemma - Everything You Need To Know - Dr. Nabil Ebraheim

Educational video describing abscess of the iliopsoas muscle.
The iliacus and the psoas are the main hip flexors supplied by the femoral nerve which lies between two muscles. The obturator nerve is medial to the psoas. The psoas arises from the transverse process of the lateral aspect of the vertebral bodies between the 12th thoracic vertebrae and the 5th lumbar vertebrae. The psoas runs downward across the pelvic brim and then passes deep to the ilioinguinal ligament where it then forms a tendon past the hip joint capsule which inserts into the lesser trochanter of the femur. The iliacus arises from upper two third of the iliac fossa and joins the psoas to insert in the same tendon as the psoas muscle. Both muscles are in the extraperitoneal space or referred to as the iliopsoas compartment. The iliopsoas tendon is separated from the hip joint capsule by the iliopsoas bursa.the iliopsoas bursa connects to the hip joint in about 15% of patients and this may facilitate the spread of infection between these two sides.
What causes abscess of the iliopsoas muscle? A primary abscess is caused by hematogenous spread of the infection. The infection starts in the muscle itself. In a secondary abscess, the infection spreads from another area to the psoas muscle. For example, the infection may travel from the spine when it is infected by tuberculosis (Pott's disease). This historically is the cause of the abscess.it can also spread from the SI joint, kidneys or bowels.
The iliopsoas abscess may initially present with signs and symptoms in the buttock, hip or thigh. Such signs and symptoms may be obscure, non-specific and misleading.
Abscess of the iliopsoas muscle is a diagnostic dilemma with a difficult diagnosis that is often delayed.
The patient may be lying supine with the hip flexed and refuses to move resisting any attempt for examination. With psoas involvement, the hip appears to be flexed, with limited and painful range of motion. This diverts attention away from the abdomen r pelvic source of the abscess. The patient may have a low-grade fever and cannot straighten the leg. A high index of suspicion is necessary and diagnosis is aided by performing the psoas sign.
Psoas sign: the patient is positioned on the side and the hip is extended to see if there is pain present in the iliopsoas region. The psoas sign is used in diagnosis of appendicitis but also helpful in diagnosing a psoas abscess.
Summary of clinical manifestations
•Pain in the abdomen, flank or groin
•Low back pain
•Flexion posture of the hip.
These abscesses are rare and present with vague clinical features. Staph aureus is the cause of iliopasoas abscess in 88% of primary types. Polymicrobial infection is usually the cause in the secondary types.
CT scan is usually diagnostic modality of choice. The right psoas muscle is clearly seen as larger than the left side in the coronal CT scan.
Treatment
•Percutaneous drainage is done if the abscess if simple, small and single, otherwise open drainage is the procedure of choice.
•Open drainage: splitting incision is made along the iliac crest for easy access to the iliacus, psoas, and SI joint (first window of inguinal approach). Other incisions may be needed such as the anterior approach in front of the hip or the posterior approach. Other sites for drainage depend on the location and extension of the abscess.
Risk factors
•Diabetes
•Immunosuppression
•Trauma
•Renal failure
•IV drug abuse
•Older individuals and AIDS patients.
•Patient with flexion posture of the hip before surgery. Patient refused any attempt for examination. Patient is comfortable laying flat after surgery. After surgery, the patient is able to sit upright in a chair without pain.
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