The differential diagnosis of a hip snap is:
Iliopsoas tendon snap
Iliopsoas bursal snap
Labral tear
ITB snap
following total hip replacement with a prominent acetabular component.
The manoeuvre to detect an iliopsoas snap is to get the patient to
Flex the hip
Externally rotate
Return to neutral
The tendinous and muscular component of the complex rotate around each other and return ton resting position with a snap.
In younger patients hip pain may be associated with a snapping sensation. many are painless. The differential diagnosis includes femoroacetabulum impingement, iliopsoas bursitis and iliopsoas tendon snap. Late presentations of developmental dysplasia and femoroacetabular impingement are sometimes linked under the term ‘Acetabular rim syndrome’ although this is most commonly used in association with labrum anomalies related to developmental dysplasia. The iliopsoas bursa communicates with the adjacet hip joint in approximately 10-15% of individuals. When enlarged it lies anterior to the anterior acetabular wall usually between the iliopsoas tendon and the adjacent neuromuscular bundle. On its deep surface a neck may be seen pointing towards the hip joint. When distended a palpable mass is felt anteriorly. Long axis images may also demonstrate its intimate relation with the iliopsoas tendon.
