Congenital absence of anterior cruciate ligament

Case contributed by Dr Abdulmajid Bawazeer


Patient came with medial sided knee pain after recent trauma. Sustainable normal range of movement with no swelling. On clinical exam: no knee instability and normal range of movement.

Patient Data

Age: 35 years
Gender: Male

The ACL is not visualized with no peri-cruciate fat pad edema.
The PCL is hypoplastic and buckled.
The posterior horn of the medial meniscus shows altered signal intensity reaching the articular surface suggesting meniscal tear.
There is subchondral bone edema with chondral defect seen in the medial femoral condyle.

Case Discussion

Congenital absence of the anterior cruciate ligament is rare with a prevalence of 0.017 per 1000 live births 1.
The intercondylar fossa appears relatively empty (except the PCL is seen which appears hypoplastic and buckled) with no knee joint effusion or peri-cruciate fat pad edema, as well as the symptoms and clinical exam, also support the diagnosis.

Stage IIA osteochondral injury of the medial femoral condyle.
Tear in the posterior horn of the medial meniscus.
The lateral meniscal tear is commonly associated with an acute ACL, while medial meniscal tear associated with a chronic ACL injury (in above case no previous history of old trauma or chronic ACL tear).

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Case information

rID: 75346
Published: 26th Mar 2020
Last edited: 27th Mar 2020
Inclusion in quiz mode: Included
Institution: The Islamic Hospital

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