21 - Unilateral Agenesis of the Anterior Cruciate Ligament

Poster Board Number: 21
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Abstract Body : Congenital absence of the anterior cruciate ligament (ACL) is a rare condition, with a reported prevalence of 1.7 per 100,000 live births, and most commonly appears in association with other congenital lower extremity abnormalities such as knee dislocation, proximal focal femoral deficiency, and fibular hemimelia. Absence of the ACL is often associated with hyperplasia of the meniscofemoral ligament. During a routine cadaveric dissection of the right knee joint of an 84-year-old female, it was observed that the anterior cruciate ligament was congenitally absent and there was hyperplasia of the meniscofemoral ligament. Dissection of the left knee joint revealed that the phenomenon was not bilateral. Further investigation revealed that the right femur had significantly more osteoarthritis than the left femur. Studies suggest that individuals with this condition are at an increased risk of developing premature osteoarthritis. Currently there is no consensus regarding management of agenesis of the ACL. Treatment depends on how disruptive the symptoms are as some individuals are asymptomatic. Conservative treatments involve cryotherapy, passive range of motion, bracing, anti-inflammatory medication, and exercises for strengthening, balance, and proprioception. When these methods fail surgical reconstruction of the ACL may be necessary and has been successful in some individuals. However, 1 in 9 patients who undergo ACL reconstruction will experience re-rupture or clinical failure at long term follow up. Further studies are needed to determine long term outcomes of individuals with and without surgical intervention.