Ligament Reconstruction in Congenital Absence of the Anterior Cruciate Ligament: A Report of Two Cases.

Abstract

Congenital absence of the anterior cruciate ligament (ACL) is an extremely rare condition (0.017 per 1000 live births) [12]. It has been reported as an isolated entity [1, 14] or associated with other abnormalities such as congenital femoral deficiency, fibular hemimelia, scoliosis, hip dysplasia, and dysplasia of the tibial intercondylar eminence [4, 9, 10, 14]. It was first reported by Giorgi [8] in 1956 in a radiographic study, and since then, several case reports have been published [4, 11]. Most reports describe patients with no complaints of instability (despite having positive objective instability tests) but pain due to osteoarthritis of the medial femorotibial joint [12]. Individuals with this condition may not have symptomatic instability if they are able to use muscle forces to provide knee stability. The cases reported with symptomatic instability are likely due to an event that may alter the knee homeostasis making the ACL deficiency manifest [15]. Given the rarity of the condition, there is no consensus regarding the optimal therapeutic approach, although most studies conclude that non-surgical options are the appropriate management despite early degenerative joint disease. Anterior cruciate ligament reconstruction is indicated when symptoms of instability appear [6]. This is a report on two cases of congenital absence of the ACL, one with a femoral length discrepancy and another with a lateral femoral condyle hypoplasia and posterior cruciate ligament (PCL) dysplasia.