Bipartite patella separation and partial quadriceps tendon rupture in the setting of trauma

Abstract

Normal development of the patella typically involves fusion of secondary ossification centers into a single bone during adolescence, with failure of fusion resulting in bipartite and tripartite patellae. In such variants, injury to incomplete ossification center fusion, though uncommon, has been reported to occur in the setting of traumatic quadriceps tendon rupture. The authors present a rare and complex case of traumatic bipartite fragment separation, patellar avulsion, and a complex partial quadriceps tendon tear confirmed surgically in a 36-year-old male. In this case, a tear in the lateral aspect of the quadriceps tendon attached to the nonfused patellar ossification center resulted in retraction of the band containing the bipartite fragment and separation of the patellar fragments, with superior displacement of the smaller bony avulsion likely due to complex attachments from the medial aspect of the quadriceps tendon. Knowledge of the classical locations of a bipartite and tripartite patella can aid in the differentiation of the anatomic variant versus patellar avulsion. Additionally, knowledge of the variable and complex nature of the quadriceps tendon aids in understanding the process of patellar avulsions and various tears, leading to the appropriate orthopedic management.

Fabella and patella variants: radiographic prevalence, distribution and clinical relevance in a population of black african descent

“…The patella protects the anterior Original Article https://doi.org/10.5115/acb.20.217 pISSN 2093-3665 eISSN 2093-3673 surface of the knee joint. It increases the lever arm of the extensor mechanism allowing for more effective knee flexion [2]. At birth it is made of cartilage and begins to ossify between 2 to 6 years of age [3].…”

“…During adolescence, secondary ossification centers of the patellar bone usually fuse to form a single ossification center, therefore forming a single bone in most of the population [ 4 ]. In a small percentage of people, a failure of fusion of the ossification centers on the patella leads to a bipartite or tripartite patella [ 2 ]. The bipartite patella was first described by Gruber [ 5 ] in 1883 and later classified by Saupe [ 6 ] in 1921 into three subgroups based on the location of the fragments.…”

“…Multipartite patella anomaly has been reported as a cause of anterior knee pain and symptomatology [ 8 , 9 ]. In addition, knowledge of multipartite patella will help in the differentiating of patella fractures and avulsions from normal variants [ 2 ].…”