Orthopedics - Oleksa A.P. 2006

Congenital and Acquired Deformities of the Lower Extremity
Congenital Defects of the Knee Joint
Congenital Bipartite/Multipartite Patella

Bipartite Patella (patella partita) is a congenital developmental anomaly occurring in approximately 1.5% of examined individuals (Pytel, 1934), with 90% of cases observed in males. Radiographically, it is clearly visible that the patella consists of two (patella bipartita), three (patella tripartita), or more (multipartita) fragments. Notably, the shape and size of the patella remain nearly always normal, and this fragmentation has minimal impact on its function.

Patellar fragmentation can occur in various regions and planes, which served as the basis for Saupe (1921) to classify Variants of the partitioned patella. However, this Classification is of limited practical significance for the clinician.

Division of the patella in the frontal plane results in patella bipartita, tripartita, and multipartita. Division in the sagittal plane produces a vertically duplicated patella (patella duplex), whereas division in the horizontal plane yields a patella transversely split into two unequal parts. Additionally, cases are observed where the patella is divided into one larger portion and several smaller ones, or presents only as a small lateral separated fragment.

Fig. 170 illustrates the most common variants of patellar fragmentation according to A. Ya. Pytel.

This congenital anomaly is generally attributed to multiple ossification centers of the patella during Embryogenesis, followed by separate ossification of each. However, another view suggests that the embryonic patella is initially solid and subsequently separates into fragments under METABOLISM/18.html">The Influence of altered mechanical stress and structural remodeling.

During the first years of life, the patella remains cartilaginous, and the ossification center appears only around the fourth or fifth year of life. Odermant (1921) notes that 15% of children present with two or more centers that subsequently fuse gradually, which should be considered a normal physiological variation. Failure of these centers to fuse may lead to patellar fragmentation.

Class="center">

Fig. 170. Variants of the fragmented patella according to A. Ya. Pytel (1934).

A fragmented patella may remain clinically silent, with the anomaly being discovered incidentally on knee radiographs performed for other indications.

Most frequently, a patellar fracture must be differentiated from patella bipartita or tripartita. Although longitudinal fractures are extremely rare, they should be differentiated from patella bipartita.

Radiographically, this congenital anomaly is characterized by smooth margins of the cleft and the absence of displacement, whereas in patellar fractures, the fragments exhibit irregular edges and often displacement. Furthermore, congenital patellar fragmentation is typically bilateral, making it advisable to obtain a radiograph of the contralateral knee.

Such a congenital anomaly requires no Treatment, except in cases of arthrosis, which, according to Pytel, may develop as a late consequence in adults following frequent knee trauma and synovitis.