Radiographic Findings of Bilateral bipartite patellae in a Domestic Short Hair Cat

Background: A ۶-month-old intact female domestic shorthair (DSH) cat was referred to the Radiology Unit, Faculty of Veterinary Medicine, University of Tehran, with a chief complaint of bilateral hindlimb lameness with history of trauma since ۱ day ago. On physical examination, multiple abrasions were noted over body, and pain was noted upon palpation of the pelvic region and stifles. Methods: Orthogonal radiographs of the pelvis and stifle joints were obtained using a Toshiba ROTANODE X-ray tube (Model E۷۲۳۹X, Toshiba Corporation, Japan) and a Venu ۱۷۱۷ flat panel detector (iRay Technology), at ۷۵ kVp and ۸ mAs, in right lateral and ventrodorsal projections. Radiographic evaluation focused on skeletal trauma, joint integrity, and osseous pathology. Incidentally, bilateral bipartite patellae were identified (Figures ۱ and ۲). To further characterize the lesions, computed tomography (CT) was performed using a Siemens Somatom Spirit dual-detector scanner. The patient was positioned longitudinally, and the protocol included a ۱-second rotation time, ۱ mm slice thickness, ۰.۵–۱ mm reconstruction interval, pitch ۱, tube potential ۱۳۰ kV, and tube current ۱۴۴ mAs. (Figure ۳). Results: Based on radiographic and CT findings, along with clinical history and physical examination, bilateral bipartite patellae was identified. The absence of sharp or reactive margins at the separation sites supports a congenital origin rather than a traumatic etiology. Conclusion: The patella is the largest sesamoid bone in the feline skeletal system and is proportionally wider and larger relative to body size compared to dogs. It has a convex articular surface and resides within the trochlear sulcus of the femur. Patella protects the quadriceps tendon during weightbearing and high-impact activities such as jumping. In cats, this bone must endure substantial forces, particularly during landing with flexed hindlimbs after jumping from elevated surfaces. Although patellar fractures are relatively uncommon in feline practice, they are more frequently observed in younger cats, with no documented breed or sex predisposition. Among these, longitudinal fractures are especially rare in routine veterinary orthopedics. Such injuries can significantly impair pelvic limb function, disrupt joint congruity, and predispose the animal to degenerative joint disease. In the absence of evidence supporting a traumatic origin, patellar