Longitudinal Patellar Fracture in a Cat - Surgical Repair

Abstract

Background: Longitudinal patellar fractures are uncommon in veterinary orthopedics routine. These fractures directly affect pelvic limb movements and can result in joint incongruity and potentially degenerative joint disease. Surgical repair
is necessary to preserve the quadriceps extensor mechanism and reduce possible complications. This paper describes the clinical status of a cat suffering from a longitudinal patellar fracture, the surgical procedure used to repair and stabilize the bone, and the postoperative outcomes during the animal’s different healing phases.
Case: One cat with a longitudinal patellar fracture of the left pelvic limb was treated at the Veterinary Hospital of the Federal University of Santa Maria (UFSM), in the state of Rio Grande do Sul, Brazil. The patient was diagnosed based on physical and radiographic examinations of the affected pelvic limb. Under anesthesia, the patella was subjected to osteosynthesis using cerclage wire and to trochlear sulcoplasty to prevent luxation. The veterinarian recommended postoperative rest and basic care involving hygiene of the surgical wound. After 60 days, the cat was brought back to the hospital for radiographic reassessment to verify the osseous consolidation of the patella. The X-ray exam revealed non-consolidation of the bone fragments, despite the cemented implant and the proper joining of the fragments. However, although the fracture did not consolidate, the animal exhibited clinical improvement of its lameness.
Discussion: Longitudinal fractures are rare and the literature contains few reports about them. It is believed that cats are more likely to present longitudinal fractures after direct blows that cause compression of the patella over the trochlear groove, since the patella in this species is relatively wider and smoother than that of dogs. The literature still lacks a clear
description of the causal mechanism of longitudinal fractures; however, but the main causes may vary according to the clinical presentation. The choice of the best method to treat patellar fractures still poses a challenge, since several methods have been described, depending on how the fracture presents. Regardless of the choice of treatment, the techniques for surgical repair of patellar fractures must involve the following steps: the fracture must be reduced, the fragments kept in apposition until the fracture closes, the soft tissues are healed, and the knee function restored. The cat’s patellar fracture was repaired with cerclage wire to restore its anatomical normality, reducing the fracture and stabilizing the bone fragments in order to immobilize them and ensure proper better bone healing. Maintenance and approximation of the lateral fragment of the longitudinal fracture, in conjunction with sulcoplasty, were proposed to ensure greater contact between the patella and the trochlear groove, thereby reducing the possibility of luxation. Despite the non-consolidation of the fracture, the fragment remained intact and immobile, and no post-surgical complications were reported. This confirmed the success of the technique employed to bring together the patellar fragments of the lateral longitudinal fracture, even in the absence of bone callus formation. Moreover, the technique proved to be simple and resulted in complete joint stability after 60 days. This is therefore an important tool for patellar fractures, whose lateral longitudinal fragment was retained, allowing for correct approximation and fragment immobilization, without the need for excision by partial patellectomy.

Keywords: fracture, patella, osteosynthesis, cerclage wire, feline, orthopedics.

Título: Fratura patelar longitudinal em um gato - correção cirúrgica

Descritores: fratura, patela, osteossíntese, cerclagem, felino, ortopedia.