Cat presented last week with refracture of the Tibia after implant removal secondary to stress protection. The cat was operated, these are the post OP radiographs. Craniocaudal and mediolateral view of the right Tibia and Ulna: Fixation with a Fix Ex, Osteostixis and Allograft There were more control re-checks in the weeks following the surgery with progressive modification and partial removal of the implant. The cat was clinically fine, with good loading of the limb. 10 weeks after the fixation other radiographs were taken. Craniocaudal view 10 weeks post OP. Radiographic findings On the craniocaudal view, there is an obvious smooth callus formation around the fibular fracture. A very faint lucent line is still visible.
- On the mediolateral view, there is still a very well visible fracture gap with small step and dislocation and no sign of callus formation. The extremity of the fracture fragments are rounded, sclerotic and mild tapering.
- A non union was diagnosed.
Mediolateral view at the same time point, 10 weeks post OP The clinician decided for a revision of the implant Craniocaudal and mediolateral view of the right tibia and fibula after revision of the implant, with Autograft and Osteostixis. Comments
- Nonunion is defined as a fracture that is not healed and has no evidence of progression of the healing process. The key factor in distinguishing a nonunion from a delayed union is when it can be determined that healing has ceased and will not progress without intervention.
- Determination of a non union is subjective but relies on lack of progression of a healing callus, remodeling of the callus at the fracture ends without bridging, lack of increase in opacity of the fracture line and duration of the healing process.
- Some long-term nonunions may develop into pseudoarthrosis as a result of chronic motion at the fracture site. Fibrocartilage fills the fracture gap. The patient may have good use of the limb with no significant pain after formation of the pesudoarthrosis.
- Nonunion fracture can be divided in
- viable (active attempts to heal the fracture with reactive bone and callus formation) classified in hypertrophic, moderately hpertrophic and oligotrophic
- non viable (result of severe distruption and lack of blood supply) classified in dystrophic, necrotic, defect nonunions and atrophic.
- The present case stresses also the importance to have always two orthogonal views in every radiographic examination, significant lesions may be missed on only one view study.
