Dogs with medial patellar luxation often have associated femoral deformities, which contribute to quadriceps malalignment and subsequent patellar luxation. Inclusion of femoral radiographs as part of a diagnostic work-up should be considered to rule out these changes, because if present, a surgical procedure to include femoral correction should be recommended in order to optimize post-operative outcome. However, radiographic positioning of the craniocaudal view is challenging due to the larger muscle mass proximally as compared to distally. Accordingly, these radiographs often contain so-called parallax magnification error. Such error could induce a femoral varus deformity, or mask it—either of which would be detrimental to appropriate surgical recommendations.

Although some studies exist evaluating the accuracy of various craniocaudal femoral projections, to date, no study has compared these projections to a CT scan as the gold standard for assessment. Not every practice has the availability of a CT scan, and not every owner can afford the cost of a CT scan, yet veterinarians should have the knowledge to be able to obtain accurate radiographs without the need for this advanced imaging modality.

To complicate things further, some studies have recommended radiographic views that require lead-lined radiology suites, which not every clinic has.

Therefore, the purpose of this project is to evaluate three different craniocaudal femoral positions against a CT scan in order to provide veterinarians and surgeons with best clinical recommendations for diagnosing associated femoral deformities for medial patellar luxation.

This trial; conducted by Dr. Danielle Marturello, Sarah Kahn, and Dr. Karen Perry; entails a comparison of three different positioning techniques for femoral radiographs to assess the accuracy of each in dogs with medial patellar luxation.

Components:

• Pre-sedation evaluation
  • Physical and orthopedic examination by orthopedic surgeon (Dr. Marturello)
  • CBC/chemistry

• Sedated imaging
  • Radiographs: three femoral views (note: tibial radiographs not included)
  • Hindlimb CT scan

*All exams, bloodwork, sedation, and imaging will be free of charge to participating dogs.
**Patients need not undergo surgical correction at Michigan State University.

• BW 14–45 kg
• Healthy dogs suitable for safe sedation and imaging
• Dogs with any grade (1-4) medial patellar luxation (no laterals) — can be clinically normal with incidental MPL found on exam or clinically affected

• Dogs outside of body weight inclusion range
• Overly anxious dogs that would not sedate well for all imaging without general anesthesia
• Dogs with cranial cruciate ligament disease concurrently