Significance of radiographic lucencies in the m femoral condyle of young TB’s

More and more common is the radiographic examination of young sport horses prior to sale. A number of “abnormalities” are being identified but what is not known is the significance of these findings. Here is a excellent study of one of the more common findings in young race horses, medial femoral condyle radiographic lucencies, with a 5 year follow up to see how the lesion changed radiographically and how the presence of the lesion correlated with future performance.
DrO

Equine Vet J. 2020 Jun 4.
Progression of shallow medial femoral condyle radiographic lucencies in Thoroughbred repository radiographs and their influence on future racing careers.
Pérez-Nogués M1, Derham A2, Marmion J3, Baker WT4.

Author information:
1. Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, One Garrod Road, Davis, CA, 95616, USA.
2. Oaklands Equine Hospital, Yarm, Yorkshire, TS15 9JT, UK.
3. Professional Equine Sports Medicine, Kennett Square, Pennsylvania, 19348, USA.
4. Hagyard Equine Medical Institute, 4250 Ironworks Pike, Lexington, Kentucky, 40511, USA.
Abstract
BACKGROUND:

Shallow lucencies less than 4 mm deep into the medial femoral condyle (MFC) are frequent in Thoroughbred horses undergoing screening sales radiographs. It is unclear if these shallow defects are precursors to larger cystic lesions or if they are fully developed defects that remodel into a flattened femoral condyle.
OBJECTIVE:

To evaluate radiological lucencies of the MFC and their progression in size, in a cohort of Thoroughbred horses, ranging from 5 to 18 months of age and to report on the racing careers of these horses compared to their maternal siblings free of stifle pathology.
STUDY DESIGN:

Retrospective cohort.
METHODS:

Radiographic reports were reviewed to identify cases with MFC lucency. Medical data including age at the time of radiographic sale set, sex, and MFC lucency radiographic measurements were recorded. The data was analysed for changes in lucency morphology. Racing data was collected and analysed for the following 5 years.
RESULTS:

From 12,938 sales reports reviewed, 3874 horses were found to have radiographic sets available at both weanling and yearling sales. A MFC lucency ≤ 3 mm in depth was diagnosed in at least one radiographic sales set in 248 horses (6.4%). The right femur was more commonly affected (73.9%) than the left. Radiographic lucencies in the left femur were significantly smaller (P = 0.02) than lucencies in the right femur. Radiographic lucencies resolved in 6.1% of cases, 3.6% of cases developed into a cyst, 40.7% of cases were unchanged in size, 23.6% of lucencies decreased in size and 8.2% increased in size. Cysts >3mm deep regressed into smaller lesions accounting for 4.9% of the lucencies, and 12.9% of lucencies developed from a normal or flat medial femoral condyle contour. Horses with a medial femoral condyle lucency had significantly less starts as a 2-year-old versus their maternal siblings (P < 0.01). MAIN LIMITATIONS: Data was collected retrospectively. Measurement errors may have occurred due to the measuring tool scale, small size of the defects and/or radiographic position. Treatments between radiographic studies were unknown and could not be accounted for. Observers were not blinded to radiographic sales reports. CONCLUSIONS: Radiographically diagnosed lucencies in the MFC of immature Thoroughbreds have the potential to fully resolve or develop into a cyst. However, most radiographic lucencies do not change in size. Thoroughbreds with MFC lucencies had less starts as 2-years-old when compared to their maternal siblings free of stifle pathology.