Vertical patellar position in large-breed dogs with clinically normal stifles and large-breed dogs with medial patellar luxation.
OBJECTIVE
To further define vertical patellar position, as measured by the ratio of patellar ligament length to patellar length (L:P), in large-breed dogs with clinically normal stifles and compare that to the L:P of large-breed dogs with medial patellar luxation (MPL).


METHODS
Retrospective study.


METHODS
Large-breed dogs (n = 50) with clinically normal stifle joints and 30 large-breed dogs with MPL.


METHODS
Large-breed dogs with clinically normal stifle joints or MPL were identified and divided into groups (NORM and MPL, respectively). L:P values were determined for each dog by 4 observers from single lateral stifle radiographs. L:P was compared between NORM and MPL groups and 95% confidence intervals (CIs) were calculated.


RESULTS
All 4 observers found a significantly higher L:P (more proximally positioned patella) for the MPL group compared with the NORM group. Overall mean (+/-SEM) L:P were: NORM, 1.71+/-0.020 and MPL, 1.87+/-0.025. The 95% CI was determined to be 1.45-1.97 for the NORM group and 1.57-2.17 for the MPL group.


CONCLUSIONS
Large-breed dogs with MPL had a significantly more proximal vertical patellar position compared with large-breed dogs with clinically normal stifles. Large-breed dogs with L:P values >1.97 are considered to have patella alta.


CONCLUSIONS
Proximal displacement of the patella within the femoral trochlear groove may play a role in MPL in large-breed dogs.
Johnson
Allen L
AL
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA. johnsonah1@msn.com
Broaddus
Kristyn D
KD
Hauptman
Joe G
JG
Marsh
Sarah
S
Monsere
Jaime
J
Sepulveda
Gustavo
G
D000704:Analysis of Variance; D000818:Animals; D016022:Case-Control Studies; D004283:Dog Diseases / Q000473:pathology*; D004285:Dogs / Q000033:anatomy & histology* / Q000293:injuries; D004204:Joint Dislocations / Q000473:pathology / Q000662:veterinary; D015588:Observer Variation; D010329:Patella / Q000033:anatomy & histology* / Q000293:injuries; D011859:Radiography; D012189:Retrospective Studies; D013264:Stifle / Q000033:anatomy & histology* / Q000000981:diagnostic imaging