Evaluation of the association between medial patellar luxation and hip dysplasia in cats.
OBJECTIVE
To investigate the association between hip dysplasia (HD) and medial patellar luxation (MPL) in cats.


METHODS
Cross-sectional prevalence study.


METHODS
78 cats.


METHODS
A complete history was obtained. Cats were examined to detect MPL and HD. Radiographs of the stifle and hip joints were obtained. Hip joints were evaluated by use of Norberg angle, distraction index, and scoring consistent with that established by the Orthopedic Foundation for Animals.


RESULTS
There were 43 male and 35 female cats mean age, 2.5 years). Eleven cats had clinical signs of disease in the pelvic limbs. Medial subluxation of the patella (subgrade 1) was seen in 31 of 33 cats with otherwise normal stifle joints. Medial patellar luxation was found in 45 of 78 (58%) cats, and 35 of 45 (78%) had grade-1 MPL. Bilateral MPL was seen in 32 of 45 (71%) cats. A weak association existed between MPL and HD, because cats were 3 times more likely to have HD and patellar luxation than to have either condition alone. Concurrent MPL and HD were detected in 19 of 78 (24%) cats, and HD was diagnosed radiographically in 25 of 78 (32%) cats (19 mild, 4 moderate, 2 severe). Eighteen of the 25 cats with HD had bilateral HD.


CONCLUSIONS
Clinically normal cats may have a certain degree of laxity in the stifle joint, evident as medial patellar subluxation (< grade 1). There is a weak association between MPL and HD, and both conditions may develop, alone or in combination, more frequently than has been reported.
Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia 19104-6010, USA.
G K
GK
Smith
A
A
Langenbach
P A
PA
Green
W H
WH
Rhodes
T P
TP
Gregor
U
U
Giger
D000818:Animals; D002371:Cat Diseases / Q000000981:diagnostic imaging / Q000453:epidemiology*; D002415:Cats; D003430:Cross-Sectional Studies; D005260:Female; D006614:Hindlimb; D006617:Hip Dislocation / Q000150:complications / Q000453:epidemiology / Q000662:veterinary*; D004204:Joint Dislocations / Q000150:complications / Q000453:epidemiology / Q000662:veterinary*; D007593:Joint Instability / Q000150:complications / Q000453:epidemiology / Q000662:veterinary; D008297:Male; D010329:Patella; D015995:Prevalence; D011859:Radiography; D011795:Surveys and Questionnaires