Abstract
Objectives Medial patellar luxation (MPL) is the most common developmental cause of hindlimb
lameness in cats. The association between femoral and tibial conformation and MPL
measured on computed tomography (CT) has not been reported in cats. The aims were
to report femoral and tibial conformation in cats with and without MPL and to report
normal femoral and tibial angles.
Methods Angle of inclination of femoral neck (AI), anatomical lateral distal femoral angle
(aLDFA), femoral trochanteric angle (FCT), angle of anteversion of femoral neck (AA),
distal and proximal anteversion angle (DAA/PAA), overall tibial valgus (TV), tibial
torsion (TT), tibial tuberosity displacement (TTD) and trochlear depth:patellar thickness
ratio (T:P) were measured by three observers on CT of cats with and without MPL. Comparisons
were made between groups. Inter-observer intraclass correlation coefficient (ICC)
was calculated.
Results Sixteen cats were recruited: eight control and eight with MPL. The aLDFA, PAA, TT,
TTD and T:P were significantly less in cats with high-grade MPL. The AI, FCT, AA,
DAA and TV were not significantly different. A high correlation was shown with inter-observer
ICC in 33.33% and good correlation in 26.67% when comparing measurements between observers.
Clinical Significance This study suggests that cats with high-grade MPL have decreased TT, TTD and T:P
and may require tibial tuberosity transposition and femoral trochleoplasty. The PAA,
TT and aLDFA were decreased, although clinical significance may vary and these cats
may not require correctional osteotomies. Results should be interpreted with caution
as high/good levels of inter-observer ICC occurred in less than two-thirds of cases
between observers.
Keywords
computed tomography - corrective osteotomy - cat - patellar luxation - hindlimb conformation
