Measurement of Femoral and Tibial Joint Reference Angles and Pelvic Limb Alignment in Cats

Abstract

To report pelvic limb joint reference angles, limb alignment, and mechanical axis deviation for the feline pelvic limb. Cadaveric radiographic anatomic study. Skeletally mature, mixed breed cats (n = 50). Extended pelvic limb radiography was performed and images analyzed to determine femoral anatomic joint reference angles, femoral and tibial mechanical joint reference angles, tibiofemoral angle, metatarsotibial angle, mechanical axis-femur and mechanical axis-metatarsus angles, and mechanical axis deviation of the stifle and tarsus. Mean ± SD and 95% confidence intervals (95% CI) were calculated. Mean ± SD angles and 95% CI were: anatomic lateral proximal femoral (103.9° ± 3.8°; 103.1° - 104.6°), anatomic lateral distal femoral (93.8° ± 2.5°; 93.3° - 94.3°), mechanical lateral proximal femoral (100.5° ± 3.7°; 99.8° - 101.2°), mechanical lateral distal femoral (97.2° ± 2.2°; 96.7° - 97.6°), mechanical medial proximal tibial (88.0° ± 3.2°; 87.3° - 88.6°), mechanical medial distal tibial (107.6° ± 4.8°; 106.6° - 108.5°), mechanical tibiofemoral (7.4° varus ± 2.5°; 6.9° - 7.9°), mechanical metatarsotibial (6.0° valgus ± 3.5°; 5.3° - 6.7°); mechanical axis-femur (3.2° ± 1.4°; 2.9° - 3.5°) and mechanical axis-metatarsus (2.4° ± 2.0°; 1.7° - 2.1°). Mechanical axis deviation of the stifle and of the tarsus were 2.0% ± 0.9% (95% CI: 1.9-2.2) and 0.8% ± 1.0% (95% CI: 0.7-1.0), respectively. Mean pelvic limb joint reference and limb alignment angles can be used for diagnosing angular limb deformities of the feline pelvic limb and for planning corrective osteotomies in affected cats.