Sagittal joint instability in the cranial cruciate ligament insufficient canine stifle is characterized by caudal subluxation of the femur

This site provides supplementary material to a publication submittet for peer review, concerning the sagittal motion pattern in the instable canine stifle joint. The most important finding of this study is the observation that in instable stifles cranio-caudal instability is charachterized by a sudden slippage of the femur, being directed caudally. The tibia does not show significant cranio-caudal motion, neither cranially nor caudally. This contrasts what has been described in veterinary literature since decades. Up to now, cranio-caudal subluxation of the tibia has been the main motion pattern when investigating stifle kinematics in vivo. Now that we know that this motion pattern is incorrect, future in vitro models should be adjusted to the real motion pattern, as this might influence our understanding of the biomechanics of cranial cruciate ligament rupture as well as its surgical treatment.

The following fluoroscopic video sequences are part of the mentioned study and show stifles with cranio-caudal instability. Just at the beginning of stance phase, the femur slipps backwards, along the tibia plateau. Except of one stifle (osteotomy of the proximal tibia) the tibia stays fixed, while the femur subluxates caudally.