Summary
Objectives: The primary objective was to develop a repeatable radiographic technique for assessment
of cranial tibial subluxation (CTS) and test the intra-observer and inter-observer
repeatability of the chosen landmarks. A secondary objective was to determine the
effects of digital radiographic magnification on CTS measurement repeatability.
Methods: Twenty-three normal canine pelvic limbs were used to determine the magnitude of CTS
before and after transection of the cranial cruciate ligament. Mediolateral radiographs
were taken with and without fiduciary markers in place. Three investigators measured
the CTS using radiographically visible anatomic landmarks at two different magnifications.
The total observed variabilities were assessed by inter-observer and intra-observer
differences. Paired t-tests were used to determine the effect of magnification and
marker presence on CTS measures.
Results: Measurement of the CTS from the caudal margin of the intercondylar fossa on the femur
to the intercondylar eminence was the most repeatable. Poor correlation between the
anatomic landmarks and the fiduciary bone markers was observed. We found no effect
of magnification or presence or absence of bone markers on measurement of CTS.
Clinical significance: Cranial tibial subluxation can be detected with the most repeatability by measuring
between the caudal margin of the intercondylar fossa and the intercondylar eminence.
Magnification of the digitized radiographic image had minimal effect on repeatability.
This technique can be used for in vivo analysis of the canine cruciate ligament deficient
stifle joint.
Keywords
Cranial cruciate ligament - radiograph - cranial tibial subluxation - stifle