Objectives—To evaluate the accuracy of 2 radiographic
methods used to assess tibial plateau slope
(TPS) in dogs and evaluate effects of film digitization
and radiographic beam placement on TPS measurements.
Sample Population—16 hind limbs from dog cadavers
weighing > 20 kg.
Procedures—Radiographs of tibiae were made with
the radiographic beam centered over the stifle joint
and midshaft of the tibia. Tibiae were collected, the
femorotibial contact area was determined, and slope
of the medial tibial condyle in relation to the tibial
shaft was measured. Radiographs were digitized.
Slope of the medial tibial condyle was measured on
printed and digitized radiographs read in random order
by 6 examiners unaware of anatomic measurements.
Three examiners used a conventional measuring technique,
and 3 examiners used an alternative measuring
Results—Anatomic measurements were significantly
higher than radiographic measurements made by use
of the conventional interpretation method but did not
differ from radiographic measurements made by use of
the alternate method. Measurements from printed radiographs
were lower than measurements from digitized
radiographs for the 4 most experienced examiners.
Conclusions and Clinical Relevance—Measurements
made by use of a line tangential to the cranial, linear portion
of the medial tibial condyle at the femorotibial contact
point were accurate measurements of the anatomic
TPS. Measurements made by use of the conventional
TPS measurement method underestimated the anatomic
TPS. Measurements made on digitized radiographs
were typically more accurate than measurements made
on printed radiographs. (Am J Vet Res 2003;64:586–589)
Objective—To measure the angles between the patellar ligament and the tibial plateau and between the patellar ligament and the common tangent at the tibiofemoral contact point (TFCP) in stifle joints of dogs with partial rupture of the cranial cruciate ligament (CrCL) for comparison with data obtained for stifle joints in dogs with intact CrCLs.
Sample Population—60 stifle joints of 54 dogs with surgically confirmed partial CrCL rupture.
Procedures—Mediolateral radiographic views of the stifle joints were obtained, and the angles between the patellar ligament and the conventionally defined tibial plateau (angle γ) and between the patellar ligament and the common tangent to the TFCP (angle α) were measured at incidental stifle joint flexion (angle β) by 2 independent observers. Data underwent linear regression analysis and were compared with findings in joints of dogs without degenerative joint disease.
Results—In stifle joints of dogs with a partial rupture of the CrCL, angles γ and α were 5° and 2° larger than each corresponding angle in healthy canine joints. At 100° of flexion, the patellar ligament was perpendicular to the conventionally defined tibial plateau. At 110° of flexion, the patellar ligament was perpendicular to the common tangent at the TFCP.
Conclusions and Clinical Relevance—In dogs, stifle joints with partially ruptured CrCLs have marginally larger angles between the patellar ligament and the tibial plateau, compared with joints with intact CrCLs; at equivalent angles of flexion, comparatively greater shear force affects the CrCLs in stifle joints with partial CrCL ruptures.