Objective—To evaluate subchondral bone density patterns
in elbow joints of clinically normal dogs by use of
computed tomographic (CT) osteoabsorptiometry.
Sample Population—20 cadaver forelimbs from 10
clinically normal dogs.
Procedure—Each elbow joint was imaged in
parasagittal and transverse planes of 1.5-mm thickness.
Slice data were converted to dipotassium phosphate
equivalent density (PPED) values. Sagittal,
parasagittal, and transverse medial coronoid process
topographic maps were constructed. Defined zones
were created for each of the 3 CT planes, and confluence
and peak PPED values were determined.
Results—The lowest PPED value was 340 mg/ml
(articular and subchondral confluence), and the highest
was 1780 mg/ml (peak subchondral density).
Detectable effects of joint laterality were not found in
the confluence or peak PPED measurements or in the
peak-to-confluence PPED ratio for all 3 CT planes.
Significant differences were found among zones in all
3 planes for confluence and peak PPED measurements
and between sagittal and transverse planes for
peak-to-confluence PPED ratios. Subjectively, the pattern
of density distribution among dogs was fairly
consistent for the sagittal and parasagittal slices.
Three specific patterns of density distribution were
apparent on the transverse topographic maps of the
medial coronoid process that corresponded to conformational
Conclusions and Clinical Relevance—The use of CT
osteoabsorptiometry provides a repeatable technique
that can be used to noninvasively examine bone density
and the effects of stress acting on joints in vivo.
Variability in density values for any of the CT planes
was not identified among clinically normal dogs.
(Am J Vet Ress 2002;63:1159–1166
Objective—To evaluate whether cutting equine subchondral bone to demarcate specific regions of interest (ROIs) influences the mean density for that bone as measured via quantitative computed tomography (QCT).
Sample population—2 metacarpophalangeal joints from equine cadavers.
Procedures—The distal portion of the third metacarpal bone of each intact metacarpophalangeal joint was scanned via CT to simulate in vivo conditions. Each joint was subsequently disarticulated and dissected, and the distal portion of the dissected third metacarpal bone in air was scanned. Then, six 1-cm2 areas representing ROIs were cut into the distal condylar surfaces to depths of approximately 1 cm, and the bone was scanned again. Three-dimensional CT models of the 3 bone preparations were generated for each third metacarpal bone on the basis of data from each set of scan images, and densities of the 6 ROIs were measured. Mean bone densities for the 6 ROIs were compared among models of intact, dissected, and cut third metacarpal bone scans.
Results—Mean bone density was significantly lower in cut bone preparations, compared with that in intact or dissected bone. Differences between mean bone densities for intact and dissected bone preparations were not significant.
Conclusions and Clinical Relevance—Cutting subchondral bone to demarcate specific ROIs prior to CT imaging significantly lowered mean bone density as measured via QCT and thus introduced substantial artifacts. These findings have direct implications on techniques for CT modeling of equine subchondral bone in the characterization of joint diseases in horses.