Objective—To evaluate areas of articular contact of
the proximal portions of the radius and ulna in normal
elbow joints of dogs and the effects of axial load on
size and location of these areas.
Sample Population—Forelimbs obtained from
cadavers of 5 adult mixed-breed dogs.
Procedure—After forelimbs were removed, liquidphase
polymethyl methacrylate was applied to articular
surfaces of the elbow joint, and limbs were axially
loaded. Articular regions void of casting material were
stained with water-soluble paint. Relative articular contact
areas were determined by computer-assisted
image analyses of stained specimens. Repeatability of
the technique was evaluated by analyses of casts from
bilateral forelimbs of 1 cadaver. Incremental axial loads
were applied to left forelimbs from 4 cadavers to
determine effects of load on articular contact.
Results—Specific areas of articular contact were
identified on the radius, the craniolateral aspect of the
anconeus, and the medial coronoid process. The
medial coronoid and radial contact areas were continuous
across the radioulnar articulation. There was no
articular contact of the medial aspect of the anconeus
with the central trochlear notch. Coefficients of variation
of contact areas between repeated tests and
between contralateral limbs was < 20%. Significant
overall effects of axial load on contact area or location
were not identified.
Conclusions—Three distinct contact areas were evident
in the elbow joint of dogs. Two ulnar contact
areas were detected, suggesting there may be physiologic
incongruity of the humeroulnar joint. There
was no evidence of surface incongruity between the
medial edge of the radial head and the lateral edge of
the medial coronoid process. (Am J Vet Res 2000;61:
Objective—To determine effects of incremental radial
shortening and subsequent ulnar ostectomies on joint
surface contact patterns in a canine elbow joint model.
Sample Population—Paired forelimbs from 9 adult
Procedure—Joint casting was performed by placement
of colored polymethylmethacrylate in the elbow
joint cavity and loading in a materials testing system
at physiologic angle and load. Joint casting was performed
in unaltered specimens, after radial shortening,
and after subsequent distal ulnar ostectomy,
proximal ulnar ostectomy, and proximal ulnar ostectomy
with intramedullary pinning. Computer-aided
analysis of photographs of proximal radial and ulnar
articular surfaces without joint casts was performed
before and after each casting procedure.
Results—All increments of radial shortening changed
the size and location of radial and ulnar contact areas.
The radial contact area became smaller, the anconeal
contact area disappeared, the medial coronoid contact
area migrated craniolaterally, and the lateral projection
of the coronoid process became a contact area. A proximal
ulnar ostectomy stabilized with an intramedullary
pin restored normal contact area size and location and
restored continuity of the radial and coronoid contact
areas across the radioulnar articulation in 6 of 10 specimens.
A midshaft ulnar ostectomy, distal to the level of
the radioulnar ligament, had no effect on contact patterns.
A proximal ulnar ostectomy without stabilization
resulted in varus deformity during loading.
Conclusion and Clinical Relevance—Proximal radial
shortening, which creates articular step incongruity,
changes the location and size of the radioulnar contact
areas. Dynamically stabilized ulnar ostectomies
proximal to the radioulnar ligament restore contact
patterns in vitro . (Am J Vet Res 2001;62:1548–1556)