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)