The stability of an arthrodesis with two cancellous-bone screws across
the ankle joint was evaluated in eighteen ankles from fresh-frozen
cadavera. Tibiotalar motion was recorded in response to the following
loading modes: medial-lateral moment, plantar flexion-dorsiflexion moment,
and internal-external tibial torque. The series of loading tests was
performed with two cancellous-bone screws through the tibia into the talus
and a lateral fibular strut graft fixed with a proximal and a distal screw.
The tests were repeated after the strut graft was removed, and again after
it had been reapplied. The amount of motion at the site of the arthrodesis
was greatest with tibial torque and was least with medial-lateral bending;
this was true for specimens with or without a fibular strut graft. Removal
of the strut graft allowed increased tibiotalar motion for all modes of
loading; increases in motion were far greater for specimens of poor bone
quality.