How To Perform An Isolated Subtalar Joint Arthrodesis

Author(s): 
By Douglas K. Blacklidge, DPM

Isolated arthrodesis procedures for the hindfoot are an interesting and sometimes controversial topic for foot and ankle surgeons. Historically, when it came to most major rearfoot deformities and joint conditions, surgeons utilized the triple arthrodesis versus any isolated joint fusions of this complex. The thinking was that the subtalar, calcaneocuboid and talonavicular joints all function together to allow pronation and supination of the entire foot, so if one joint needed fusion, they all needed fusion.
The trend during the past decade or two has been more toward preserving mobility when possible. Isolated hindfoot arthrodesis procedures have been under investigation and can certainly provide solutions to a variety of rearfoot pathologies. Studies have demonstrated very satisfactory results with isolated subtalar arthrodesis procedures.1
One must consider the impact of an isolated rearfoot arthrodesis on the other two joints. Studies have demonstrated the effect of isolated rearfoot fusions and significant restriction of motion occurs at the remaining joints after one of the three joints has undergone fusion. An isolated subtalar joint arthrodesis limits talonavicular motion to about 26 percent and calcaneocuboid motion to about 56 percent.2,3
The percentage of restriction of motion obviously depends upon the position of the bones being fused. If the subtalar joint underwent fusion in supination, one would expect more restriction of the calcaneocuboid and talonavicular joints. Alternatively, if the subtalar joint underwent fusion in pronation, surgeons would expect more motion of the midtarsal complex.4-6
With an isolated rearfoot fusion, one must consider the condition of the remaining rearfoot joints. If either of the remaining joints has significant arthrosis, this lack of freedom to move will likely facilitate degeneration and intensify any preexisting symptoms. The position of the subtalar joint fusion in a more pronated position will allow more midtarsal motion whereas subtalar fusion in a more supinated position will restrict midtarsal motion. An understanding of the functional relationship between the subtalar joint and the midtarsal joint complex affords the surgeon the opportunity to optimize functional results for arthrodesis.

Key Considerations In Procedure Selection

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