Assessing The Merits Of The Talonavicular Arthrodesis For Hindfoot Correction In Reconstructive Flatfoot Surgery

The definition of a principle is "a fundamental truth or proposition that serves as the foundation for a system of belief or behavior or for a chain of reasoning."¹ Reconstructive flatfoot surgery principles are threefold, in my experience. First, remove any deforming force of the leg onto the foot. Second, align the hindfoot perpendicular to the ground to reestablish the columnar effect of the lower extremity. Finally, position the forefoot parallel to the hindfoot. Achieving these principles in flatfoot reconstruction yields consistent outcomes. 

The choices to accomplish each of these principles ultimately are up to the surgeon. One may choose from multiple procedures to achieve correction of the hindfoot. One of those procedures is talonavicular arthrodesis (TNA), which is an underappreciated option in my opinion. Talonavicular arthrodesis offers significant advantages over double or triple arthrodesis. 

In a 2010 study, Thelen and colleagues concluded, "Isolated talonavicular arthrodesis is a useful and elective alternative to double arthrodesis. It is the less complicated, less invasive and functionally equivalent operative option for arthritic alterations of the hindfoot and transverse tarsal joint."² 

In a 2007 cadaver study, Suckel and team demonstrated "more evenly distributed peak pressure load in the ankle joint after talonavicular arthrodesis than after triple arthrodesis; thus, mechanically, a selective arthrodesis appears to be more favorable."³ 

In a landmark article by O'Malley and coworkers, the authors' research revealed that the talonavicular joint controlled the hindfoot joint complex and that the talonavicular arthrodesis offered superior correction of corrected hindfoot valgus in comparison to an isolated subtalar arthrodesis.⁴

In a recent study employing finite element modeling to examine flatfoot scenarios treated by arthrodesis procedures, Cifuentes-De la Portilla and colleagues recommended talonavicular arthrodesis over subtalar arthrodesis, and considered talonavicular arthrodesis at least equivalent to a triple arthrodesis.⁵

The subtalar joint axis (STJA) spatial location and subtalar joint rotational equilibrium align with the talar position anatomically. The subtalar joint axis courses typically from the posterior lateral calcaneus through the talus, exiting at the first intermetatarsal space.⁶ Huson theorized the foot rotates in inversion and eversion around a fixed talus as a unit in a predictable fashion.⁷ So, if one interprets the Huson theory and applies it to surgical goals, structural realignment of the subtalar joint axis via talonavicular arthrodesis normalizes the moment arms about the subtalar joint axis without relying on subordinate structures like the spring ligament and posterior tibial tendon to stabilize the medial arch. 

A positive unintended consequence of a talonavicular arthrodesis is the limit of subtalar motion. In their milestone research, Astion and colleagues found that talonavicular arthrodesis reduced subtalar joint range of motion to approximately two degrees of total movement.⁸ The authors concluded, "The talonavicular joint is the key joint of the triple joint complex. The talonavicular joint had the greatest range of motion and simulated arthrodesis of this joint essentially eliminated motion of the other joints of the complex." Reporting similar findings in 2000, Wülker and team agreed the talonavicular joint is the critical articulation of the hindfoot.⁹

An important concept regarding this limitation of subtalar motion is that an uncorrected or under-corrected forefoot varus will result in lateral column overload. It is imperative to fully correct any forefoot varus deformity with a Lapidus or Cotton procedure. The remaining two degrees of motion at the subtalar joint after talonavicular arthrodesis provides minimal compensation for the forefoot. 

Final Notes

Adhering to the principles of flatfoot correction is essential for consistent outcomes. Talonavicular arthrodesis provides an excellent biomechanically-sound approach to verticalizing the hindfoot for the structural correction of adult flatfoot deformity.

Dr. DeHeer is the Residency Director of the St. Vincent Hospital Podiatry Program in Indianapolis. He is a Fellow of the American College of Foot and Ankle Surgeons, a Fellow of the American Society of Podiatric Surgeons, and a Fellow of the American College of Foot and Ankle Pediatrics. Dr DeHeer is also a Fellow of the Royal College of Physicians and Surgeons of Glasgow, and a Diplomate of the American Board of Foot and Ankle Surgery.

References

1. Google Dictionary. Principle. Available at: https://www.google.com/search?sxsrf=ALeKk01EiysWmlhKTMSrIGXxkYttyVhF6A%3A1609048671114&source=hp&ei=XyLoX4eeBKaP9PwP2b2S0AY&q=principle+definition&oq=&gs_lcp=CgZwc3ktYWIQARgAMgcIIxDqAhAnMgcIIxDqAhAnMgcIIxDqAhAnMgcIIxDqAhAnMgcIIxDqAhAnMgcILhDqAhAnMgcIIxDqAhAnMgcIIxDqAhAnMgcIIxDqAhAnMgcIIxDqAhAnUABYAGCIMGgBcAB4AIABAIgBAJIBAJgBAKoBB2d3cy13aXqwAQo&sclient=psy-ab . Accessed December 28, 2020.

2. Thelen S, Rutt J, Wild M, Logters T, Windolf J, Koebke J. The influence of talonavicular versus double arthrodesis on load dependent motion of the midtarsal joint. Arch Orthop Trauma Surg. 2010;130(1):47-53. 

3. Suckel A, Muller O, Herberts T, Langenstein P, Reize P, Wulker N. Talonavicular arthrodesis or triple arthrodesis: peak pressure in the adjacent joints measured in 8 cadaver specimens." Acta Orthop. 2007;78(5):592-597.

4. O'Malley MJ, Deland JT, Lee K-T. Selective hindfoot arthrodesis for the treatment of adult acquired flatfoot deformity: an in vitro study. Foot Ankle Int. 1995;16(7):411-417.

5. Cifuentes-De la Portilla C, Larrainzar-Garijo R, Bayod J. Analysis of biomechanical stresses caused by hindfoot joint arthrodesis in the treatment of adult acquired flatfoot deformity: A finite element study. Foot Ankle Surg. 2020;26(4):412-420.

6. Kirby KA. Subtalar joint axis location and rotational equilibrium theory of foot function. J Am Podiatr Med Assoc. 2001;91(9):465-487.

7. Huson A. Functional anatomy of the foot. In: Jahss MH (ed). Disorders of the Foot and Ankle. Philadelphia: WB Saunders; 1991:409.

8. Astion DJ, Deland JT, Otis JC, Kenneally S. Motion of the hindfoot after simulated arthrodesis. J Bone Joint Surg Am. 1997;79(2):241-246.

9. Wülker N, Stukenborg C, Savory KJM, Alfke D. Hindfoot motion after isolated and combined arthrodeses: measurements in anatomic specimens. Foot Ankle Int. 2000;21(11):921-927.