Are We Facing The Death Of The Austin Bunionectomy?

It is a rarity when a revolutionary idea that has the backing of evidence-based medicine challenges a long-held belief, but this is what leads to a paradigm shift resulting in a major breakthrough in medicine.

Paul Dayton, DPM, has led a paradigm shift in bunion surgery with the substantial work he and his group have compiled over the past several years and brought it full circle in their recent article “Is Our Current Paradigm for Evaluation and Management of the Bunion Deformity Flawed? A Discussion of Procedure Philosophy Relative
 to Anatomy” in the Journal of Foot and Ankle Surgery.¹ I believe this paradigm shift in fact is the death of the Austin bunionectomy or at least it should be. 

I have done hundreds if not thousands of Austin bunionectomies over my career. I have over the past five years or so gradually drifted away from the Austin. My procedures of choice for hallux abucto valgus have become either first metatarsophalangeal joint (MPJ) arthrodesis or first metatarsocuneiform arthrodesis. The first metatarsocuneiform arthrodesis is a technically demanding procedure that can be fraught with complications, mostly iatrogenic. However, after reading and listening to Dayton’s theory, it is clearly the most appropriate choice for deformity correction in hallux abducto valgus if first MPJ arthrodesis is not appropriate.

The basis of Dayton’s premise is twofold, focusing on the center of rotation of angulation (CORA) location and the triplane nature of hallux abducto valgus. Numerous surgeons have shown the CORA to be located at the metatarsocuneiform joint.^1-7 This is a critical consideration as translational osteotomies of the head, midshaft or base are all distal to the CORA or as Dayton states, “Instead these popular procedures have focused correction on a non-deformed metatarsal with the singular priority of reducing the (intermetatarsal angle).”¹

The frontal plane deformity of the first metatarsal in hallux abucto valgus is a complex, underappreciated component of the deformity that led Dayton and his colleagues to their conclusions of our current state of bunion correction.¹ They have shown in conjunction with others the valgus rotation of the first metatarsal occurring at the first metatarsocuneiform joint is at least partially responsible for the sesamoid malalignment, not solely transverse plane deformity as previously thought.^5-7 Studies have shown that the perceived abnormal position of the sesamoids on an AP X-ray view do not correlate with axial sesamoid views showing the sesamoids to be in their grooves separated by the median cristae.^5-7 With valgus rotation, the tibial sesamoid position and dorsal medial eminence worsen, but varus rotation of the first metatarsal reduces the tibial sesamoid position and the dorsal medial eminence.

What about all those Austin bunionectomies with the sesamoids centered beneath the metatarsal head postoperatively? Dayton suggests “iatrogenic subluxation of the sesamoids medial to the median crista has created the perception that the sesamoids are correctly positioned under the metatarsal on the AP radiograph … after the lateral release and during the medial capsular plication.” Alternately, Dayton notes “in some cases a degree of frontal plane correction occurs spontaneously when retrograde buckling forces of the hallux acting on the metatarsal are relieved.”¹ Over time, there is a resultant lateral drift of the sesamoids.

The only surgical method that addresses both the CORA and frontal plane component of the triplanar hallux abducto valgus deformity is first metatarsocuneiform arthrodesis. This procedure is not an easy one to get consistent positional results but evidence-based medicine shows we must refine our techniques not only to correct the transverse and sagittal planes, but the frontal plane as well. It appears that at long last and after hundreds of procedures, there is finally a definitive answer for hallux abducto valgus.

References

1. Dayton P, Kauwe M, Feilmeier M. Is our current paradigm for evaluation and management of the bunion deformity flawed? A discussion of procedure philosophy relative to anatomy. J Foot Ankle Surg. 2015; 54(1):102-111.
2. Paley D, Herzenber JE. Principles of Deformity Correction, Springer-Velag, Berlin, 2005.
3. Dayton P, Feilmeier M, Kauwe M, Hirschi J. Relationship of frontal plane rotation of first metatarsal to proximal articular set angle and hallux alignment in patients undergoing tarsal metatarsal arthrodesis for hallux abducto valgus: a case series and critical review of the literature. J Foot Ankle Surg. 2013; 52(3):348–354.
4. DiDomenico LA, Fahim R, Rollandini J, Thomas ZM. Correction of frontal plane rotation of sesamoid apparatus during Lapidus procedure: a novel approach. J Foot Ankle Surg. 2014; 53(2):248–251.
5. Dayton P, Feilmeier M, Hirschi J, Kauwe M, Kauwe JS. Observed changes in radiographic measurements of the first ray after frontal plane rotation of the first metatarsal in a cadaveric foot model. J Foot Ankle Surg. 2014; 53(3):274–278.
6. Dayton P, Feilmeier M, Hirschi J, Kauwe M, Kauwe JS. Observed changes in radiographic measurements of the first ray after frontal plane rotation of the first metatarsal in a cadaveric foot model. J Foot Ankle Surg. 2014; 53(3):274–278.
7. Dayton P, Kauwe M, Feilmeier M. Clarification of the anatomic definition of the bunion deformity. J Foot Ankle Surg. 2014; 53(2):160–163.

Editor’s note: For a related article, look for “Addressing The Impact Of Frontal Plane Rotation On Bunion Repair” by Lawrence A. DiDomenico, DPM, FACFAS, and Frank A. Luckino III, DPM, AACFAS, in the forthcoming April 2015 issue of Podiatry Today.