Emerging Concepts In Redefining Our Approach To Bunion Correction

The paradigm of hallux abducto valgus (HAV) surgery has undergone a significant shift in the literature over the past five years.

Dayton and colleagues’ extensive research on the frontal plane component of HAV deformity is the basis of the change.^1-4 Kim and colleagues provided additional insight on the frontal plane component in HAV, demonstrating a pronation deformity of the first metatarsal in 87.3 percent and sesamoid dislocation in 71.7 percent of the HAV patients in their study.⁵ The later finding of 71.7 percent by Kim and coworkers was remarkably similar to the 73 percent recurrence rate Pentakainen and colleagues described in the longest long-term study on the Austin bunionectomy.⁶ The similarity is logical as sesmoid malalignment will result in eventual valgus rotation of the hallux proximal phalanx via the plantar plate and therefore result in recurrence.

Arguments against the triplanar concept of HAV exist. The arguments seem based on terminology and a lack of acceptance of the evidence-based research on the topic. The literature purported to refute this emerging concept is based on older theoretical biomechanical literature and a few newer, contradictory articles.^7-12 Objective analysis demonstrates the preponderance of literature is clearly trending toward confirming the frontal plane component of HAV.

What if this frontal plane deformity is not actually a rotational deformity but a torsional deformity? Does that change how we treat HAV surgically? Does it matter if the frontal plane deformity is torsional or rotational? Emerging research proposes torsion of the first metatarsal is the source of frontal plane rotation and the findings correspond to Dayton’s and Kim’s studies on the amount of valgus rotation.^1–5

Ota and colleagues examined the torsion of the first metatarsal head in comparison to the first metatarsal base in HAV patients.¹³ Using three-dimensional computed tomography (CT) scans to evaluate the first metatarsal in study participants with HAV and a control group, the study authors noted the first metatarsal in the HAV group averaged a torsional deformity of 17.6 degrees in comparison to 4.7 degrees in the control group. Ota and coworkers concluded, “The first metatarsal showed significant eversion in hallux valgus patients compared to control group patients.”¹³ The authors discussed the morphological change in the first metatarsal as potentially a congenital or developmental deformity without stating a definitive opinion either way. The torsional deformity appeared to occur in the diaphyseal region of the first metatarsal and not the metatsrsal head.

Both Dayton’s and Kim’s studies found a similar amount of frontal plane deformity in their studies: 22.2 degrees and 21.9 degrees respectively.^4,6 These findings were within the range of torsional deformity Ota and coworkers found.¹³ The numbers are lining up among different studies, which leads credence to the findings. There needs to be more research on the torsional component of HAV as the participants in the study by Ota and colleagues were drawn from a very narrow subset.¹³ As the understanding of the frontal plane deformity for HAV continues to evolve, hopefully improved consistency and reproducibility of surgical outcomes will result.

Whether HAV frontal plane deformity is rotational or torsional, it is apparent that translational osteotomies like the Austin bunionectomy have limited roles (only in cases in which no frontal plane deformity is present based on axial sesamoid views or 3D CT scans). The sooner the foot and ankle community put purely translational osteotomies to bed, better patient outcomes will follow. Recurrence rates of 73 percent are not acceptable and no matter how sacred the Austin bunionectomy, patients with HAV deserve better.

References

1. 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 tarsometatarsal arthrodesis for hallux abducto valgus: a case series and critical review of the literature. J Foot Ankle Surg. 2013; 52(3):348-354.
2. Dayton P, Feilmeier M, Hirschi J, et al. 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.
3. 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.
4. Dayton P, Kauwe M, DiDomenico L, et al. Quantitative analysis of the degree of frontal rotation required to anatomically align the first metatarsal phalangeal joint during modified tarsal-metatarsal arthrodesis without capsular balancing. J Foot Ankle Surg. 2016; 55(2):220-225.
5. Kim Y, Kim JS, Young KW, et al. A new measure of tibial sesamoid position in hallux valgus in relation to the coronal rotation of the first metatarsal in CT scans. Foot Ankle Int. 2015; 36(8):944-952.
6. Pentikainen I, Ojala R, Ohtonen P, et al. Preoperative radiological factors correlated to long-term recurrence of hallux valgus following distal chevron osteotomy. Foot Ankle Int. 2014; 35(12):1262-1267.
7. Klemola T, Leppilahti J, Kalinainen S, Ohtonen P, Ojala R, Savola O. First tarsometatarsal joint derotational arthrodesis: a new operative technique for flexible hallux valgus without touching the first metatarsophalangeal joint. J Foot Ankle Surg. 2014;53(1):22-28. 
8. Klemola T, Leppilahti J, Laine V, Pentikainen I, Ojala R, Ohtonen P, Savola O. Effect of first tarsometataral joint derotational arthrodesis on first ray dynamic stability compared to distal chevron osteotomy. Foot Ankle Int. 
2017; 38(8):847–854

9. Klemola T, Savolainen O, Ohtonen P, Ojala R, Leppilahti J. First tarsometatarsal joint derotational arthrodesis for flexible hallux valgus: results from follow-up of 3 to 8 years. Scand J Surg. 2017; 106(4):325–31.
10. Root ML, Orien WP, Weed JH. Normal and abnormal function of the foot. In: Clinical Biomechanics, 1st Edition, Los Angeles, Clinical Biomechanics Corporation, 1977.
11. Kelso SF, Richie DH Jr, Cohen IR, Weed JH, Root ML. Direction and range of motion of the first ray. J Am Podiatr Med Assoc. 1982; 72(12):600–605.
12. Kitaoka HB, Lundberg A, Luo ZP, An K. Kinematics of the normal arch of the foot and ankle under physiologic loading. Foot Ankle Int. 1995; 16(8):492-499.
13. Ota T, Nagura T, Kokubo T, et al. Etiological factors in hallux valgus, a three-dimensional analysis of the first metatarsal. J Foot Ankle Res. 2017; 10(1): 43.