New Study Fuels Controversy Over Frontal Plane HAV Correction

A new article fuels the controversy about a new method to correct hallux abducto valgus (HAV) deformity in the frontal plane. Klemola and coworkers have published the third in their series of studies using their new modification of the Lapidus procedure to correct HAV, incorporating a frontal plane rotation of the first metatarsal when fusing the first tarsometatarsal joint.^1-3 However, contrary to the trend here in the United States incorporating a varus or inversion correction, Klemola and coworkers rotate the first metatarsal in the opposite direction.  

For those unfamiliar, here is a brief history of the current frontal plane controversy in HAV surgery. The longstanding theory of HAV pathomechanics is based upon recognition that the first ray of the human foot moves about an axis of rotation that combines plantarflexion with eversion and dorsiflexion with inversion.^4,5 Hallux abducto valgus deformity results from instability of the first ray where there is excessive mobility in both the transverse and sagittal planes.⁶ As the first metatarsal moves dorsal and medial with inversion, the hallux moves laterally and into eversion.⁷ This lateral shift of the first metatarsal and hallux causes a lateral displacement of the flexor tendons of the hallux.⁸ This inversion of the first metatarsal causes a plantar displacement of the abductor hallucis, allowing further pronation of the hallux.⁹ If the entire foot moves into excessive pronation, the first ray will appear pronated to the ground while this segment is still dorsiflexed and inverted relative to the second metatarsal.¹⁰

The advocates of correcting HAV deformity with inversion of the first metatarsal rely on studies showing this “pronated position” of the first metatarsal yet fail to recognize that this is an illusion of the true frontal plane position of the first and second rays to each other.¹¹ Furthermore, some authors advocating inversion correction of HAV deformity suggest that the axis of motion of the first ray is opposite that of previously published research.¹²

Klemola and colleagues cite the studies of Kelso, Kitaoka and Johnson and their respective coworkers that all validate the original axis of rotation of the first ray as described by Hicks.^4,13–15 They also cite and place great emphasis on the findings of Perez and colleagues, who describe a “locking” or stabilizing mechanism of the first ray, which one achieves by frontal plane rotation.¹⁶ Perez and coworkers demonstrated that one stabilizes the first ray by eversion and makes the first ray more mobile by inversion. Thus, it appears intuitive to Klemola and many others that any frontal plane correction of the first metatarsal in HAV surgery should be in the direction of eversion, not inversion, in order to gain stability and reduce deformity.

To test this notion, Klemola and coworkers evaluated 58 patients (76 feet) five years after surgical correction for HAV.³ The authors used a new modified Lapidus surgical procedure in which the surgeon rotates the first metatarsal into eversion before fusion to the medial cuneiform. With a five-year follow up, the American Orthopaedic Foot and Ankle Society metatarsophalangeal-interphalangeal (AOFAS MTP-IP) clinical outcome score was excellent or good in 72.4 percent of patients. In addition, 88 percent of all patients indicated they would choose this surgical procedure again under similar preoperative circumstances.

Equally as impressive was another study by Klemola and colleagues in which they demonstrated significant improvement of stability or loading capacity of the first ray after performing the eversion-correction Lapidus procedure.² These authors concluded that eversion rotation correction of the first metatarsal enhanced the “locking” mechanism of the first ray as described previously by Johnson, Perez and their respective colleagues.^15,16 In this study, Klemola and colleagues make this astute observation: “If overall pronation of the foot is increased due to any reason (ankle equinus, hindfoot valgus, forefoot varus, etc.), the sesamoids seem to be located laterally on an anteroposterior weightbearing view, even if metatarsosesamoid joints could be congruent.” Like others, they see the illusion of sesamoid alignment and first metatarsal rotation when the entire foot is pronated.

There are no short-term or long-term outcome studies published showing the benefits of incorporating inversion rotation of the first metatarsal into HAV correction. Since such a correction clearly violates the stabilizing motion and position of the first ray, I will continue to question the validity of such a surgical procedure.

References

1. 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. 

2. 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

3. 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.
4. Hicks JH. The mechanics of the foot. Part I: the joints. J Anat. 1953; 87(4):345–357.
5. Cornwall MW, McPoil TG. Motion of the calcaneus, navicular and first metatarsal during the stance phase of gait. J Am Podiatr Med Assoc. 2002; 92(2):67–76.
6. Coughlin MJ. Hallux valgus. J Bone Joint Surg Am. 1996; 78(6):932–66.
7. Helal B, Rowley DI, Cracchiolo A, Myerson MS. Hallux valgus and rigidus. In Surgery of Disorders of the Foot and Ankle, 1st Edition, Lippincott-Raven, London, 1996, pp. 303 – 326.
8. Thomas S, Barrington R. Hallux valgus. Curr Orthop. 2003; 17:299–307.

9. Saltzman CL, Aper RL, Brown TD. Anatomic determinants of first metatarsophalangeal flexion moments in hallux valgus. Clin Orthop. 1997; 339:261–9.
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. 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.
12. Dayton P, Kauwe M, Feilmeier M. Clarification of the anatomic definition of the bunion deformity. J Foot Ankle Surg. 2014; 53(2):160–163.
13. 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.
14.  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.
15. Johnson C, Christensen JC. Biomechanics of the first ray part 1. The effects of the peroneus longus function. A three dimensional kinematic study on a cadaver model. J Foot Ankle Surg. 1999; 38(5):313–21.  
16. 
Perez HR, Leon KR, Jeffrey CC. The effect of frontal plane position on first ray motion: Forefoot locking mechanism. Foot Ankle Int. 2008;29(1):72–76.