Does the Akin Osteotomy Protect a Loss of Hallux Valgus Correction?

Yes.

Citing outcome studies comparing hallux valgus surgery with and without the Akin osteotomy, the authors claim that the Akin procedure is often an afterthought and should be a serious consideration for inclusion when correcting hallux valgus.

By Zeeshan S. Husain, DPM, FACFAS, FASPS, and Stephanie Behme, DPM

During the senior author’s residency training 20 years ago, an Akin osteotomy was a frequent inclusion in hallux valgus surgery. At that time, he recalls selecting bunion procedures primarily to correct the first intermetatarsal angle (IMA) in the transverse plane to create a “straight” hallux based on clinical appearance, usually without assessing intraoperative first ray triplanar correction or radiographic sesamoid position. Historically, a surgeon would choose a lateral release to improve additional lateral deviation of the hallux. But, if the hallux was still not straight enough afterwards, then surgeons included what some called the “cheater” Akin to achieve the desired clinical result.

At that time, I (the senior author) did not understand the biomechanical rationale for these choices. To compound the problem, I was not impressed personally with observed recurrence rates. After reflecting on past experiences, I have a better appreciation for how to incorporate the Akin osteotomy into hallux valgus surgery to achieve improved cosmesis, lower recurrence rates, and overall better outcomes.

Adult hallux valgus surgery recurrence rates are historically relatively high at 24.86% based on a meta-analysis of 23 studies.¹ More recently, Dayton and associates popularized the triplanar nature of the first ray as it pertains to hallux valgus deformity.² Furthermore, Kim and associates found an 87.3% rate of frontal plane deformity in hallux valgus patients.³ Shibuya and colleagues found the postoperative medial sesamoid position was the only factor associated with hallux valgus recurrence.⁴ Properly correcting the deformity requires attention to these factors to minimize the probability of recurrence. The medial sesamoid position holds the key to lowering recurrence rates in hallux valgus surgery because of its influence on the pull of the flexor hallucis tendons on the hallux.

Currently, our first step is to reduce the triplanar deformity of the first metatarsal either through a first tarsometatarsal joint arthrodesis or a distal first metatarsal Hohmann osteotomy through a minimally invasive surgery (MIS) technique. The next step we focus on is the medial sesamoid reduction to optimize the postoperative outcome.

The Akin osteotomy was first described in 1925 as a medial closing wedge osteotomy of the proximal phalanx⁵ and is commonly utilized to address hallux interphalangeal abduction deformity and any residual hallux valgus deformity after proximal first ray correction and capsular rebalancing around the first metatarsophalangeal joint.⁶ The procedure is rarely used as the primary way to treat hallux valgus conditions. We will review how this relatively minor procedure impacts the medial sesamoid position and its role in postoperative outcomes. 

Considering the Biomechanical and Radiographic Impact

Lee and colleagues assessed how a modified Akin osteotomy affected the medial sesamoid position in a cadaveric study.⁷ The authors reported some medial sesamoid improvement with an isolated modified Akin osteotomy based on supinating the insertion of the flexor hallucis brevis tendon insertion. By medializing the hallux, the vector pull of the flexor hallucis longus tendon is more in line with the long axis of the first metatarsal. Performing a proximal metatarsal osteotomy with the modified Akin osteotomy showed a more synergistic effect in the medial sesamoid position correction.⁷ Another study evaluated the corrective ability of chevron and Akin osteotomies on the medial sesamoid position.⁸ Using the Hardy-Clapham sesamoid position grading system, Chen and colleagues were able to correct 14/14 feet (100%) with grade V, 6/9 feet (66.7%) with grade VI, 10/16 feet (62.5%) with grade VII (P = .037).

Figure 1 shows the important radiographic angles to assess for surgical planning. The hallux valgus angle (HVA), intermetatarsal angle (IMA), and medial sesamoid position are standard radiographic assessments. The proximal-to-distal phalangeal joint angle (PDPAA) should also factor into deciding whether to include an Akin osteotomy.

Examining Outcomes of the Akin Osteotomy

Recently, third- and fourth-generation MIS for hallux valgus deformity has gained popularity with utilization of low speed, high torque burrs for making osteotomies and providing internal rigid fixation compared to earlier MIS techniques.

Table 1 summarizes the improvement in IMA and HVA and show statistically significant improvement following third-generation MIS techniques utilizing chevron and Akin osteotomies.^9-14 Numerous studies investigated the long-term outcomes on distal metatarsal and Akin osteotomies. Recurrence rates in this group of studies ranged from 0–7.7%^9-11 and satisfaction rates were reported as high as 91.6% with the Foot Function Index¹² and 93 with the AOFAS scale.¹³

Several studies evaluated traditional and MIS first metatarsal osteotomies with and without the Akin osteotomy and found similar results. Table 2 summarizes these findings. Kaufmann and colleagues compared 785 feet with chevron osteotomies to 74 feet with chevron and Akin osteotomies.^15,16 As seen with other studies, both groups demonstrated statistically significant improvement in HVA and IMA. The authors monitored the postoperative follow-up of HVA, IMA, and PDPAA, medial sesamoid position, and joint congruity. When the preoperative PDPAA was greater than 8°, the chevron and Akin osteotomies group maintained better correction than the chevron osteotomy group at the mean follow-up of 34.2 months (P < .001).^15,16

Kulinski and associates showed the Akin osteotomy provided long-term protection from developing hallux valgus recurrence when combined with a chevron osteotomy in comparison to the chevron osteotomy alone.¹⁷ Furthermore, the double osteotomy group maintained lower HVA and interphalangeal angle in comparison to the chevron osteotomy group only. Kaufmann and colleagues investigated similar outcomes in patients receiving a Scarf osteotomy with (n = 184) and without Akin osteotomies (n = 63) for hallux valgus correction.¹⁸ They found that the Akin osteotomy protected patients from loss of correction by the mean follow-up of 45.4 months. Again, they found the PDPAA greater than 8° showed statistically significant superiority in the combined osteotomy group. These studies show direct evidence of the protective nature of the Akin osteotomy in conjunction with first metatarsal osteotomies from developing recurrent hallux valgus.

Figure 2 and Figure 3 show surgical outcomes using MIS distal first metatarsal osteotomy and first tarsometatarsal joint arthrodesis procedures with Akin osteotomy respectively to demonstrate prolonged preservation of correction postoperatively.

A Closer Look at Complications With the Akin Osteotomy

When performing the Akin osteotomy, technical complications can arise. In review of 45 Akin procedures, the most common technical problem was plantar angulation at the osteotomy site (22%).¹⁹ The authors also noted that less than 50% bone apposition at the osteotomy site may lead to nonunion or recurrence. Shortening was also reported, but limited if care was taken to minimize bone removal.

Another study investigated 132 patients undergoing the Akin osteotomy retrospectively.²⁰ There was compromise of the lateral cortex in 47 (35.6%) with intraoperative fluoroscopy. From this group, 9 (19.1%) experienced displacement during the postoperative course, of whom, 3 (6.38%) required revisional surgery. Healing time directly correlated to lateral hinge being intact.²⁰

Personal Observations on the Akin Procedure

Based on literature presented, measuring the PDPAA preoperatively should provide guidelines on whether or not to include an Akin osteotomy when performing hallux valgus surgery. In addition, the authors’ preferred intraoperative assessment method is to evaluate the amount of reduction of the medial sesamoid and the hallux alignment after the first metatarsal procedure (tarsometatarsal arthrodesis or distal osteotomy). Placing a folded gauze in the first interdigital space approximates the impact of an adjunctive Akin osteotomy to the medial sesamoid alignment. In the event the medial sesamoid position does not improve enough, then we find a first metatarsophalangeal joint lateral release and/or medial capsulorrhaphy may be necessary. The authors prefer the predictability of osseous correction over soft tissue rebalancing.

In Summary

After reviewing the literature, the authors conclude that the Akin osteotomy can play a vital role in preventing hallux valgus recurrence. Biomechanically, this osteotomy helps realign the vector pull of the flexor hallucis tendons and aids in improving the medial sesamoid position, which is the most significant parameter in predicting hallux valgus recurrence. Evidence has been presented that if the proximal to distal phalangeal articular angle is greater than 8°, then the Akin osteotomy should strongly be considered for inclusion in conjunction with a first metatarsal procedure. The Akin osteotomy should not be underestimated in its inclusion for hallux valgus surgery.

Dr. Husain is the Residency Director of the McLaren Oakland Hospital Podiatric Surgery and Medicine Residency Program in Pontiac, MI. He is a Fellow of the American College of Foot and Ankle Surgeons and a Fellow of the American Society of Podiatric Surgeons.

Dr. Husain is also the President of the Michigan Podiatric Medical Association and Chairman of the Michigan Podiatric Residency Consortium.

Dr. Behme is a third-year podiatric resident at McLaren Oakland Hospital in Pontiac, MI.

References
1.     Momodu II, Ezzatvar Y, López-Bueno L, Fuentes-Aparicio L, Dueñas L. Prevalence and predisposing factors for recurrence after hallux valgus surgery: a systematic review and meta-analysis. J Clin Med. 2021; 10(24):5753.
2.    Dayton P, Kauwe M, DiDomenico L, Feilmeier M, Reimer R. Quantitative analysis of the degree of frontal rotation required to anatomically align the first metatarsal phalangeal joint during modified tarsal-metatarsal arthrodesis without capsular rebalancing. J Foot Ankle Surg. 2016; 55(2):220-5.
3.    Kim Y, Kim JS, Young KW, Naraghi R, Cho HK, Lee SY. 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):944-52.
4.    Shibuya N, Kyprios EM, Panchani PN, Martin LR, Thorud JC, Jupiter DC. Factors associated with early loss of hallux valgus correction. J Foot Ankle Surg. 2018; 57(2):236-40.
5.    Akin OF. The treatment of hallux valgus: a new operative procedure and its results. Med Sentinel. 1925; 33:678-9.
6.    Springer KR. The role of the akin osteotomy in the surgical management of hallux abducto valgus. Clin Podiatr Med Surg. 1989; 6(1):115-31.
7.    Lee DO, Hong E, Kwak DS. The improved proximal phalanx osteotomy for reducing sesamoid in hallux valgus surgery- a cadaver study. Int J Environ Res Public Health. 2022; 19(11):6487.
8.    Chen J, Stautberg E, Spak D, Schneider G, Panchbhavi V. The corrective ability of the double chevron and akin osteotomies on medial sesamoid position in hallux valgus deformity. Foot Ankle Orthop. 2017; 2(3):2473011417S0001.
9.    Neufeld SK, Dean D, Hussaini S. Outcomes and surgical strategies of minimally invasive chevron/akin procedures. Foot Ankle Int. 2021; 42(6):676-88.
10.    Lewis TL, Robinson PW, Ray R, Dearden PMC, Goff TAJ, Watt C, Lam P. Five-year follow-up of third-generation percutaneous chevron and akin osteotomies (PECA) for hallux valgus. Foot Ankle Int. 2023; 44(2):104-17.
11.    de Carvalho KAM, Baptista AD, de Cesar Netto C, Johnson AH, Dalmau-Pastor M. Minimally invasive chevron-akin for correction of moderate and severe hallux valgus deformities: clinical and radiologic outcomes with a minimum 2-year follow-up. Foot Ankle Int. 2022; 43(10):1317-30.
12.    Mikhail CM, Markowitz J, Di Lenarda L, Guzman J, Vulcano E. Clinical and radiographic outcomes of percutaneous chevron-akin osteotomies for the correction of hallux valgus deformity. Foot Ankle Int. 2022; 43(1):32-41.
13.    Holme TJ, Sivaloganathan SS, Patel B, Kunasingam K. Third-generation minimally invasive chevron akin osteotomy for hallux valgus. Foot Ankle Int. 2020; 41(1):50-6.
14.    Lewis TL, Lau B, Alkhalfan Y, Trowbridge S, Gordon D, Vernois J, Lam P, Ray R. Fourth-generation minimally invasive hallux valgus surgery with metaphyseal extra-articular transverse and akin osteotomy (META): 12 month clinical and radiologic results. Foot Ankle Int. 2023; 44(3):178-91.
15.    Kaufmann G, Hofmann M, Braito M, Ulmer H, Brunner A, Dammerer D. Need for concomitant akin osteotomy in patients undergoing chevron osteotomy can be determined preoperatively: a retrospective comparative study of 859 cases. J Orthop Surg Res. 2019; 14(1):277.
16.    Kaufmann G, Braito M, Wagner M, Putzer D, Ulmer H, Dammerer D. Correlation of loss of correction with postoperative radiological factors after distal chevron osteotomy in dependence of concomitant akin osteotomy. J Foot Ankle Surg. 2022; 61(4):785-91.
17.    Kulinski P, Rutkowski M, Tomczyk L, Miekisiak G, Morasiewicz G. Outcomes after chevron osteotomy with and without additional akin osteotomy: a retrospective comparative study. Indian J Orthop. 2023; 1-10.
18.    Kaufmann G, Hofmann M, Ulmer H, Putzer D, Hofer P, Dammerer D. Outcomes after scarf osteotomy with and without akin osteotomy a retrospective comparative study. J Orthop Surg Res. 2019; 14(1):193.
19.    Frey C, Jahss M, Kummer FJ. The akin procedure: an analysis of results. Foot Ankle. 1991; 12(1):1-6.
20.    Douthett SM, Plaskey NK, Fallat LM, Kish J. Retrospective analysis of the akin osteotomy. J Foot Ankle Surg. 2018; 57(1):38-43.

No.

This author urges surgeons to evaluate for the foundational etiology behind deformities and not to use the Akin osteotomy as an unnecessary accommodation.

By Anthony R. Giordano, DPM, FACFAS   

Literature favorable to the Akin osteotomy^1-5 seems to be re-emerging, especially with the relative ease and modern fixation techniques available with minimally invasive surgery (MIS) for hallux valgus repair.^6-8 Alas, in any good debate, someone must take the counterpoint argument, and I’ll give it a try. Due to the apparent paucity of negative literature regarding the Akin, I will also share my observations and experience over my 20 years of performing foot surgery.

Let me state from the outset that I do perform the Akin osteotomy in certain situations. I consent my patients for the potential addition of an Akin when hallux abductus interphalangeus (HAI) is easily identifiable preoperatively, although I perform the osteotomy much less often than I consider it. I’m also a fan of the cylindrical Akin and its ability to correct in multiple planes (primarily with respect to frontal plane rotation) in difficult revisional cases.⁹ 

Why Is the Akin Having a Resurgence?

While the Akin has been around for quite some time with recorded scientific studies dating to as early as 1967, I’ve been contemplating its recent resurgence.¹⁰ Why is it so often added to MIS hallux valgus corrective procedures, to the point where I’ve noticed some consider it a fundamental inclusion? Is it the inherent greatness of the Akin, previously unrealized? Is it so often performed because we can utilize new MIS burrs and screws, creating (and fixating) these osteotomies through several pinhole-sized incisions? Many questions come to mind.

The Akin, whether performed open or percutaneously, isn’t without its complications. Some evidence points to the fracture of the lateral cortex not impairing bone healing or correction of pathologic interphalangeal angle¹¹ while other evidence shows a direct correlation between the integrity of the lateral hinge, healing time of the osteotomy, and need for surgical revision.¹²

Are Trends in MIS and Akin Procedures Related?

I don’t perform MIS surgery. I have nothing against it—the foot, in clinical preoperative-to-postoperative comparison photographs, looks amazing. The incisions are barely visible. I’ll admit that there is evidence showing maintenance of correction and patient satisfaction in 2- and 5-year follow-ups, with minimal recurrence rates.^13–14 But the jury might still be out.

My initial observations of postoperative radiographs of MIS chevron/Akin procedures were puzzling. How did that foot heal when the head seemed to be floating in the interspace? It was air between metatarsal head and diaphysis, with minimal (if any) bone contact. In my practice, the vast majority of moderate-to-severe hallux valgus cases have their apex of deformity, their center of axis of rotation (CORA) at an angled, deformed distal articular surface of the medial cuneiform, the first metatarsal having no other option than to rotate and angulate medially at the first tarsometatarsal joint (TMT-1) to continue to articulate. Hypermobility arguments aside, what I see is an issue at TMT-1. TMT-1 correction is primary performed via the Lapidus procedure, and significant strides have occurred in the last several years to improve fixation and reproducibility.¹³ It could be said that TMT-1 correction has had just as much recent fanfare in the last several years as MIS has. They’ve also been compared head-to-head, Lapidus versus minimally invasive chevron, and both exhibit similar radiographic correction and patient outcomes in a match-up.¹⁵

More Thoughts on First Ray Alignment

Back to the current upsurge in Akin procedures. When correcting an intermetatarsal angle with a distal metatarsal osteotomy, irrespective of open or MIS, one creates a new center of rotation angulation (CORA) within the first ray. I see this often in postoperative MIS radiographs­—a significant angulation of the proximal one-half to two-thirds of the first metatarsal from TMT-1, followed by a dynamic shift of the distal metatarsal at the site of the MIS correction, often so aggressive that the initial radiographs show no bone contact whatsoever. It’s simply 2 screws traversing a dead space that very often fills in, still to my amazement.  

I’m not entirely convinced that there is normal articulation of the first metatarsophalangeal joint (MPJ) after this occurs. I’ve observed dialogue among colleagues about stiffness after MIS bunion surgery. I would think that significantly less dissection/capsular violation (compared to open bunionectomy) would lend itself to minimal stiffness postoperatively? But if not, is the hallux realigning properly with the metatarsal head? Might this inspire a surgeon to choose an Akin osteotomy, but this then adds another, new CORA, distal to the one we just tried to fix. We create an angular deformity within the first proximal phalanx to add the appearance of a straighter toe. We have a happier patient—hopefully.

Hopefully our correction lasts. Hopefully it realigns the flexor tendon apparatus well enough that deforming forces will not continue to abduct the sesamoids and great toe, leading to recurrence. The force vectors around a hallux valgus repair were recently looked at by Kim and colleagues¹⁷ and despite being more focused on development of hallux varus deformity, it’s quite interesting reading. We’ve also been shown by Shibuya and colleagues¹⁸ that the greatest risk for postoperative recurrence of hallux valgus is postoperative tibial sesamoid position. Are those sesamoids actually functioning properly? Is that where any stiffness comes from? I’m just not convinced that we’ve put everything back where it belongs when we try to stretch the indications of what can be corrected percutaneously.

Final Argument

The Akin osteotomy (and MIS procedures) absolutely have their place. In a mild-to-moderate deformity without frontal plane rotation of the first metatarsal, that is able to be corrected by distal metatarsal osteotomy, why wouldn’t one want to fix with minimal incisions? It just makes good sense, and I’m game.

But we must take caution not to undercorrect hallux valgus deformities percutaneously or open, and instead add an Akin to accommodate. We all are familiar with the wonderful work of Paley, who is the master of the CORA.¹⁹ Osteotomy level and type should be considered relative to the CORA to avoid creating secondary deformities.²⁰ Examine the anteroposterior radiographs of a percutaneous chevron/Akin procedure to see if this is the case. I strongly advocate for surgeons to fix the foundation of a deformity, not the roof, as this will not satisfy your or your patients’ goals.

Dr. Giordano is part of the teaching faculty of both Henry Ford Macomb Hospital and Ascension St. John Hospital Podiatric Surgical residencies in Clinton Township and Detroit, MI, respectively. He is in private practice in Shelby Township, MI.  
 
References

1.    Kaufmann G, Braito M, Wagner M, Putzer D, Ulmer H, Dammerer D. Correlation of loss of correction with postoperative radiological factors after distal chevron osteotomy in dependence of concomitant Akin osteotomy. J Foot Ankle Surg. 2022; 61(4):785-791.
2.    Kaufmann G, Hofmann M, Ulmer H, Putzer D, Hofer P, Dammerer D. Outcomes after Scarf osteotomy with and without Akin osteotomy. A retrospective comparative study. J Orthop Surg Res. 2019; 14(1):193.
3.    Xie W, Lu H, Zhen S, Li G, Yuan Y, Xu H. A better treatment for moderate to severe hallux valgus: scarf + Akin osteotomy combined with lateral soft tissue release in a single medial incision. Orthop Surg. 2022; 14(10):2633-2640.  
4.    Rajeev A, Tumia N. Three-Year follow-up results of combined short scarf osteotomy with Akin procedure for hallux valgus. J Foot Ankle Surg. 2019; 58(8):837-841.
5.    Lechler P, Feldmann C, Xaver Kock F, Schaumburger J, Grifka J, Handel M.  Clinical outcome after chevron-Akin double osteotomy versus isolated chevron procedure: a prospective matched group analysis. Arch Orthop Trauma Surg. 2012; 132(1):9-13.  
6.    Nunes GA, Carvalho KAM, Ferreira GF, Filho MVP, Baptista AD, Zambelli R, Vega J. Minimally invasive chevron Akin (MICA) osteotomy for severe hallux valgus. Arch Orthop Trauma Surg. 2023; March 28 (online ahead of print).
7.    Altenberger S, Kriegelstein S, Gottschalk O, Dreyer F, Mehlhorn A, Roser A, Walther M. The minimally invasive Chevron and Akin osteotomy (MICA). Oper Orthop Traumatol. 2018; 30(3):148-160.
8.    Toepfer A, Strassel M. The percutaneous learning curve of 3rd generation minimally invasive Chevron and Akin osteotomy (MICA). Foot Ankle Surg. 2022; 28(8):1389-1398.
9.    Gerbert J (ed). Textbook of Bunion Surgery. Futura Publishing, Mount Kisco NY, 1981
10.    Colloff B, Weitz EM. Proximal phalangeal osteotomy in hallux valgus. Clin Orthop Relat Res. 1967; 54:105-113.
11.    Schilde S, Delank KS, Arbab D, Gutteck N. Minimally invasive vs open Akin osteotomy. Foot Ankle Int. 2021; 42(3):278-286.
12.    Douthett SM, Plaskey NK, Fallat LM, Kish J. Retrospective analysis of the Akin osteotomy. J Foot Ankle Surg. 2018; 57(1):38-43.  
13.    de Carvalho KAM, Baptista AD, de Cesar Netto C, Johnson AH, Dalmau-Pastor M.  Minimally invasive chevron-Akin for correction of moderate and severe hallux valgus deformities: clinical and radiologic outcomes with a minimum 2-year follow-up. Foot Ankle Int. 2022; 43(10):1317-1330.
14.    Lewis T, Robinson P, Ray R, Dearden P, Goff T, Watt C, Lam P. Five-year follow-up of third-generation percutaneous chevron and Akin osteotomies (PECA) for hallux valgus. Foot Ankle Int. 2023; 44(2):104-117.
15.    Do DH, Sun JJ, Wukich DK. Modified Lapidus procedure and hallux valgus: a systematic review and update on triplanar correction. Orthop Clin North Am. 2022; 53(4):499-508.
16.    Cody EA, Caolo K, Ellis SJ, Johnson AH. Early radiographic outcomes of minimally invasive chevron bunionectomy compared to the modified Lapidus procedure. Foot Ankle Orthop. 2022 July; 7(3):24730114221112103. Published online 2022 Jul 21. doi 10.1177/24730114221112103.
17.    Kim M, Lee HS, Choi YR, Kim J, Chee CG, Hong SH. Long hallucal tendon force vectors and first metatarsophalangeal deformity after hallux valgus surgery. Foot Ankle Int. 2023; 44(2):159-166.
18.    Shibuya N, Kyprios EM, Panchani PN, Martin LR, Thorud JC, Jupiter DC. Factors associated with early loss of hallux valgus correction. J Foot Ankle Surg. 2018 Mar-Apr;57(2):236-240.
19.     Gladbach B, Heijens E, Pfeil J, Paley D. Calculation and correction of secondary translation deformities and secondary length deformities. Orthopedics. 2004; 27(7):760-766.
20.    Paley D, Herzenberg JE, Tetsworth K, McKie J, Bhave A. Deformity planning for frontal and sagittal plane corrective osteotomies. Orthop Clin North Am. 1994; 25(3):425-465.