Hallux Valgus Correction: Is It All About The Sesamoids?

With each new iteration of hallux valgus correction and each new technology introduced, there must be a common thread.  

How many times have you had a patient present with sub-second metatarsal pain and a history of hallux valgus correction? You ask the pertinent questions about activity level, shoe gear and current pain. Then the patient comments on the previous procedure and postoperative course. During a thorough examination, you note reduced range of motion and lateral tracking of the extensor hallucis longus as well as a rotated hallux. A patient’s perception and expectations are obviously very important throughout the postoperative course and into the recovery phase as he or she gears up to a higher level of activity. You examine the radiographs and notice undercorrection of the tibial sesamoid position and that the metatarsal remains rotated. These situations can lead to disdain and discouragement but focusing on the educational component and tailoring the conversation toward positive patient outcomes will never get you in trouble.

It is all about the sesamoid position.

Joint-sparing hallux valgus correction is obviously one of the most difficult procedures we perform. There is a reason why there are over 40 procedures named for hallux valgus correction. There is a reason why we continue to publish high-level studies assessing the validity of certain procedures and the advantages of certain approaches. 

Our understanding of hallux valgus continues to evolve. When it comes to traditional osteotomies of the first metatarsal, we already know that the recurrence rate of hallux valgus is high, ranging between 25 to 78 percent for Z-type ostetotomies.^1,2 We also know that the satisfaction rate over a 14-year follow-up of distal metatarsal osteotomies is approximately 30 percent.²  One of the risk factors for recurrence is lack of reduction of the frontal plane and sesamoid position.^3,4 

I think we can all concur that frontal plane correction is more top of mind than ever as we are seeing greater attention and research on the first metatarsal-sesamoid complex and its role in hallux valgus correction. This first starts with understanding what we are looking at on an everyday basis. Anteroposterior foot radiographs are the most common radiograph we assess but they are frequently misleading when we look at the sesamoid position. Often, the sesamoid complex can appear subluxed or even dislocated, but it may only be the rotation of the first metatarsal as it relates to the weightbearing surface of the foot. With the advent of weightbearing computed tomography (CT), we can better understand this complex pathoanatomy. Indeed, we need to better understand and be able to evaluate sesamoid position in order to more accurately correct the deformity surgically.  

Kim and colleagues studied the sesamoid complex on weightbearing CT scans and placed the deformity into four categories based on degree of rotation. They found that about 87 percent of bunions have rotation in the frontal plane and up to 61 percent of bunions have rotation of the metatarsal and subluxed sesamoids.⁵ These studies highlight the importance of the sesamoid complex and the attention it deserves. What these CTs also assess is the degree of metatarsal-sesamoid arthritis. This cannot go unnoticed as the examination of this joint surface is elusive but important. 

As we reassess our patient with hallux valgus recurrence and sub-metatarsal pain, it is important to have an educational conversation about the rotation of the metatarsal and/or sesamoids. However, we should also reassess the metatarsal-sesamoid complex. In the aforementioned patient case example, the previous metatarsal osteotomy performed did not allow for frontal plane rotation of the capital fragment and realignment of the sesamoids. This then allowed the sesamoids to continue to track out of their grooves and worsen the arthritic changes over time.  

Especially for revisions but frequently for primary hallux valgus deformities, I am learning new ways to become a better diagnostician. I am paying more attention to manual reducibility of the deformity but I am also monitoring how the tibial sesamoid is tracking. Often, manual compression of the tibial sesamoid on the first metatarsal with slow dorsiflexion of the hallux will elicit pain. We then perform ultrasound or fluoroscopic-guided injections into the joint space. If this is not doing the trick, we then order a CT. Do not hesitate to order a quick CT scan of the forefoot. 

The appropriate position of the sesamoids and therefore the appropriate tracking of the extensors and flexors allow for a properly functioning joint. Focus more on the reduction of the sesamoids, whether it be in the form of a distal metatarsal minimally invasive approach or proximal rotational fusion. But even before that, focus on procedure selection and sesamoid arthritis.

Dr. McAlister is a fellowship-trained foot and ankle surgeon. He is in private practice and is the founder of the Phoenix Foot and Ankle Institute. (www.phoenixfai.com) One can reach Dr. McAlister at jeff.mcalister@phoenixfai.com.

References 

1. Coetzee JC. Scarf osteotomy for hallux valgus repair; the dark side. Foot Ankle Int. 2003;24(1):29-33.
2. Jueken RM, Schotanus MCM, Kort NP, Deenik A, Jong B, Hendrickx RPM. Long-term follow up of a randomized controlled trial comparing Scarf to Chevron osteotomy in hallux valgus correction. Foot Ankle Int. 2016;37(7):687-695. 
3. 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):236-240.
4. Okuda R, Kinoshita M, Yasuda T, Jotoku T, Kitano N, Shima H. Postoperative incomplete reduction of the sesamoids as a risk factor for recurrence of hallux valgus. J Bone Joint Surg Am. 2009;91(7):1637-1645.
5. 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):944-952.