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Fig. 1 The before (A) and after (B) radiographs of a 34-year-old woman who underwent Lapiplasty threedimensional hallux valgus correction
Copyright: Treace Medical Concepts, INC.®, Ponte Vedra Beach, FLA.

AAOS Now

Published 5/1/2020
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Robert D. Santrock, MD, FAAOS

Treatment of Hallux Valgus Deformity Benefits from 3D ‘Revolution’

Bunions are common, perhaps afflicting up to 36 percent of the population. However, surgical treatment of hallux valgus has been maligned throughout the history of foot and ankle surgery. Contributing to the negative impression of hallux valgus surgery is the remarkably high rate of recurrence of the deformity following correction. Multiple studies utilizing various techniques of hallux valgus correction have shown that the recurrence rate ranges from 30 percent to 78 percent. How we got here is an interesting look at how language steered our trajectory off course.

Prior to 1870, the deformity of the great toe was referred to as a “bunion,” a term that means a “bump” or “tumor.” Clearly, that mischaracterization was a failure to understand the malalignment of the hallux. German surgeon Carl Hueter is most often credited with coining the term hallux valgus, moving our medical understanding forward in accepting that the hallux has drifted laterally. Although that was a giant leap forward, the deformity and its pathogenesis remained poorly defined. Walter Truslow followed up in 1925 with additional understanding of the deformity, adding the term metatarsus primus varus. This added the position of the metatarsal as a component of the deformity; however, this is when we start to veer off track, as most surgeons continue to concentrate only on the metatarsophalangeal joint (MTP), ignoring Truslow’s call to look at more proximal components of the deformity.

For nearly the next 100 years, and to the present, hallux valgus persists as the dominant descriptor of the deformity. The focus at the MTP only, ignoring the position of the metatarsal and the stability of the tarsometatarsal joint (TMT), leads us away from further exploration of the pathogenesis of the deformity. There have been exceptions—most notably Paul Lapidus, MD. In 1934, Dr. Lapidus developed the procedure that bears his name. His surgery was a stabilization (arthrodesis) of the first TMT joint after correcting the transverse angular deformities of both the MTP and TMT. His indication was metatarsus primus varus and midfoot instability. The surgery was technically challenging, and although it was widely known, it was reserved for only the most severe deformities. The latter point was likely because it was indeed difficult to perform with the largely “freehand” techniques of the angular correction; surgeons likely just chose easier techniques.

In 1989, Sangeorzan and Hansen described their modification of Lapidus’ original technique. Advances included evolution of the correction from a uniplanar, transverse plane correction to a biplanar correction to include the sagittal plane. They also added modern fixation with rigid lag-screw compression arthrodesis. The original technique and its subsequent modification remained the only two surgeries for hallux valgus that addressed the deformity at the center of rotation and angulation (CORA). Unfortunately, it remained technically challenging to achieve consistent and reproducible outcomes, so the modified Lapidus technique continued to be relegated to only the most severe deformities or cases of TMT joint “hypermobility.” As a result, the vast majority of hallux valgus cases have been treated with metatarsal osteotomies—back to the uniplanar technique and not treating at the CORA.

Most uniplanar metatarsal osteotomies and some biplanar TMT arthrodesis techniques fail because most cases of hallux valgus represent three-dimensional (3D)/triplanar deformities. This means that there is not only a widening of the intermetatarsal angle (transverse plane), and often an elevation of the inclination of the first ray (sagittal plane), but also a rotational component of the frontal (coronal) plane. Routine X-ray evaluation misses the coronal plane rotation. Standard weight-bearing X-ray evaluation usually includes anterior-posterior, internal oblique, and lateral views. Those views do not assess the frontal plane position or possible rotation of the first metatarsal. Kim et al., published a 3D weight-bearing CT study in 2015 that showed that 87 percent of hallux valgus cases have frontal plane rotation. Dayton et al., showed that the rotation occurs at an average of 22 degrees. Without that realization, we may inappropriately describe the pathology of the sesamoids as dislocated into the first web space—but that is not always true. And worse, many of the hallux valgus surgical techniques include a procedure to “pull” the sesamoids back over medially. Without correcting rotation of the metatarsal, the position of the metatarsal-sesamoid complex will leave a moment vector that will push the metatarsal back into varus and the hallux back into valgus.

By understanding this rotation of the entire metatarsal, it is not complicated to suggest that the pathology of hallux valgus is largely the result of first TMT joint instability. Evidence supports this. In 2012, Mason et al., showed that there were indeed morphological differences in the TMT joints of those afflicted with hallux valgus and those who are not. Hallux valgus patients have fewer facets in the TMT joint, allowing for more degrees of freedom of movement, and arguably more instability.

Where are we today?

Today, almost all foot and ankle surgeons widely accept that hallux valgus is a 3D deformity, with a significant contribution coming from the frontal plane rotation. By adopting this principle and addressing it in surgery, it is believed that maintenance of correction can be significantly improved. Additionally, by addressing the first TMT instability, the hallux valgus deformity can be truly treated at not only the CORA, but also at the inciting pathology. If, in 1870, we had called this deformity “midfoot instability” instead of hallux valgus, our focus might have been different, and better techniques could have come along sooner.

Today, the third generation of the Lapidus procedure has been developed: the anatomic triplane first TMT arthrodesis. The technique incorporates the giant strides taken by Drs. Lapidus, Sangeorzan, and Hansen and adds the following: correction of the frontal plane rotation (triplanar correction), precision instrumentation for reproducibility, and multiplanar fixation. In that multiplanar fixation has been shown by the AO Institute to be extremely stable, akin to the thin-wire external fixation frame, the fixation change attempts to expedite weight-bearing. Because that portion of the foot experiences multiple vectors of force when weight-bearing, multiplanar control is needed. In our study of near-immediate weight-bearing after anatomic triplane first TMT arthrodesis using multiplanar fixation (Lapiplasty® 3D Bunion Correction, Treace Medical Concepts, Inc.®, Ponte Vedra Beach, Fla.), at 13 months of follow-up, we showed a maintenance of correction of nearly 97 percent and a nonunion rate of less than 2 percent.

The anatomic triplane first TMT arthrodesis technique, using the Lapiplasty system, starts with a full soft-tissue release of the TMT joint and a minor release of the lateral contractures of the MTP joint. This “correct before you cut” technique protects the first ray and allows the surgeon to see the full correction before any bone is cut or removed. Bone-positioning tools and a precision cutting guide are used to make the final bone correction. Then, additional instruments are deployed to control alignment and compression. The final step is to apply the fixation. The construct of two independent locking plates, placed 90 degrees from one another dorsally and medially, ensures multiplanar control and stability. Postoperatively, the patient ambulates in a controlled ankle motion boot for six weeks.

Although the Lapiplasty system is a patented technique, tool set, and instrumentation, some principles can be widely applied to ensure that all TMT corrections have good outcomes. First is proper preoperative radiographic evaluation. A modern approach is to expand the standard weight-bearing radiograph set to include an axial sesamoid view, which allows for evaluation of frontal plane rotation. Second, intraoperatively, the surgeon needs to be mindful of the primary goal of this 3D approach—concentrate on getting the metatarsal-sesamoid complex into the proper biomechanical position. Most failures are associated with a failure to align the sesamoids under the metatarsal head, which leads to a moment vector with weight-bearing that will push the metatarsal head medially, thus opening the intermetatarsal angle. Third is to be aware of the effects of weight-bearing. This joint arthrodesis sits in a peculiar location that sees multiple different vectors of force when weight-bearing. If immediate weight-bearing is desired, the fixation construct must be compatible to see those varying forces; otherwise, limited weight-bearing is best. Finally, each case demands a look at intercuneiform instability. That is not an uncommon finding and should be addressed if an intraoperative splay test points to that pathology.

Fig. 1 The before (A) and after (B) radiographs of a 34-year-old woman who underwent Lapiplasty threedimensional hallux valgus correction
Copyright: Treace Medical Concepts, INC.®, Ponte Vedra Beach, FLA.
Fig. 2 The surgical (A) and radiographic (B) images of the instruments employed in the Lapiplasty threedimensional hallux valgus correction
Copyright: Treace Medical Concepts, INC.®, Ponte Vedra Beach, FLA.

Modern understanding of the 3D aspects of hallux valgus deformity and its pathological contributions from the abnormal TMT joint may “revolutionize” patients’ and surgeons’ options for sustained corrections and cosmetically pleasing results.

Robert D. Santrock, MD, FAAOS, is associate professor and chief of foot and ankle surgery in the Department of Orthopaedics at West Virginia University. He is a consultant, royalty bearer, and patent holder for the Lapiplasty® 3D Bunion Correction System – Treace Medical Concepts, Inc.®, Ponte Vedra Beach, Fla.

References

  1. Nix S, Smith M, Vicenzino B: Prevalence of hallux valgus in the general population: a systemic review and meta-analysis. J Foot Ankle Res 2010;27:3:21.
  2. Bock S, Kluger R, Kristen KH, et al: The scarf osteotomy with minimally invasive lateral release for treatment of hallux valgus deformity: intermediate and long-term results. J Bone Joint Surg Am 2015;97:1238-45.
  3. Jeuken RM, Schotanus MG, Kort NP, et al: Long-term follow-up of a randomized controlled trial comparing scarf to chevron osteotomy in hallux valgus correction. Foot Ankle Int 2016;37:687-95.
  4. Hueter C: Klinik der Genfenkkranheiren mit Einschlub der Orthopadie, 1870;2:10-11, Verlog Von FCW Vogel, Leipzig.
  5. Truslow W: Metatarsus primus varus or hallux valgus. J Bone Joint Surg Am 1926;7:98-108.
  6. Lapidus PW: The operative correction of metatarsus primus varus in hallux valgus. Surg Gynecol Obstet 1934;58:183.
  7. Sangeorzan BY, Hansen ST: Modified lapidus procedure for hallux valgus. Foot Ankle Int 1989;9:262-6.
  8. 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;36:8:944-52.
  9. 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;55:2:220-5.
  10. Mason LW, Tanaka, H: The first tarsometatarsal joint and its association with hallux valgus. Bone Joint Res 2012;1:6.
  11. Ray JJ, Koay J, Dayton PD, et al: Multicenter early radiographic outcomes of triplanar tarsometatarsal arthrodesis with early weightbearing. Foot Ankle Int 2019;40:8:955-60.

The road to the Lapiplasty procedure

Over the years, during training and then in practice, I always wondered why there were so many operations for “bunions.” I noticed that, in most patients with the condition, radiographs demonstrated an oblique takeoff of the first metatarsal from the medial cuneiform. The abnormality appeared even worse when the patient had what was classified as metatarsus primus varus, in which the great toe took on a significant valgus turn at the first metacarpophalangeal joint because the first to second intermetatarsal angle was very large. I thought that was probably the main cause of the deformity.

I was aware of the Lapidus operation, which could correct that oblique takeoff, and I had performed a few of them myself. But as a pediatric orthopaedic surgeon, I was loath to fuse a nondiseased joint in a skeletally immature person, so I experimented with the whole raft of what seems now to be utterly ridiculous procedures. Those procedures seek to correct the problem far away from the center of rotation of angulation, and they neglect the three-plane deformity that is hallux valgus. My concern about the oblique takeoff at the first metatarsal-cuneiform joint and the rotational deformity of the great toe was vindicated when I learned about the work my partner Robert D. Santrock, MD, FAAOS, and his colleagues around the country were doing, which ultimately led to the development of the Lapiplasty procedure. What follows is a sort of veni, vidi, vici story of the “bunion” and ultimately the true three-plane deformity of hallux valgus. Lapiplasty involves angular and rotation correction of the first ray. In most cases, the “bump” implied by the term “bunion” resolves, relegating that term to the trash heap.

This type of procedure can be done “freehand” or with other types of instruments to provide correction and stabilize the anatomy until the internal fixation is inserted. Those techniques have been displayed by a number of authors. The advantages of the Lapiplasty system are the specific instruments such as the cutting block that help make the surgery more precise and reproducible.

John P. Lubicky, MD, FAAOS, FAAP, FAOA, is professor of orthopaedic surgery and pediatrics at West Virginia University School of Medicine and a member of the AAOS Now Editorial Board.

A note from the AAOS Now editor-in-chief

We thank Robert D. Santrock, MD, FAAOS, for this informative article. In that Dr. Santrock has a conflict of interest due to royalties for the proprietary system he describes in his article, we wish to include a couple of considerations. The editors of AAOS Now are not foot and ankle specialists, and our publication timeline did not allow for our typical subspecialty review process in this case. With that said, we are informed that:

  1. There are other proprietary systems that seek to address rotational deformity in bunion surgery (e.g., PROMOTM Tri-planar Hallux Valgus System, Phantom® Intramedullary Nail, and IncoreTM Lapidus System).
  2. Our informal polling of foot and ankle specialists revealed that for a continuum of deformities seen, the article’s stated high failure and recurrence rates for traditional hallux valgus correction are contentious.

We welcome any comments or further discussion from our readers.

Eeric Truumees, MD, FAAOS, is the chair of the AAOS Now Editorial Board; editor-in-chief of AAOS Now; and an orthopaedic spine surgeon in Austin, Texas, where he is also professor of orthopaedics at the Dell Medical School, University of Texas.