Identifying The Ideal Metatarsal Head Osteotomies For Bunion Correction

Over the past decade or so, I have written several articles regarding bunions, their treatment options, including the best surgical option for each type of hallux valgus, and why.^1-5 The overall solution in my hands for hallux valgus deformity is quite simple. I divide my corrections into unstable and stable bunion deformities and add the secondary factors of intermetatarsal angle and hallux valgus angle to determine the best surgical option. If the bunion is either very large or unstable, the solution I choose is a Lapidus-type correction, which I have extensively written about.^1,2,5 If the bunion is medium or small and not unstable, I opt for various head osteotomy corrections. In this article, I will detail my current thinking on hallux valgus, the best distal osteotomy options when indicated, and why.

Bunion deformities involve an often hereditary shift of the first metatarsal in a medial direction. With this medial shift, the great toe pulls laterally due to the bowing effect of the tendons.⁶ Ultimately, I aim to place the first metatarsal directly over the sesamoid complex and balance the ligamentous and tendon structures. In my experience, bunions benefitting most from a head osteotomy range from an intermetatarsal angle of 10 degrees to a maximum of about 16 degrees. In some rare cases, which are not unstable at the metatarsal-cuneiform region, I find that a head osteotomy can correct an intermetatarsal angle of up to 20 degrees, but this is a relatively rare occurrence. Regarding head osteotomies, I find that one procedure does not fit all. I have three options that I personally choose from that I will share and explain.

Pertinent Points Regarding Procedure Selection

Before picking the right osteotomy, I first question what I am trying to correct and what deformities or issues are relevant in procedure selection. Again, the most important issue to me is first ray instability, but for this paper’s sake, we will assume stable rays that do not require a Lapidus procedure. The second question is the bunion’s size, so here I will assume an intermetatarsal angle of definitively fewer than 20 degrees and truly no more than 16 degrees. The third factor to consider is range of motion of the great toe joint. Is there tracking or a track-bound joint, and is the joint reducible? Is there impingement of the great toe joint? Is there any elevation of the first metatarsal limiting motion? These factors will help us address the type of surgery to consider. A final factor to ponder is frontal plane rotation. I’ve observed correction of frontal plane deformities becoming increasingly considered in bunion correction, and I also find this important in decision making. My osteotomy of choice will change if there is significant frontal plane correction necessary.

Standard radiographs allow further assessment of the bunion deformity, including anterior-posterior, medial oblique, and lateral weight-bearing. Further imaging may be necessary, and a sesamoid axial view looks at sesamoid position and frontal plane rotation of the metatarsal head as needed. Finally, in certain complicated or difficult cases that may have additional imaging needs, weight-bearing CT (computerized tomography) may help visualize the deformity in a three-dimensional fashion.

When deciding on the best procedure for each patient, I divide my head osteotomies into:

• minimally invasive;

• open long dorsal arm; and

• open L-type osteotomy with decompression or articular cartilage realignment.

Why three procedures? Let me explain. My go-to workhorse bunion correction osteotomy is a long dorsal arm cut. In my experience, this is a very stable cut with multiple fixation options, and the length of the dorsal arm allows correction of larger deformities with ease. I find the cut is also stable enough for rapid and immediate ambulation and a reasonably quick return to shoe gear. My second preferred osteotomy is a distal L osteotomy, used in cases that require decompression of a long, jamming metatarsal, an elevated first metatarsal, and if there is dorsal spur formation that requires removal. In all three of these cases, the L osteotomy is a solid option, as I find that the cut angle allows for plantarflexion and spur removal without risk to the osteotomy stability. Additionally, the L osteotomy allows for correction of severe angular deformity of the distal cartilage.⁷ In such cases of laterally rotated cartilage, a small V wedge is removed from the dorsal arm of the L osteotomy, and this corrects the distal cartilage angle. Finally, for straightforward bunion deformities, those that require frontal plane correction, and those that require significant plantarflexion, a minimally invasive through-and-through cut is my preferred option.

A Deeper Dive Into Select Distal First Metatarsal Osteotomies

Let’s discuss each osteotomy in more detail. In the long dorsal arm option, I prefer a medial incision, which I believe heals with less scar formation. Upon opening the capsule of the first MPJ, I take a wedge of tissue from the medial capsule in an ellipse form. I release the medial and lateral collateral ligaments, and, if necessary, execute an intracapsular lateral release from inside the joint, out. The osteotomy is at an approximately 60-degree angle at the distal head, with the dorsal cut made as long as necessary to correct the intermetatarsal angle. The larger the angle of correction necessary, the longer I make the cut.

In cases of a very large 20-degree first intermetarsal angle deformity without instability, the long cut may extend almost to the base of the first metatarsal for proper correction.8 I find that the maximum possible medial-to-lateral shift is two-thirds the width of the metatarsal head. Fixation is one or two points depending on the amount of shift and length of the dorsal cut. If the cut is relatively short, a single screw is sufficient, in my experience. If the cut is longer or not as stable, a second point of fixation is ideal. I used traditional 3-0 headed screws for years, but recently switched to the OSSIOfiber^® 2.4 trimmable fixation nails (OSSIO). The fixation needs to be bi-cortical for ideal stability and, with these nails, I suggest two points of fixation.⁸

The L osteotomy is actually a very practical cut with a great deal of versatility but cannot correct larger intermetatarsal angles.⁷ I reserve this cut mainly for cases that need a bit of metatarsal decompression and those that require dorsal spur removal. In such cases, I use a medial incision, the same soft tissue correction as the long dorsal arm, remove the spurring, and perform the L cut a bit more distal in the metatarsal head. A second cut removes one or two millimeters of bone from the metatarsal to allow correction.

The most important point with an L osteotomy is to consider that the less the plantar angle, the more plantarflexion one can achieve. For example, a 90-degree cut with a second small wedge resection will result in decompression only. A 70-degree cut with a lesser degree at the plantar arm will allow plantar shift with a small wedge removed. The angle of the cut is essential for addressing the goals of the osteotomy. If there is lateral shift of the articular surface, I remove a medially based wedge for better cartilage rotation, fixating with a single screw from proximal-to-distal, and not through the articular surface. The OSSIOfiber 2.4 mm trimmable fixation nails are also possibilities. I suggest two pins, one from dorsal-to-plantar and proximal-to-distal and a second from medial-to-lateral and proximal-to-distal. Neither pin should go through the distal cartilage. Immediate weight-bearing is again possible with this stable osteotomy.⁷

Our final option is a minimally invasive osteotomy, which I find myself performing more and more. This option does not necessitate opening the joint, which in my experience, results in a little more rapid healing, less swelling, and better range of motion. However, one must note that minimally invasive surgery is more difficult, and some things are harder to correct. I use minimally invasive osteotomies in bunions that are fairly straightforward, not very big, not arthritic, and have no spurs. I also use minimally invasive options for frontal plane correction. As the cut is through-and-through, rotation of the head is a feature possible with minimally invasive options and I believe one of the biggest benefits.

We successfully use two different techniques; a two-screw fixation system and the miniBunion® plate system(CrossRoads^® Extremity Systems). Surgeons can address larger bunions with minimally invasive options also, in my experience, but as this is more difficult to perform, I suggest you grow into those over time. What I find difficult with minimally invasive surgery is correction of the soft tissue contracture, so often I feel I must add an Akin osteotomy. I rarely perform this procedure otherwise. For that reason, the jury is still out for me if minimally invasive surgery is truly the best option for most head procedures.

The procedure involves a small medial incision and a special burr that performs a through-and-through cut of the bone at the distal neck region. The lateral soft tissue release takes place through a second small intermetatarsal 1-2 incision. One shifts the metatarsal and fixates with two screws from the proximal medial metatarsal into the distal head and from medial-to-lateral. The CrossRoads system is through a one-centimeter medial incision, a straight through-and-through saw cut, and metatarsal shift with fixation through an intramedullary plate screwed into the shaft and the head. Medial capsular imbrication is possible with the CrossRoads plate, in my experience, but not easy. I find both options to be very stable, allow immediate weight-bearing and rapid return to shoe gear.

Final Thoughts

In conclusion, I feel it behooves the foot and ankle surgeon to be open to multiple head osteotomy options in order to be able to correct a hallux valgus deformity in the most ideal fashion, realizing that one option is not ideal for all patients. 

Dr. Baravarian is an Assistant Clinical Professor at the UCLA School of Medicine. He is the Director and Fellowship Director at the University Foot and Ankle Institute in Los Angeles (https://www.footankleinstitute. com/podiatrist/dr-bob-baravarian).

Dr. Baravarian discloses that he is a consultant, shareholder and head of foot and ankle advisory for OSSIO, along with a consultant and shareholder for CrossRoads.

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2. Baravarian B. What bunion procedures does a surgeon need to master? Podiatry Today. 2021;33(3).

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6. Perera AM, Mason L, Stephens MM. The pathogenesis of hallux valgus. J Bone Joint Surg. 2011;93(17):1650-1661.

7. Zyzda MJ, Hineser W. Distal L osteotomy in treatment of hallux abducto valgus. J Foot Surg. 1989;28:445.

8. Chang TJ. Distal metaphyseal osteotomies in hallux abducto valgus surgery. Musculoskeletal Key website. Available at: https://musculoskeletalkey.com/distal-metaphyseal-osteotomies-in-hallux-abducto-valgus-surgery-2/ . Published July 26, 2016. Accessed September 29, 2021.