Current Perspectives On The Lapidus Bunionectomy, Triplanar Correction And Emerging Fixation Options

The Lapidus procedure for hallux abductovalgus (HAV) has certainly grown in popularity in recent years. Our understanding of the triplanar deformity that is HAV is expanding. The Lapidus is a powerful procedure with a recent influx of emerging hardware fixation options from industry. I have had the privilege of using many different types of these options. 

It is important to review the general indications for the Lapidus procedure. The relevant McGlamry chapter states that an intermetatarsal 1-2 angle of 14 to 30 degrees requires a proximal procedure such as the Lapidus procedure.¹ The big indication for the first metatarsocuneiform fusion is hypermobility of the first ray. For those of you playing the board studying game at home, hypermobility is a buzzword for the boards. Clinical signs of hypermobility are callus formation under the second metatarsal head and an exaggerated range of motion when one performs the Root test as well as the dynamic Hicks test. 

To review, one would perform the Root test by stabilizing the lesser metatarsals with one hand and putting the first metatarsal through dorsal and plantar range of motion with the other hand. The accepted range is equal dorsal and plantar motion of about four to six mm. Podiatrists can perform the dynamic Hicks test by maximally dorsiflexing the hallux and performing the Root test. This helps to simulate weightbearing function of the hallux.¹

What The Literature Reveals About The Role Of The Lapidus Procedure In Triplanar Correction 

Dayton and associates have addressed the impact of the frontal plane rotational deformity in HAV.^2,3 In one publication the authors discuss many literature reviews that investigate the triplanar nature of the HAV deformity as well as express opinions about the first tarsometatarsal joint being the center of rotational angulation (CORA). Dayton and coworkers have also discussed how the proximal articular set angle (PASA) may appear to be abnormal due to the malpositioning of the metatarsal as opposed to a bony deformity.^2,3

We could discuss these topics for quite some time but I want to try and stay focused on the triplanar nature of the HAV deformity, and the need to correct all aspects of the deformity. With the Lapidus procedure, surgeons are able to correct the intermetatarsal 1-2 angle (transverse plane), hypermobility (sagittal plane) and the sesamoid position and rotation of the metatarsal (frontal plane). In a recent discussion of early hallux valgus recurrence, Shibuya and colleagues noted the only factor correlating with this early loss of correction was the tibial sesamoid position.⁴ I feel that this emphasizes the importance of correcting the frontal plane deformity in HAV. 

The Lapidus procedure itself can be quite challenging. With the typical approach being dorsomedial, one must be aware of the depth of the first tarsometatarsal joint. In 2012, Ryan and colleagues examined 51 cadaver specimens to find the average depth of the tarsometatarsal joints, which was approximately 32.3 mm.⁵ Accordingly, when the surgeon is selecting a saw blade, he or she must choose one that can reach this depth. Most commonly, there is a 35 mm blade, which allows adequate joint resection down to the plantar cortex. It is very important to ensure adequate removal of the plantar cortex to avoid dorsiflexion of the first metatarsal with fixation application.

Pertinent Insights On Instrumentation

One tool that I find invaluable is the K-wire distractor. This allows distraction of the joint for great visualization to resect cartilage, visualization of any remaining plantar cortical bone and easy fenestration of the bone and fish scaling if desired. One may employ a lamina spreader but this requires frequent repositioning as this instrument sits in the joint on the working surfaces. 

Another valuable instrument for the Lapidus procedure is the point reduction clamp. After joint preparation is complete, I rotate the metatarsal out of valgus and apply the reduction clamp from the head of the first metatarsal to the head of the second metatarsal. This device nicely closes down the intermetatarsal angle but also helps to reduce the tibial sesamoid position. When this position is adequate on anteroposterior fluoroscopic imaging, I place a temporary K-wire across the joint. The lateral view is also important to rule out any elevatus or plantarflexion of the first ray. 

Key Fixation Considerations With The Lapidus Procedure

Fixation constructs vary with more systems added all of the time. I think it is most important to be familiar with the crossing screw construct. This is the most basic method and often takes much less time than some plating systems that are on the market. Also, when something happens in the OR that prohibits use of a plate, it is important to know how to get back to the basics. 

The plating systems in my opinion are all basically the same. Almost every plate now is a locking plate with some sort of built-in spot for a compression screw. They operate on the same concept with usually one minor variance that makes that system “unique.” 

I am not a fan of the double-plating Lapidus system. This system seems to go against the standard dynamic compression of a transarticular screw for fusion. It essentially causes compression with a threaded olive wire-type device, which is followed by placement of two locking plates across the joint with removal of the olive wire, essentially making the plates positional with no constant compression being applied to the joint. I have assisted with this system a few times and do not feel it is worth the money nor the complicated process of application. I have also seen some less than ideal postoperative complications. 

The postoperative course varies from doctor to doctor. Typically, the patient is in a cast or posterior splint, and is non-weightbearing for two weeks after the surgery or until the incision is healed and sutures are removed. After that, patients often transition into a CAM walker but remain non-weightbearing for two more weeks. At the four to six week mark, depending on patient adherence and physician preference, one can allow protected weightbearing in the CAM walker with transition to full weightbearing in a shoe when there are radiographic signs of fusion. 

Overall, the Lapidus procedure is a powerful option to correct HAV in a triplanar fashion and there is a myriad of fixation options to choose from. With the right tools in the OR and a great understanding of the anatomy, the Lapidus procedure can offer great results. 

References

1. DiDomenico LA, Wargo-Dorsey M. Lapidus bunionectomy: first metatarsal-cuneiform arthrodesis. In: Southerland JT, Boberg JS, Downey MS, Nakra A, Rabjohn LV, eds. McGlamry’s Comprehensive Textbook of Foot and Ankle Surgery. 4^th ed. Philadelphia, PA: Lippincott, Williams and Wilkins;2012:322-331. 
2. Dayton P, Feilmeier M, Kauwe M, Hirschi J. Relationship of frontal plane rotation of first metatarsal to proximal articular set angle and hallux alignment in patients undergoing tarsometatarsal arthrodesis for hallux abducto valgus: A case series and critical literature review. J Foot Ankle Surg. 2013;52(3):348-354.
3. Dayton P, Feilmeier M, Kauwe M, Holmes C, McArdle A, Coleman N. Observed changes in radiographic measurements of the first ray after frontal and transverse plane rotation of the hallux: Does the hallux drive the metatarsal in a bunion deformity? J Foot Ankle Surg. 2014;53(5):584-587.
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):236-240.
5. Ryan JD, Timpano ED, Brosky TA 2^nd. Average depth of tarsometatarsal joint for trephine arthrodesis. J Foot Ankle Surg. 2012;51(2):168-171.