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Emphasizing The Role Of Sagittal Plane Reduction In The Lapidus Procedure
Since its inception in 1934, the Lapidus surgical procedure for hallux valgus correction has evolved to increase stability to the first tarsometatarsal (TMT) joint, improve pedal biomechanics, decrease deformity recurrence and decrease duration of postoperative non-ambulatory status.1 The literature has molded our understanding of the triplanar nature of hallux valgus deformity, generally consisting of a malrotated or pronated first metatarsal in the coronal plane, a dorsiflexed metatarsal with respect to the sagittal plane, and a medially deviated metatarsal in the transverse plane.1
Yejejon and colleagues evaluated 166 feet with hallux valgus deformity using weight bearing AP radiographic views to evaluate intermetatarsal angles.1 They also used semi-weight bearing computed tomorgraphy (CT) axial views to demonstrate that patients with hallux valgus deformity exhibit a more pronated first metatarsal. Their data shows just over 25 percent of patients with hallux valgus deformity demonstrated a “pseudo subluxation” of the sesamoid complex.1 This study suggests that surgical derotation of the first metatarsal is indicated as part of proper correction for hallux valgus deformity. Mortier and team found that patients with hallux valgus deformity exhibited on average 12.7 degrees of first metatarsal pronation.2 Dayton, DiDomenico and colleagues demonstrated the mean amount of varus (supination) rotation performed during correction was 22.1 ± 5.2 degrees.3 These studies provide strong support for addressing rotational deformities of the first metatarsal.
What Is The Role Of Sagittal Plane Correction During Lapidus Arthrodesis?
Surgeons may often overlook the necessity of sufficiently addressing sagittal plane alignment during Lapidus arthrodesis. In the authors’ opinion, first metatarsal elevatus, an underlying etiology of hallux rigidus, is often a contributing factor to development of hallux valgus as well. Biomechanically speaking, a chronically elevated first metatarsal will result in accelerated degeneration of the first MPJ and lesser metatarsalgia as pressures distribute laterally among the lesser metatarsal heads.4,5 Failing to stabilize and neutralize the first metatarsal in the sagittal plane is a risk factor for recurrence, as the element of hypermobility may persist. In the authors’ experience, sagittal plane correction is essential for improved outcomes.
The literature pertaining to rates of postoperative metatarsal elevatus after Lapidus arthrodesis is limited. There is no consensus on the underlying etiology of postoperative elevation of first metatarsal, either. Blitz, DiDomenico and colleagues retrospectively reviewed 80 feet in 76 patients who began weight bearing wearing a walking boot two weeks post-Lapidus arthrodesis.6 They reported 100 percent successful union with a mean time to union of 44.5 days. These patients demonstrated no postoperative findings of first ray elevatus.6
How Can One Measure First Ray Elevatus?
There are several proposed methods of measuring and evaluating metatarsus primus elevatus in the literature. The Seiberg index is a standard method of evaluation of the sagittal plane relationship between the first and second metatarsals.7 The measure compares the segmental dorsal cortices of the first and second metatarsals, starting proximal at 15mm distal to the first metatarsal base and extending distally to the first metatarsal neck. One can measure the distance between the first and second metatarsals at each of these points. The clinician can subtract this measurement at the neck of the first metatarsal from the measurement 15mm from base of the first metatarsal. Larger differences indicate greater metatarsus primus elevatus deformity.7
Bouaicha and team described a standardized technique to radiographically assess for metatarsus primus elevatus utilizing a weight bearing lateral X-ray. On a lateral radiographic view, researchers fit a circle in the head of the first metatarsal in order to obtain a congruence between the circle and joint surface. Then they drew a tangential line along the dorsal cortex of the first metatarsal shaft. At the proximal point where the circle cuts the tangent line, they placed a vertical 90 degree angle line down to the dorsal cortical bone of the second metatarsal shaft. The distance between the two intersection points of two dorsal cortical bones along the vertical line is determinant of the value for metatarsus primus elevatus in this method.8
Measuring elevatus is useful for classification and assessment of pre- and postoperative outcomes. However, in our experience, evaluation is primarily clinical, considering any visible elevation of the dorsal cortex of the first metatarsal with respect to the second metatarsal as pathological, warranting attention in the surgical setting.
The Challenge Of Triplanar Hallux Valgus Evaluation
Historically, we find surgeons directed little attention to the triplanar nature of hallux valgus, primarily using two standard radiographic angles; the hallux abductus angle and the first intermetatarsal angle. These measurements typically stem from a standard AP weight bearing X-ray. In our experience, these parameters generally evaluate deformity in the transverse plane, however foot biomechanics consists of much more. The foot is a dynamic structure, therefore we advise caution when making decisions based on a “snapshot” static radiograph. The surgeon must understand this is a dynamic deformity with motion and instability.
One can evaluate the coronal plane through the position of the tibial sesamoid, as well as the roundness of the first metatarsal head. In our experience, the the distance between the tibial sesamoid and the second metatarsal remains constant between an AP radiograph and an AP fluoroscopic live view. This demonstrates that the sesamoid complex remains constant as the head of the first metatarsal drifts medially, giving the radiographic appearance of subluxation. Therefore, this radiographic appearance is a direct consequence of multiplanar metatarsal deformity. We also find that roundness of the metatarsal head can also evaluate coronal plane rotation. In a pathologic foot, the lateral and plantar aspects of the metatarsal create a rounded appearance as the metatarsal assumes a pronated position.
One can evaluate sagittal plane first ray deformity on the lateral radiograph with the metatarsus primus elevatus angle, however, this is more of a clinical evaluation and diagnosis. Metatarsus primus elevatus describes a dorsal elevation of the first metatarsal bone with respect to the lesser metatarsals. Lambrinudi first described this phenomenon as a possible factor for limitation of first MPJ motion and the underlying etiology of hallux rigidus and arthritis of the first metatarsophalangeal joint.9
Determining When A Lapidus Is The Best Surgical Choice
Historically, inclusion criteria for the Lapidus procedure includes moderate-to-severe hallux valgus, a first intermetatarsal angle greater than 15 degrees and concurrent ligamentous laxity or instability at the first TMT joint. Morton was the first to document the phenomenon of first ray hypermobility in 1928, and later Lapidus documented that most feet with hallux valgus deformity demonstrated clinical and radiographic evidence of hypermobility.10,11 Furthermore, Klaue and colleagues quantified first ray hypermobility clinically, using an original device.12 Most of these studies only examined hypermobility with respect to dorsiflexion and plantarflexion, failing to recognize pathologic hypermobility of the first ray in the transverse and coronal planes. Kimura and team presented evidence that hypermobility is not only a sagittal plane process and involves more than just the first tarsometatarsal joint, finding significantly greater mobility in other joints of the first ray.13
The hypothesis exists that the malaligned peroneus longus, plantar fascia and plantar ligamentous structures all lose their mechanical advantage in the setting of hallux valgus deformity.14,15 This is the underlying etiology of first ray instability. Shibuya and coworkers found that patients with hallux valgus demonstrated an average of 3.62mm greater motion in the sagittal plane than those without.14 Ellington and team demonstrated in a retrospective study of 52 feet that 96 percent of those feet demonstrated clinical hypermobility and 52 patients exhibited radiographic evidence of hypermobility.15 To date, fusion of the first TMT joint utilizing the Lapidus procedure is the best known solution in our experience to stabilize the first ray while offering triplanar correction of a hallux valgus deformity.
The first ray is supposed to bear approximately 40 percent of the forefoot load.16 When this fails to occur in the presence of the previously described malaligned mechanics, stress transfers to the lesser metatarsals. This can lead to plantar plate attenuation and loss of lesser digit stabilization. With an emphasis on the sagittal plane during surgical correction, we can correct all three planes of the deformity adequately with good reduction, identifiable clinically as well as radiographically. In our experience, the reduction of the sagittal plane in addition to the frontal and transverse planes aids in restoring the first MPJ to normal anatomic alignment, subsequently improving gait function. We find in our practice that this can decrease painful first MPJ range of motion without need for additional procedures.
The Lapidus procedure is powerful, with relatively few contraindications to consider. With usual and routine joint resection/preparation at the first TMT joint it it is not a significant contributor to a noticeable decrease in first metatarsal length. However, one may perceive this sagittally corrected (plantarflexed) metatarsal post- Lapidus as a short first metatarsal as it can falsely resemble a shortened first metatarsal radiographically, despite improving foot biomechanics and function.
Pertinent Pearls That Promote Proper Sagittal Plane Correction
Here we describe an approach to sagittal plane first ray alignment and stabilization via a modified Lapidus procedure which we find transfers weight back to the first ray, anatomically aligns the first MPJ and decreases stress to the lesser metatarsals. First we make a four cm incision over the first metatarsal-cuneiform joint with anatomic sharp and blunt dissection carried down to that joint. Initial resection of the articular surface of the first metatarsal base takes place perpendicular to the long axis of the first metatarsal and parallel to its base. We address the first metatarsal first to strive to maintain as much proximal stability as possible throughout the procedure. There is no correction made through the metatarsal itself. It is also important to recognize that the articular surface of the first metatarsal base is concave, and the articular surface of the medial cuneiform is convex. We aim to address our triplane deformity with resection of the most distal aspect of the convex medial cuneiform.
We spend the most surgical time on joint preparation and utilizing appropriate internal fixation. A successful surgical outcome without deformity recurrence of deformity highly depends upon successful first TMT joint fusion. Use of a “home run screw” as described by Hansen should be a long solid cortical screw, which will assist in stabilizing and maintaining the first metatarsal position.17
Henning and team found that first metatarsal elevatus recurrence correlated with lack of joint preparation.18 Patients with adequate joint preparation demonstrated an overall incidence of postoperative elevatus of 12.5 percent with an average angle of 0.87 degrees between the dorsal cortices of the first and second metatarsals. Patients who underwent simple planar resection and did not undergo joint preparation exhibited a 77.8 percent incidence of postoperative elevatus and an average of 5.4 degrees between the dorsal cortices of the first and second metatarsals on a weight bearing lateral X-ray view.18
Achieving Triplane Reduction With A Sagittal Focus
It is critical for the surgeon achieve good articular joint preparation and deformity reduction. We temporarily fixate the first TMT joint with two K-wires; one from dorsal-distal to plantar-proximal and another thrown from the first to second metatarsal. Anatomic reduction of the sagittal, frontal and transverse planes takes place prior to temporary fixation of the first TMT joint. In the senior author’s experience, the sagittal plane is the most critical to correct. A K-wire “joystick” can assist in first metatarsal correction, derotating the bone out of a valgus position in the frontal plane. Next, the K-wire from the first to second metatarsals can assist in reduction of the intermetatarsal angle/transverse plane (one can also use a large Weber reduction forceps if needed). This first to second metatarsal K-wire will also stabilize and confirm the sagittal plane correction of the first metatarsal relative to the lesser rays. Following this reduction, the great toe should assume a neutral position.
For sagittal plane reduction, we recommend activating the windlass mechanism by passively dorsiflexing the hallux. Simultaneously, an assistant should stabilize the hindfoot in order to allow the surgeon to apply retrograde force to the plantar TMT joint. This will cause the first metatarsal to plantarflex and correct the sagittal plane appropriately. The surgeon should ensure metatarsal positioning such that the first metatarsal dorsal cortex becomes consistent with the dorsal cortices of the lesser metatarsals. The dorsiflexory force of the great toe on the first metatarsal also aids sagittal plane deformity correction.19
Bofelli and colleagueas describe simulating intraoperative weight bearing after applying temporary as well as definitive fixation.20 They placed the image intensifier against the medial aspect of the foot, with the flat plate 90 degrees to the image intensifier and the surgeon’s palm loading the foot in ankle dorsiflexion to neutral at 90 degrees.20 Unfortunately, capturing a true intraoperative weight bearing image is difficult. The surgeon can simulate weight bearing by manually loading the forefoot and evaluating for stability. Preferably the surgeon will achieve parallel dorsal cortices of the first and second metatarsals and anatomical reduction of the deformity in the transverse and frontal planes.
Concluding Thoughts
In the senior author’s experience, the sagittal plane is the most important plane of correction as it relates to first ray pathology, such as hallux valgus, hallux limitus and lesser metatarsal pathology. Similarly, first ray stability is paramount in most forefoot pathology. We advocate that the Lapidus procedure is an extremely versatile when performed well and when one addresses and achieves sagittal plane stability.
Dr. DiDomenico is the Director of the Reconstructive Rearfoot and Ankle Surgical Fellowship at NOMS Ankle and Foot Care Center in Youngstown, Ohio. He is also the Director of Podiatric Residency Training at East Liverpool City Hospital in East Liverpool, Ohio.
Dr. Spingola is an Associate of the American College of Foot and Ankle Surgeons and a recent Fellow at Ankle Foot Care Center in Youngstown, Ohio.
Dr. Cameron is a second-year podiatric resident at East Liverpool City Hospital in East Liverpool, Ohio.
1. Rush SM, Christensen JC, Johnson CH. Biomechanics of the first ray. Part II: Metatarsus primus varus as a cause of hypermobility. A three-dimensional kinematic analysis in a cadaver model. J Foot Ankle Surg. 2000;39(2):68-77.
2. Mortier J-P, Bernard J-L, Maestro M. Axial rotation of the first metatarsal head in a normal population and hallux valgus patients. Orthop Traumatol Surg Res. 2012;98(6):677–683.
3. 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 balancing. J Foot Ankle Surg. 2016;55(2):220-225.
4. DiDomenico LA, Wargo-Dorsey M. Lapidus bunionectomy: first metatarsal-cuneiform arthrodesis. In: Southerland JT, Boberg JS, Downey MS, Nakra A, Rabjohn LT (eds). McGlamrys Comprehensive Textbook of Foot and Ankle Surgery (4th ed.). Lippincott, Williams & Wilkins;2013:322–330.
5. Boffeli, TJ, Collier RC, Thompson JC, Luer SA. Cheilectomy combined with first tarsometatarsal joint arthrodesis for surgical treatment of midstage hallux rigidus complicated by medial column insufficiency: prospective evaluation of outcomes. J Foot Ankle Surg. 2020;59(4):829–834.
6. Blitz NM, Lee T, Williams K, Barkan H, DiDomenico LA. Early weight bearing after modified Lapidus arthodesis: a multicenter review of 80 cases. J Foot Ankle Surg. 2010:49(4):357–362.
7. Seiberg M, Felson S, Colson JP Barth AH, Green RM, Green DR. Closing base wedge versus Austin bunionectomies for metatarsus primus adductus. J Am Podiatr Med Assoc. 1994;84(11):548–563.
8. Bouaicha S, Ehrmann C, Moor BK, Maquieira GJ, Espinosa N. Radiographic analysis of metatarsus primus elevatus and hallux rigidus. Foot Ankle Int. 2010;31(9):807-814.
9. Lambrinudi C. Metatarsus primus elevatus. Proc Royal Soc Med. 1938;31(11):1273.
10. Morton DJ. Hypermobility of the first metatarsal bone: the interlinking factor between metatarsalgia and longitudinal arch strains. J Bone Joint Surg. 1928;10(2):187-196.
11. Lapidus PW. The operative correction of metatarsus varus primus in hallux valgus. Surg Gynecol Obstet. 1934;58:183–189.
12. Klaue K, Hansen ST, Masquelet AC. Clinical quantitative assessment of first tarsometatarsal mobility in the sagittal plane and its relation to hallux valgus deformity. Foot Ankle Int. 1994;15(1):9–13.
13. Kimura T, Kubota M, Taguchi T, Suzuki N, Hattori A, Marumo K. Evaluation of first-ray mobility in patients with hallux valgus using weight-bearing CT and a 3-D analysis system: a comparison with normal feet. J Bone Joint Surg Am. 2017;99(3):247-255.
14. Shibuya N, Roukis T, Jupiter D. Mobility of the first ray in patients with or without hallux valgus deformity: systematic review and meta-analysis. J Foot Ankle Surg. 2017;56(5):1070-1075.
15. Ellington JK, Myerson MS, Coetzee LC, Stone RM. The use of the Lapidus procedure for recurrent hallux valgus. Foot Ankle Int. 2011;32(7):674- 680.
16. Greisberg J. Foot and ankle anatomy and biomechanics. In: DiGiovanni C, Greisberg J. (eds.) Core Knowledge in Orthopedics Foot and Ankle. Elsevier;2007:6,7,12,15.
17. Hansen Jr. ST. Hallux valgus surgery. Morton and Lapidus were right. Clin Podiatr Med. 1996;13:347-354.
18. Henning JA, Shane NS, Maker JM. Elevation and shortening of the first metatarsal following the modified Lapidus: a radiographic comparison of two techniques. Poster presented at: American College of Foot and Ankle Surgeons Annual Scientific Conference. February 14-17, 2019. New Orleans, La.
19. Boffeli TJ, Mahoney KJ. Intraoperative simulated weightbearing lateral foot imaging: the clinical utility and ability to predict sagittal plane position of the first ray in Lapidus fusion. J Foot Ankle Surg. 2016;55(6):1158-1163.
