DEFINITION

The first reports of a distal metatarsal osteotomy date back to Reverdin, who described in 1881 a subcapital closing wedge osteotomy for the correction of hallux valgus deformity.

The chevron osteotomy has become widely accepted for correction of mild and moderate hallux valgus

deformities. In the initial reports by Austin and Leventen1 and Miller and Croce,13 no fixation was mentioned. They suggested that the shape of the osteotomy and impaction of the cancellous capital fragment on the shaft of the first metatarsal provided sufficient stability to forego fixation.

To increase the indication for this technically simple osteotomy, internal fixation and a lateral soft tissue release have been added.

ANATOMY

The special situation distinguishing the first metatarsophalangeal (MTP) joint from the lesser MTP joints is the sesamoid mechanism.

On the plantar surface of the metatarsal head are two longitudinal cartilage-covered grooves separated by a rounded ridge. The sesamoids run in these grooves.

The sesamoid bone is contained in each tendon of the flexor hallucis brevis; they are distally attached by the fibrous plantar plate to the base of the proximal phalanx.

The head of the first metatarsal is rounded and cartilagecovered and articulates with the smaller concave elliptic base of the proximal phalanx.

Fan-shaped ligamentous bands originate from the medial and lateral condyles of the metatarsal head and run to the base of the proximal phalanx and the margins of the sesamoids and the plantar plate.

Tendons and muscles that move the great toe are arranged in four groups:

Long and short extensor tendons Long and short flexor tendons Abductor hallucis

Adductor hallucis

Blood supply to the metatarsal head

First dorsal metatarsal artery

Branches from the first plantar metatarsal artery

PATHOGENESIS

Extrinsic causes

Hallux valgus occurs predominantly in shoe-wearing populations and only occasionally in the unshod individual.

Although shoes are an essential factor in the cause of hallux valgus, not all individuals wearing fashionable shoes develop this deformity.

Intrinsic causes

Hardy and Clapham3 found in a series of 91 patients a positive family history in 63%.

Coughlin2 reported that a bunion was identified in 94% of 31 mothers whose children inherited a hallux valgus deformity.

Association of pes planus with the development of a hallux valgus deformity has been controversial. Hohmann5 was the most definitive that hallux valgus is always combined with pes planus.

Coughlin2 and Kilmartin and Wallace8 noted no incidence of pes planus in the juvenile patient.

Pronation of the foot imposes a longitudinal rotation of the first ray, which places the axis of the MTP joint in an oblique plane relative to the floor. In this position, the foot appears to be less able to withstand the deformity pressures exerted on it by either shoes or weight bearing.

The simultaneous occurrence of hallux valgus and metatarsus primus varus has been frequently described. The question of cause and effect continues to be debated.

PATIENT HISTORY AND PHYSICAL FINDINGS

Patient history often includes the following:

Pain in narrow shoes

Symptomatic intractable keratoses beneath the second metatarsal head (in 40% of patients) Lateral deviation of the great toe

Pronation of the great toe

Keratosis medial plantar underneath the interphalangeal joint

Bursitis over the medial aspect of the medial condyle of the first metatarsal head Hypermobility of the first metatarsocuneiform joint

Physical examination for hallux valgus deformity includes the following:

Hallux valgus angle: Normal is 15 degrees or less. Intermetatarsal angle: Normal is 9 degrees or less.

Measurement of the position of the medial sesamoid relative to a longitudinal line bisecting the first metatarsal shaft

Grade 0: no displacement of sesamoid relative to the reference line

Grade I: overlap of less than 50% of sesamoid relative to the reference line Grade II: overlap of greater than 50% of sesamoid relative to the reference line

Grade III: sesamoid completely displaced beyond the reference line

Joint congruency: measuring the lateral displacement of the articular surface of the proximal phalanx with respect

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to the corresponding articular surface of the metatarsal head, as seen on a dorsoplantar roentgenogram

IMAGING AND OTHER DIAGNOSTIC STUDIES

Radiographs of the foot should always be obtained with the patient in the weight-bearing position with anteroposterior (AP) (FIG 1), lateral, and oblique views. The following criteria are examined:

Hallux valgus angle Intermetatarsal angle Sesamoid position Joint congruency

Distal metatarsal articular angle (DMAA): the relationship between the articular surface of the first metatarsal head and a line bisecting the first metatarsal shaft (normal is 10 degrees or less)

Arthrosis of the first MTP joint

DIFFERENTIAL DIAGNOSIS

Ganglion Hallux rigidus

FIG 1 • A 72-year-old woman with hallux valgus before surgery.

NONOPERATIVE MANAGEMENT

Comfortable wider shoes Orthotics

Spiral dynamics physiotherapy in adolescents

SURGICAL MANAGEMENT

Indications

Symptomatic hallux valgus deformity with a first intermetatarsal angle of up to 16 degrees Stable first metatarsocuneiform joint

Contraindications

Narrow metatarsal head so that adequate translation is not possible Intermetatarsal angle of more than 16 degrees

Impaired vascular status Skeletally immature patient Severe osteoarthritic changes

Preoperative Planning

Standard weight-bearing AP and lateral radiographs are mandatory.

The hallux valgus and intermetatarsal angles and tibial sesamoid position are measured. A preoperative drawing is helpful.

Clinical examination includes measurement of active and passive range of motion of the first MTP joint as well as inspection of the foot for plantar callus formation indicative of transfer metatarsalgia and stability of the first tarsometatarsal joint.

Positioning

The foot is prepared in the standard manner. The patient is positioned supine.

An ankle tourniquet is optional.

Approach

The lateral soft tissue release is performed through a dorsal approach.

The chevron osteotomy is performed through a straight midline incision.

TECHNIQUES

• Chevron and Transarticular Lateral Soft Tissue Release

Exposure

The procedure is typically performed under peripheral nerve block.

A straight medial incision over the metatarsal head is performed (TECH FIG 1A).

The medial MTP joint capsule is opened with a longitudinal incision (TECH FIG 1B). The joint is inspected for degenerative changes.

TECH FIG 1 • A. Medial skin incision. B. Longitudinal capsular incision.

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Lateral Release and Preparation of the Metatarsal Head

The capsule is released from the plantar and the dorsal aspect of the base of the proximal phalanx (TECH FIG 2A,B).

While the toe is plantar subluxed (TECH FIG 2C), scissors are placed intra-articular proximal to the sesamoids from medial to lateral (TECH FIG 2D).

Parallel to this, a beaver knife is inserted and the lateral joint capsule (metatarsosesamoid ligament) is divided immediately superior to the lateral sesamoid (TECH FIG 2E).

The lateral capsule is fenestrated at the first MTP joint, and a varus stress is applied to the hallux to complete the lateral release (TECH FIG 2F,G).

The metatarsal head is now exposed, and Hohmann retractors are placed dorsal and plantar just extra-articular of the first MTP joint.

The plantar Hohmann retractor protects the plantar artery to the metatarsal head and the dorsal retractor protects the dorsal intra-articular blood supply originating from the capsule.

 

TECH FIG 2 • A-C. The capsule is released and the toe is plantar subluxed. D. A scissor is now placed intra-articular proximal to the sesamoids from medial to lateral. E. A beaver knife is inserted and the lateral capsule is incised. F. The great toe is brought into 20 degrees of varus to demonstrate the release of the lateral structures. G,H. The medial eminence is minimally resected.

The medial eminence is now minimally shaved to achieve a plane surface but also to preserve as much metatarsal head width as possible (TECH FIG 2H).

This is one of the most important principles if a chevron osteotomy is carried out in a moderate to severe deformity.

Osteotomy Creation

A 1.0-mm Kirschner wire is drilled a little bit dorsal to the center of the exposed medial eminence. This wire is generally inclined 20 degrees from medial to lateral, aiming at the head of the fourth metatarsal (TECH FIG 3A,B).

In the situation of an elevated position of the first metatarsal, the inclination may be increased.

If shortening or lengthening of the first metatarsal is needed, the wire can be aimed to the fifth or third metatarsal head.

By using a saw guide (TECH FIG 3C), two cuts are then made with an oscillating power saw so that they form an angle of 60 degrees proximal to the drill hole.

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TECH FIG 3 • A,B. A guidewire marks the apex of the osteotomy. It should be 10 degrees inclined from medial to lateral and pointing at the head of the fourth metatarsal. C. The osteotomy is performed using an osteotomy guide. D,E. The metatarsal head is pushed laterally, whereas the metatarsal shaft is pulled medially.

Once the capital fragment is freely mobile, the metatarsal shaft is pulled medially by using a towel clip while pushing the metatarsal head laterally with the help of the thumb of the other hand (TECH FIG 3D,E).

In the situation that the DMAA is increased, a wedge from the distal dorsal cut can be excised to place the metatarsal head in a more varus position. If there is only a minor increase of the DMAA, this may also be achieved by impacting the metatarsal head onto the shaft.

Guidewire Placement

A guidewire for a cannulated Charlotte multiuse compression screw (Wright Medical Technology, Arlington, TN) is inserted from the distal dorsal metatarsal shaft obliquely to lateral plantar of the metatarsal head (TECH FIG 4).

It is now advised to check the position of the osteotomy and the guidewire with a C-arm or a Fluoroscan.

 

 

TECH FIG 4 • A guidewire for the 3.0 Charlotte multiuse compression screw (Wright Medical Technology) is placed.

Screw Insertion and Closure

The length of the screw is now measured with the cannulated depth gauge (TECH FIG 5A).

Multiuse compression screws are designed to be totally selftapping and self-drilling. To avoid dislocation of the head, however, it is advised to use the cannulated drill (TECH FIG 5B) and cannulated head drill (TECH FIG 5C).

The screw is inserted (TECH FIG 5D).

Then, the medial eminence is excised in line with the metatarsal shaft, taking care not to excise too much bone off the metatarsal head (TECH FIG 5E).

While an assistant holds the great toe in a slightly overcorrected position, the medial joint capsule is repaired with U-type sutures and the first web space sutures are tightened (TECH FIG 5F).

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TECH FIG 5 • A. Screw length determination using the depth gauge. B. Prepare a countersunk area with the Charlotte cannulated head drill. C. Predrilling with the Charlotte cannulated drill. D. Insertion of the screw until the head is completely counterstunk within the bone. E. The medial eminence is resected. F. Closing of the medial capsule with U-type sutures.

Lateral tilt of the

metatarsal head

• Lateral release to avoid lateral tilting of the head, intraoperative

Fluoroscan control

Avascular necrosis

• Careful soft tissue dissection

Intraoperative fracture of

the metatarsal head

• A guidewire at the apex of the osteotomy will prevent

overpenetration of the distal fragment with the saw blade.

PEARLS AND PITFALLS

POSTOPERATIVE CARE

Starting immediately postoperatively, ice application to the foot is helpful to reduce swelling.

Provided that the bone quality was intraoperatively sufficient, patients are allowed to walk with a postsurgical type shoe (OFA Rathgeber, Germany) (FIG 2A) on the same day (limited for 4 weeks).

Weekly changes of the tape dressing are necessary.

An alternative to weekly dressing changes is the postoperative hallux valgus sock, which also reduces postoperative edema (FIG 2B).

Radiographs are taken intraoperatively and at 4 weeks of follow-up.

After radiographic union is achieved, normal dress shoes with a more rigid sole are allowed. After 4 weeks, physiotherapy to achieve normal forefoot function is recommended.

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FIG 2 • A. Rathgeber postoperative shoe (OFA Rathgeber). B. Postoperative hallux valgus compression stocking used after suture removal.

OUTCOMES

In the early years of this technique, it was limited to patients 50 years and younger. This was represented by the study of Johnson et al,7 which established a contraindication for using a chevron osteotomy in patients older than 50 years. However, Trnka20,21,22 and Schneider et al18 have shown that age is not a

limiting factor for the chevron osteotomy (FIG 3).

Another important issue that was stretched out over the years was the combination of a lateral soft tissue release and a distal chevron osteotomy. Earlier reports expressed concern about an increased risk of

avascular necrosis if a lateral release is performed in addition to a chevron osteotomy. Jahss,6 Mann,9,10,11 and Meier and Kenzora12 have all suggested that avascular necrosis frequently accompanies distal chevron with lateral soft tissue release, citing an incidence of up to 40%. Pochatko et

al15 and Trnka20,21,22 could not support this in their publications and found no increased risk of avascular necrosis.

Chevron osteotomy was for many years limited to mild hallux valgus deformities.17,19 Designed primarily without fixation, the concern was stability and loss of fixation. As it became more obvious that a lateral soft tissue release is important for correction of more severe deformities, this concern gained weight.

According to papers by Harper4 and Sarrafian,17 lateral displacement is limited up to 50% of metatarsal width.

 

FIG 3 • The same patient as in FIG 1 after surgery.

Over a period of 14 years, we have modified and developed the chevron osteotomy. By reviewing each step of the development with clinical studies, we now perform a chevron osteotomy with lateral soft tissue release and single screw fixation.

Trnka et al21 reported in 2000 a series of 43 patients (57 feet) with 2-year and 5-year follow-up. Radiographic evaluation revealed a preoperative average hallux valgus angle of 29 degrees and a preoperative average intermetatarsal angle of 13 degrees. At the 2-year follow-up, those angles averaged 15 and 8 degrees, respectively, and at the 5-year follow-up, they averaged 16 and 9 degrees. The results at these two follow-up periods proved that the chevron osteotomy is a reliable procedure for mild and moderate hallux valgus deformity and that there are no differences in outcome based on age.

Schneider et al18 reported in 2004 a series of 112 feet (73 patients) with a minimum follow-up of 10 years. For 47 feet (30 patients), the results were compared with those from an interim follow-up of 5.6 years. The American Orthopaedic Foot and Ankle Society (AOFAS) score improved from a preoperative mean of 46.5 points to a mean of 88.8 points after a mean of 12.7 years. The first MTP angle showed a mean preoperative value of 27.6 degrees and was improved to 14.0 degrees. The first intermetatarsal angle improved from a preoperative mean of 13.8 degrees to 8.7 degrees. The mean preoperative grade of sesamoid subluxation was 1.7 on a scale of 0 to 3 and improved to 1.2. Measured on a scale of 0 to 3,

arthritis of the first MTP joint progressed from a mean of 0.8 to 1.7. The progression of arthritis of the first MTP joint between 5.6 and 12.7 years postoperatively was statistically significant. Excellent clinical results after chevron osteotomy not only proved to be consistent but also showed further improvement over a longer followup period. The mean radiographic angles were constant, without recurrence of the deformity. So far, the statistically significant progression of first MTP joint arthritis has not affected the clinical result, but this needs further observation.

Sanhudo16 retrospectively reviewed 50 feet with moderate to severe hallux valgus deformity in 34 patients with a mean follow-up of 30 months. There was a mean AOFAS score improvement of 39.6 (44.5 to 84.1) points. The hallux valgus angle and intermetatarsal angle improved a mean of 22.7 degrees and

10.4 degrees, respectively. He concluded that the chevron osteotomy is also indicated for moderate to severe hallux valgus deformity.

Park et al14 performed a level II study to compare chevron osteotomies with dorsolateral approach for lateral release and chevron osteotomies with transarticular lateral release. One hundred and twenty-two female patients (122 feet) who underwent a distal chevron osteotomy as part of a distal soft tissue procedure for the treatment of symptomatic unilateral moderate to severe hallux valgus constituted the study cohort. The 122 feet were randomly divided into two groups: namely, a dorsal first web space approach (group D; 60 feet) and a medial transarticular approach (group M; 62 feet). The clinical and radiographic results of the two groups were compared at a mean follow-up time of 38 months.

The final clinical and radiographic outcomes between the two approaches for distal soft tissue procedures were comparable and equally successful. Accordingly, the results of

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this study suggest that the medial transarticular approach is an effective and reliable means of lateral soft tissue release compared with the dorsal first web space approach.

COMPLICATIONS

Avascular necrosis of the metatarsal head

 

A lateral release does not increase the incidence.15 Hallux varus

Malpositioning

Loss of fixation

REFERENCES

1. Austin DW, Leventen EO. A new osteotomy for hallux valgus: a horizontally directed “V” displacement osteotomy of the metatarsal head for hallux valgus and primus varus. Clin Orthop Relat Res 1981;(157):25-30.

2. Coughlin MJ. Roger A. Mann Award. Juvenile hallux valgus: etiology and treatment. Foot Ankle Int 1995;16:682-697.

3. Hardy RH, Clapham JC. Observations on hallux valgus based on a controlled series. J Bone Joint Surg Br

   1951;33:376-391.

4. Harper MC. Correction of metatarsus primus varus with the chevron metatarsal osteotomy: an analysis of corrective factors. Clin Orthop Relat Res 1989;(243):180-198.

5. Hohmann G. Hallux valgus. In: Fuss und Bein. Ihre Erkrankungen und deren Behandlung. München, Germany: J.F. Bergmann, 1951:145-156.

6. Jahss MH. Hallux valgus: further considerations—the first metatarsal head. Foot Ankle 1981;2:1-4.

7. Johnson JE, Clanton TO, Baxter DE, et al. Comparison of chevron osteotomy and modified McBride bunionectomy for correction of mild to moderate hallux valgus deformity. Foot Ankle 1991;12:61-68.

8. Kilmartin TE, Wallace WA. The significance of pes planus in juvenile hallux valgus. Foot Ankle 1992;13:53-56.

9. Mann RA. Bunion surgery: decision making. Orthopedics 1990;13: 951-957.

10. Mann RA, Coughlin MJ. Adult hallux valgus. In: Coughlin MJ, Mann RA, eds. Surgery of the Foot and Ankle. St. Louis: Mosby, 1999: 150-269.

11. Mann RA, Donatto KC. The chevron osteotomy: a clinical and radiographic analysis. Foot Ankle Int 1997;18:255-261.

12. Meier PJ, Kenzora JE. The risks and benefits of distal metatarsal osteotomies. Foot Ankle 1985;6:7-17.

13. Miller S, Croce WA. The Austin procedure for surgical correction of hallux abductor valgus deformity. J Am Podiatry Assoc 1979;69: 110-118.

14. Park YB, Lee KB, Kim SK, et al. Comparison of distal soft-tissue procedures combined with a distal chevron osteotomy for moderate to severe hallux valgus: first web-space versus transarticular approach. J Bone Joint Surg Am 2013;95(21):e158.

15. Pochatko DJ, Schlehr FJ, Murphey MD, et al. Distal chevron osteotomy with lateral release for treatment of hallux valgus deformity. Foot Ankle Int 1994;15:457-461.

16. Sanhudo JA. Correction of moderate to severe hallux valgus deformity by a modified chevron shaft osteotomy. Foot Ankle Int 2006;27: 581-585.

17. Sarrafian SK. A method of predicting the degree of functional correction of the metatarsus primus varus with a distal lateral displacement osteotomy in hallux valgus. Foot Ankle 1985;5:322-326.

18. Schneider W, Aigner N, Pinggera O, et al. Chevron osteotomy in hallux valgus: ten-year results of 112 cases. J Bone Joint Surg Br 2004;86(7):1016-1020.

19. Shereff MJ, Yang QM, Kummer FJ. Extraosseous and intraosseous arterial supply to the first metatarsal and metatarsophalangeal joint. Foot Ankle 1987;8:81-93.

20. Trnka HJ, Hofmann S, Salzer M, et al. Clinical and radiological results after Austin bunionectomy for treatment of hallux valgus. Arch Orthop Trauma Surg 1996;115:171-175.

21. Trnka HJ, Zembsch A, Easley ME, et al. The chevron osteotomy for correction of hallux valgus: comparison of findings after two and five years of follow-up. J Bone Joint Surg Am 2000;82-A(10): 1373-1378.

22. Trnka HJ, Zembsch A, Wiesauer H, et al. Modified Austin procedure for correction of hallux valgus. Foot Ankle Int 1997;18:119-127.