DEFINITION

A bunionette deformity is a painful prominence on the lateral aspect of the fifth metatarsal head. This is usually caused by a prominent lateral metatarsal condyle, bowing of the fifth metatarsal, or increased intermetatarsal angle (IMA).

 

 

ANATOMY

 

The Coughlin classification4 illustrates the pertinent anatomic differences between the different types of bunionette deformities:

 

 

 

In type 1, a prominent lateral condyle may be noticeable under the callus. In type 2, a curvature in the metatarsal shaft may be evident.

 

In type 3, there is a wider than expected angle between the fourth and fifth metatarsal.

 

All may be associated with an inflamed bursa or callus, depending on the chronicity of the problem.

 

PATHOGENESIS

 

This was historically named a tailor's bunionette because tailors spent long hours with crossed legs, causing pressure over the fifth metatarsal head and resulting in local pressure and formation of a callus and occasionally a painful bursa.

 

Local pressure can also be increased by a larger than normal lateral metatarsal condyle, angulation in the shaft of the metatarsal, or a wide intermetatarsal space, resulting in local tissue inflammation, pain, and swelling.

 

NATURAL HISTORY

 

It has a female-to-male ratio of between 1:1 and 10:1.5

 

The natural history is increasing formation of painful callus and bursae over the area.

 

 

It can result in ulceration if proper foot care is not instituted or if underlying neuropathy is present. It usually requires regular paring of callus, wide toe box shoe modifications, or surgical treatment.

PATIENT HISTORY AND PHYSICAL FINDINGS

 

Patients complain of pain and tenderness over the lateral aspect of the foot over the fifth metatarsal head.

 

Symptoms are usually worse with activity, especially any position causing increased pressure over the metatarsal head.

 

Enclosed shoes will exacerbate symptoms when causing local pressure. Hence, it is often described as improved in the summer, with less restrictive footwear and perhaps reduced work hours.

 

The examiner should view both feet simultaneously while standing.

 

The examiner should look for a prominent lateral metatarsal condyle, an obvious curvature in the metatarsal shaft, or a wide IMA.

 

The examiner should note any hard or soft callus over the lateral aspect of the metatarsal.

 

The examiner should look for any ulceration over the callus or between the fourth and fifth toes.

 

IMAGING AND OTHER DIAGNOSTIC STUDIES

 

Standing plain radiographs (anteroposterior [AP], lateral, and oblique views) are necessary.

 

For all views, the radiographs are evaluated for osteoarthritis, narrow joint space, subchondral sclerosis, osteophyte formation, enlarged metatarsal condyle, curvature of metatarsal shaft, or a wide IMA between the fourth and fifth metatarsal shafts.

 

Oblique radiographs may give a better view of the metatarsal head.

 

On the lateral radiograph, the surgeon should look for any flexion or extension of the interphalangeal joints suggestive of claw or hammer toes.

 

DIFFERENTIAL DIAGNOSIS

Curly toe Claw toe Hammer toe

Stress fracture of the fifth metatarsal

Fifth metatarsal fracture with prominent fracture callus

 

 

NONOPERATIVE MANAGEMENT

 

Nonoperative management focuses on decreasing pressure.

 

It is very important for the patient to avoid sitting positions that place lateral-sided pressure on the fifth metatarsal.

 

Placing lamb's wool or cotton between the fourth and fifth toes to reduce medial deviation of the fifth toe can reduce lateral-sided pressure.

 

Proper-fitting wide toe box or orthopaedic shoes can alleviate pressure caused by footwear.

 

SURGICAL MANAGEMENT

Preoperative Planning

 

The surgeon should take into consideration any previous scars, edema, or skin abnormalities that would affect incision placement.

 

Plain weight-bearing films are reviewed to determine which type of bunionette is present. Soft tissue release or osteotomy is based on the type of deformity.

 

 

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Type 1 deformity is treated with excision of the lateral metatarsal condyle.

 

 

Type 2 deformity is treated with a distal metatarsal osteotomy. We describe the chevron type of osteotomy to correct the lateral deviation in the distal metatarsal shaft. The lateral deviation angle measures the degree of lateral bowing and is measured off the medial aspect of the fifth metatarsal shaft base to the center of the

metatarsal head. The normal value is 2.6 degrees (range 0 to 7 degrees).4

 

In type 3 deformity, a wide IMA between the fourth and fifth metatarsal is noted, with the mean angle being 6.5 degrees (range 3 to 11 degrees).7 This is best treated with a proximal Ludloff metatarsal osteotomy.

Positioning

 

The patient is positioned supine on a radiolucent operating table. A small lift is placed under the buttock on the operative side. A tourniquet is placed on the upper thigh or a sterile Esmarch tourniquet is placed above the ankle.

 

 

 

 

FIG 1 • Lateral incision over bunionette.

 

Approach

 

All skin incisions should be lateral, with caution to avoid any digital nerves on the lateral aspect of the fifth toe (FIG 1).

 

This approach allows for bunionectomy and osteotomy of the shaft with screw, pin, or plate fixation, and the approach can be extended proximally or distally if needed.

 

TECHNIQUES

• Lateral Metatarsal Condylectomy with Capsular Plication

 

Exposure

 

Use a lateral approach, making an incision down to the capsule.

 

Free the soft tissue between the capsule and the overlying skin to expose the lateral aspect of the metatarsal head (TECH FIG 1A,B).

 

Make a V-shaped capsulotomy with the proximal apex to allow for plication on closure (TECH FIG 1C,D).

 

 

 

TECH FIG 1 • A. Dissection through subcutaneous tissue to bursa. B. Excision of bursa over bunionette.

C,D. V-shaped capsulotomy performed to expose bunionette.

 

Bunionectomy

 

Expose the enlarged lateral condyle of the fifth metatarsal. Place small Hohmann retractors below and above the metatarsal head to protect both flexor and extensor tendons (TECH FIG 2A).

 

With a small saw, excise the prominent lateral condyle head parallel to the shaft of the metatarsal (TECH FIG 2B,C).

 

Pull the distal part of the V-shaped capsulotomy proximally to the desired amount of tension and sew with a heavy nonabsorbable suture (TECH FIG 2D).

 

Close the subcutaneous tissue with small absorbable suture and the skin with small nonabsorbable suture.

 

Place a small amount of gauze between the fourth and fifth toes to keep the fifth toe from deviating medially while it heals.

 

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TECH FIG 2 • A. Bunionette exposed through capsulotomy. B,C. Bunionette excised with saw. D. V-shaped capsulotomy repaired with proximal advancement to correct deformity.

• Chevron Osteotomy of the Fifth Metatarsal

Exposure and Bunionectomy

 

Make a lateral incision down to the capsule.

 

Free the soft tissue between the capsule and the overlying skin to expose the lateral aspect of the metatarsal head.

 

Make a V-shaped capsulotomy with the proximal apex to allow for plication on closure.

 

Expose the enlarged lateral condyle of the fifth metatarsal and perform excision of the lateral metatarsal condyle as described previously (TECH FIG 3A-C).

Osteotomy

 

Mark the center of the freshly cut lateral aspect of the metatarsal head with a sterile marker (TECH FIG 4A).

 

The limbs of the chevron osteotomy are 60 degrees.

 

Use your free hand to palpate the plane of the metatarsal heads, and make the chevron osteotomy parallel to the plantar surface of the foot (TECH FIG 4B,C).

 

 

Shift the metatarsal head medially, leaving 3 to 4 mm of exposed metatarsal shaft (TECH FIG 4D-G). Cut the residual lateral bone with the saw again parallel to the metatarsal shaft.

Fixation

 

Secure the osteotomy with a minifragment screw inserted from proximal to distal fixing the osteotomy site

 

(TECH FIG 5). Alternatively, a Kirschner wire can be used to secure the osteotomy site. Close the capsule with a heavy nonabsorbable suture.

 

Close the subcutaneous tissue with small absorbable suture and the skin with small nonabsorbable suture.

 

 

 

TECH FIG 3 • A. Bunionette exposed through lateral approach and V-shaped capsulotomy. (continued)

 

 

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TECH FIG 3 • (continued) B,C. Bunionette excision performed with saw.

 

 

 

TECH FIG 4 • A. Center of metatarsal head marked. B,C. Chevron osteotomy performed using saw. D. Chevron osteotomy mobilized using osteotome. E. Fifth metatarsal displaced medially 3 to 4 mm by using a towel clip to pull the metatarsal shaft lateral and impacting the metatarsal head distally. (continued)

 

 

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TECH FIG 4 • (continued) F,G. Amount of displacement of the chevron osteotomy.

 

 

 

TECH FIG 5 • A,B. Metatarsal head is stabilized with a towel clip and fixed using a minifragment screw. C.

Overhanging bone on the proximal and lateral aspect of the metatarsal shaft is excised.

• Oblique Metatarsal Shaft Osteotomy (Coughlin)

  Exposure

   

  Make a lateral skin incision and carry it down to the capsule.

   

  Free the soft tissue between the capsule and the overlying skin to expose the lateral aspect of the metatarsal head.

   

  With a sterile marker, mark the plantar aspect of the metatarsal where the capsule meets the metatarsal neck. Then mark the osteotomy on the dorsal proximal aspect.

   

  Place Hohmann retractors above and below to protect the extensor and flexor tendons.

  Osteotomy

   

  Cut the osteotomy two-thirds of the way, leaving the plantar third intact.

   

  Insert a minifragment screw (2.0 or 2.7 mm) in the proximal portion of the osteotomy. Tighten the screw completely and then loosen it before completing the osteotomy.

   

  Complete the osteotomy.

   

  Swing the distal portion medially to the desired amount of correction and tighten the proximal screw. Insert another 2.0- or 2.7-mm screw more distally to supplement fixation.

   

  Cut the excess bone from the proximal osteotomy site with the saw.

   

  Close the subcutaneous tissue with small nonabsorbable suture and the skin with nonabsorbable suture.

   

   

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• Case Example (Courtesy of Mark E. Easley, MD)

Background and Imaging

 

A 37-year-old man with symptomatic right bunionette deformity who had failed nonoperative measures including shoe wear modifications

 

Wide forefoot

 

 

Tenderness over fifth metatarsal head Medial deviation of fifth toe

 

Weight-bearing AP radiograph of the right foot demonstrated a wide fourth to fifth IMA and medial deviation of the fifth toe (TECH FIG 6).

Exposure

 

Longitudinal approach over the dorsolateral fifth metatarsal is used.

 

Sural nerve and extensor digitorum longus tendon are identified and protected.

Distal Soft Tissue Procedure

 

 

Lateral fifth metatarsophalangeal (MTP) joint capsule is exposed. Lateral capsulotomy and capsule is reflected.

 

A simple longitudinal lateral midaxial capsulotomy is usually all that is required provided the bony correction is adequate.

 

Through the joint, the medial capsule can be released.

Fifth Metatarsal Osteotomy and Fixation

 

Lateral fifth metatarsal is exposed with minimal periosteal stripping.

 

The long oblique osteotomy is similar to the long oblique Ludloff first metatarsal osteotomy described for hallux valgus correction.

 

Using a microsagittal saw, the dorsal/proximal two-thirds of the osteotomy is completed, leaving the plantar/distal one-third intact.

 

A lag screw is placed across the proximal completed aspect of the osteotomy, tightened to confirm compression and then the screw is loosened slightly, maintaining osteotomy stability and allowing for completion of the distal aspect of the osteotomy.

 

The distal osteotomy is completed using the microsagittal saw (TECH FIG 7A).

 

With one hand applying tension on a towel clip attached to the proximal fragment and the other hand applying pressure to the lateral metatarsal head, the distal fragment is rotated to correct the IMA (TECH FIG 7B).

 

 

 

TECH FIG 6 • Weight-bearing AP radiograph of the right foot demonstrated a wide fourth to fifth IMA and medial deviation of the fifth toe.

 

 

 

TECH FIG 7 • Long oblique metatarsal osteotomy. A. After performing the dorsal/proximal two-thirds of

the osteotomy and stabilizing it with a proximal lag screw, the long oblique osteotomy is completed using the microsagittal saw. B. With one hand applying tension on a towel clip attached to the proximal fragment and the other hand applying pressure to the lateral metatarsal head, the distal fragment is rotated to correct the IMA. (continued)

 

 

The screw in the proximal osteotomy is tightened to secure the osteotomy and maintain correction (TECH FIG 7C).

 

Fluoroscopic confirmation that the IMA is appropriately corrected

 

A second lag screw is placed from plantar to dorsal to fully stabilize the osteotomy (TECH FIG 7D).

Closure

 

 

The medial eminence is excised with the microsagittal saw (TECH FIG 8). The medial capsule is imbricated.

 

Final intraoperative fluoroscopy to confirm appropriate correction of the IMA and hallux valgus angle (HVA)

 

 

The tourniquet is released and meticulous hemostasis is achieved. Subcutaneous layer and skin are reapproximated.

 

Bunion-type dressing is applied to the fifth toe.

Postoperative Care

 

Protected weight bearing on the heel for 4 to 6 weeks

 

Bunion-type dressings are maintained for 4 to 6 weeks (TECH FIG 9).

 

Provided follow-up weight-bearing radiographs suggest satisfactory healing, the patient can return to full activities at 3 months.

 

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TECH FIG 7 • (continued) C. The screw in the proximal osteotomy is tightened to secure the osteotomy and maintain correction. D. A second lag screw is placed from plantar to dorsal to fully stabilize the osteotomy.

 

 

 

TECH FIG 8 • The medial eminence is excised with the microsagittal saw.

 

 

 

TECH FIG 9 • Bunion-type dressing to be maintained for 4 to 6 weeks. The larger bunion-type dressing may be eventually replaced with a toe spacer.

 

 

PEARLS AND PITFALLS
	Lateral ▪ Avoid excising too much metatarsal because it can result in joint instability. metatarsal ▪ The osteotomy should be directed away from the metatarsal shaft to avoid splitting head the metatarsal with the osteotomy. excision     Chevron ▪ The apex of the osteotomy should be located at the center of the metatarsal head. osteotomy If it is too distal, it can fracture the head. If it is too proximal, the location of the osteotomy is diaphyseal bone, which may take longer to heal.

 

	If the plane of the osteotomy is not parallel to the plantar aspect of the foot, it will prevent shifting of the metatarsal head.     Oblique ▪ A long oblique osteotomy is needed to achieve better correction and more stable osteotomy fixation. Screw placement for the osteotomy is important. If it is too close to the end of the osteotomy, it will fracture the osteotomy. If it is too distal to the end of the osteotomy, it limits the correction because the point of rotation is more distal than the apex of the osteotomy. Stable fixation is key to union and maintaining the correction.

 

 

 

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POSTOPERATIVE CARE

 

 

The wound is checked at 1 week postoperatively to examine for any evidence of infection. Sutures are removed at 2 weeks.

 

 

If a pin was used, it is removed at 6 weeks. Heel walking only is permitted for 6 weeks.

 

In the oblique metatarsal osteotomy, a postoperative fiberglass splint is applied in the operating room and is changed to an air cast at 2 weeks. This is continued for 6 weeks.

 

FIG 2 is the case example at 6-week follow-up.

OUTCOMES

Although the bunionette deformity is common, it is rarely symptomatic enough to warrant surgical intervention. This is reflected by the small numbers found in case studies reported in the literature.

Kitaoka and Holiday5 reported results on 21 feet (16 patients) who underwent lateral condylar resection for bunionette. The overall results were considered good in 15 feet, fair in 3, and poor in 3. However, 23% of the patients had recurrent or persistent lateral forefoot pain. They attributed the failures to an inadequate amount of resection, MTP joint subluxation, and severe forefoot splaying. Limitations of the procedure included lack of deformity correction, a significant incidence of residual lateral forefoot pain, and difficulty treating bunionettes with intractable plantar keratosis.

 

 

 

 

FIG 2 • Patient in TECH FIGS 6, 7, 8 at 6-week follow-up. A. Lateral view. B. Dorsal view. C. Weight-bearing radiograph suggest satisfactory correction: narrowed forefoot with corrected IMA and HVA.

 

 

Several studies have reported good results in the surgical treatment of bunionette with chevron osteotomies.2,6,7

 

Moran and Claridge7 felt that stabilization of the osteotomy site with fixation was necessary to minimize the risk of displacement.

 

One study reported that Kirschner wire fixation led to less dorsal displacement of the distal fragment.8

 

In Kitaoka et al's6 series of chevron osteotomies for bunionettes, they used Kirschner wire fixation in only 1 of 19 patients due to intraoperative instability at the osteotomy site; however, they did note postoperative displacement in another patient.

 

No incidence of displacement was found in series that routinely used fixation.2,7

 

Limited correction of the fourth to fifth IMA was seen, where 1 mm of translation results in a decrease

 

of that angle of only 1 degree.3,6

The fifth metatarsal head can be shifted only 33% to 40% of its width, generally in the range of 3 to 4 mm.2,3,6,7

Kitaoka et al6 noted that neither the preoperative nor the postoperative intermetatarsal fourth to fifth angle correlated with the postoperative foot score.

Oblique metatarsal osteotomies have been shown to provide the biggest correction for a type II or III deformity with a high IMA.4,9,12 Coughlin4 found that the IMA decreased from an average of 16 degrees preoperatively to 0.5 degrees postoperatively. Results have shown a reliable improvement in

postoperative subjective scores.4,9,12 With the use of internal fixation, there was

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only one report of delayed union.4,9,12 This is compared to other series reporting rates of delayed union of up to 11% without fixation.11 However, prominent hardware can be an issue, and in one study, 87% of patients required later removal.4 Proximal osteotomies are not recommended due to the poor blood supply in the region and the higher risk of delayed or nonunion.1,10

 

 

COMPLICATIONS

Infection

Recurrent deformity Digital nerve injury

Nonunion of the osteotomy Displacement of the osteotomy

Avascular necrosis of the fifth metatarsal head Transfer metatarsalgia

 

 

REFERENCES

1. Baumhauer JF, DiGiovanni BF. Osteotomies of the fifth metatarsal. Foot Ankle Clin 2001;6:491-498.

    

    

2. Boyer ML, Deorio JK. Bunionette deformity correction with distal chevron osteotomy and single absorbable pin fixation. Foot Ankle Int 2003;24:845-857.

    

    

3. Cooper PS. Disorders and deformities of the lesser toes. In: Myerson MS, ed. Foot and Ankle Disorders. Philadelphia: WB Saunders, 2000:335-358.

    

    

4. Coughlin MJ. Treatment of bunionette deformity with longitudinal diaphyseal osteotomy with distal soft tissue repair. Foot Ankle 1991;11:195-203.

    

    

5. Kitaoka HB, Holiday AD Jr. Lateral condylar resection for bunionette. Clin Orthop Relat Res 1992; (278):183-192.

    

    

6. Kitaoka HB, Holiday AD Jr, Campbell DC II. Distal chevron metatarsal osteotomy for bunionette. Foot Ankle 1991;12:80-85.

    

    

7. Moran MM, Claridge RJ. Chevron osteotomy for bunionette. Foot Ankle Int 1994;15:684-688.

    

    

8. Pontious J, Brook JW, Hillstrom HJ. Tailor's bunion. Is fixation necessary? J Am Podiatr Med Assoc 1996;86:63-73.

    

    

9. Radl R, Leithner A, Koehler W, et al. The modified distal horizontal metatarsal osteotomy for correction of bunionette deformity. Foot Ankle Int 2005;26:454-457.

    

    

10. Shereff MJ, Yang QM, Krummer FJ. Vascular anatomy of the fifth metatarsal. Foot Ankle Int 1991;11:350-353.

     

     

11. Sponsel KH. Bunionette correction by metatarsal osteotomy: preliminary report. Orthop Clin North Am 1976;7:808-819.

     

     

12. Vienne P, Oesselmann M, Espinosa N, et al. Modified Coughlin procedure for surgical treatment of symptomatic tailor's bunion: a prospective follow-up study of 33 consecutive operations. Foot Ankle Int 2006;27:573-580.