Bunionette Deformity

Bunionette Deformity (also called a tailor’s bunionette) is the bony prominence on the lateral side of the fifth metatarsal head of the foot.

Tailor’s bunionette, referring to the position in which tailors would sit on the floor with their legs crossed, forcing the lateral border of the foot against the floor.

• More common in adolescents and adults.
• Women > Men
• Usually a bilateral deformity.

Etiology

• Bunionette Deformity often is seen in splay foot combined with hallux valgus, or the head of the fifth metatarsal may be congenitally or traumatically enlarged.
• Also, the shaft may be angulated laterally, making the fifth metatarsal head more prominent.
• It may be caused by compression of forefoot (tight shoes).
• In case of inflammatory arthropathies.

Bunionette Deformity Radiology

Radiographic evaluation of this deformity should include standard weight-bearing views of the foot, including dorsoplantar, lateral, and oblique, should be obtained for measurement of the 4-5 intermetatarsal angle (4-5 IMA).

This angle is formed by two lines that bisect the fourth and fifth metatarsals:

• The normal angle is less than 6.5 to 8 degrees
• In symptomatic bunionette: the angle is 9.6 degrees.

Other angles that may be useful are:

1. The lateral deviation angle: which is formed by a line from the center of the metatarsal head and neck to the metatarsal base and a line along the medial cortex of the fifth metatarsal (normal= 2.6 degrees; with bunionette = 8 degrees).
2. The fifth metatarsophalangeal angle, which usually is more than 14 degrees in symptomatic patients.

MRI is indicated to rule out other pathology and clarify pathology of surrounding structures.

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Classification of Bunionette Deformity

Bunionette Deformity is classified into three distinct types based on the anatomic location of the deformity along the fifth metatarsal:

1. Type I deformity: distinguished by presence of an enlarged fifth metatarsal head, or a lateral exostosis.
2. Type II deformity: demonstrates lateral bowing of fifth metatarsal diaphysis.
3. Type III deformity: demonstrates an abnormally widened fourth-fifth metatarsal angle (an increased 4-5 IMA >8 degrees).

Type III is the most common deformity

Bunionette Deformity Symptoms

1. Pain over lateral or plantar aspect of MTP joint, particularly with compressive shoewear.
2. Constricting shoes are the main source of discomfort. With continuous pressure over this bony prominence, a bursa develops and enlarges because of chronic irritation.
3. Ulceration may develop.
4. An intractable keratosis may develop over a prominent bunionette because of shoe pressure. In diabetes, advanced Charcot-Marie-Tooth disease, or certain types of spinal dysraphism with poor sensibility, this complication can result in loss of the entire fifth ray or even the foot.
5. A diffuse callus or localized intractable keratosis can develop beneath the plantar aspect of the fifth metatarsal head.

Bunionette Treatment

Conservative treatment:

Conservative treatment is usually effective, it consists of:

1. Shoewear modification
2. Strategic padding
3. Shaving the symptomatic callus.
4. With plantar callus or associated pes planus, consider a metatarsal pad or custom orthotic device.

Surgical treatment:

If surgical treatment becomes necessary, the choices are:

1. Lateral metatarsal head condylectomy (in type I).
2. Distal fifth metatarsal osteotomy (i.e., chevron; in type II).
3. Oblique diaphyseal osteotomy (in type III).
4. Consider metatarsal head resection for salvage.

Proximal osteotomy should be avoided owing to the tenuous blood supply at the proximal metadiaphyseal junction of the fifth metatarsal.

Questions for patients

References

1. Bruce E Cohen, Christopher W Nicholson:Bunionette deformity. J Am Acad Orthop Surg. 2007 May;15(5):300-7. PMID: 17478753.
2. Giannini S, Faldini C, Vannini F, et al: The minimally invasive osteotomy “S.E.R.I.” (simple, effective, rapid, inexpensive) for correction of bunionette deformity, Foot Ankle Int 29:282, 2008.
3. Legenstein R, Bonomo J, Huber W, Boesch P: Correction of tailor’s bunion with the Boesch technique: a retrospective study, Foot Ankle Int 28:799, 2007.
4. Magnan B, Samaila E, Merlini M, et al: Percutaneous distal osteotomy of the fifth metatarsal for correction of bunionette, J Bone Joint Surg 93A:2116, 2011.
5. Radl R, Leithner A, Koehler W, et al: The modified distal horizontal metatarsal osteotomy for correction of bunionette deformity, Foot Ankle Int 26:454, 2005.
6. Vienne P, Oesselmann M, Espinosa N, et al: Modified Coughlin procedure for surgical treatment of symptomatic tailor’s bunion: a prospective followup study of 33 consecutive operations, Foot Ankle Int 27:573, 2006.
7. Weil L Jr, Weil LS Sr: Osteotomies for bunionette deformity, Foot Ankle Clin 16:689, 2011.
8. Weitzel S, Trnka HJ, Petroutsas J: Transverse medial slide osteotomy for bunionette deformity: long-term results, Foot Ankle Int 28:794, 2007.
9. Coughlin MJ et al: Surgery of the foot and ankle, ed 8, Philadelphia, 2006, Mosby.
10. Campbel’s Operative Orthopaedics 12th edition Book.
11. Millers Review of Orthopaedics -7th Edition book.