Bunionette Deformity

Introduction

Characterized by prominence of the lateral distal 5th MT head.
- commonly called "tailor's bunion"
Casued by
- widened 4-5 intermetatarsal angle
- abnormal transverse metatarsal angle
Associated with
- varus MTP joint
- assocaited with pes planus

Classification

	Description	Treatment
Type I	Enlarged 5th MT head or lateral exostosis	Condylectomy (excision of lateral bony eminence)
Type II	Congenital bow of 5th MT, normal 4-5 IMA	Chevron (distal) osteotomy +/- lateral eminence resection
Type III	Increased 4-5 IMA (most common)	Oblique mid-diaphyseal metatarsal osteotomy - shave plantal aspect 5th MT head if plantar callosity present (never excise 5th MT head)

Presentation

Symptoms
- painful lateral callus
Physical exam
- plantar keratosis
- pain with shoe wear

Evaluation

Radiographs
- recommended views
  - standard weight-bearing films, dorsoplantar, lateral & oblique films
- characteristic findings
  - increased 4-5 IMA (normal 6.5-8 degrees)
  - increased lateral deviation angle (normal 0-7 degrees)
  - increased width of MT head (normal <13mm)

Treatment

Nonoperative
- shoe wear modification, keratosis padding & shaving
  - indications
    - inital mode of treatement
  - outcomes
    - 75-90% sucess rate
Operative
- exostectomy vs. metatarsal osteotomy (proximal, diaphyseal, distal)
  - indications
    - poor response to non-surgical management

Complications

Recurrence
- is the most common complication with condylectomy alone
Transfer metatarsalgia
- seen with isolated metatarsal head resection
Claw toe

TAG

(OBQ11.134) Distal chevron osteotomies are most indicated for which of following scenarios involving a bunionette deformity? Topic

Review Topic

1. Type I deformities in patients who will not tolerate weight bearing restrictions post-operatively
2. Patients with a laterally bowed fifth metatarsal, no keratotic lesions, and a normal 4-5 intermetatarsal angle
3. Patients who remain symptomatic after prior extensive lateral condylar resection
4. Type III deformity with a 4-5 intermetatarsal angle of 13 degrees
5. Painful type II deformity with associated intractable plantar keratotic lesions

PREFERRED RESPONSE ▶

DISCUSSION: Patients with a Type II deformity (ie. laterally bowed fifth metatarsal and normal intermetatarsal (IM) angle) require a distal chevron osteotomy. Coughlin's classification scheme for bunionette deformities includes: Type I-lateral prominence of the metatarsal, Type II-lateral bowing of the fifth metatarsal, Type III-widening of the 4-5 IM angle. Examples of the three types are shown in Illustration A with types I,II,III correlating with A,B,C in the figure, respectively.

The review article by Cohen et al review the work-up and surgical indications for bunionette deformities. They state that lateral eminence resection may be considered in type I deformities in patients who will not tolerate weight-bearing restrictions associated with the osteotomies. With regards to type III deformities that have an increased 4-5 IM angle, the authors state that these are best treated with diaphyseal osteotomies. This procedure is also for painful type II and III bunionettes with associated keratotic lesions. Finally, proximal osteotomies are recommended only in patients who remain symptomatic after undergoing a prior distal procedure.

Koti et al provide of review of Bunionette deformities. They state that distal metatarsal osteotomies are indicated if medial translation of the head for one-third of the width of the metatarsal shaft produces a normal fourth-fifth intermetatarsal angle.

Illustrations: A

REFERENCES:

1. Cohen BE, Nicholson CW. Bunionette deformity. J Am Acad Orthop Surg. 2007 May;15(5):300-7. Review. PMID:17478753 (Link to Abstract)

2. Koti M, Maffulli N. Bunionette. J Bone Joint Surg Am. 2001 Jul;83-A(7):1076-82. Review. PMID:11451980 (Link to Abstract)

Question Authors:

Joshua Blomberg MD, Michael Hughes MD, Ben Taylor MD,

Please Rate Educational Value!

2.0

Average 2.0 of 4 Ratings

TAG

(OBQ10.250) A diaphyseal fifth metatarsal osteotomy is the optimal surgical treatment for which of the following patients who has failed nonsurgical management? Topic

Review Topic

1. 28-year-old woman with a Jones fracture nonunion
2. 50-year-old woman with a physiologic bow to the 5th metatarsal and a lateral prominence of the 5th metatarsal head
3. 54-year-old woman with a widened 4-5 intermetatarsal angle and a lateral prominence of the 5th metatarsal head
4. 35-year-old woman with prominent lateral condyle of her 5th metatarsal head, without bowing of the metatarsal and with normal 4-5 intermetatarsal angle
5. 60-year-old woman with rheumatoid arthritis and a plantar plate rupture

PREFERRED RESPONSE ▶

DISCUSSION: A bunionette, "tailor's bunion", is a lateral prominence of the fifth metatarsal head, as seen in the photo in illustration A. Illustration B shows a standard bunion and a bunionette on the same forefoot. Usually a large 4-5 intermetatarsal (IM) angle and varus of the metatarsophalangeal joint are associated with the tender prominence, but not always. Conservative measures include wide toe boxed shoes and pads. Surgical treatment is fairly rare and only appropriate when nonoperative measures fail. A simple lateral eminence resection alone is indicated when the 4-5 IM angle is normal, but there is risk of recurrence and for overresection. A distal chevron osteotomy is reliable for those with a lateral bow to the fifth metatarsal, but a diaphyseal osteotomy of the 5th is needed if the 4-5 IM angle is widened. Baumhauer et al. actually state that they favor distal chevron osteotomies in most cases because there is more reliable union in the more vascular distal regions than in the diaphysis. However, Cohen et al. argue that adequate correction can rarely be achieved without a diaphyseal osteotomy when the 4-5 IM angle is increased. Osteotomies are not generally used to treat Jones fracture nonunions. The patient in scenario 2 would be best treated with a distal chevron osteotomy, while the woman in scenario 4 could be treated with lateral eminence resection alone. Rheumatoid patients with plantar plate rupture can be treated with metatarsal head excision but not with diaphyseal osteotomies.

Illustrations: A

REFERENCES:

1. Baumhauer JF, DiGiovanni BF. Osteotomies of the fifth metatarsal. Foot Ankle Clin. 2001 Sep;6(3):491-8. PMID:11692494 (Link to Abstract)

2. Coughlin MJ. Etiology and treatment of the bunionette deformity. Instr Course Lect. 1990;39:37-48. PMID:2186126 (Link to Abstract)

3. Cohen BE, Nicholson CW. Bunionette deformity. J Am Acad Orthop Surg. 2007 May;15(5):300-7. PMID:17478753 (Link to Abstract)

Question Authors:

Dave Marcu MD,

Please Rate Educational Value!

4.0

Average 4.0 of 8 Ratings

Textbooks

Review of Orthopaedics, 6th Edition, Mark D. Miller MD, Stephen R. Thompson MBBS MEd FRCSC, Jennifer Hart MPAS PA-C ATC, an imprint of Elsevier, Philadelphia, Copyright 2012
AAOS Comprehensive Orthopaedic Review, Jay R. Leiberman. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2009
Orthopaedic Knowledge Update 10, John M Flyn. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2011
Hoppenfeld SP. Surgical Exposures in Orthopaedics: The Anatomic Approach. Lipponcott, Williams, and Wilkins, Philadelphia, PA, Copyright 2009
Orthopaedic In-training Examination (OITE) Questions 2004-2012, American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2004-2012
Self-Assessment Examination (SAE) Questions 2004-2012, American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2004-2012

Undefined

Cohen BE, Nicholson CW. Bunionette deformity. J Am Acad Orthop Surg. 2007 May;15(5):300-7. Review. PMID:17478753 (Link to Abstract)
Koti M, Maffulli N. Bunionette. J Bone Joint Surg Am. 2001 Jul;83-A(7):1076-82. Review. PMID:11451980 (Link to Abstract)
Baumhauer JF, DiGiovanni BF. Osteotomies of the fifth metatarsal. Foot Ankle Clin. 2001 Sep;6(3):491-8. PMID:11692494 (Link to Abstract)
Coughlin MJ. Etiology and treatment of the bunionette deformity. Instr Course Lect. 1990;39:37-48. PMID:2186126 (Link to Abstract)
Cohen BE, Nicholson CW. Bunionette deformity. J Am Acad Orthop Surg. 2007 May;15(5):300-7. PMID:17478753 (Link to Abstract)

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