Updated: 4/15/2018

Bunionette Deformity

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Introduction
  • Prominence on the lateral aspect of the 5th metatarsal head
    • commonly called "tailor's bunion"
  • Epidemiology
    • demographics
      • commonly seen in adolescents and adults
      • 2-4x more common in women
      • often bilateral deformities
  • Pathophysiology
    • mechanism of disease
      • extrinsic causes
        • compression of forefoot (e.g. tight shoes)
        • abnormal loading on the lateral aspect of the foot
      • intrinsic causes
        • congenital deformities (e.g. splayfoot, brachymetatarsia)
        • inflammatory arthropathies
        • residual malalignments from surgery
    • pathoanatomy
      • boney prominence +/- bursitis over lateral aspect of 5th metatarsal head
      • increased 4-5 intermetatarsal angle  (normal 6.5-8 degrees)  
      • increased lateral deviation angle (normal 0-7 degrees)  
      • increased width of MT head (normal <13mm)
      • lateral bowing of the 5th metatarsal bone
  • Associated conditions
    • varus MTP joint
    • pes planus
Classification
 
 
Description
 
Type I Enlarged 5th MT head or lateral exostosis  
Type II Congenital bow of 5th MT, normal 4-5 IMA
 
Type III Increased 4-5 IMA (most common)
 
 Presentation
  • History
    • effect on activities and employment
  • Symptoms
    • cosmetic deformity
      • medial deviation of 5th toe
      • prominence of the 5th metatarsal head
    • pain
      • lateral bunion 
      • plantar callous
      • worse with constrictive shoe wear 
  • Physical exam
    • inspection
      • plantar or lateral hyperkeratosis 
      • widened forefoot
      • erythema and swollen 5th bunion
      • check shoe wear 
    • motion
      • often painless passive ROM of 5th MTP joint
Imaging
  • 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)
  • CT scan
    • indications
      • ancillary studies rarely required
      • may be used if there is associated trauma or malignancy
Treatment
  • Nonoperative
    • NSAIDS, shoe wear modification, orthotics, keratosis padding, callous shaving
      • indications
        • indicated as first-line treatment of all types
        • asymptomatic deformities
      • techniques
        • semi-rigid shoe inserts
        • wide based shoes 
        • stretching the forefoot of existing shoes
      • outcomes
        • 75-90% success rate
  • Operative
    • lateral condylectomy
      • indications
        • symptomatic Type I deformities 
      • technique
        • resection of lateral third of the 5th MT head
        • combine with tightening of lateral MTP joint capsule
      • outcome
        • does not require extended period of immobilization
    • distal metatarsal osteotomy 
      • indications
        • long-standing or severely symptomatic Type I deformity
        • Type 2 and 3 deformities if IMA is < 12 degrees 
      • technique
        • different techniques described
          • chevron-medializing osteotomy (most common)
          • distal transverse osteotomy
          • peg-and-slot type osteotomy
          • stepcut osteotomy
        • better stability of fragments with internal fixation (e.g. K-wire or screw)
        • may be combined with distal condylectomy and tightening of lateral capsule
      • outcomes
        • chevron osteotomy is biomechanically the strongest construct compared to the other proximal osteotomies
    • oblique diaphyseal rotational osteotomy 
      • indications
        • symptomatic Type 2 and 3 if IMA is > 12 degrees   
      • technique
        • shave plantar aspect 5th MT head if plantar callosity present
        • proximal osteotomy should be avoided due to poor blood supply in this region of the metatarsal
        • fixation achieved with screw
      • outcomes
        • may produce 5th MT shortening 
    • metatarsal head resection
      • indications
        • salvage procedure only
        • leads to unacceptable instability of MTP joint
Complications
  • Recurrence 
    • is the most common complication with condylectomy alone
  • Transfer metatarsalgia 
    • seen with isolated metatarsal head resection
  • Claw toe
 

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

QID: 3557
1

Type I deformities in patients who will not tolerate weight bearing restrictions post-operatively

2%

(40/1713)

2

Patients with a laterally bowed fifth metatarsal, no keratotic lesions, and a normal 4-5 intermetatarsal angle

43%

(745/1713)

3

Patients who remain symptomatic after prior extensive lateral condylar resection

6%

(104/1713)

4

Type III deformity with a 4-5 intermetatarsal angle of 13 degrees

29%

(489/1713)

5

Painful type I deformity with associated intractable lateral keratotic lesions

18%

(311/1713)

ML 4

Select Answer to see Preferred Response

PREFERRED RESPONSE 2

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

QID: 3355
1

28-year-old woman with a Jones fracture nonunion

2%

(41/2187)

2

50-year-old woman with a physiologic bow to the 5th metatarsal and a lateral prominence of the 5th metatarsal head

18%

(392/2187)

3

54-year-old woman with a widened 4-5 intermetatarsal angle and a lateral prominence of the 5th metatarsal head

73%

(1593/2187)

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%

(114/2187)

5

60-year-old woman with rheumatoid arthritis and a plantar plate rupture

2%

(36/2187)

ML 2

Select Answer to see Preferred Response

PREFERRED RESPONSE 3
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