First Ray Surgery
BUNION EVALUATION
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Metatarsus Adductus Angle
Normal is 15°.
Values less than 15° represent a rectus foot.
At birth, MTA angle is around 30°.
At one year (begin walking), it is around 20°.
By age 4 years, the MTA angle reaches its adult normal value of 15°.
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Intermetatarsal Angle
Also known as metatarsus primus adductus angle, metatarsus primus varus
Normal is 8° to 12° in a rectus foot and 8° to 10° in an adductus foot.
Base wedge osteotomies are indicated in feet with an IM of 15° or higher in a rectus foot or 12° or higher in an adducted foot.
When metatarsus adductus is present, the foot functions as if the IM angle is larger. The formula to account for this metatarsus adductus and find the “true IM angle” is as follows:
True IM angle = IM angle + (metatarsus adductus angle – 15°)
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Hallux Abductus Angle
Also known as hallux valgus angle
Normal 0° to 15°
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PASA (Proximal Articular Set Angle)
Also known as DMAA (distal metatarsal articular angle)
Normal 7.5° to 12°
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DASA (Distal Articular Set Angle)
Normal 7.5°
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Hallux Abductus Interphalangeus Angle
Normal 10°
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Metatarsal Protrusion Distance
Normal (+ or -) 2 mm
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Tibial Sesamoid Position
Normal 1 to 3
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BUNIONECTOMIES
Head Procedures
Austin
Corrects IM
Chevron osteotomy with a 60° angle
Can incorporate wedge (bicorrectional) to correct PASA
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Youngswick Modification
A modification of the Austin designed to shorten and plantarflex the metatarsal head
Indicated in metatarsus elevatus
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Reverdin
Corrects PASA
Lateral cortex remains intact.
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Reverdin-Green
Corrects PASA
“L-shaped” cut preserves the integrity of the sesamoid articulation.
Lateral cortex remains intact.
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Reverdin-Laird
Corrects PASA and IM
Same as Reverdin-Green with completion of the osteotomy through the lateral cortex to allow IM correction
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Reverdin-Todd
Corrects PASA and IM, and allows plantarflexion of the metatarsal head
Same as Reverdin-Laird with penetration of the plantar cortex to allow sagittal plane correction
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Watermann
Indicated in hallux limitus
Plantar cortex is left intact.
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Green-Watermann
Indicated in hallux limitus
Preserves the sesamoid articulation
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Neck Procedures
Peabody
Similar to the Reverdin but the osteotomy is made more proximal to avoid the sesamoids
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Hohmann
Corrects IM (capital fragment shifted laterally)
Corrects PASA (medial wedge resected)
Corrects metatarsus elevatus (capital fragment plantarflexed)
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Wilson
Shortens and laterally displaces head
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DRATO (Derotational Abductory Transpositional Osteotomy)
Metatarsal head can be manipulated at any angle in any plane.
Wedge resection can be incorporated.
Very unstable osteotomy
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