Background

DefinitionHallux Valgus Severe

 

Bunion

- medial prominence of head of 1st MT

 

Hallux Valgus

- medial deviation 1st MT

- lateral deviation of great toe

 

Anatomy

 

Metatarsal head

- has 2 grooves separating ridge (cristae)

 

Sesamoid

- in each tendon of FHB

- sesamoids attach to P1

- no attachment to MT head

- sesamoid ligaments attach to sesamoids and plantar plate

- FHL passes plantar to the plate & between the sesamoids

 

Plantar plate

- formed by

- FHB / Abd. Hall / Add. Hall / Plantar aponeurosis /  capsule

 

Sesamoids and plantar plate stabilised

- abductor hallucis (medial)

- adductor hallucis & trans metatarsal ligament (lateral)

- insert into sesamoids & Base P1

- no muscles insert into head MT

 

Collateral ligaments

- from head of MT to base of P1

- insert into sesamoids

 

Biomechanics

 

Great Toe provides stability to the medial aspect of the foot

 

Windlass mechanism of plantar aponeurosis

- plantar aponeurosis arises from tubercle of calcaneum

- medial slip inserts into base of proximal phalanx via sesamoids

- as body passes over foot, P1 forced into DF & slides over MT head

- plantar aponeurosis winds around MT head & plantarflexes the 1st MT

- creates arch

 

In hallux valgus, windlass is less effective

- results in transfer of weight to lateral aspect of foot

- especially second MT head

 

Blood Supply

 

3 main

- 1st dorsal and plantar metatarsal artery

- superficial branch of medial plantar artery

 

Medial

 

Medial plantar artery

- remains plantar to the MT until the level of the neck when it runs obliquely dorsally

- divides into the medial cervical branch, and the medial sesamoid branch

 

Lateral

 

First plantar MT artery

- is formed by the deep plantar arch and a perforating branch from the DPA

- runs distally in the 1st MT space

- nutrient artery to neck (variable)

- cervico-sesamoid branch (constant)

 

Lateral Cervical branch

- enters plantar surface at base of neck

- supply major part of head

- care in not stripping under the neck to preserve the cervical branch

 

Dorsolateral

- small branch from DPA

- penetrates the dorso-lateral capsule near margin of  articular cartilage

- not big enough to provide sole supply

- can be sacrificed if needed

 

Characteristics

 

Great toe

- lateral deviation of the great toe  (HVA > 15o)

- medial deviation of the first metatarsal  (IMA > 9o)

- +/- subluxation of the first MTPJ

- hallux pronation

- prominent mediation eminence

- sesamoid rotation / uncovering

 

Lesser toes

- overriding of the second toe

- metatarsalgia

- lesser toe hammer & claw

 

Epidemiology

 

Two ages of presentation

 

1.  Adolescent form

- usually bilateral

 

2.  Adult form ~ 50's

- strongly familial

- positive FHx in 2/3

- F > M

- F:M = 9:1 in those needing operations

 

Aetiology

 

Likely multifactorial

 

1.  Shoe Wearing

 

Evidence

- more women are affected

- women's shoes are tight-toed

- unshod 2% vs 33% shod

- unshod toes separate on weight bearing

- in shoes, toes crowded & hallux abducted

 

2.  Hereditary

- usually strong FHx

- tend to present earlier

- AD with incomplete penetrance

- made worse by female's shoe wear

 

3.  Generalised Ligamentous Laxity

- splaying of forefoot

- excessive mobility of 1st TMT

- laxity of medial capsule of MTPJ

 

4.  Anatomical factors

 

Metatarsus Primus Varus

- associated with HV

- especially adolescent variety

 

Metatarsus Varus

 

1st MT

- long / short

- hyper pronated

 

2nd Toe amputation

- loss of lateral support for great toe

 

MTPJ

- rounded joint

 

TMTJ

- hypermobile

- medially slanted

 

Flatfoot

 

Short achilles tendon

 

5.  Pathological Conditions

 

Rheumatoid arthritis

- leads to loss of capsular support

- RA best treated with fusion

 

Neurological conditions

- CP best treated with fusion

 

Pathology

 

A.  Congruent MTP joint

 

Cause

- increased DMAA 

- Hallux valgus interphalangeus

 

Present

- enlarged medial eminence (bunion)

- pressure against shoe

- painful bursa or cutaneous nerve

 

Management

- MTP joint usually stable & won't sublux

- can’t do distal soft tissue release

- will sublux a congruent joint

 

B.  Incongruent MTPJ

 

Hallux Valgus Incongruent Joint, ex

 

Subluxed MTPJ

- usually progressive

 

Origin

- starts with lateral pressure on great toe

- tight high heels

- P1 moves laterally

 

Progression

- PI moves laterally & puts pressure on MT head

- moves it medially, thus increasing intermetatarsal angle

- attenuation of medial joint capsule

- sesamoid sling held in place by ADDH & transverse metatarsal ligament

- MT head moves further medially / varus deformity

- slides off sesamoids

 

Final deformity

- appearance of lateral migration of sesamoids

- however sesamoids maintain constant distance from second MT

- lateral sesamoid lies beside MT head in intermetatarsal space

- ADDH pronates the great toe

- medial extensor hood / capsule stretched

- EHL & FHL comes to lie lateral to MTPJ

- finally, lateral capsular structures become contracted & the deformity becomes fixed

 

C.  Medial Eminence

- MT head changes occur

- groove or medial sagittal sulcus develops at medial border of articular cartilage

 

D.  Bunion

- callosity of skin + bursa

 

E.  Lesser Toes

- MTP less stable & weight transferred to MT 2 & 3 -> callosities

- great toe may drift beneath 2nd toe

- alternatively, 2nd toe may subluxate laterally

- lateral toes become crowded

- often develop claw or hammer deformity

- increased weight bearing through middle MT heads may lead to metatarsalgia

- worse with clawing of lesser toes

 

History

 

Pain

- over medial eminence (75%)

- metatarsalgia under lesser toes

- degeneration of sesamoid joint

- dorsal aspect osteophytes / rigidus

 

Shoe problems

- wide foot

- difficulty fitting shoes

 

Secondary deformity of lesser toes

- especially hammer deformity of the second toe

- rubbing of the PIPJ on shoe

 

Cosmetic appearance

 

Examination

 

Hallux Valgus Clinical

 

Standing

- bunion

- HV

- clawing / hammer toes

 

Assess ROM ankle and STJ

- tight T Achilles

 

Look at wear patterns on foot

- callosities under 2/3 MT head

 

MTPJ

- tender bunion

- painful MTJP

- correctable / ROM correctable

- pain over sesamoids

 

TMTJ

- hypermobility

- > 9mm abnormal

 

Lesser toes

- deformity / correctable

 

Neurovascular examination

           

Weight Bearing AP X-ray

 

1.  Hallux Valgus Angle / MTPA

- metatarso-phalangeal angle

- normal < 15o

 

Hallux Valgus MTPA > 40

 

2.  Intermetatarsal angle/ IMA

- normal < 9o

 

Hallux Valgus Intermetatarsal Angle > 20 degrees

 

3.  Congruence

- place dots

- medial & lateral edges of the articular surfaces of the MT head & P1 base

- assess to see if line up / joint congruent

 

Hallux valgus Incongruent Joint

 

4. Interphalangeal angle

- normal is <10°

- identify hallux interphalangeus

 

5.  DMAA

- distal metatarsal articular angle

- normal < 6o

 

Hallux Valgus Increased DMAA

 

5.  Sesamoid subluxation

- amount of lateral sesamoid uncovered by MT

- medial sesamoid should not cross midline axis of MT

 

Hallux Valgus Lateral Sesamoid Uncovered

 

6.  MTPJ OA

 

7.  Size of the medial eminence

- amount of MT head medial to the line along the medial border of the MT

 

8.  TMT Angle

- medial sloping

 

Hallux Valgus Medial Sloping TMTJ

 

Mann Classification  

 

1.  Congruent

 

2.  Incongruent

 

A.  Mild

 

MTPA < 30°

IMA < 15°

Lateral sesamoid < 50% uncovered

 

Hallux Valgus Mild

 

B. Moderate

 

MTPA 30 - 40°

IMTA 15 - 20o

Lateral sesamoid 50 - 75% uncovered

 

C. Severe

 

MTPA > 40°

IMTA > 20°

Lateral sesamoid > 75% uncovered

 

Hallux Valgus Severe Unilateral

 

3.  Degenerative

 

Hallux Valgus Severe Degenerative