Definition
Crushing osteochondritis of metatarsal head
Epidemiology
Usually 2nd metatarsal (80%)
- occasionally third
- can occur in any
Age 10-15 years
- peak 15 year old girls
- F:M = 3:1
- occurs during the growth spurt at puberty
Bilateral in 6%
Aetiology
Trauma / repetitive stress
- interrupts blood supply to epiphysis
- fragmentation and AVN
2nd MT prone to stress fracture & AVN
- long MT
- fixed base
- thin shaft
Pathology
Ischaemic necrosis of epiphysis
Commonly have synovitis as well
Clinical
Tender enlarged MT head
- pain on dorsiflexion
- limited dorsiflexion due to synovitis or degenerative change
DDx
MTPJ synovitis / arthritis / synovial cyst
Interdigital neuroma
Stress fracture
X-ray
Enlarged flattened MT head
- widened joint space
- osteolysis & collapse in late stages
Leads to MTPJ OA
MRI
Classification Smillie
Stage I
Subchondral fissure in epiphysis
Xray normal
Bone scan / MRI positive
Stage II
Collapse of dorsal central portion of MT head
Xray
- slight widening of joint space
- sclerosis of epiphysis
Stage III
Xray
- progressive flattening of the head / osteolysis / collapse
Stage IV
Xray
- fragmentation of epiphysis
- multiple loose bodies
Stage V
Xray
- advanced degenerative arthrosis
- joint space narrowing
- hypertrophy of MT head
- osteophyte formation
MRI
Management
Non-operative
Algorithm
Limit activities 6/52
Metatarsal bar / preMT dome to unload MT head
Avoid high heels
Consider POP / moonboot to reduce symptoms
Operative
Options
Synovectomy & joint debridement / removal of loose bodies
Indication
- stage II / III disease
Osteophyte removal / Cheilectomy
Closing wedge extension osteotomy
Concept
- dorsiflexion osteotomy
- most affected portion MT head is dorsal
- redirects plantar articular surface
Excision of MT head
Indication
- severe disease
Issue
- not a great operation
- associated with hallux valgus and transfer metatarsalgia