| Introduction |
 Osteonecrosis most often seen in 2nd second metatarsal (MT) head
- also known as Freiberg's infraction
- term is a combination of infarction and fracture
- Epidemiology
- demographics
- most commonly seen in patients 13-18 years
- more common in female adolescent athletes
- risk factors
- more common in patients with long 2nd metatarsals
- Pathophysiology
- thought to be related to a disruption in the blood supply due to microtrauma and stress overloading
- leads to eventual collapse of 2nd MT head
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Classification
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| Smillie Classification |
| Stage 1 |
Subchondral fracture visible only on MRI |
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| Stage 2 |
Dorsal collapse of articular surface on plain radiographs
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| Stage 3 |
Collapse of dorsal MT head, with plantar articular portion intact |
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| Stage 4 |
Collapse of entire MT head, joint space narrowing |
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| Stage 5 |
Severe arthritic changes and joint space obliteration |
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| Presentation |
- Symptoms
- forefoot pain localized to head of the second MT
- worse with weight bearing activities
- Physical exam
- swelling and limitation of motion in 2nd MTP joint
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| Imaging |
- Radiographs
- recommended views
- AP, lateral, obliques of foot
- findings (see Smillie classification)
- sclerosis in early disease
- flattening of involved MT head
- joint destruction in late disease
- MRI
- findings
- can show patchy edema in metatarsal head
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| Treatment |
- Nonoperative
- activity limitations, NSAIDS, immobilization
- technique
- short leg walking cast for 3-4 weeks
- can be used if symptoms are severe and do not improve with orthotics
- stiff-soled shoe with MT bars or pads
- typically used after period of casting
- Operative
- metatarsophalangeal arthrotomy with removal of loose bodies
- indications
- very rarely indicated
- only if extensive nonoperative management fails
- dorsiflexion closing and shortening osteotomy
- indications
- dorsal disease involvement of bone and cartilage
- DuVries arthroplasty (partial MT head resection)
- indications
- severe stage 4 or 5 disease
- plantar cartilage is not sufficient to reconstruct joint
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| Techniques |
- Metatarsophalangeal arthrotomy with removal of loose bodies
- approach
- lesser toe MTP joint approach
- technique
- may be combined with drilling of metatarsal head, subchondral bone grafting, and interposition arthroplasty using EDL tendon
- metatarsal head resection should be avoided due to increased loads on adjacent metatarsal heads
- Dorsiflexion closing and shortening osteotomy
- goals
- shortening offloads stress on metatarsal head
- approach
- lesser toe MTP joint approach
- technique
- bring less affected plantar cartilage into contact with proximal phalanx
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| Complications |
- Degenerative joint disease
- of 2nd MTP joint in adulthood
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