PRISM

1. Metatarsal Head AVN
Review Questions

2. 1. List and describe the radiographic
stages of AVN.

3. Stage 1: Avascular Stage (several weeks to 3 months)
- Relatively few clinical and radiographic changes
• Soft tissue inflammation (increase in soft tissue density)
• Thickened synovium (appears as capsulitis/synovitis)
- The ossific nucleus of the epiphysis ceases to grown due to the interrupted blood supply
- Smaller epiphysis on affected side
- There is a relative increase in the density of the epiphysis which is illusional due to the adjacent osteopenia
seen in the metaphysis
- Joint space appears increased secondary to decreased size of the epiphysis
- Articular cartilage is unaffected since it is nourished by synovial fluid
- Minimal deformity
- Mild arthralgia with associated edema, muscle atrophy and antalgic gait

4. Stage 2: Revasculization Stage (1 – 4 years)
- Revascularization of the dead epiphysis, which further undermines its integrity due to significant vascular
inbudding
- There is a true increase in density of the epiphysis due to condensation and impaction, as the epiphysis
collapses on itself
- “Head within head” appearance – the epiphysis appears very irregular due to deposition of new bone around
existing dead bone
- Subchondral fractures may occur during this extremely vulnerable stage, in which osteogenesis produces
primary woven bone (soft bone)

5. Stage 3: Re-modelling Stage/Bony Healing
- Bony deposition predominates over bony resorption, replacing old necrotic bone
- Osseous structures still susceptible to injury and deformity, but to a lesser degree
than stage 2
- Radiographic finding: return of the contour and outline of the epiphyseal center,
which can only adequately be assessed when re-ossification is complete
Stage 4: Residual Deformity
- Complete bony healing has occurred
- Epiphysis may be normal if sufficient treatment was rendered
- Resultant end stage deformity is assessed at this point

6. How do you diagnose AVN?

7. Sequential radiographs and clinical
correlation

8. If not evident on plain films, what other
imaging modality can be used to detect
AVN and how does it appear?

9. - MR imaging.
- Since most bone infarct occur in fatty tissue, MR
imaging is very useful.
- Decreased signal intensity within medullary bone
would be noticed in T1 and T2 weighted images.
- More sensitive and has better resolution than a bone
scan.

10. How do you treat AVN?

11. This is a self limiting process. We are trying to prevent residual
deformity.
Conservative Treatment:
- NSAIDs
- Orthotics
- Analgesics
- Protected/off weightbearing (casting, bracing, padding)
Surgical Treatment: - Arthrodesis

12. According to the literature, what is the
incidence of post-operative AVN
following a distal 1st metatarsal
osteotomy?

13. - Wilkinson et al using MR imaging found a 50% incidence of AVN following Austin
bunionectomy, with 10% of plain film in this study showing signs of AVN.
- Wallace et al using a mailed survey to 45 podiatry surgeons, reported an incidence of
only 0.11% in 13,000 head osteotomy bunionectomies.
- Although AVN is a recognized complication of first metatarsal head osteotomy and
may occur at a higher incidence than first recognized, clinical signs and symptoms are
relatively rare.
- Lateral release of the fibular sesamoid, conjoined adductor tendon, deep transverse
intermetatarsal ligament and joint capsule and excessive dissection, especially the
periosteal tissues can compromise the blood supply to the first metatarsal head.

14. How do you reduce the incidence of
AVN when performing a first metatarsal
osteotomy?

15. - Rigid fixation
- Minimal dissection
- Minimal lateral release

16. Name the true AVNs.

17. - Renandier’s disease – tibial sesamoid
- Trevor’s disease – fibular sesamoid
- Freiberg’s disease – second metatarsal head
- Kohler’s disease – navicular
- Diaz/Mouchet disease – talus
- Blount’s disease in adolescents – medial proximal tibial epiphysis
- Legg Calve Perthes Disease – femoral head

18. Name the AVNs that are NOT true.

19. - Sever’s disease – calcaneus
- Theimann’s disease – phalanges (hand and foot)
- Islen’s disease – 5th MT base
- Haglund’s disease – accessory navicular
- Osgood Schlatter’s disease – tibial tuberosity
- Blount’s disease in children – proximal medial tibial epiphysis
- Scheurman’s disease – ring epiphysis of the vertebral body
- Calve’s disease – solitary vertebral body
- Buchman’s disease – iliac crest
- Van Neck’s disease – ischiopubic synchondrosis
- Mandle’s disease – greater trochanter of the femur
- Singling-Larson-Johannson disease – lower patella

20. Name the AVNs that may or may not be
true AVNs.

21. - Buschke’s disease – cuneiform(s)
- Lewis/Liffert/Arkin – distal tibial epiphysis
- Ritter’s disease – proximal fibula

22. List the AVNs by Bones in the foot.

23. - Calcaneus – Sever’s disease
- Talus – Diaz disease
- Navicular – Kohler’s disease
- Cuboid – Lance’s disease
- Cuneiforms – Buschke’s disease
- 1st MT Head – Assman’s disease
- Tibial sesamoid disease – Renandier’s disease
- Fibular sesamoid disease – Trevor’s disease
- Lesser met heads – Frieberg’s disease
- Phlanages – Theimann’s disease