Deformity of the great toe in fibrodysplasia ossificans progressiva.
BACKGROUND
As invasive medical procedures can induce permanent heterotopic ossification in fibrodysplasia ossificans progressiva (FOP), caution should be exercised in clinical practice. The present study was conducted to examine the characteristics of the great toe deformity in patients with FOP, which may lead to an early diagnosis of this condition.


METHODS
The subjects consisted of 31 feet from 16 FOP patients (8 males, 8 females) with an average age of 17.3 years (range 1-47 years) at the time of this study. Gross and radiographic findings, including the hallux valgus angles (HVA), intermetatarsal angles (IMA), and the deformity of the proximal phalanx and metatarsal bone, were examined.


RESULTS
Of the 31 feet, 29 (93.5%) showed several degrees of great toe deformity. A shortened great toe was the typical gross finding and was observed in 20 feet (64.5%). The mean HVA and IMA were 19.7° and 8.5°, respectively; and 22 (71.0%) feet satisfied the radiographic definition of hallux valgus (HVA ≥ 20° or IMA ≥ 10°). The proximal phalanx was consistently shortened but morphologically dissimilar from case to case. The metatarsal bone was also shortened and sharpened to the medial side, deviating the proximal phalanx laterally from the metatarsal axis. Fusion between the distal and proximal phalanx occurred with advancing age. Only two feet in one patient showed no obvious deformity of the great toe.


CONCLUSIONS
A shortened great toe and hallux valgus were frequently found in patients with FOP. Shortening and sharpening of the proximal phalanx and metatarsal bone consistently existed and contributed to the great toe deformity. These findings were thought to exist from birth and may be a key to an early diagnosis.
Department of Orthopaedic Surgery, Kyushu University, 1-3-3 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Yasuharu
Y
Nakashima
Nobuhiko
N
Haga
Hiroshi
H
Kitoh
Junji
J
Kamizono
Koji
K
Tozawa
Takenobu
T
Katagiri
Takafumi
T
Susami
Jun-ichi
J
Fukushi
Yukihide
Y
Iwamoto
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D042241:Early Diagnosis; D005260:Female; D005531:Foot Deformities, Acquired / Q000000981:diagnostic imaging* / Q000209:etiology*; D006214:Hallux / Q000000981:diagnostic imaging* / Q000473:pathology*; D006801:Humans; D007223:Infant; D008297:Male; D008683:Metatarsophalangeal Joint / Q000000981:diagnostic imaging / Q000473:pathology; D008875:Middle Aged; D009221:Myositis Ossificans / Q000150:complications* / Q000000981:diagnostic imaging* / Q000473:pathology; D011859:Radiography; D055815:Young Adult