Bone and Soft-Tissue Disorders
= TREVOR DISEASE = TARSOEPIPHYSEAL ACLASIS
= uncommon skeletal developmental disorder representing an epiphyseal osteochondroma
Prevalence: 1÷1,000,000
Age: 24 years; M÷F = 3÷1
Cause: failure of normal progression of cellular cartilage breakdown (= aclasis); spontaneous occurrence
Path: lobulated mass protruding from epiphysis with a cartilaginous cap
Histo: normal bone + hyaline cartilage with abundant enchondral ossification (= abnormal cellular activity at cartilaginous ossification center)
Types:
- Localized form = monostotic involvement: usually hindfoot and ankle
- Classic form (>66%) = more than one area of involvement in a single extremity with characteristic hemimelic distribution: talus, distal femur, distal tibia
- Generalized / severe form = disease involving the whole lower extremity
- pelvic involvement: femoral head, symphysis pubis, triradiate cartilage
- hypertrophy of ipsilateral iliac bone
- antalgic (= pain-avoiding) gait; palpable mass
- varus / valgus deformity; limb length discrepancy
- limited joint mobility and function
Location: lower extremity (tarsus, knee, ankle); rare in upper extremity (humerus, ulna, scapula)
Site: restricted to medial OR lateral side of limb (= hemimelic), ie, medial÷lateral = 2÷1
- Infant & toddler
- premature appearance of an eccentric, lobulated, overgrown, asymmetric ossification center
- stippled calcification of anomalous cartilage
- Childhood
- disorganized epiphyseal calcification accompanied by irregular ossification
- osteochondroma-like growth from one side of epiphysis
- premature closure of physis results in limb deformity and limb length discrepancy
- irregular articular surface combined with angular deformity
- undertubulation of bone as a consequence of secondary involvement of metaphysis
Cx: premature secondary osteoarthritis
DDx: osteochondroma