THE SITES OF ELONGATION OF HUMAN METACARPALS AND METATARSALS

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Abstract
Normally human metacarpals and metatarsals have epiphyses at one end only. It might be assumed, therefore, that all the elongation of the shafts of these bones would occur at their epiphyseal ends. The 1st metacarpal and the 1st metatarsal have epiphyses at their proximal ends and the 2nd metacarpal and 2nd metatarsal have epiphyses at their distal ends. Measurements were made on serial standardized radiographs of children between the ages of 2 and 11 years using lines of arrested growth and areas of fixed trabecular pattern as landmarks within these bones. These measurements showed that 20.7-30.2% of shafts elongation of the 1st and 2nd metacarpals and metatarsals occurs at their non-epiphyseal ends during this period. These changes are associated with distal migration of the 1st metacarpal (metatarsal) relative to the 2nd metacarpal (metatarsal). In 1 child, the 2nd metacarpal had a supernumerary proximal epiphysis. This was associated with more than usual elongation at the proximal end of this bone (elongation of the shaft + elongation of the epiphysis) and with less than usual distal migration of the 1st metacarpal relative to the 2nd metacarpal. Histo-logical evidence of bone formation at the non-epiphyseal ends of the metacarpals and metatarsals was presented.