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Background: Congenital longitudinal deficiency of the fibula is the most common lower extremity congenital deficiency, with a broad spectrum of severity and subsequent reconstructive treatment. Published classification schemes do not accurately predict reconstructive treatment currently in practice., Methods: We reviewed all medical records of patients with a dominant deformity of congenital fibular deficiency who were managed at our institution between 1971 and 2005. We assessed the impact of limb-length inequality, foot deformity, bilateral extremity involvement, and extent of fibular preservation on the treatment of the limb deficiency., Results: One hundred and four patients (including twenty-two with bilateral congenital fibular deficiency) with 126 affected extremities had adequate radiographs to be included in the study. Femoral shortening was noted in seventy (85.4%) of eighty-two patients with unilateral limb involvement. Limb-length discrepancy prior to any treatment remained proportional in forty-seven (82.5%) of fifty-seven patients during an average duration of follow-up of ten years and ten months (range, two years to fifteen years and six months). Limb salvage with foot preservation was deemed feasible in thirty-eight (97.4%) of thirty-nine five-rayed feet, thirty (81.1%) of thirty-seven four-rayed feet, twenty (48.8%) of forty-one three-rayed feet, and one of nine feet having fewer than three rays. Twenty-two (41.5%) of fifty-three limbs with an absent or vestigial fibula were not treated with amputation. Of the twenty-two patients with bilateral fibular deficiency, twelve (54.5%) had preservation of both feet, three (13.6%) had unilateral amputation, and seven (31.8%) had bilateral amputation., Conclusions: We propose a simplified classification for congenital fibular deficiency based on the clinical status of the foot and the magnitude of limb shortening as a percentage of the contralateral limb on radiographs. This classification may be effectively applied in infancy to allow the physician and family to anticipate the extent of deformity at maturity and to estimate the amount of treatment required to reconstruct this limb deformity. This system more accurately predicted the management of patients with fibular deficiency who were managed at our institution over the past three decades .

A chimeric mouse variable::human constant immunoglobulin heavy-chain gene was expressed in transfected mouse Sp2/0 cells. The chimeric immunoglobulin genes were integrated in tandem in the genome of stably transformed cells. These integrated gene copies were amplified by selection with a second drug marker. The gene amplification led to an increase in the expression of chimeric heavy-chain protein. The level of gene expression appears to be related to the site of integration; a few gene copies in one transfectant can yield as much heavy-chain protein as many copies in a second transfectant. In addition, we found that an adventitious oligo(C) sequence, introduced by our method of gene construction at a site located 8 nt residues downstream from a splice acceptor, can apparently direct splicing towards a cryptic splice acceptor downstream from the oligo(C).