Leite José Alberto Dias, Lima Luciana Cascão, Sampaio Marianna Luiza Bezerra
Department of Orthopaedic †Surgery Post-Graduation Program, Federal University of Ceara, Brazil.
J Pediatr Orthop. 2010 Oct-Nov;30(7):742-5. doi: 10.1097/BPO.0b013e3181edba12.
Tibial hemimelia, a rare congenital anomaly, is characterized by deficiency of the tibia with relatively intact fibula. The incidence of congenital deficiency of the tibia is approximately 1 per 1 million live births. The percentage of monozygotic twins is 0.8% of all newborns. Therefore, the occurrence of tibial hemimelia in monozygotic twins is 1 case per 125 million. The purpose of this article is to present a case of identical twins, in which 1 had tibial hemimelia, a double metatarsal bone and preaxial polydactyly and the other had no alterations. The patient that was affected had an anomaly in the left leg and foot. She had 7 fingers in her left foot and a left duplicated great toe. Her legs had a 3-cm difference in length, rigid inversion, adduction of feet, and severe bowing. A roentgenogram showed right tibial hemimelia with intact fibula corresponding to Jones type 3 and the first metacarpo was duplicated with a proximal osseus synostosis. Karyotyping confirmed that the twins were monozygotic. Only 1 of the identical twins had tibial hemimelia, a double metatarsal bone, and preaxial polydactyly. Congenital defects may result from aberrations in the developmental stage, the growth stage, or both. Hemimelia may result from a primary failure to form an anlage, or a primary failure to chronologically synthesize collagen. This case shows that tibial hemimelia can have variable phenotypic manifestations.
胫骨半侧发育不全是一种罕见的先天性畸形，其特征是胫骨缺损而腓骨相对完整。先天性胫骨缺损的发病率约为每100万活产中有1例。单卵双胞胎的比例占所有新生儿的0.8%。因此，单卵双胞胎中胫骨半侧发育不全的发生率为每1.25亿例中有1例。本文的目的是介绍一对同卵双胞胎的病例，其中1例患有胫骨半侧发育不全、双跖骨和轴前多指畸形，而另1例没有异常。患病的患者左腿和足部有畸形。她左脚有7个脚趾，左拇趾重复。她的双腿长度相差3厘米，足呈僵硬内翻、内收，严重弓形。X线片显示右胫骨半侧发育不全，腓骨完整，符合琼斯3型，第一掌骨重复并伴有近端骨性融合。染色体核型分析证实这对双胞胎是单卵双胞胎。仅1例同卵双胞胎患有胫骨半侧发育不全、双跖骨和轴前多指畸形。先天性缺陷可能是由于发育阶段、生长阶段或两者的畸变所致。半侧发育不全可能是由于原基形成的原发性失败，或按时间顺序合成胶原蛋白的原发性失败所致。本病例表明，胫骨半侧发育不全可具有多种表型表现。
