This condition may be an isolated phenomenon or may be associated with other segmental anomalies of the vertebral bodies such as spina bifida, kyphoscoliosis, butterfly vertebra, hemivertebra and block vertebrae which are observed in most of the cases. Scoliosis is identified in more than half of these patients. In most of the symptomatic patients, the spinal cord is split into halves by a bony spicule or fibrous band, each half being surrounded by a dural sac. Other conditions, such as intramedullary tumors, tethered cord, dermoids, lipoma, syringomyelia, hydromyelia and Arnold–Chiari malformations have been described in medical literature, but they are exceptionally rare. Diastematomyelia usually occurs between 9th thoracic and 1st sacral levels of the spinal column with most being at the level of the upper lumbar vertebra. Cervical diastematomyelia is a very rare entity. The extent (or length of spinal cord involved) varies from one affected individual to another. In approximately 60% of patients with diastematomyelia, the two hemicords, each covered by an intact layer of pia arachnoid, travel through a single subarachnoid space surrounded by a single dural sac. Each hemicord has its own anterior spinal artery. This form of diastematomyelia is not accompanied by any bony spur or fibrous band and is rarely symptomatic unless hydromyelia or tethering is present. The other 40% of patients have a bony spur or a fibrous band that passes through the two hemicords.
Similarly, while a valgus deformity of the knee would currently describe knocked knees, the original Latin meaning was "bow-legged"
Application of these words in adjectival form to other portions of the body by the medical community has resulted in their definitions changing so that they now refer to the angle of the distal segment (i.e. valgus impaction in a Garden I femoral neck fracture). It is correct for a knock-kneed deformity to be called both a varus deformity at the hip (coxa vara) and a valgus deformity at the knee (genu valgum); although the common terminology is to simply refer to it as a valgus knee.When the terminology refers to a bone rather than a joint, the distal segment of the bone is being described. Thus, a varus deformity of the tibia (i.e. a mid-shaft tibial fracture with varus deformity) refers to the distal segment in a varus alignment compared to the proximal segment. Examples
Hip: coxa vara —  the angle between the head and the shaft of the femur is reduced, resulting in a limp. Knee: genu varum (from Latin genu = knee) — the tibia is turned inward in relation to the femur, resulting in a bowlegged deformity. Ankle: talipes varus (from Latin talus = ankle and pes = foot). A notable subtype is clubfoot or talipes equinovarus, which is where one or both feet are rotated inwards and downwards. Toe: hallux varus (Latin hallux = big toe) — inward deviation of the big toe away from the second toe.