A positional abnormality marked by outward bowing of the legs in which the knees stay wide apart when a person stands with the feet and ankles together.

A bending or abnormal curvature of the tibia.

A bending or abnormal curvature of the radius.

Bending of the diaphysis (shaft) of the ulna.

Disproportionate shortening of the proximal segment of limbs (i.e. the femur and humerus).

Limited ability to straighten the arm at the elbow joint.

Coxa vara includes all forms of decrease of the femoral neck shaft angle (the angle between the neck and the shaft of the femur) to less than 120 degrees.

Weakness of the hip girdle and upper thigh muscles, for instance in myopathies, leads to an instability of the pelvis on standing and walking. If the muscles extending the hip joint are affected, the posture in that joint becomes flexed and lumbar lordosis increases. The patients usually have difficulties standing up from a sitting position. Due to weakness in the gluteus medius muscle, the hip on the side of the swinging leg drops with each step (referred to as Trendelenburg sign). The gait appears waddling. The patients frequently attempt to counteract the dropping of the hip on the swinging side by bending the trunk towards the side which is in the stance phase (in the German language literature this is referred to as Duchenne sign). Similar gait patterns can be caused by orthopedic conditions when the origin and the insertion site of the gluteus medius muscle are closer to each other than normal, for instance due to a posttraumatic elevation of the trochanter or pseudarthrosis of the femoral neck.

Osteoarthritis (OA) is a degenerative disease of the joints characterized by degradation of the hyaline articular cartilage and remodeling of the subchondral bone with sclerosis (Meulenbelt et al., 2006). Clinical problems include pain and joint stiffness often leading to significant disability and joint replacement. Osteoarthritis exhibits a clear predilection for specific joints; it appears most commonly in the hip and knee joints and lumbar and cervical spine, as well as in the distal interphalangeal and the first carpometacarpal (base of thumb) and proximal interphalangeal joints of the hand; however, patients with osteoarthritis may have 1, a few, or all of these sites affected (Stefansson et al., 2003). According to a conservative estimate, greater than 70% of the population of the United States at age 65 years is affected by the disease, reflecting its age dependence. Genetic Heterogeneity of Susceptibility to Osteoarthritis Susceptibility to osteoarthritis has been associated with variation in other genes: OS2 (140600) with variation in the MATN3 gene (602109) on chromosome 2p24; OS3 (607850) with variation in the ASPN gene (608135) on chromosome 9q22; and OS5 (612400) with variation in the GDF5 gene (601146) on chromosome 20q11. Other susceptibility loci for osteoarthritis have been mapped to chromosomes 2q33 (OS4; 610839) and 3p24 (OS6; 612401).

An osteochondrodysplasia that results in abnormalities of bone growth in the vertebral column, epiphysis, and metaphysis.

A decreased rate of skeletal maturation. Delayed skeletal maturation can be diagnosed on the basis of an estimation of the bone age from radiographs of specific bones in the human body.

Metaphyseal cupping refers to an inward bulging of the metaphyseal profile giving the metaphysis a cup-like appearance.

A flattened vertebral body shape with reduced distance between the vertebral endplates.

Reduction in the size or volume of epiphyses.

The presence of a splayed (i.e.,flared) metaphyseal segment of one or more long bones.

Abnormal flatness (decreased height) of epiphyses.

Bowing (abnormal curvature) of the femur.

Widening of the ilium ala, that is of the wing of the ilium, combined with external rotation, leading to a flared appearance of the iliac wing.

Bulbous appearance of the anterior vertebral bodies, such that the vertebral bodies have the greatest vertical height anteriorly as well as bulbous anterior superior-inferior contours.