Clubfoot is a congenital limb deformity defined as fixation of the foot in cavus, adductus, varus, and equinus (i.e., inclined inwards, axially rotated outwards, and pointing downwards) with concomitant soft tissue abnormalities (Cardy et al., 2007). Clubfoot may occur in isolation or as part of a syndrome (e.g., diastrophic dysplasia, 222600). Clubfoot has been reported with deficiency of long bones and mirror-image polydactyly (Gurnett et al., 2008; Klopocki et al., 2012).

An increase in height of the medial longitudinal arch of the foot that does not flatten on weight bearing (i.e., a distinctly hollow form of the sole of the foot when it is bearing weight).

Weakness of the muscles of the arms.

Reduced strength of the distal musculature of the legs.

Underdevelopment of the thenar eminence with reduced palmar soft tissue mass surrounding the base of the thumb.

Reduced muscle mass on the ulnar side of the palm, that is, reduction in size of the hypothenar eminence.

Decreased ability to perceive touch.

A shaky or wobbly manner of walking.

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.

Absence of neurologic reflexes such as the knee-jerk reaction.

Reduction of neurologic reflexes such as the knee-jerk reaction.

An abnormal reduction in sensation in the distal portions of the extremities.

Repeated episodes of segmental demyelination and remyelination lead to the accumulation of supernumerary Schwann cells around axons, which is referred to as onion bulb formation. This finding affects peripheral nerves.

A type of Developmental delay characterized by a delay in acquiring motor skills.

A loss of myelinated nerve fibers in the peripheral nervous system (in general, this finding can be observed on nerve biopsy).

A type of decreased nerve conduction velocity that affects the motor neuron.

Reduced amount of myelin in the nervous system resulting from defective myelinogenesis in the peripheral nervous system.

The presence of an abnormal lateral curvature of the spine.

Muscular atrophy of distal leg muscles.