Dr Guichet

Bone Deformities

INTRODUCTION

Deformities can occur after a trauma with or without fracture, during growth or thereafter. They can also be at birth, congenital, or hereditary.

In children, the deformity should be evaluated, but also its evolution risk during residual growth. A small deformity can enlarge over time, and reversely.

Deformities can be observed in the three planes of the space:

Frontal plane: varus and valgus deformities

Transverse plane: torsional problems

Sagittal plane: recurvatum (extension deformities) and flexum (flexion deformities)

Angles can be measured along various planes.

FRONTAL PLANE

The frontal (or coronal) plane refers to the front half of the body. Bone and joint deformities that occur in the front plane include :

Varus/valgus: These deformities occur mainly at the level of the knee. Varus knees produce an "O" -shape to the legs (see Figure), and valgus knees result in an "X" -shape to the knees (see Figure). This deformity is not specific to the knees, and can also apply along the limbs, for instance at the heels, resulting in varus or valgus heels.

Supination/pronation: These deformities occur to the hand or to the forefoot. Hand supination corresponds to a varus where the hand turns upwards. Pronation, as in seizing or grasping, occurs when the hand turns downwards, as in an extreme valgus motion.

Pictures : Genu Valgum (left), Genu Varum (right)

TRANSVERSE PLANE

The transverse plane is defined as that occurring horizontally across the body. In this plane, the following deformities can occur:

- External/internal rotation. This rotation involves two different anatomical elements; for example, two different bones, such as the femora, can turn with respect to the pelvis in an internal or external rotation.
- Torsion. Torsion is a rotatory motion within a single bone between its two extremities. For example, excessive femoral torsion means that the torsion or rotation between the upper and the lower extremities of the femur is greater than the normal range.

SAGITTAL PLANE

The sagittal plane separates the left and right sides of the body from top to bottom and from front to back. Deformities in the sagittal plane include:

Flexor/extensor. These deformities apply to joints and involve the position of two bones. Flexor deformities describe backward bending (or flexion), while extensor deformities describe forward bending or extension of the joint.

Procurvatum/recurvatum. These deformities occur within a single bone ; procurvatum describes backward bending of the bone or flexion, and recurvatum forward bending of the bone.

POSITION

Lesions can be positioned as follows:

At the joint level. This deformity prevents full range of motion. For example, a flexor deformity of a joint prevents full extension.

At the bone level. This deformity can be observed at the epiphysis or joint portion of the bone; metaphysis (between epiphysis and diaphysis) ; or diaphysis, at the bone shaft.

Lesions can also combine deformities at different levels.

COMBINATION OF SEVERAL BONE DEFORMITIES

Bone deformities can be combined within the same bone, or among a few bones. Bone and joint deformities can also be combined. Soft tissues are often involved.

According to the lesions, a custom-made program can be proposed, addressing bone, joint and soft-tissue lesions.

All deformities can be analyzed in 3 planes of space at each level of deformity. Corrections should, if possible, be performed at the level of the deformity and should be clearly planned to allow for a full correction.

Pictures from left to right: 1) 20° genu recurvatum (knee recurvatum); 2) In standing front position, it may mimic a genu varum (knee varus); 3)When the recurvatum is corrected with knee extension at 0°, the genu varum corrects by itself: it is so far a false genu varum which does not need correction in itself; 4) On X-rays, the origin of the genu varum is observed: proximal tibial recurvatum of 10° (angle B at 90° instead of 80°), and a 10° joint recurvatum (laxity in the joint). A tibial bony correction will correct in a great par the deformity.