LONG BONE MEASUREMENT

OUTLINE

ORTHOROENTGENOGRAPHY

ABBREVIATIONS

Radiation protection

Position of patient

Position of part

Localization of joints

Computed tomography technique

ORTHOROENTGENOGRAPHY

Radiography provides the most reliable means of obtaining accurate measurements of the length of long bones, specifically length differences between the two sides. Although studies are occasionally made of the upper limbs, radiography is most frequently applied to the lower limbs. This chapter considers only a few of the many radiographic methods that have been devised for long bone measurement.

ABBREVIATIONS USED IN CHAPTER 11

AP	Anteroposterior
CT	Computed tomography
IR	Image receptor

See Addendum B for a summary of all abbreviations used in Volume 2.

Radiation Protection

Differences in limb length are common in children and may occur in association with various disorders. Patients with unequal limb growth may require yearly radiographic evaluations. More frequent examinations may be necessary in patients who have undergone surgical procedures to equalize limb length. One treatment method controls bone growth on the normal side usually by means of metaphyseal-epiphyseal fusion at the distal femoral or proximal tibial level. Another treatment technique is to increase the growth of the shorter limb by surgically cutting the femur or tibia-fibula, or both. A frame is placed around the cut ends and extended to the outside of the body. Gradual pressure on the frame separates the bone, extends the leg, and promotes healing at the same time.

Because patients with limb length differences require checkups at regular intervals over years, gonad shielding is necessary to guard their well-being. In addition, careful patient positioning, secure immobilization, and accurate centering of a closely collimated beam of radiation are important to prevent unnecessary repeat exposures.

Position of Patient

Three exposures are made of each limb, with the accuracy of the examination depending on the patient not moving the limb or limbs even slightly. Small children must be carefully immobilized to prevent motion. If movement of the limb occurs before the examination is completed, all radiographs may need to be repeated.

• Place the patient in the supine position for all techniques, and examine both sides for comparison.

• When a soft tissue abnormality (swelling or atrophy) is causing rotation of the pelvis, elevate the low side on a radiolucent support to overcome the rotation, if necessary.

Position of Part

The limb to be examined should be positioned as follows:

• Adjust and immobilize the limb for an AP projection.

• If the two lower limbs are examined simultaneously, separate the ankles 5 to 6 inches (13 to 15 cm) and place the specialized ruler under the pelvis and extended down between the legs.

• If the limbs are examined separately, position the patient with a special ruler beneath each limb.

• When the knee of the patient’s abnormal side cannot be fully extended, flex the normal knee to the same degree and support each knee on one of a pair of supports of identical size to ensure that the joints are flexed to the same degree and are equidistant from the image receptor (IR).

Localization of Joints

For the methods that require centering of the ray above the joints, the following steps should be taken:

• Localize each joint accurately, and use a skin-marking pencil to indicate the central ray centering point.

• Because both sides are examined for comparison and a discrepancy in bone length usually exists, mark the joints of each side after the patient is in the supine position.

• With the upper limb, place the marks as follows: for the shoulder joint, over the superior margin of the head of the humerus; for the elbow joint,

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Tags: Merrills Atlas of Radiographic Positioning and Procedures Volume

Mar 4, 2016 | Posted by admin in GENERAL RADIOLOGY | Comments Off

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Radiology Key

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LONG BONE MEASUREMENT

LONG BONE MEASUREMENT

ORTHOROENTGENOGRAPHY

Radiation Protection

Position of Patient

Position of Part

Localization of Joints

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Radiology Key

Fastest Radiology Insight Engine

LONG BONE MEASUREMENT

LONG BONE MEASUREMENT

ORTHOROENTGENOGRAPHY

Radiation Protection

Position of Patient

Position of Part

Localization of Joints

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