Presentation on theme: "Diagnostic Imaging of Bones and Joints"— Presentation transcript:
1 Diagnostic Imaging of Bones and Joints Introduction to Orthopedic Radiology
2 Why PT’s Need to Know About Medical Imaging To correctly interpret radiologists written reportTo speak the same language as physiciansTo enhance awareness of patients conditionRadiologist reports are often written for the MD’s and may not take into account information the PT needs to treat the patient and to adequately formulate a prognosis
3 Important Facts About Xrays Plain film radiography remains as the 1rst order diagnostic imaging modalityXrays are a form of electromagnetic radiation similar to visible light but of shorter wavelengthXray tube generates xrays and beams them toward the patient. Some of the energy is absorbed; rest passes through patient and hits the film plate.Shades of gray on film are a representation of the different densities of the anatomic tissues through which the xrays have passed.
4 Tissues with greater density will absorb more of the xray so less of the beam reaches the film plate. The resultant image is therefore lighter. Tissues with less density will allow more xray to reach the film so it will be darker. This is called radiodensity and is determined by:*composition of the structure*thickness of the structure
5 BODY COMPOSITION AIR: Black Examples- trachea, lungs, stomach, digestive tractFAT: Gray blackExamples- subcutaneously alongmuscle sheaths; aroundviscera
6 Continued WATER: Gray Examples: Muscles, nerves, tendons, ligaments, vessels(All of these structures have the same density and therefore are hard to distinguish on plain xrays.)
7 Continued BONE: Gray/White CONTRAST MEDIUM: White Outline HEAVY METALS: White Solid
11 PERCEIVING 3 DIMENSIONS The center of the xray beam is always perpendicular to the film plate. The position of the body will determine the outline of the image.SEE FIGURES 5 -6
12 ROUTINE RADIOLOGIC EVALUATION Consists of the angles of projection that best demonstrate the anatomy while utilizing the least amount of exposures.Common Views:Anteroposterior (AP)Lateral (R and L)Oblique (R and L)(See Figure 7)Patient positioning for each projection is standardized throughout the USA
13 VIEWING RADIOGRAPHSIn AP and Lateral views, the film is always positioned on the view box with the patient positioned as if facing the viewer in anatomical position.Hands and feet are placed with fingers or toes pointing upLateral views are placed on the box in the direction that the beam traveled.Magnetic markers are used for R and L. Use this as the reference to place the patient facing the viewer in anatomical position (Fig 8)
15 FACTORS INFLUENCING QUALITY OF XRAYS Detail: Geometric sharpness. Can be affected by movementDistortion: Difference between the actual imagery and the recorded image. Geometric distortion occurs as the beam progresses away from the perpendicular. Fig. 9
16 ContinuedContrast: Difference between adjacent images. It is controlled by adjusting the energy of the beam.
17 ANATOMY OF BONE Compact Bone: forms outer shell or cortex of bone; denseCancellous Bone: forms the inner aspect ofbone except for the marrowcavity; spongy
18 FIGURE 10Periosteum: Covers the cortex; fibrous layer which contains blood vessels, nerves and lymphatics.Endosteum: Membrane lining the inner aspect of the cortes and medullary (marrow) cavityDiaphysis: ShaftMetaphysis: Flared part at either end of shaftEpiphysis: Either end of the bone
20 PROCESSES OF BONE GROWTH Ossification: Process of replacing cartilagenous model with boneEndochondral Ossification: How bones grow in lengthIntramembraneous Ossification: How bones grow in widthPhysis: The growth plate evidenced by the “open space” Fig 11 and 12
23 REMODELING OF BONE WOLFF’S LAW Bone will be deposited in sites subjected to mechanical stress with trabeculae aligning in ways that best absorb stress. Bone will resorb from sites deprived of stress.Clinical Relevance: As soon as it is safe, weight bearing should be allowed through the bones
24 ABC’S OF VIEWING FILMS A: ALIGNMENT 1. Assess the size of the bones: gigantism,dwarfism, etc2. Assess the number of bones3. Assess each bone for normal shape andcontour; irregularities can be fromtrauma, congenital, developmental orpathological4. Assess joint position: trauma, inflammatoryor degenerative disease (Fig 13)
28 1. Assess general bone density B. BONE DENSITY1. Assess general bone density*contrast between soft tissues and bone*contrast between cortical margin and thecancellous bone and medullary cavity*loss of contrast means loss of bone densityie: osteoporosis*labeled as osteopenia, demineralization orrarefaction
29 Originally coined for the changes of senile osteoporosis, biconcave deformities of the vertebral bodies ("fish vertebrae") are characteristic of disorders in which there is diffuse weakening of the bone. The name is derived from the actual appearance of a fish vertebrae which normally has depressions in the superior and inferior surfaces of each vertebral body. This sign is typically used for osteopenia.
32 appearance 2. Assess local bone density: looking for sclerosis; sign of repair in the bone. Excessive sclerosis isindicative of DJD. (Fig 15)Bone Lesions:Osteolytic- bone destroying so appear radiolucentas in RA or Gout (Fig 16)Osteoblastic- bone forming; osteoblastomas,osteoid osteomas3. Assess texture abnormalities: looking at trabeculaeappearance
41 1. Assess the gross size of the musculature s: SOFT TISSUES1. Assess the gross size of the musculature(Fig 17)2. Assess outline of joint capsules: normallyindistinct; become obvious during episodesof increased joint volume from infection,hemorrhage or inflammation3. Assess the periosteum: normally indistinct;(Fig 18)