Roentgenometrics S.THIYAGARAJAN Application of standard lines and measurements to radiographs Allows the detection of subtle abnormalities Assists in avoiding misdiagnosis Comparison of studies is facilitated Basilar Angle Welcker’s basilar angle/Martin’s basilar angle / Sphenobasilar angle Lateral skull The Nasion(Frontal-nasal junction) The center of the Sella turcica (Midpoint between the clinoid processes) The Basion (Anterior margin of the foramen magnum) Index of the relationship between the anterior skull and its base >152° - Platybasia Congenital AVERAGE MINIMUM MAXIMUM Isolated impression 137 123 152 Occipitalization Acquired Paget’s disease Rheumatoid arthritis Fibrous dysplasia This may or may not be associated with basilar impression Chamberlain’s Line Palato-occipital line.Projection: Lateral skull; lateral cervical spine. The posterior margin of the Hard palate The posterior aspect of the foramen magnum (OPISTHION) The relationship of this line to the tip of the odontoid process is then assessed
Tip of the odontoid process should not project above this line Normal variation of 3 mm above this line may occur A measurement of ≥7 mm is definitely abnormal. An abnormal superior position of the odontoid Basilar impression Platybasia Atlas occipitalization Bone-softening diseases of the skull base Paget’s disease Osteomalacia Fibrous dysplasia Rheumatoid arthritis McGregor’s Line (Basal line) Projection: Lateral skull; lateral cervical spine. Postero superior margin of the hard palate Most inferior surface of the occipital bone The relationship of the odontoid apex to this line is examined > 8 mm in males > 10 mm in females In children younger than 18 years, these maximum values diminish with decreasing chronologic age. McGregor’s line appears to be the most accurate and reproducible Abnormal superior position of the odontoid Basilar impression Macrae’s Line Foramen magnum line The Basion (anterior margin of the foramen magnum) Posterior (Opisthion) margins of the foramen magnum The inferior margin of the occipital bone should lie at or below this line
In addition a perpendicular line drawn through the odontoid apex should intersect this line in its anterior quarter If the inferior margin of the occipital bone is convex in a superior direction and/or lies above this line, then basilar impression is present. If the odontoid apex does not lie in the ventral quarter of this line Dislocation of the atlanto-occipital joint Fracture Dysplasia of the dens Digastric Line (Biventer line) Projection: AP open mouth The digastric groove medial to the base of the mastoid process The vertical distance to the odontoid apex and atlanto occipital joints is measured Measure Average (mm) Minimum (mm) Maximum (mm) Digastric line-odontoid apex 11 1 21 Digastric line-atlanto-occipital 12 4 20 joint Both measurements will decrease in basilar impression • Platybasia • Atlas occipitalization • Bone-softening diseases of the skull base • Paget’s disease • Osteomalacia • Fibrous dysplasia • Rheumatoid arthritisOccipitoatlantal alignment Projection: Lateral skull. Two lines are constructed
1. Foramen magnum line (FML) is drawn along the inferior margin of the occiput (MACRAE’S LINE) 2. Atlas plane line (APL) is drawn through the center of the anterior tubercle and the narrowest portion of the posterior arch of atlas The FML and APL should be parallel. Divergence of the FML and APL anteriorly suggests anterior-superior malposition of the occiput Divergence of the lines posteriorly suggests posterior-superior malposition of the occiputOther method The anterior margin of the foramen magnum should line up with the dens. A line projected downward from the dorsum sellae along the clivus to the basion should point to the dens. Wachenheims line The posterior margin of foramen magnum should line up with the C1 spinolaminar line. Power ratio :The ratio of Basion - spinolaminar line of C1 to Opisthion - posterior cortex of C1 anterior arch normally ranges from 0.6 to 1.0, with the mean being 0.8. A ratio greater than 1.0 implies anterior cranio-cervical dislocation.Sella Turcica SizeThe greatest AP diameter and the greatest vertical diameter Diameter Average (mm) Minimum (mm) Maximum (mm) Anteroposterior 11 5 16 Vertical 8 4 12
Small sella Normal variant Hypopituitarism (long after Sheehans) Microcephaly Myotonic dystrophy Prader-Willi-Lambert syndrome Cockayne syndrome Dystrophia myotonica Enlarged sella Pituitary neoplasm Empty sella syndrome Extrapituitary mass Neoplasm Aneurysm Normal variant J shaped sellaElongated sella with shallow anteriorconvexity which represents exaggerated of sulcus chiasmaticus Normal variant MPS Achondroplasia Chronic hydrocephalus Optic chiasmatic glioma Osteogenisis imperfecta Neurofibromatosis Atlantoaxial "overhang" sign AP open-mouth projection Lateral margin of the lateral masses of atlas should not appear more lateral than the superior articular processes of axis If the lateral margin of the atlas lateral mass lies
lateral to the lateral axis margin, Radiologic sign of Jefferson’s fracture Odontoid fracture Alar ligament instability Rotatory atlantoaxial subluxation Mild degree of overhanging may be a normal variant Atlantodental Interspace Atlas-odontoid space, predental interspace, atlas-dens interval Projection: Lateral neutral; flexion- extension cervical Age Minimum Maximum spine. (mm) (mm) The distance measured is Adults 1 3 between the posterior margin of Children 1 5 the anterior tubercle and the anterior surface of the odontoidDecreased space Advancing age (Degenerative joint disease of the atlantodental joint)Widened space with reduction in the neuralcanal size Trauma Occipitalization Down’s syndrome Pharyngeal infections (Grisel’s disease) Inflammatory arthropathies Ankylosing spondylitis Rheumatoid arthritis Psoriatic arthritis Reiter’s syndrome Cervical Gravity Line A vertical line is drawn through the apex of the odontoid process
This line should pass through the C7 body Gross assessment of where the gravitational stresses are acting at the cervicothoracic junction. Stress Lines of the Cervical Spine Ruth Jackson’s lines Projection: Lateral cervical spine (flexion, extension) Two lines are constructed on each film 1) The first line is drawn along the posterior surface of the axis 2) The second line is drawn along the posterior surface of the C7 body until it intersects the axis line Normal Measurements Flexion - lines should intersect at the level of the C5-C6 disc or facet joints. Extension - lines should intersect at the level of the C4-C5 disc or facet joints. The intersection point represents the focus of stress when the cervical spine is placed in the respective positions The point of intersection does not appear to correlate with the level of degenerative disc disease Muscle spasm, joint fixation, and disc degeneration may alter the stress point. Cervical LordosisVisual assessment (Subjective) On the lateral cervical projection Well maintained anterior convexity is lordosis Exaggerated anterior convexity is hyperlordosis
Slight anterior convexity hypolordosis Lack of curvature is alordosis Posterior convexity is kyphosis Altered cervical lordosis Trauma Degeneration Muscle spasm Aberrant inter-segmental mechanics Depth method Lateral cervical projection A line is drawn from the tip of the odontoid process to the posterior surface of C7 A horizontal measure is taken from the vertical line to the posterior surface of the C4 body (X) The average depth is 12 mm Negative – Kyphosis Largest values – Hyperlordosis The depth method provides a more accurate assessment of cervical lordosis Angle of curve Lateral cervical projection A line is drawn connecting the anterior and posterior tubercles of the atlas Second line is drawn along the inferior endplate of C7 Perpendicular lines are drawn from the atlas and C7 lines, and their angle of intersection is recorded as the cervical lordosis (X°) The average value is 40 degrees Negative – kyphosis Large – hyperlordosis Less accurate than the depth method. Because the measurements depend only on CI and C7 Prevertebral Soft Tissues
The soft tissue in front of the vertebral bodies and behind the air shadow of the pharynx, larynx, and trachea is measured The bony landmarks Anterior arch of the atlas Inferior corners of the axis & C3 Superior corner of C4 Inferior corners of C5, C6, and C7 C2-C3 - RPI Behind the larynx (C4-C5) - RLI Behind the trachea (C5-C7) - RTI. Widening Post-traumatic hematoma Retropharyngeal abscess Neoplasm from the adjacent bone and soft tissue structures. Level Flexion (mm) Neutral (mm) Extension (mm) C1 11 10 8 C2 6 5 6 C3 7 7 6 C4 7 7 8 C5 22 20 20 C6 20 20 19 C7 20 20 21 Spinolaminar junction line Posterior Cervical Line, arch-body line. Projection: Lateral cervical spine (neutral, flexion, extension). The cortical white line of the spinolaminar junction identified at each level C1 to C7• Each spinolaminar junction will be curved slightly anteriorly from superior to inferior
• For consistency, the most anterior part of the convexity is compared between levels Discontinuous at any level Anterior or posterior displacement This line is especially useful for detecting subtle odontoid fractures and atlantoaxial subluxation (anterior) A disruption in the middle to lower cervical spine may also be a sign of anterolisthesis, retrolisthesis, or frank dislocation. Cervical Spinal Canal Projection: Lateral cervical (neutral, flexion, extension) The sagittal diameter is measured from the posterior surface of the midvertebral body to the nearest surface of the same segmental spinolaminar junction line Level Average (mm) Minimum (mm) Maximum (mm) C1 22 16 31 C2 20 14 27 C3 18 13 23 C4 17 12 22 C5 17 12 22 C6 17 12 22 C7 17 12 22 Narrowing of the canal (stenosis) < 12 mm Significance
If degenerative posterior osteophytes are present, the measurement can be made from their tip to examine the magnitude of the stenotic effect. The degree of stenosis from these spurs is best measured on extension films An abnormally widened canal may be associated with a spinal cord neoplasm or syringomyelia. The most accurate measurement is by the ratio of the sagittal dimension of the canal and vertebral body (canal to body ratio, Pavlov’s ratio) A ratio of less than 0.82 is significant for spinal stenosis. The benefit of this method is that it removes the effects of radiographic magnification. Cervical, thoracic, and lumbar endplate lines On the lateral cervical projection, lines arc drawn along the inferior endplate of the C2-T1 vertebrae and extended posteriorly to the cervical spine The cervical endplate lines should all intersect at a common point located posterior to the spine Lack of convergence Normal lordotic cervical spine curve Intersegmental malpositions Lines that cross closely to the spine Extension malposition of the superior segment Lines that diverge sharply flexion malposition of the superior segment.
Frontal cervical, thoracic, and lumbar projections Lines are drawn to approximate the inferior vertebral endplates The lines at adjacent levels should be parallel Divergence of the endplate lines Lateral flexion malposition opposite the side of divergence Cervical, thoracic, and lumbar vertebral rotationBody width method Distance from the lateral margins of the vertebral bodies to the origin of the spinous process should be equal bilaterally. Distances not equal Vertebral rotation Spinous process deviation to the side of the smaller distance. Pedicle methodFrontal projection The appearance of the pedicle shadows may suggest vertebral rotation It is expected the pedicle shadows demonstrate bilateral symmetry If the width of a pedicle shadow appears narrower than the contralateral pedicle shadow, it suggests Segmental rotation with the spinous process deviated to the side of the narrower pedicle shadow Posterior vertebral body
rotation to the side of the wider pedicle shadow Cervical, thoracic, and lumbar vertebral sagittal alignmentGeorges lineLateral projections Curvilinear line is drawn along the posterior surfaces of the vertebral bodies The curve should maintain a smooth contour throughout the spinal region without segmental disruption. Disruption Segmental anterolisthesis Retrolisthesis Disruptions at multiple consecutive levels Normal flexion and extension patterns. However, the adjacent posterior body lines should not demonstrate more than 3 mm of net translation in a comparison of the flexion and extension radiographs Barges "e" space Lateral lumbar projection Lines are drawn along the superior and inferior vertebral endplates of each segment Lines perpendicular to each endplate line are then drawn and extended across the intervertebral disc space. The distance between the perpendicular lines at the inferior end- plate of each lumbar segment is measured as the "e" space The space should not exceed 3 mm Larger Barges "e" space Retrolisthesis of the segment above Negative values indicate
Anterolisthesis Visual method Segmental retrolisthesis Intervertebral disc degeneration (osteophytes, eburnation, reduced disc space, Schmorls nodes, endplate irregularity) The lowest segment of a "stack" of three or more vertebrae that do not contribute to a sagittal curvature may be posterior The lowest involved segment of three or more consecutive segments that appear to be flexed or extended during neutral patient posture may be posterior Segmental rotation in a coronal plane that produces an hourglass appearance Narrowed sagittal diameter of the intervertebral foramen Visual disparity of segmental alignment when comparing the margins of adjacent vertebrae Retrolisthesis of L5 is often seen as a normal variant, accompanying short pedicles Cervical toggle analysis Atlas tilt Lateral cervical projection Three lines are constructed Occipital condyle line (OCL) is drawn along the base of the occipital condyles Atlas plane line (APL) is drawn through the center of the anterior tubercle and the narrowest portion of the posterior arch of the atlas Listing line (LL) is drawn parallel to the occipital condyle line and
through the narrowest portion of the posterior arch of the atlas. The atlas plane line should be 4 degrees above the listing line APL > 4 degrees above the listing line Superior malposition of the atlas APL < 4 degrees Inferior malposition of atlas Atlas laterality 4 lines are constructed: Horizontal ocular orbit line (OOL) is drawn through similar matched points of the orbits Superior basic line (SBL) is drawn parallel to the OOL through the tip of the most superior occipital condyle Inferior basic line (IBL) is drawn through the inferior tips of the lateral masses Vertical median line (ViML) is drawn perpendicular to the OOL and through the center of the foramen magnum The distances between the inferior lateral tip of each lateral mass and the VML should be equal. The atlas is lateral toward the side of the greater measurement when the distances between the lateral inferior tip of each lateral mass and the VML are not equal In addition, the SBL and IBL lines are thought to converge to the side of atlas laterality 70% of the time Atlas rotation On a cervical film whose projection is directed vertical to the atlas (base posterior) Two lines are constructed
Transverse atlas line (TAL) is drawn through the transverse foramen bilaterally Perpendicular skull line (PSL) is drawn through points representing the centers of the nasal septum and the basal process of the occiput The angle of intersection of the two lines should be approximately 90 degrees. The atlas is rotated posteriorly on the side of the larger angle created by the intersection of the PSL and TAL. In addition, 70% of the time the atlas is posteriorly rotated to the side of the diverging superior basic line (SBL) and inferior basic line (IBL) on the frontal open mouth projection. ATLAS MALPOSITION Frontal open-mouth projection Four lines are constructed Ocular orbit line (OOL) is drawn through a set of similar points of the orbit Superior basic line (SBL) is drawn bilaterally through the jugular processes Inferior basic line (IBL) is drawn through the lateral inferior tip of both lateral masses Vertical median line (VML) is drawn perpendicular to the OOL through the center of the foramen magnum VML should approximate the center of the odontoid process base If the VML does not bisect the odontoid, the axis is laterally malpositioned to the side opposite the VML. In addition, the center of the odontoid process base is compared with the center of the spinous process to assess for possible spinous deviation. The direction and magnitude of spinous process lateral malposition may be different from the lateral malposition of the axis body (i.e., the body of the axis may be exhibit right laterality with left spinous deviation).
Cobb’s Method of Scoliosis Evaluation Cobb-Lippman method Projection: AP spine. End vertebrae Last segment that contributes to the spinal curvature. Extreme ends of the scoliosis, where the endplates tilt to the side of the curvature concavity Endplate lines On the superior end vertebra, a line is drawn through and parallel to the superior endplate On the inferior end vertebra, a line is constructed in a similar manner through and parallel to the inferior endplate This is the preferred method in scoliosis assessment In patients with double scoliotic curves each component should be measured. 5° progression of a scoliosis between two successive radiographs is considered significant Curvatures < 20° - No bracing or surgical intervention Patient between 10 and 15 years of age, careful monitoring should be implemented to assess for progression of 5° or more in any 3-month period. Curves between 20° and 40° - Bracing / Surgical intervention Curvature progression in an immature spine, or curvature in excess of 40° - Surgical intervention Risser-Ferguson Method of Scoliosis EvaluationAP spine. Apical vertebra Most laterally placed segment in the curveVertebral body center For each end vertebra and apical segment diagonals are drawn from opposing corners of the body to locate the body center Connecting line
Two lines are constructed connecting the body centers of the apical segment with each end vertebra, and the resultant angle is measured This method gives values approximately 25% lower than those of Cobb’s method (10°) Advocated its use for larger curves Coupled spinal motion sign Spinal motion is not pure and occurs in directions other than the primary direction of movement For example, on frontal cervical, thoracic, or lumbar lateral bending projections, the lateral tilting of each vertebra is accompanied by concurrent vertebral rotation In the cervical and upper thoracic region the spinous processes rotate to the convexity of the curve In the lumbar and lower thoracic region the spinous processes rotate to the concavity of the curve The amount of coupled motion may be small and therefore radiographically imperceptible. Alteration of the normal coupled motion occurs with aberrant intersegmental mechanics, muscle spasm, and vertebral fusion Interpedicular Distance Coronal dimension of the spinal canal Projection: AP cervical spine, thoracic spine, and lumbar spine. The shortest distance between the inner convex cortical surfaces of the opposing segmental pedicles is measured Spinal Level Maximum (mm) Cervical spine 30 Thoracic spine 20 L1 TO L3 25 L4, L5 30
This is a useful measurement applied in the evaluation of spinal stenosis, congenital malformation, and intraspinal neoplasms The maximum interpediculate distance may be increased as a result of pedicular erosion from an expanding spinal cord tumor (Elseberg-Dyke sign) Thoracic Cage Dimension Straight back syndrome evaluation Projection: Lateral chest. The distance between the posterior sternum and the anterior surface of the T8 body is measured Normal Sagittal Dimensions of the Thoracic Cage Sex Average (cm) Minimum (cm) Maximum (cm) Male 14 11 18 Female 12 9 15 Sagittal Dimensions of the Thoracic Cage in Straight Back Syndrome Sex Average (cm) Minimum (cm) Maximum (cm) Male 11 9 13 Female 10 8 11 Thoracic KyphosisLateral thoracic spine A line is drawn parallel to and through the superior endplate of the T1 body A similar line is drawn through the inferior endplate of the T12 body. Perpendicular lines to these endplate lines are then constructed Intersecting angle is measured
Physiologic anterior vertebral body wedging accounts for the natural kyphotic curvature of the thoracic spine Normal anterior wedging for each vertebral body is 4-5° or 2-3 mm The wedging increases by almost 1 mm for each successive level, with approximately 45° of thoracic kyphosis accounted for by this wedging Increased kyphosis Old age Osteoporosis Scheuermann’s disease Congenital anomalies Muscular paralysis Cystic fibrosis Reduction in kyphosis straight back syndrome Lumbar Intervertebral Disc Angles Lines are drawn through and parallel to each lumbar body endplate The lines are extended posteriorly until they intersect Intersecting angle is measured Normal Values for Lumbar Intervertebral Disc Angles Disc Level Average Angle (°) L1 8 L2 10 L3 12 L4 14 L5 14Mean angle alteration Antalgia Muscular imbalance
Improper postureFacet syndrome - Increased AngleAcute discal injuries - Decreased AngleLumbar Intervertebral DiscHeightLateral lumbar spine Visual assessment Disc height compared with the adjacent levels Past experience Hurxthal’s method The distance between the opposing endplates at the midpoint between the anterior and the posterior vertebral body margins is measured. Farfan’s method Anterior disc height (A) & posterior disc height (P) are measured and expressed as a ratio to disc diameter (D) These two ratios are then reduced to a ratio of each other Lumbar spine - normal disc ratios increase LI 0.17 L2 0.18 L3 0.20 L4 0.25 L5 0.28 When segmental rotation is > 40° or lateral flexion is > 20°, these methods become unreliable. Decreased disc height Disc degeneration Post surgery Post chemonucleolysis Infection Congenital hypoplasia
Hadley’s S Curve Lumbar facet curve Projection: Oblique, AP lumbar spine Curvilinear line is constructed along the inferior margin of the transverse process and down along the inferior articular process to the apophyseal joint space Line is then continued across the articulation to connect with the outer edge of the opposing superior articular process The resultant configuration of this line will look like the letter S The key region of the S is the normally smooth transition across the joint space Abrupt interruption in the smooth contour of this line may indicate facet imbrication (subluxation) Lumbar Gravity Line The center of the L3 body is located by intersecting diagonals from opposing body corners A vertical line is constructed through center point Relationship to the upper sacrum is assessed Center of gravity of the trunk passes through the center of the L3 body and continues vertically to intersect the sacral base Normally the vertical line will pass through the anterior third of the sacral base. If this line passes anterior to the sacrum by > 0.5 inch (> 10 mm), an increase in shearing stresses in an anterior direction between the lumbosacral apophyseal joints may be occurring. Conversely, it has been suggested that a posterior shift in this gravity line may indicate increased weight bearing forces on these same lumbosacral joints that may also be active in the production of low back pain
Van Akkerveeken’s Measurement of Lumbar Instability Projection: Lateral lumbar spine (neutral, flexion, extension). Two lines are drawn through and parallel to opposing segmental endplates until they intersect posteriorly. The distance from the posterior body margins to the point of intersection is then measured. Alternatively, the displacement can be assessed by measuring the offset in the opposing body cornersNormal Measurements There should be < 1.5 mm displacement, as determined by either measurement method If there is > 1.5 mm (3mm) difference in measurement, then it is likely that nuclear, annular, and posterior ligament damage at the displaced segment is present Lumbar Lordosis Lumbar curve, lumbar spinal angle, lumbar angle Projection: Lateral lumbar spine. Line is drawn through and parallel to the superior endplate of the first lumbar segment Second line is drawn through the superior endplate of the first sacral segment Perpendiculars are then created, and the angle at their intersection is measured A wide variation exists within normal individuals. The average appears to be 50-60°
Lumbar spinal canalEisensteins methodLateral lumbar projection Line is drawn connecting the tips of the superior and inferior articular processes of the same segment The canal width (x) is expressed as the distance from the posterior body margin to the middle portion of the facet line The canal dimension should not fall below 15 mm (although some use 14 mm or 12 mm as the cutoff) Smaller measurements may indicate spinal stenosis Spinal stenosis is more accurately assessed on axial MRI and CT imagesRATIO METHODFrontal lumbar projection Interpedicular distance is multiplied by sagittal width Coronal width of the vertebrae is multiplied by the sagittal width The product of the two canal measures is divided by the product of the two vertebral measures, expressing the canal size as a ratio of the vertebral body In the lumbar spine, the canal ratio should not fall below 1:3 Meyerding’s Grading Method in Spondylolisthesis The superior surface of the first sacral segment is divided into four equal divisions. The relative position of the posterior inferior corner of the L5 body to these segments is then made
The posterior inferior corner of the L5 body should be aligned with the posterior-superior corner of the first sacral segment. The same assessment can be applied to other spinal levels by dividing the superior endplate of the segment below the spondylolisthesis into four equal spaces. In spondylolisthesis, > 12° dynamic angulation or 8% translation on flexion- extension views is considered evidence of instability The degree of anterolisthesis of the affected vertebral body can be categorized according to the division in which the posterior-inferior corner of the body lies Grade 1 The posterior-inferior corner is aligned within the first division Grade 2 The posterior-inferior corner is aligned within the second division Grade 3 The posterior-inferior corner is aligned within the third division Grade 4 The posterior-inferior corner is aligned within the fourth division If the vertebral body has completely slipped beyond the sacral promontory, the condition is called spondyloptosis Lumbosacral Angle Two lines First, a horizontal line is made parallel to the bottom edge of the film Second, an oblique line is drawn through and parallel to the sacral base. Normal Values for Lumbosacral AnglePosition Average Standard Minimum Maximum (°) Deviation (°) (°)Upright 41 ±7 26 57
Sacral angle / Barges angle The angle of the superior margin of the sacrum from the horizontal plane, measured in the sagittal plane lumbar lordosis increased if the sacral angle increased Ullmann’s Line Garland-Thomas line, right-angle test line Projection: Lateral lumbar spine, lumbosacral Parallel to and through the sacral base Perpendicular to the first line at the anterior margin of the sacral base. The relationship of the L5 body to this perpendicular line is then assessed Anterior margin of the L5 body crosses the perpendicular line,Anterolisthesis This is a useful line for detecting the presence of spondylolisthesis when there is poor visualization of the pars region
Upper Extremity Measurements Acromioclavicular joint space AP or posteroanterior (PA) shoulder. The joint space is measured at the superior (S) and inferior (I) borders, and the two values are averaged Normal Values for Acromioclavicular Joint Space Sex Average (mm) Minimum (mm) Maximum (mm)Male 3.3 2.5 4.1Female 2.9 2.1 3.7 Decreased joint space Degenerative joint disease Increased joint space Traumatic separation Hyperparathyroidism Rheumatoid arthritis Acromiohumeral joint space AP shoulder. The distance between the inferior surface of the acromion and the articular cortex of the humeral head is measured Normal Values for Acromiohumeral Joint Space Average Minimum Maximum (mm) (mm) (mm) 9 7 11Narrowed space (<7mm) Superior shoulder displacement, which is often secondary to shoulder impingement syndrome with rotator cuff tendonopathy.Enlarged space (>11mm) Dislocation Joint effusion Paralysis
Brachial plexus lesions (drooping shoulder)Glenohumeral joint space AP shoulder with external rotation. The measurements are made at the superior, middle, and inferior aspects of the joint. These are combined and averaged. Each distance is ascertained between the opposing articular surfaces The average joint space is 4-5 mm Joint space diminished Degenerative arthritis, Calcium pyrophosphate dihydrate (CPPD) crystal disease Post-traumatic arthritis. Widened space Acromegaly Posterior humeral dislocation. Axial Relationships of the Shoulder Humeral axial angle AP shoulder with external rotation. Humeral shaft line (A). A line is drawn through and parallel to the humeral shaft. The average humeral angles are 60° for males and 62° for females This relationship may be altered following a fracture, especially in the surgical neck.
Elbow - Anterior humeral line On the lateral elbow projection a line drawn along the anterior surface of the humerus should intersect the middle third of the lateral condylar ossific center. If the line passes anterior or posterior to the middle third of the lateral condyle, a fracture may be present Radiocapitellar LineRadiocarpal line Lateral elbow. A line is drawn through the center of and parallel to the long axis of the radius and is extended through the elbow joint. This line should pass through the center of the capitellum in all stages of flexion of the elbow This assists in determining the presence of radial head subluxation (pulled elbow) or dislocation Axial Relationships of the Wrist PA and lateral wrist. Radioulnar articular line (A). A tangential line is drawn from the tip of the radial styloid to the base of the ulnar styloid. Radial shaft line (B). A line is drawn through and parallel to the shaft of the radius. Radioulnar angle (I). The ulnar side angle between the two lines is measured.
Normal Values for Axial Relationships of the Wrist Angle Average (°) Minimum (°) Maximum (°) PA radioulnar 83 72 95 Lateral radius 86 79 94These lines and constructed angles aid inthe assessment of radioulnar deformities,especially those caused by displacedfractures Hand - Capitolunate sign On the lateral wrist projection, lines are drawn to approximate the long axes of the lunate and capitate. Assessment assists in determining the presence of fracture or dislocation. Scapholunate angle (scaphoid tilt) On the lateral wrist projection, lines are drawn to approximate the long axes of the scaphoid and lunate. If the angle is greater than 80 and the lunate is also extended (dorsiflexed), dorsal intercalated segmental instability (DISI) is suggested. Metacarpal Sign PA hand
A line is drawn tangentially through the articular cortex of the fourth and fifth metacarpal heads The line should pass distal to or just touch the third metacarpal headPostive in Turner’s syndrome Fracture deformity Pseudo/ pseudo-pseudo hypoparathyroidism Metacarpal index Determined by dividing the length of each of the last four metacarpals by the width of its midpoint and averaging the values Marfans patients are often grater than 8.4, while normals are less than 8. Method 2 The outer and inner diameters of the metacarpal bone is measured, as shown below. From these measurements, the Combined Cortical Thickness (CCT) and the Metacarpal Index (MCI) are easily calculated CCT = L1 - L2 MCI = CCT / L1 Radiolunate angle (lunate tilt) On the lateral wrist projection, lines drawn to approximate the long axes of the radius and lunate should be parallel. If the lunate is flexed more than 15 degrees, volar intercalated segment instability (VISI) is suggested.
If the angle is greater than 10 degrees in extension, dorsal intercalated segment instability (DISI) is suggested. Occasionally VISI and usually DISI occur with scapholunate dissociation VISI is also related to triquetrolunate dissociation Radioulnar variance On the anteroposterior wrist projection, the distal ulnar articular surface should align with the inner portion of the distal radial articular surface. Short ulna Avascular necrosis of the lunate (Kienbocks disease) Greater carpal stress distribution to the radius Long ulna Greater carpal stress distribution to the ulna. Differences of less than 5 mm are probably not significant. Teardrop Distance Medial joint space of hip. The distance between the most medial margin of the femoral head and the outer cortex of the pelvic teardrop is measuredABNORMAL MEASUREMENT • >11 mm or • > 2 mm discrepancy from right to left (Waldenstrom’s sign)Normal Values for Teardrop DistanceAverage Minimum Maximum (mm) (mm) (mm) 9 6 11 Left to right discrepancies of > 1 mm will be present in 90% of hip joint effusions. Legg-Calve-Perthes disease Septic arthritis Other inflammatory diseases.
Hip Joint Space Width Three measurements are made of the joint cavity Superior joint space: Space between the most superior point on the convex articular surface of the femur and adjacent acetabular cortex. Axial joint space: Space between the femoral head and acetabulum immediately lateral to the acetabular notch. Medial joint space (teardrop distance): Space between the most medial surface of the femoral head and opposing acetabular surface Normal Values for Hip Joint Space Width Space Average (mm) Minimum (mm) Maximum (mm) Superior 4 3 6 Axial 4 3 7 Medial 8 4 13 The superior and axial compartments are approximately equal (4 mm), The medial space is twice the distance (8 mm) Superior joint space Reduction Degenerative joint disease Axial joint space Degenerative arthritis Inflammatory arthritis (RA) Medial joint space Degenerative or inflammatory arthritis Acetabular Depth A line is drawn from the superior margin of the pubis at the symphysis joint to the upper outer acetabular margin.
Normal Values for Acetabular Depth The greatest distance Space Average (mm) Minimum Maximum from this line to the (mm) (mm) acetabular floor is Male 13 7 18 measured Female 12 9 18 An acetabular depth < 9 mm in females and < 7 mm in males is considered to be shallow and dysplastic, which may be a factor in precipitating degenerative joint disease of the hip. Acetabular center-edge angleCE angle, CE angle of Wiberg. A vertical line is drawn through the center point of the femoral head. Another line is constructed through the femoral head center to the outer upper acetabular margin. Normal Values for Center-Edge Angle The angle formed is then Average (°) Minimum (°) Maximum (°) measured. 36 20 40 Shallow angle Acetabular dysplasia degenerative joint disease. It provides a measure of coverage of the femoral head, which means the amount of the acetabulum primarily concerned with weight bearing Symphysis Pubis Width The measured distance is between the opposing articular surfaces, halfway Normal Values for Symphysis Pubis Width Sex Average (mm) Minimum (mm) Maximum (mm)Male 6 4.8 7.2Female 5 3.8 6
between the superior and inferior margins of the jointWidening of thesymphysis cleidocranial dysplasia, bladder exostrophy Hyperparathyroidism Normal Values for Acetabular Angle in 1-Year- post-traumatic diastasis Old inflammatory resorption Average (°) Minimum Maximum ankylosing spondylitis (°) (°) osteitis pubis 20 12 29 gout Presacral Space Retrorectal space The gray soft tissue density located between the anterior surface of the sacrum and the posterior wall of the rectum is assessed The most consistent measurement was obtained at the level opposite the S3-S4 disc spaceAn increase Normal Values for Presacral Spacemeasurement sacral destruction Age Average Minimum Maximum Tumor (mm) (mm) (mm) Children (1- 3 1 5 infection 15 years) sacral fracture and Adults 7 2 20 associated hematoma inflammatory bowel disease (in which there is thickening of the intestinal wall). Acetabular Angle
A transverse line is drawn through the right and left triradiate cartilages at the pelvic rim A second oblique line connecting the lateral and medial acetabular surfaces is then constructed The angle of intersection is measured Increased acetabular angle acetabular dysplasia congenital hip dislocation Decreased acetabular angle Down’s syndrome. Acetabular index Horizontal line is drawn through the right and left triradiate cartilage (Hilgenreiners Line). Another line is drawn along each of the acetabuli to intersect the horizontal triradiate cartilage line Dividing the hip into 4 quadrants. The proximal medial femur should be in the lower medial quadrant, or the ossific nucleus of the femoral head, if present (usually observed in patients aged 4-7 month), should be in the lower medial quadrant. The acetabular index is the angle between the Hilgenreiner line and a line drawn from the triradiate epiphysis to the lateral edge of the acetabulum.
The angles of intersection (x°) should not exceed standards based on age: @ Birth < 36 degrees in females, < 30 degrees in males; 6 months < 28 degrees in females, < 25 degrees in males; 1 year < 25 degrees in females, 24 degrees in males; 7 years < 19 degrees in females, < 18 degrees in males Enlarged angle Acetabular dysplasia Congenital dislocation of the hip Shallow angle - Down syndrome
Iliac Angle and Index A line is drawn through the triradiate cartilage at the pelvic rim A second line is constructed tangential to the most lateral margin of the iliac wing and iliac body Iliac index: This is the sum of both the iliac angles and the acetabular angles divided by 2. The iliac index is most useful in the determination of Down’s syndrome. When the index is < 60, Down’s syndrome is probable; when the index is 60-68, the syndrome is possible; if > 68, the syndrome is unlikely Normal Values for Iliac Angle Age Average (°) Minimum (°) Maximum (°) 0-3 months 44 35 58 3-12 months 55 43 67 Normal Values for Iliac Index Age Average (°) Minimum (°) Maximum (°) 0-3 months 60 48 87 3-12 months 81 68 97
Measurements of Protrusio AcetabuliKöhler’s Line A line is constructed tangentially to the cortical margin of the pelvic inlet and outer border of the obturator foramen. The relationship of the acetabular floor to this line is assessed The acetabular floor should not cross this line and usually lies laterally to it. If the acetabular floor crosses the line, then protrusio acetabuli is present. The most common causes Idiopathic form Rheumatoid arthritis Paget’s disease Ankylosing spondylitis Shenton’s Line Makka’s line, Menard’s line. A curvilinear line is constructed along the undersurface of the femoral neck and is continued across the joint to the inferior margin of the superior pubic ramus. The constructed line should be smooth, especially in the transition zone between the femoral neck and superior pubic ramus. Occasionally, a small portion of the inferior femoral head may just cross the line Interrupted, discontinuous in Hip dislocation, Femoral neck fracture Slipped femoral capital epiphysis.
Iliofemoral Line A curvilinear line is constructed along the outer surface of the ilium, across the joint, and onto the femoral neck A small portion of the superior femoral head may cause a slight convexity in the line. The most important normal feature is that the line should be bilaterally symmetrical. A discrepancy in symmetry may be the result of congenital dysplasia, slipped femoral capital epiphysis, dislocation, or fracture Femoral Angle Femoral angle of incidence, femoral neck angle, Mikulicz’s angle. Two lines are drawn through and parallel to the midaxis of the femoral shaft and femoral neck. The angle subtended is then measured.
Skinner’s Line A line is drawn through and parallel to the axis of the femoral shaft. A second line is constructed at right angles to the shaft line and tangential to the tip of the greater trochanter. The relationship of the fovea capitis to this trochanteric line is assessed. The fovea capitis should lie above or at the level of the trochanteric line. The fovea lies below this line when there is a superior displacement of the femur relative to the femoral head. The most common causes are fracture and conditions leading to coxa vara. Klein’s Line A line is constructed tangential to the outer margin of the femoral neck. The degree of overlap of the femoral head will be apparent. Comparison should be made with the opposite side Generally there will be the same degree of overlap of the femoral head In most normal hips the outer margin of the femoral head will be lateral to the line. This line can be drawn on both the AP and frog-leg projections If the femoral head does not overlap the line or if there is asymmetry from side to side, then slippage of the femoral capital epiphysis should be suspected. Pelvic misalignmentInnominate rotation On the weight- bearing frontal pelvic projection Femoral head line (FHL) is drawn along the superior margins of the femoral heads bilaterally.
A perpendicular line from the FHL is constructed to intersect the second sacral tubercle and should pass through the center of the pubic symphysis when extended interiorly. If the perpendicular line intersects the pubic bone instead of the symphysis, the innominate is externally rotated on the side the line crosses through. The innominate on the opposite side is internally rotated. Rotation can be double-checked by measuring the width of the ilium (a) and the obturator foramen (b). External rotation of the innominate, using the posterior superior iliac spine (PSIS) as a reference point, is accompanied by a narrower ilium width and a wider obturator foramen on the ipsilateral side. Internal rotation is associated with a wider ilium and narrower obturator width ipsilaterally. Innominate flexion-extension. On the weight-bearing frontal pelvic projection, the distance from the top of the iliac crest to the inferior margin of the ischial tuberosity should be bilaterally similar Sacrum rotation. On the weight-bearing frontal pelvic projection, the distances from the lateral margins of the sacrum to the second sacral tubercle (c and d) are measured parallel to the FHL and should be similar. Leg length inequality. On the frontal weight bearing pelvic projection, a line is drawn parallel to the lower margin of the film to the superior margin of the highest femoral head. The line should approximate both femoral heads if the legs are of equal length The vertical measurement of the innominate is larger on the flexed side (PSIS has moved posterior and inferior) and smaller on the extended side (the PSIS has moved anterior and superior). The sacrum is rotated posteriorly on the wider side and anteriorly on the narrower side. If the line constructed parallel to the bottom of the film does not approximate the femoral heads bilaterally, the line is drawn to the higher femoral head, and the distance from the line to the lower femoral head estimates the measured leg length deficiency. Flexed (PI) or externally rotated (EX) innominate will decrease the leg length discrepancy when the innominate misalignment is corrected on the ipsilateral side of the short leg. In other words, correction of flexed or externally rotated innominate raises the ipsilateral femoral head
Conversely, an extended (AS) or internally (IN) rotated innominate will increase the leg length discrepancy when corrected on the ipsilateral side of the short leg. The opposite will be noted if the short leg is on the contralateral side of the innominate misalignment. Axial Relationships of the Knee AP knee. Four lines and two angles are drawn Femoral shaft line (A). A line is drawn through and parallel to the midaxis of the femoral shaft. Tibial shaft line (B). A line is drawn through and parallel to the midaxis of the tibial shaft. Femoral condyle line (C). A line is drawn through and tangential to the articular surfaces of the condyles Tibial plateau line (D). A line is drawn through the medial and lateral tibial plateau margins Femoral angle (FA). This is the angle formed between the femoral shaft and femoral condyle lines. Tibial angle (TA). This is the angle formed between the tibial shaft and tibial plateau lines Normal Values for Axial Relationships of the Knee Angle Average (°) Minimum (°) Maximum (°)Femoral 81 75 85Tibial 93 85 100 Significance. These angles will be altered in fractures and other deformities about the knee.
Patellar PositionPatella alta evaluation Lateral knee (semiflexed) Patellar length (PL). This is the greatest diagonal dimension between the superior and the inferior poles. Patellar tendon length (PT). The distance measured is between the insertion points of the posterior tendon surface at the inferior patellar pole and the notch at the tibial tubercle. Normal Measurements. Patellar length and patellar tendon length are usually equal to each other. A normal variation up to 20% > 20% - patella alta • chondromalacia patellae. A low-riding patella (patella baja) Polio Achondroplasia juvenile rheumatoid arthritis tibial tubercle transposition Patellar Malalignment Patellar tracking, patellar subluxation, patellofemoral joint incongruence. Tangential knee (skyline) Patella apex The patella is centered when its apex is directly above the
deepest section of the intercondylar sulcus. Sulcus angle By drawing lines from the highest points on the medial and lateral condyles to the lowest point of the intercondylar sulcus, an angle is formed. Normally, this should be 138° ± 6°. Larger angles (shallow intercondylar groove) predispose the individual to subluxation and dislocation. Lateral patellofemoral joint index: The narrowest medial joint space measurement is divided by the narrowest lateral joint space measurement. This index is normally ≤ 1.0. A value > 1.0 is noted in patients with chondromalacia patellae. Lateral patellofemoral angle. A line tangential to the femoral condyles is intersected by a line joining the limits of the lateral facet. The angle is normally open. In patellar subluxation these lines are parallel or open medially. Significance. The combined use of these measurements may reveal contributing causes to patellofemoral joint pain syndromes and instability
Axial Relationships of the Ankle Four lines and two angles are constructed. Tibial shaft line (A). A line is drawn through and parallel to the tibial shaft. Medial malleolus line (B). A line is drawn tangential to the articular surface of the medial malleolus. Lateral malleolus line (C). A line is drawn tangential to the articular surface of the lateral malleolus. Talus line (D). A line is drawn tangential to the articular surface of the talar dome. Tibial angle (I). The angle is formed medially between the medial malleolus line and talus line. Fibular angle (II). The angle is formedlaterally between the lateral malleolus lineand talus line Normal Values for Axial Relationships of the Ankle Angle Average Minimum Maximum (°) (°) (°)Tibial (I) 53 45 65Fibular (II) 52 43 63 Significance. These angles will be altered in fractures of the malleoli, ankle mortise instability, and tibiotalar slant deformities. The tibiotalar joint space is measured at the lateral and medial joint margins. This should be done on varus-valgus stress studies, on which there should not be > 3 mm difference between the normal and injured sides. Talar tilt is assessed by drawing a line tangential to the talar dome and another line along the adjacent tibial surface. In the neutral position, an angle > 6° indicates significant ligamentous injury. On valgus-varus stress views, the normal range is 5-23°.
A difference between right and left of > 10° also indicates significant ligamentous damage. An anterior drawer of 4 mm is another indicator of instability. Boehler’s AngleAxial relationships of the calcaneus, tuber angle. Lateral foot, lateral calcaneus. The three highest points on the superior surface of the calcaneus are connected with two tangential lines. The angle formed posteriorly is then assessed Normal Measurements. The angle formed posteriorly averages between 30° and 35° in most normal subjects but may range between 28° and 40°. Any angle < 28° is abnormal. The most common cause for an angle < 28° is a fracture with displacement through the calcaneus. Dysplastic development of the calcaneus may also disturb the angle. Heel Pad Measurement Two lines are drawn First line connecting the superior tuborosity to superior most point of anterior process of calcaneum
Parallel to above line touching plantar surface of calcaneum Shortest perpendicular distance to second line is measured Normal Values for Heel Pad Measurement Sex Average Maximum (mm) (mm)Male 19 25Female 19 23 • Increased in • Obesity • myxedema • Acromegaly • Local inflammation First metatarsal angle On the anteroposterior foot projection, lines drawn to approximate the long axes of the first metatarsal and proximal first phalanx should form an angle (x°) of less than 15 degrees. An increased angle indicates a hallux valgus deformity. Mearys angle On the lateral foot projection, lines drawn to approximate the longitudinal axis of the first metatarsal and talus should be parallel If the lines are not parallel and form an angle that is greater than 0 degrees, forefoot cavus deformity is indicated.
Calcaneal pitch A line is drawn from the plantar most surface of the calcaneus to the inferior border of the distal articular surface. The angle made between this line and the transverse plane (or the line from the plantar surface of the calcaneus to the inferior surface of the 5th metatarsal head) is the calcaneal pitch. A decreased calcaneal pitch is consistent with pes planus. Unfortunately, there have been differing opinions between authors concerning the normal range of calcaneal pitch 18 to 20°is generally considered normal (12), although measurements ranging from 17 to 32° have been reported to be normal
Lateral Talocalcaneal Angle The lateral talocalcaneal angle is the angle formed by the intersection of the line bisecting the talus with the line along the axis of the calcaneus on lateral weight bearing views. A line is drawn at the plantar border of the calcaneus (or a line can be drawn bisecting the long axis of the calcaneus). The other line is drawn through two midpoints in the talus, one at the body and one at the neck. The angle is formed by the intersection of these axes. The normal range is 25-45 degrees. An angle over 45 degrees indicates hindfoot valgus, a component of pes planus Kites angle AP talocalcaneal angle Angle formed by the longitudinal axis of the Calcaneus and the Talus Kite Angle < 15° : Tendency to supine rearfoot 15° < Kite Angle < 25° : Normality range Kite Angle > 25°: Tendency to prone rearfootREFERENCE CLINICAL IMAGING – Dennis M.Marchiori Essentials of Skeletal Radiology 3rd Edition - Terry R. Yochum B.S., D.C., D.A.C.B.R., F.C.C.R. (C), F.I.C.C., Fellow, A.C.C.R