Chapter 23: RadiologyStandard Radiographic Techniques Specific Radiographic Studies Anatomic AnglesCommon Structural Measurements (Diagrams)Pediatric RadiologyThe OsteochondrititiesThe Accessory Bones of the Foot

RADIOLOGYStandard Radiographic Techniques of the Foot and Ankle

1. Dorsoplantar Projection: X-ray tube angled 15° from vertical and aimed at the lateral aspect of the navicular.

2. Weight-bearing Lateral Projection: X-ray tube angled at 900 from vertical

3. Non-weight-bearing Medial Projection: Useful in examining the talus, calcaneus, and lesser tarsal bones for the effects of trauma.

4. Lateral Oblique Projection: Gives a magnified and slightly distorted representation of the bones of the foot. Gives the most accurate picture of the shape of the proximal phalanx of the fifth toe.

5. Medial Oblique Projection: Has limited value in examining the foot.

6. Axial Sesamoidal Projection: Good for examining the plantar aspect of the sesamoids and their relationship with the 1st metatarsal head.

7. Axial Calcaneal Projecton: Useful when examining the calcaneus for fractures, abnormalities of shape, or neoplasms

8. Harris and Beath (ski jump/coalition) Projection: Useful in examining the STJ (T-C coalitions of the posterior or middle facets), Calcaneal fractures, and sustentaculum tali. 3 exposures taken with the x-ray tube set at 35°, next at 40°, and then at 45°

9. Ankle Mortise Projection: The ankle is internally rotated 15° with the x-ray tube at 90° from vertical. Good for evaluating the joint space. The view for measuring the angles of the ankle (see Anatomic Angles below).

10. Lateral & Oblique Projections of the Ankle: Used in looking for the effects from trauma.

11. Stress Inversion Projection of the Ankle: Usually taken following inversion sprains. With the ankle joint anesthetized, bilateral views should be taken in plantarflexion and at right angles. It can sometimes be difficult to correlate the number of degrees of talar tilt with the number of ligaments ruptured.

The standard of our profession's technique (especially for pre-operative planning) is a weight-bearing x-ray of each foot individually, in the angle and base of gait, with proper shielding to the patient. This allows us to reproduce the same bony architectural relationships consistently.

12. Anterior Drawer Projection: Is taken following trauma to the ankle joint, with a distraction force placed on the forefoot. (looking for an anterior excursion of the talus out of the mortise). If the excursion is greater than 4 mm. as compared to the opposite side, then disruption of the anterior talofibular ligament is assumed.

13. Stress Dorsiflexion Projection: Can be useful for the evaluation of talipes equinovarus (measure the T-C angle).

14. Isherwood Projections: Consist of 3 projections to fully visualize the STJ. They are: the lateral oblique, medial oblique axial, and lateral oblique axial. Positioning is very difficult with these positions, so better use tomograms or CT.

15. Broden Projections: For examination of the STJ (Broden #1 examines the posterior facet & Broden #2 examines the sinus tarsi). Consists of 4 views with the beam angled at 10°, 20°, 30°, and 40° while centering the x-ray tube on a point 2 cm anterior and distal to the tip of the lateral malleolus. Has generally been replaced by tomography and CT.

16. Anthansen Projections: To view the medial and posterior facet of the STJ.

Specific Radiographic Studies1. Bone Scanning: Bone scintigraphy using technetium-99m MDP is excellent for screening as it provides extremely good sensitivity but at the expense of being very nonspecific.Increased tracer uptake occurs as a result of hyperemia. A positive bone scan does not necessarily represent an osseous lesion, because juxtacapsular joint lesions, periosteal inflammation, or inflammation at tendonous insertions can also produce positive results. The predominant scintigraphic finding is a "hot spot" (increased tracer localization). The exception to this are "cold spots" which is due to NO delivery of the tracer as a result of poor circulation, necrosis, or a fulminant destructive osteomyelitis not accompanied by significant reparative processes which is also due to poor circulation. To obtain good-quality scintigraphic results the following guidelines should be followed: Request close up views of the foot and ankle with multiple angles of view (not whole body shots), and have the studies supervised by a radiologist who can ensure that the images are filmed at appropriate densities (this avoids white-outs or black outs). a. 99m Technetium-MDP is currently the most frequently used radionuclide.b. It is renally excretedc. Has a half-life of 6 hours,

Note* Some feel that a tilt of 159= rupture of the anterior talo-fib ligament, 15309= rupture of the anterior talo-fib ligament and calcaneofib ligaments, and over 30° of talar tilt= all three ligaments ruptures (this is a guide, not a hard and fast rule)

d. MDP chemiadsorbs to bone with the hydroxyapatite crystal (99mTc is just a label)e. Provides more anatomic information with less time, exposure and expense than Gallium 67 imaging.f. May continue to show abnormal isotope accumulation after infection subsides as a result of continued bone repair.g. Uptake of technetium 99m MDP will occur in any focus of increased bone turnover, whether due to physical stress (osteoarthritis), repair (fracture, reactive periostitis, rheumatoid arthritis, plantar fasciitis), or tumor (primary or secondary; multiple myeloma is a relative exception) h. When to order: Persistent pain with negative x-rays, osteomyelitis from overlying soft tissue infection (x-ray negative), extent of osteomyelitis, progress of healing of osteomyelitis and fracture, osteomyelitis ve Charcot, and unexpected x-ray or MRI abnormality

2. Gallium Scanning: The isotope, Gallium-67 citrate, was originally developed as a marker for certain tumors, i.e. lymphoma, and is considered an imaging marker for inflammation. It is less dependent upon blood flow than technetium.a. There are 3 mechanisms for Gallium-67 localization: i. Leukocyte localization or incorporationii. Direct lactoferrin and transferrin binding at the site of infection (also Gallium binds to the siderophores of bacteria)iii. Direct bacterial uptake by phagocytesb. The usual dosage of is 3-5 mCi, and is usually performed 24 hours after injection

Three Phase Bone Scan: is used to differentiate OM from cellulitis.Phase 1: at time of injection shows an immediate radionuclide angiogram or dynamic blood flow, OM and cellulitis both show increased uptake at this point.Phase 2: 10 minutes after injection looking for focal increases (blood pool image) cellulitis and OM are still positive at this point. Phase 3: 4 hours after injection (delayed static scan or bone image), cellulitis becomes quiescent at this point- ONLY CLASSICALLYPhase 4: 24 hours later used for patients with poor vascular flow and the 3rd phase looks almost exactly like the 2nd phase (increased sensitivity for detecting osteomyelitis in the diabetic foot)

NOTE* False negatives have been reported in infants and children

NOTE* Osteomyelitis has intense and focal uptake in all 3 phasesNOTE* Bone scans are a good indicator if the Reflex Sympathetic Dystrophy patient will be responsive to treatment

NOTE* Gallium is more reliable in differentiating benign from malignant tumors, assessing subacute and chronic infections. The only tumor Gallium is specifically used for is lymphoma

c. Combination of gallium scanning following technetium scanning by 24 hours (due to the short half life of Tc-99m)is helpful in distinguishing chronic from acute OM, and cellutitis from OM. d. Gallium is valuable in monitoring disease activity and response to treatment in patients with chronic osteomyelitis (gallium is not as sensitive to bone remodeling as technetium)e. Gallium imaging is for chronic infection, predominantly lymphocytes

3. 111 Indium White Cell Scanning (Indium is just the label): This scan is much more specific for infection (especially acute infections) and involves predomininantly granulocytes. With this scan, the patient's white blood cells are labeled with the tracer and injected intravenously. This technique was developed to detect leukocyte accumulation at sites of inflammation and abscess formation. Scans are performed 24 hours after injection. A positive scan is defined as a focal accumulation of leukocytes that is higher than the surrounding bone activity. This technique is reserved for complicated post-traumatic or post-surgical patients with equivocal conventional bone scans, in cases where 99mTc MDP scanning reveals false positive results because of rapid turnover. Therefore, it may be more accurate in detecting acute infections. VIII. Limitations of Scans: Some patients show multiple hot spots at an early stage of S. aureus septicemia but do not progress to OM. You can have a negative scan with a confirmed OM due to impaired blood supply (false-negative). You can have difficulty in differentiating OM from cellulitis. You can have difficulty in differentiating normal bone repair from bone infection (false-positive).

4. Xeroradiography: A process in which an image is produced on a selenium-coated plate. This process tends to emphasize the characteristics of borders between tissues, making detailed information more easily seen. It is sensitive enough to visualize non-metallic foreign bodies. (no longer readily available)

5. Fluoroscopy: An imaging modality in which x-rays are produced continuously on demand to give a real-time, dynamic image that is displayed on a television screen. The C-arm fluoroscope is the usual unit used intraoperatively.

6. MRI: MRI gathers information (imaging the nucleus of the atom) in theform of low energy radiowaves and transduces this energy into imageswith the use of computers. Four components are necessary for theproduction of such images: Magnetic nuclei (the sample) The strong magnetic field Coils to transmit and receive radio frequency waves Magnetic gradiance (small magnetic fields with known, carefullycontrolled spatial variation)

a. On T1-weighted images, tissue characterized by a short T1 relaxation time produces a high-intensity signal, whereas, long T1 tissue yields a low-intensity signal. Conversely, on T2-weighted images, a long T2 relaxation time which results in high signal intensity, and a short T2 results in low signal intensity.

b. T1-weighted images provide the best signal-to-noise ratio, resulting in superior anatomic definition. A typical T1 weighted image : repetition time of 500 millisec and echo time of 30 millisec (TR500/TE30). These numbers can be seen to the right of the image on the film, which allows you to determine if the image is T1 or T2 or or a proton image. c. T2-weighted images provide the best soft tissue contrast, and are therefore, best for many pathologic processes, such as neoplasms and inflammation.d. High density (bright) areas most often reflect a high density of mobile protons or tissues with a short T1 or a long T2 (bone marrow and subcutaneous tissues that contain large amounts of fat). Low intensity (dark)

NOTE* Protons spin on their long axis, making a magnetic field. In the human body, these protons spin randomly. When the body is placed in the MRI machine, most (or more) of the protons line up parallel to the magnetic field of the machine. Feeding radiowaves into the body (RF), the protons are excited and energy is released producing an image.

Most clinical MR imaging is performed with spin-echo pulse sequences.A spin-echo sequence consists of a 90° pulse followed after a time period by a 180° pulse, with a consequent production of a signal (echo). The echo-time (TE) is the time elapsed from the beginning of the 90° pulse to the peak of the echo. The repetition time (TR) is the time elapsed between successive 90° pulses. In typical MRl foot ankle studies the spin echo sequence is performed twice (referred to as 2 averages or excitations)

By varying both TR and TE, images that primarily reflect TI-relaxation, T2-relaxation, or proton density may be obtained.a. A signal that reflects primarily T1 images is produced by using a spin-echo sequence of a short TE (20-30 msec) and short TR (300-800 msec)b. T2 images are produced with a long TE (60-120 msec) and long TR (15003000 msec)c. A proton image (or balanced image containing properties of both T1 and T2) is produced with a short TE and long TR

With all other factors being equal, imaging time is directly proportional to TR, with T2 images taking the longest time to obtain (prone to degradation due to motion by the patient)

NOTE* Adequate characterization of musculoskeletal disease usually requires both T1 & T2-weighted images, because each provides complimentary information in terms of soft tissue contrast and anatomic detail.

areas have fewer mobile protons (cortical bone and tendons). Most soft tissue tumors (with the exception to those composed of fat) have an appearance to those of muscle (low to intermediate signal intensity) on T1 weighted images, but can be differentiated from muscle on a T2 weighted image.

NOTE* Evaluation of T1 weighted images:a. Dark (black) areas are: tendons, subchondral cortex of bone, blood vessels with moving blood, ligaments, muscles, tumors b. Light (white) areas: fat (whitest), medullary bone, stationary blood Evaluation of T2 weighted images:a. Dark areas: ligaments, compact boneb. Intermediate areas (gray): subcutaneous fat, bone marrow, muscle c. Light areas: stationary blood, tumorEvaluation of proton image:a. Intermediate (gray): fluid , muscles

e. Benefits of MRI:i. MRI is better than CT in evaluating bone tumors of the medullary canal

NOTE* There are other MRI Stues: STIR mage wcs gooor tumors anGradient echo (also known as magnetic resonance angiography) which is good for hyaline cartilage

(CT has higher resolution for tumors of the cortex). It permits better delineation of the tumor and has superior soft tissue contrast

ii. MRI is excellent in diagnosing trauma with patients that have preexisting metallic implants.iii. MRI is the imaging modality of choice for avascular necrosis.iv. MRI gives direct multiplanar imaging capabilities in any desired plane (sagittal, axial, and coronal)

f. Precautions:i. MRI not to be done in the first trimester of pregnancy (no studies showing fetal abnormalities with MRI to date)ii. MRI should be avoided with cerebral aneurysm clips (may become dislodged), cardiac pacemaker (interfere with function), and implanted metallic objects near the orbit of the eye)iii. Patients with claustrophobia may require sedation

NOTE* MRI cannot predict malignancy vs. non-malignancy

NOTE* When ordering an MRI you must specify what you are trying to look for, and if you want a certain view, you must specify this too

7. CT Scanning: Can establish the presence, nature, size, margination, and exact location of tumors. Muscle and soft tissue involvement can be determined. If a tumor is located next to blood vessels, a contrast medium is needed to enhance its identification. Is excellent to evaluate metabolic bones diseases (osteoporosis, aseptic necrosis, osteomalacia). It is excellent in evaluating trauma especially the calcaneus and STJ. The CT can dictatewhether open reduction would be beneficial and whether one or a twosided approach is indicated to effect the reduction. CT is excellent in the diagnosis of tarsal coalition and degenerative changes of the tarsus or lesser tarsus where superimposition has always been a problem.

8. Arthrography: Following the injection of contrast medium into a joint, x-rays are taken. Good for the diagnosis of capsular or ligamentous tears. Has been replaced by MRI when available. Contrast media can cause anaphylactic reactions

9. Tomography: This procedure requires a complex reciprocal motion of both the radiographic tube and cassette around the patient. It requires a relatively large number of radiation exposures and demands exacting technique, but has the advantage of providing excellent bony detail in areas of complex osseous anatomy. The most useful applications of tomography are in the evaluation of osteochondral fractures in the dome of the talus; arthritic changes or loose bony fragments of the STJ and the tarsometatarsal joints, stress fractures of the navicular, union vs. non-union of an arthrodesis site, and the status of metallic implants (metallic implants affect the quality of CT and MRI).

10. Tenography: Is most often used on the ankle tendons. It can also document calcaneofibular ligament tears, because this ligament is contiguous with a part of the peroneal tendon sheath. It has been used to identify irregularities of the peroneal tendons themselves. Has generally be replaced with MRI (non-invasive).a. Tenogram shows narrowing and irregularity of the involved tendon b. Is only useful in tendons that go around a bone (like the malleoli) c. Tenography of the posterior tibial tendon reveals 3 types of pathology: central swelling, thinning of the tendon, and rupture d. The results of tenography can be:i. Normalii. Mild marginal irregularityiii. Moderate marginal irregularityiv. Marked marginal irregularityv. Occlusion of the tendon sheathe. Contrast is injected into the proximal portion of the tendon sheath (Conray 43®) mixed 50/50 with Xylocaine®. Upon completion of thetenogram, a steroid is injected

Anatomic Angles1. Angles of the Ankle: Are helpful when evaluating ankle trauma. on the D-P projection.

2. Angular Relationships on the D-P Projection:a. Talocalcaneal Angle or Angle of Kite (normal for ages 0-5 years= 35-50° & ages 5-adult= 15-35°): Has long been used as an index of relative foot pronation and supination. It is a measure of the transverse plane angular relationship between the longitudinal bisectors of the talus and calcaneus. It becomes increased with STJ pronation and reduced with supination.

b. Cuboid Abduction Angle (normal= 0-5°): Lines along the lateral surfaces of both the cuboid and calcaneus. With pronation (increased abduction: Lenoire's sign) the angle increases. This is important with serial casting.

c. Forefoot Adductus Angle (normal=0-15° In the rectus foot): Is the angle formed by the longitudinal reference of the rearfoot and the bisection of the second metatarsal.

d. Metatarsus Adductus Angle (normal= 0-15°): The relative position of the forefoot to the rearfoot. It is measured on D-P view by comparing the longitudinal bisection of the second metatarsal, with the bisection of the lesser tarsus. An increase of the angle results in medial deviations of the first metatarsal.

e. Metatarsus Primus Adductus Angle or First Intermetatarsal Angle (normal in rectus foot--8-1 2° and 8-10° In adductus foot): Represents the medial deviation of the first metatarsal relative to the second. The angle is measured on D-P view by the intersection of longitudinal bisections of the first metatarsal and second metatarsal.

f.

Tibial Sesamoid Position (positions 1-3 can be considered normal): This position is sometimes used to decide the necessity for fibular sesamoid removal during HAV surgery. The change in sesamoid position occurs relative to the 1 st metatarsal head. TSP is measured relative to the 1 st metatarsal bisector. There are 7 positions.

g. Hallux Abductus Angle (normal= 10-15°): Represents the transverse plane position of the hallux relative to the long axis of the first metatarsal. This angle is produced by the intersection of the first metatarsal and first proximal phalangeal bisectors. This measurement quantifies the lateral deviation of the hallux in HAV.

h. Hallux Interphalangeal Angle (normal= 0-10°): Represents the lateral hallux deviation at the level of the IP joint. It is the measurement of the angle produced by the intersection of the proximal and distal phalangeal bisectors. Increases in this value produce a lateral curvature of the hallux that become clinically significant, and becomes an important assessment of HAV when attempting to determine whether a proximal or distal Akin or Akin arthrodesis should be performed.

NOTE* In general, angular increases up to 15° are correctable by distal osteotomies, while increases greater than 15° require proximal osteotomies

NOTE* A severely dislocated fibular sesamoid becomes a strong deforming force maintaining the hallux in the laterally rotated position, and impeding correction of a high metatarsus primus adductus angleNOTE* Removal of the fibular sesamoid plus cutting the adductor tendon will result in a hallux varus. Prior to its removal a plantar-axial view should be evaluated, and if there are no degenerative changes and lateral subluxation is not severe then the sesamoids can be relocated.

i. Proximal Articular Set Angle (normal= 7.5°): An angle formed by a perpendicular to a bisection of the 1 st metatarsal and a line representing the effective articular cartilage. This represents the effective cartilage in relation to the shaft of the metatarsal. Any increase in the PASA is pathological and may either add to a structural deformity or combined deformity (lateral deviation of the cartilage).j. Distal Articular Set Angle (normal= 7.5°): The angle that measures the relationship of the effective articulating cartilage of the base of the proximal phalanx to a mid-line bisection of the proximal phalanx of the hallux. If the DASA is highly abnormal, this may indicate the need for some type of osteotomy to reduce the angulation of the proximal phalanx.

k. Metatarsal Protrusion distance (normal = +/- 2 mm.): The measure in the difference on length between the 1st and 2nd metatarsals. This parameter is of primary concern when 1 st metatarsal surgery is being considered on a patient with an abnormally increased negative protrusion distance.

I. Metatarsus Quintus Abductus Angle (normal = 8-10°): The angle created by the intersection of the 4th and 5th metatarsal bisectors. This angle is increased with a splayed foot.

m. Metatarsal Parabola (normal= 142.5°): The angle formed by the intersection of lines touching the 1 st and 2nd metatarsal heads intersecting with 2nd-5th metatarsal heads.

3. Angular Relationships on the Lateral Projection:a. Calcaneal Inclination Angle (normal= 18-21°): Is a measurement of thesagittal plane position of the calcaneus as seen on the lateral x-ray. This angle is increased in rearfoot cavus deformities and decreased (or negative) in flatfoot deformities.

NOTE* The intermetatarsal angle between the 4th and 5th metatarsals can also be drawn using a line parallel to the proximal medial portion of the 5th metatarsal as the lateral arm and bisected the 4th metatarsal as the medial arm of the angle

NOTE* When examining for lateral bowing of the 5th metatarsal an angle calledthe lateral deviation angle of the 5th metatarsal is examined. This angle isformed by a line bisecting the head and neck of the 5th metatarsal and the line previous described to simulate the proximal 5th metatarsal shaft. Normal= 2.640 With pathology of the 5th metatarsal this number usually = 8°. When this is present the structural deviation should be considered as a significant contributing factor in the tailor's bunion deformity, and addressed surgically.

b. Talar Declination Angle (normal=21°): Is the angle formed by the plane of support and the column tali axis (bisector of the head and neck of the talus). This axis will be colinear with the 1st metatarsal declination axis. This angle increases with pronation and decreases with supination.

c. Cyma Line: A lazy S curve formed by the T-N and C-C joints (Chopart's joint). Pronation causes the T-N joint to be anteriorly displaced, and supination causes the T-N joint to be posteriorly displaced.

d. Sinus Tarsi: In the normal foot it is seen on lateral view as an oval area of decreased bone density, separating the posterior from middle subtalar facets. When pronation occurs, as the talus rides anteriorly on the calcaneus and plantarflexes, the sinus tarsi is obliterated.

e. Fowler-Phillip Angle (normal=44-69°): This is used to evaluate the posterosuperior tuberosity of the calcaneus (Haglund's deformity). Symptoms are common when this angle exceeds 700

f. Talocalcaneal Angle (normal=15-35°): Compares the long axis of the head and neck of the talus to the inferior surface of the calcaneus. This angle is decreased in the supinated foot and increased in the pronated foot. It is useful in determining the treatment with talipes equinovarus.

g. Bohler's Angle (normal=25-40°): Is used to describe the calcaneal architecture by defining the contour of the dorsal calcaneal surface. The angle is decreased in joint compression and beak fractures of the calcaneus as well as with Haglund's deformity.

h. Talometatarsal Angle or Meary's Angle (normal 0-10°): The angle formed from the bisection of the talus and the bisection of the first metatarsal. Is used in evaluating whether a plantarflexed or hypermobile ray is present.

i. Critical Angle of Gissane (normal=120-145°): This angle is created by the subchondral bone of the posterior calcaneal facet and of the middle and anterior calcaneal processes, as seen on the lateral view. It is utilized when evaluating calcaneal injuries.

j. Neutral Triangle: For reference, the sparsely trabeculated neutral triangle occurs just below, and posterior to the apex of the Critical Angle of Gissane.

4. Arthromorphic Variants: In HAV surgery there are further considerations that must be given to the structural anatomy of the 1st MPJ and the shape of the 1 st metatarsal head.a. Congruous joint: The measurement of the articulating cartilage of the

Note* The Talar Declination Angle and the Calcaneal Inclination Angle are inversely proportional

head of the 1st metatarsal and proximal phalanx is parallel

b. Deviated joint: The lines intersect outside the joint

c. Subluxed joint: The lines intersect within the joint

d. Dislocated joint: see diagram to follow

d. Round head: The weakest variant and deviates easily.

e. Square head: A more stable shape of joint

f. Square head with a central ridge: The most stable variant. It is believed that the central ridge is an extention of the plantar crista.

5. Hallux Abductus Deformity:a. Structural Deformity (bony): A deformity in which there is osseous change in either the PASA the DASA or both. The structural deformity has as its characteristics the congruous joint. The HA deformity is also equal to the summation of the PASA and the DASA.b. Positional Deformity (soft tissue): There is an abnormality in the HA angle. The PASA and DASA are normal. The joint is either deviated or subluxed. The summation of the PASA and DASA are less than the HA angle.

c. Combined Deformity: Has elements of both structural and positional deformities. Either the PASA or the DASA or both are abnormal, and when added together they do not equal the HA angle. The joint is either deviated or subluxed.

Common Structural Measurements (diagrams to follow)

Common Structural Measurements (A to W)A: Metatarsus adductus angle (normal 15°) B: Metatarsus adductus angle (alternate) C: Metatarsus primus adductus angle (normal 8-12°) D: Proximal articular set angle (normal 0-10°) E: Distal articular set angle (normal 5.2°)1st MPJ articulation: (F-I)F: CongruousG: Deviated

H: SubluxedI: DislocatedJ: Hallux abductus angle (normal 10-15°)K: Hallux abductus interphalangeal angle (normal 0-10°) L: Metatarsal protrusion distance (normal +/- 2mm) M: Tibial sesamoid positionN: Tangential angle to the second axis +5° to -5°O: Metatarsus quintus abductus angle (normal 7°) P: 1st metatarsal declination angle Q: Calcaneal inclination angle (normal 18-21°) R: Fowler-Phillip angle (normal 44-69°) S: Bohler's angle (normal 28-40°) T: Critical angle of Gissane (normal 120-145°)U: Dorsoplantar talocalcaneal angle (Kite) (normal 20-40°) V: Lateral talocalcaneal angle (normal 35-50°) W: Anterior cyma line

Pediatric Radiology1. Roentgenographic Development of the Foot:a. Important ossification points to remember:i. 1st bone to ossify before birth: calcaneus ii. Last bone to ossify before birth: cuboidiii. 1st bone to ossify after birth: lateral cuneiformiv. Last tarsal bone to ossify after birth: navicular at 3.5 years v. Calcaneal apophysis appears at age 7 years vi. Sesamoids appear at age 12 yearsb. Ossification at birth:i. Talusii. Calcaneusiii. Cuboid (can be absent in the premature baby) iv. Metatarsalsv. Proximal phalangesvi. Middle and distal phalanges 2-4 vii. Distal phalanx 1c. Age 3 months: lateral cuneiformd. Age 4 months: tibial epiphysise. Age 6 months: cuboid and lateral cuneiform articulatef. Age 7 months: talar neck appears, base of metatarsals widen g. Age 11 months: fibular epiphysis appears h. Age 18 months: phalangeal epiphyses appeari. Age 24 months: medial cuneiform and ossification of epiphysis of metatarsal 1j. Age 30 months: intermediate cuneiform ossifiesk. Age 36 months: ossification of epiphysis of metatarsals 2,3, and 4 l. Age 3.7 years: ossification of navicular m. Age 4.2 years: ossification of epiphysis metatarsal 5 n. Age 4.9 years: alignment of tarsal and metatarsal bones

o. Age 6.7: ossification of calcaneal epiphysisp. Age 12 years: sesamoids appearq. Age 13 years: os trigonum and os vesalianum appearr. Age 14 years: fusion of epiphyses of distal phalanges of toes 2, 3, and 4 s. Age 15 years: epiphyseal fusion of tibia/fibula, metatarsals 2/3/4, and phalanges 1, 3, 4, and hallux.t. Age 17.5 years: epiphyseal fusion complete

2. The Talocalcaneal Angular Relationships in the Diagnosis of Normal and Pathological Conditions:

NOTE* Boys lag behind girls with regard to skeletal age

3. Secondary Centers of Ossification:a. Metatarsals 2-5: at the metatarsal heads b. Metatarsal 1: at the base c. Phalanges: at the basesd. Calcaneus: only constant tarsal bone

The Osteochondritities1. These are a group of related disorders which effect the primary or secondary centers of ossification. Its etiology probably relates to some type of vascular disturbance to the ossification center, during the time of their greatest developmental activity.

2. The radiographic findings of lucency and fragmentation of the articular surface with collapse of a wedge shaped fragment of epiphysis and subsequent sclerosis are the manifestations of ischemic bone.

3. Originally classified together as a spontaneous osteonecrosis, but are a heterogenous group of entities with several different etiologies.

4. The Aseptic Necroses:a. Freiberg- metatarsal heads b. Kohler- navicularc. Bunchke/Buckman/Lewin/Wagner- cuneiforms d. Theimann- phalanges e. Sever- calcaneus (apophysis) f. Diaz/Mouchet- calcaneus g. Lance- cuboid

h. Iselin- base of 5th metatarsali. Relander- tibial sesamoid (1st metatarsal)j. Lewin/Wagner/Theimann- epiphysis of toe phalanges k. Legg-Calve'-Perthes- femoral capital epiphyses 1. Mandl/Buchman- greater trochanter of femur m. Felix/Monde- lesser trochanter femur n. Kohler/Sindins/Larsen- patellao. Osgood-Schlatter- tibial tuberosity p. Blount- proximal tibial epiphysis

The Accessory Bones of the Foot

Illustration of oblique and A-P projection with most common accessory bones:1. Os trigonum2. Os sustentaculi3. Os tibiale externum4. Os supranaviculare5. Pars peronaea metatarsalis primi 6. Os intermetatarseum 7. Calcaneus secundarium 8. Cuboides secundarium 9. Os vesalianum