PMP 2 Midterm Study Guide

PMP 2 Midterm Study Guide

• Key topics include radiology, orthotics, bone healing, digital pathology, and forefoot surgery
• The faculty lead for this course is Dr. Hamedani

Exam Breakdown

• There are 16 radiology questions from Dr. Sadra
• Dr. Hamedani provides 4-5 questions on special imaging and bone healing subjects
• Future questions will have greater complexity

Radiology Objectives

• Radiology objectives consist of 6 topics

Radiographic Position Terminology

• Projection relates to the direction of the x-ray beam relative to the patient's body planes
• Position refers to the patient's orientation, particularly in oblique views
• View indicates the final image obtained
• "View" is a broad term and can replace "projection" or "position"

Radiographic Views, Projections, and Positions

• DP Projection (aka AP foot) is a weight-bearing projection with the foot flat on the IR and the leg at a 90-degree angle to the foot
• The x-ray beam should cover the patient, and there is an angle of declination around 15 degrees to the ground
• Medial Oblique Position is non-weight bearing, with the medial aspect of the sole against the IR
• The extremity is rotated medially so the sole forms a 45-degree angle with the IR
• This position ideally involves the patient seated with the leg at a 90-degree angle to the foot
• Lateral Oblique Projection/Medial Oblique View are both weight-bearing
• Lateral Oblique Position is a non-weight bearing position with the lateral aspect of the sole against the IR
• The extremity is rotated laterally so the sole forms a 45-degree angle with the IR
• This position ideally involves the patient seated with the leg at a 90-degree angle to the foot
• Medial Oblique Projection/Lateral Oblique View are for weight-bearing
• Lateral Projection involves placing medial surface against IR and the leg is 90 deg to foot.
• Calcaneal axial projection (dorsoplantar) - Position: flat on IR, pt steps forward w opposite extremity such that AJ is dorsiflexed, add lead apron on back of pt.
• Harris-Beath Projection: flat on IR, pt steps forward w opposite extremity such that AJ is dorsiflexed, add lead apron on back of pt, less radiation exposure
• Sesamoid axial projection (posteroanterior): flat on orthoposer, toes dorsiflexed against IR and heel elevated lead apron on back of pt, better view of middle and posterior facet, talus, calcaneus
• Standard ankle studies (all weight-bearing): AP; Mortise; Lateral; Medial oblique; Lateral oblique -- foot positioned at 90 deg to leg
• AP Projection - Position: back of heel against IR, foot midline perpendicular to IR (toes straight ahead);
• Ankle Mortise involves placing the back of the heel against the IR and rotating the extremity medially approximately 15 degrees from the AP position, such that the AJ axis is parallel to the IR
• Tibia and fibula overlap
• Lateral Projection (lateromedial) involves placing medial surface of the forefoot against IR and heel pulled away such that the AJ axis is perpendicular to IR, assess lateral gutter.
• Medial Oblique Position involves placing the back of the heel against the IR and rotating the extremity medially 45 deg from AP
• Lateral Oblique Position involves placing the back of the heel against the IR and rotating the extremity laterally 45 deg from AP
• Full view of ankle joint can show both Ap and mortise

Radiographic View Selection

• Radiographic studies are ordered when needed, and to why with the use H&P, diagnostic restraint, and other decision-making factors to determine justification
• Why use to confirm or disconfirm provisional diagnosis, known diagnosis (surgical planning), healing
• Indications for radiographic studies can be remembered using the mnemonic MINT CAPS
• MINT CAPS: Metabolic, endocrine, nutritional disorders; Infection; Neoplasm; Trauma; Congenital; Arthritis; Positional abnormality; Soft tissue abnormality

Tangential Surfaces

• Tangential surfaces are about how to best isolate or allow visibility of the area in question, which allows precise determination of lesion location and correlation
• Tangential surfaces for dorsoplantar: Medial, lateral, anterior, posterior margins
• Tangential surfaces for lateral: Superior, inferior, anterior, posterior margins
• Tangential surfaces for medial oblique: Superomedial, inferolateral, anterior, posterior
• Viewing lesion directly, “head on" is called En Face
• Viewing a lesion tangentially from the side is In Profile
• Anteroposterior (medial, lateral, superior, inferior) & Mortise (same but slightly rotated)
• Medial/Lateral (Internal/External) Oblique Anterolateral, posteromedial, superior, inferior

Radiographic Interpretation Principles

• Image formation is a important thing to keep in mind by payingmindful of image perception as well as compare mental images of patterns to arrive at diagnosis
• Black, white, and varying shades of gray are relative radiodensities to keep inind while viewing a radiograph
• Dense objects like bone are radiopaque, while air is radiolucent
• Relative radiodensities order: Muscle > Fat > Bone > Air > Lead
• There is a summation effect where overlapping structures create pathology
• Appropriate view selection of the medial tubercle is best isolated with the lateral oblique view, which is superimposed on the medial oblique view
• Essential skills required to interpret a radiographic study include the ability to recognize abnormalities; apply appropriate terminology and list differential diagnoses
• To properly use skils, make a mental 3D picture of foot and ankle osteology from two dimensional images
• Essential skills required to interpret a radiographic study include the ability to recognize abnormalities; apply appropriate terminology and list differential diagnoses

Radiographic Anatomy

• It's important to understand a normal appearance of foot bones and joints, recognizing accessory ossicles with os interphalangeus at base between 1st/2nd MT
• Os Peroneum found (like a sesamoid) and (within tendon of peroneus longus)
• Accessory Navicular (isolate in lateral oblique view) and (operate on Type II)
• Os Vesalianum (found tip of 5th MT) and (best seen on medial oblique view)
• Os Supranaviculare (can cause impingement and pain at joint level)
• Os Trigonum
• Bipartite Sesamoids (2)
• Medial Oblique View: Metatarsals

Systematic Radiographic Assessments

• Advantages of is that it makes you be familiar normal, variant, and positional presentations and Abnormal findings may be found in asymptomatic areas and easily compare between normal and affected
• Organization of thought process → 5 step approach to interpretation, including image quality, soft tissue and bone assessment, Joints (articulations), and Biochemical assessment (if WB)

Special Imaging studies

• Special Imaging Modalities is made up with the following 6 topics
• Ultrasound (US) uses high-frequency sound waves to create images and structures
• US transducer creates and sends a sound wave (pulse) into tissue which then echoes back to probe and creates a gray-scale image on monitor
• From most dense to least dense: -Metal > bone > water > fat > air
• Diagnostic: to assess internal organs/muscles
• Functional: doppler US to visualize blood flow
• Therapeutic/interventional
• Longitudinal: probe is parallel to structure, to shows length and depth
• Transverse: probe is perpendicular to structure, that shows width and Cross-sectional view of structure
• MRI (Magnetic Resonance Imaging) is Based on magnetic resonance of H+ protons
• H+ atoms positively charged and susceptible to external magnetic fields
• 1.5 T wide bore MRI = lower signal strength, safer for pts w implants, more routine imaging
• 3.0 T wide bore MRI = higher signal strength, highly detailed, however higher chance of artifacts
• Types of MRI: T1 weighted images: Shorter T1 relaxation time, Shows proton energy in fatty tissues where T1 = FAT is bright and is ideal for evaluating anatomy or has pathology
• T2 weighted images consists of Shorter T2 relaxation time, Show proton energy in water-based and fatty tissues where T2 = FAT and WATER are bright w Localization from infection or trauma where water = T2 = H2O
• STIR images: Short Tau Inversion Recovery, this is Sensitive to water and suppresses fat signal, so Only water appears bright on imaging and best assessment pathology w Low T1 signal + high T2 signal = indicates increased fluid
• Contrast administered intravenously prior to MRI study is Gadolinium-based
• CT imaging: computed tomography images or previously called computerized axial tomography (CAT scans), uses X-rays to create cross-sectional images and is administered through W contrast/Iodine-based contrast.

Special Imaging study indications and usages

• Ultrasound Pros: safe; non-ionizing signal (no risk of carcinogenesis), is cost - effective,has dynamic imaging where there are no metallic artifacts and less contraindications compared to other imaging studies vs cannot penetrate past bone cortex and it is operator-dependent with artifacts such as Anisotropy
• MRI Pros consists of non-ionizing signal (not carcinogenic), provides good soft tissue contrast, and acquires images in multiple planes vs Cons bybeing expensive, takes up a long time,has artifacts, clausterphobia, and not safe for certain implants
• CT Pros: faster study compared to MRI, is less claustrophobic compared to MRI, views images in multiple planes vs Cons of Significant radiation exposure compared to X-ray with expensive cost

Special Imaging orders

• Ultrasound include foreign body, plantar fasciitis, tendon rupture, fluid collection vs not indicated for past the head
• foreign body and plantar fasciitis (normal plantar fascia thickness <4 mm),tendon rupture,fluid collection
• MRI includs osteomyelitis,abscess,tissue masses, neuroma, necrosis,fibrous/cartilaginous coalitions,tendon pathology,bone tumors,plantar plate tears vs is advised but not mandatory
• soft tissue masses (ganglions, lipoma)/osteomyelitis/abscess/ neuroma/avascular necrosis
• CT includs tissue emphysema (black circles are gas), fluid collection (abscess, hematoma, seroma)/nonunion/ osseous and coalition/ fractures.

When to use contracts

MRI : Advised for infection, tumors, vascular studies (not necessary vs kidney issues:caution if eGFR and avoid under specific levels

• CT : Pt has iodine allergy or abnormal renal function/tumors