Musculoskeletal X-Rays for Medical Students and Trainees E-Book

Andrew K. Brown

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 220

Veröffentlichungsjahr: 2016

Beschreibung

Musculoskeletal X-rays for Medical Students provides the key principles and skills needed for the assessment of normal and abnormal musculoskeletal radiographs. With a focus on concise information and clear visual presentation, it uses a unique colour overlay system to clearly present abnormalities.

Musculoskeletal X-rays for Medical Students:

• Presents each radiograph twice, side by side – once as would be seen in a clinical setting and again with clearly highlighted anatomy or pathology
• Focuses on radiographic appearances and abnormalities seen in common clinical presentations, highlighting key learning points relevant to each condition
• Covers introductory principles, normal anatomy and common pathologies, in addition to disease-specific sections covering adult and paediatric practice
• Includes self-assessment to test knowledge and presentation techniques

Musculoskeletal X-rays for Medical Students is designed for medical students, junior doctors, nurses and radiographers, and is ideal for both study and clinical reference.

Leseprobe

Table of Contents

Cover

Title Page

Preface

Acknowledgements

PART 1: Introduction

1 Musculoskeletal X‐rays

Introduction

Basic principles of requesting plain radiographs of bones and joints

Basic principles of examining and reporting plain radiographs of bones and joints

Normal anatomy on musculoskeletal X‐rays

Reference

PART 2: Pathology

2 Trauma

Bone and joint injuries

Specific injuries

Spine

Paediatric fractures

Fractures in child abuse

Further reading

3 Arthritis

Osteoarthritis

Rheumatoid arthritis

Crystal arthropathy

Gout

Calcium pyrophosphate disease

Psoriatic arthritis

Axial spondyloarthritis (ankylosing spondylitis)

4 Tumours and tumour‐like lesions

Radiological evaluation of the patient

X‐rays – general principles

Malignant tumours

Bone metastases

Multiple myeloma

Plasmacytoma

Osteosarcoma

Chondrosarcoma

Ewing’s sarcoma

Benign tumours

Exostosis (Osteochondroma)

Osteoid osteoma

Tumour‐like lesions

Simple bone cyst

Infection

5 Metabolic bone disease

Osteoporosis

Osteomalacia

Hyperparathyroidism

Chronic kidney disease metabolic bone disorder

Haemochromatosis

6 Infection

Routes of spread

Causative organisms

Osteomyelitis

Septic arthritis

Infective discitis

7 Non‐traumatic paediatric conditions

Developmental dysplasia of the hip

Perthes’ disease

Tarsal coalition

Osteochondritis dissecans

8 Other bone pathology

Paget’s disease of bone

Hypertrophic Osteoarthropathy (HOA)

Avascular necrosis

9 Joint replacement

Hardware failure and aseptic loosening

Infection

Malalignment and instability

Periprosthetic fracture

PART 3

Self‐assessment questions

Self‐assessment questions

Index

End User License Agreement

List of Illustrations

Chapter 01

Figure 1.1 X‐ray of the forearm illustrating the naturally occurring densities in a patient. White = calcium (in bone), dark grey = fat, lighter grey = all other soft tissue structures. Surrounding air is black.

Figure 1.2 Recommended terminology for describing bone anatomy in adults and children.

Figure 1.3 Normal hand.

Figure 1.4 Normal wrist, PA view.

Figure 1.5 Normal wrist, lateral view (see the 4 Cs in Chapter 2).

Figure 1.6 Normal elbow, AP view.

Figure 1.7 Normal elbow, lateral view.

Figure 1.8 Normal shoulder, AP view.

Figure 1.9 Normal shoulder, axial view.

Figure 1.10 Normal cervical spine, lateral view.

Figure 1.11 Normal cervical spine, AP view.

Figure 1.12 Normal cervical spine, through‐mouth view.

Figure 1.13 Normal lumbar spine and sacroiliac joints, AP view.

Figure 1.14 Normal lumbar spine, lateral view.

Figure 1.15 Normal pelvis, AP view.

Figure 1.16 Normal hip, lateral view.

Figure 1.17 Normal knee, AP view.

Figure 1.18 Normal knee, lateral view

.

Figure 1.19 Normal knee, sky‐line patella view.

Figure 1.20 Normal ankle, AP view.

Figure 1.21 Normal ankle, lateral view.

Figure 1.22 Normal foot, AP and oblique views (note bipartite medial sesamoid bone which is a normal variant). Cuneiform bones: l = lateral, i = intermediate, m = medial.

Chapter 02

Figure 2.1 Fracture of the distal humerus. Signs: Deformity of the bone due to displacement at the fracture site. The darker fracture line (orange) interrupts the dense bone structure.

Figure 2.2 Undisplaced fracture of the radial styloid process. Signs: The normal shape of the bone is preserved, but a subtle less dense, that is dark, fracture line (orange) can be seen separating the radial styloid from the rest of the bone.

Figure 2.3 Minimally displaced fracture of the radial neck. Signs: The cortex normally has a smooth contour. Carefully following the cortex around the margin of the radius (yellow) reveals a small step just distal to the head.

Figure 2.4 Minimally displaced fracture of the neck of the femur. Signs: Increased density partially crossing the femoral neck due to impaction at the fracture site (orange) and steps in the cortex medially and laterally (yellow).

Figure 2.5 Soft tissue swelling overlying an undisplaced transverse fracture of the lateral malleolus (orange). The localised swelling is best appreciated by looking at the silhouette of the skin surface against the darker surrounding air (green).

Figure 2.6 Osteochondral fracture of the lateral corner of the dome of the talus. Signs: Following the outline of the articular surface reveals an interruption in the cortex (yellow) and a small fragment of calcium density (green). This is slightly displaced and projected within the joint space. Fractures of the medial or lateral corner of the dome of the talus are relatively common but easy to miss on X‐rays. In fact, one‐third of fractures are not visible on initial X‐rays. It is important to look closely at the dome of the talus in any patient with an ankle injury.

Figure 2.7 Two avulsion fractures are visible on the AP view of this adolescent patient’s knee. The fragment coloured green is a fracture of the tibial eminence, avulsed by the anterior cruciate ligament. The fragment coloured orange is an avulsion of the tibial cortex by the attachment of the lateral joint capsule. Although this lateral injury looks innocuous, it has a strong association with ACL and meniscal tears and is named a Segond fracture.

Figure 2.8 A typical stress fracture of the distal shaft of the index metatarsal. The fracture is undisplaced and no fracture line is visible on the film, but its presence is shown by the callus which has developed on either side of the fracture site (orange).

Figure 2.9 An elderly woman with back pain but no history of a specific injury. The film shows mildly and moderately severe wedge fractures of two vertebral bodies (blue). The fractures do not show specific radiological signs to indicate that they are fragility fractures. This comes from the history and exclusion of other causes.

Figure 2.10 A pathological fracture of the right ischiopubic ramus. There are two fracture lines (orange) across the bone, but the underlying bone texture is also abnormal, with ill‐defined lucency extending from the acetabulum to the inferior pubic ramus, due to the presence of a lytic metastasis (green). Compare the bone texture in this area with the normal appearance in the rest of the image.

Figure 2.11 An accessory ossicle (blue) lying adjacent to the medial malleolus. Note that the ossicle is smooth and rounded and has a complete surrounding cortex.

Figure 2.12 A soft tissue crease causing a dark line (blue) across the intertrochanteric region of the left femoral neck. Initially, this might be mistaken for a fracture, but the line can be followed into the soft tissues beyond the margins of the bone.

Figure 2.13 Fracture

site

: There is a fracture of the proximal shaft of the middle metacarpal of the right hand (orange).

Figure 2.14 Articular surface involvement: This middle phalanx fracture extends into the proximal interphalangeal joint.

Figure 2.15 There are more than two bone fragments in this distal femoral shaft fracture, and therefore it is described as comminuted or multi‐fragmentary.

Figure 2.16 Fracture orientation: (a) Longitudinal fractures – proximal phalanx. (b) Oblique fracture – tibia. (c) Spiral fracture – tibia.

Figure 2.17 The anatomical position.

Figure 2.18 (a and b) Two views at 90° to one another are needed to detect injuries and also to evaluate displacement. This proximal interphalangeal joint injury is difficult to appreciate on the AP view, but the lateral film clearly demonstrates dorsal subluxation, with loss of congruity of the articular surfaces (blue). It also reveals the presence of a small fracture fragment (orange).

Figure 2.19 A fracture of the distal diaphysis of the radius. Evaluating the films for displacement of the distal fragment, the lateral view shows dorsal shift and the ‘AP’ view shows lateral shift and lateral angulation.

Figure 2.20 Dislocation of the elbow. Predominantly, the distal bones of the joint (radius and ulna) have moved posteriorly from their normal anatomical position. Articular surfaces of the trochlea and olecranon are in blue. The injury could be described thus: ‘The radius and ulna have dislocated in a posterior direction’, but this is usually shortened to, ‘There is a posterior dislocation of the elbow’.

Figure 2.21 Normal lateral knee. The lighter grey suprapatellar pouch lies between the dark grey of the fat planes on its anterior and posterior aspects, and therefore its thickness can be seen. Normally, the thickness is just 2 or 3 mm (green).

Figure 2.22 When the knee joint is swollen, the suprapatellar pouch can be seen to increase in thickness (green).

Figure 2.23 Lipohaemarthrosis in a patient with a fracture of the tibial joint surface. Low‐density fat (yellow) forms a layer floating on top of denser blood (red) inside the suprapatellar pouch. Therefore, an intra‐articular fracture must be present. A subtle fracture line is visible extending into the tibial joint surface (blue).

Figure 2.24 (a) At the ankle, the lighter grey of the swollen joint (orange) may be visible on the lateral view. Normally this area is occupied by a darker grey fat plane as in figure (b) for comparison.

Figure 2.25 (a and b) Detecting swelling at the elbow also relies on contrast between fat and other tissues, but in a slightly different way. Here the anterior and posterior fat pads do not outline the joint capsule, but they can indicate the presence of joint swelling. They normally sit in the fossae on the anterior and posterior aspects of the distal humerus where they are barely visible on a lateral X‐ray. However, increased joint fluid or synovial thickening gets underneath them in the fossae, lifting them out and pushing them superiorly so that they become more prominent (purple). Image (b) is normal for comparison.

Figure 2.26 (a) Anterior shoulder dislocation, AP view. Signs: The articular surface of the humeral head (green) no longer lies congruently against that of the glenoid (yellow). The head is displaced medially and is projected over the glenoid. (b) Anterior shoulder dislocation, axial view. By identifying the bony anatomy, it is possible to find the articular surfaces of the humeral head and glenoid and again see that they are not articulating with one another. Also by determining the anterior aspect of the scapula, for example by identifying the coracoid process (purple), it is possible to say that the humerus has dislocated anteriorly. (c) Anterior shoulder dislocation, lateral view. As with the previous projection, the humeral head, glenoid and anterior and posterior aspects of the scapula should be checked to establish that there is an anterior dislocation of the shoulder.

Figure 2.27 (a) Posterior shoulder dislocation. Signs: On this AP view, the dislocation is not obvious because the humeral head (green) lies level with the articular surface of the glenoid (yellow). However, an abnormal amount of the surface of the glenoid is visible – the ‘bare glenoid’ sign. The humerus has a ‘light bulb’ appearance caused by internal rotation. The arm is locked in internal rotation in patients who have a posterior dislocation. (b) Posterior shoulder dislocation, axial view. Less of the scapula is visible on this film as the patient has had difficulty abducting the shoulder for the X‐ray. As a result, the corocoid process is not included on the film, but once again identification of the bony anatomy allows the dislocation and the fact that it is posterior to be confirmed. The acromion (orange) can be seen turning anteriorly to meet the lateral end of the clavicle at the acromioclavicular joint.

Figure 2.28 Fracture of the greater tuberosity of the humerus with shoulder dislocation. Signs: Fracture lines (orange) causing breaks in the cortex and running through the bone between the greater tuberosity and the humeral head.

Figure 2.29 (a and b) The elevated anterior fat pad (orange) is a clue that there is a significant abnormality. The neck of the radius shows a subtle break in the cortex (yellow) and slight anterior angulation. Fracture line (green).

Figure 2.30 (a and b) Wrist injury in a young adult. Standard AP and lateral wrist films (a) do not show any definite bony injury but one of the additional specific scaphoid oblique views (b) demonstrate a transverse fracture across the waist of the scaphoid (orange).

Figure 2.31 (a and b) Occult scaphoid fracture. (a) Representative image from a scaphoid series in a young adult with clinical features of a scaphoid injury. This, and the other views, shows no fracture. (b) Corresponding MRI image of the wrist demonstrating a linear fracture (blue) across the waist of the scaphoid with surrounding abnormal signal (orange) due to oedema and haemorrhage in the bone marrow.

Figure 2.32 (a and b) Fracture of the distal radius in an elderly female patient. The AP view shows a transverse fracture with shortening along with lateral displacement of the distal fragment. The lateral view also shows dorsal angulation.

Figure 2.33 (a, lateral and b, AP): Perilunate dislocation. Signs: Although it is not easy to see because of the overlapping shadows of several different bones, the lateral view demonstrates that the distal surface of the lunate (orange) is not articulating with the proximal surface of the capitate (yellow). The latter is displaced dorsally, along with the other carpal bones, leaving just the lunate normally aligned with the radius. This is best appreciated by looking for the ‘four Cs’. This row of four C‐shaped articular surfaces (white) is always present on a normal lateral film. They are, moving from proximal to distal, the articular surfaces of the radius, proximal lunate, distal lunate and the capitate. On the AP film (b), the relationship of the carpal bones is also abnormal. The normally equal joint spaces around the bones are less regular, and there is an abnormal amount of overlap of the lunate with the capitate. Compare these views with the normal AP and lateral wrist in Figure 1.4.

Figure 2.34 Diagram of blood supply to the femoral head.

Figure 2.35 (a and b) Displaced intra‐articular fracture of the right femoral neck. Signs: Fracture line across the femoral neck (yellow). Displacement: The femur has migrated proximally due to angulation at the fracture site. (b) The vessels supplying the femoral head are likely to be torn and, therefore, the best treatment is to replace the non‐viable femoral head with a prosthesis, in this case a hemiarthroplasty.

Note

: The round metallic density below the pelvis in the midline on Figures 2.35b and 2.36b is a marker used to calibrate measurements of hip replacements and other implants.

Figure 2.36 (a and b) Intertrochanteric fracture of the right femoral neck. The fracture line (orange) is distal to the joint capsule attachment and the intra‐articular part of the femoral neck and therefore the vessels to the head are not at risk. (b) This fracture is treated using a dynamic hip screw to provide secure fixation and allow early mobilisation. The femoral head is retained as there is no risk of AVN.

Figure 2.37 (a and b) Occult femoral neck fracture. This is a patient who has suffered a fall and has significant hip pain and cannot weight‐bear. The AP film (a) shows normal appearances, as did the lateral view (not shown). MRI (b) shows a linear fracture (orange) across the bone marrow of the femoral neck.

Figure 2.38 Undisplaced medial tibial plateau fracture, AP view. (The corresponding lateral film is Figure 2.23.) Signs: Linear radiolucent fracture lines are present, running horizontally in the medial tibial plateau and vertically in the proximal tibial shaft (orange).

Figure 2.39 (a and b) Lateral tibial plateau fracture (blue) with severe disruption of the articular surface. AP film (a) and CT coronal and sagittal reconstructions (b). CT allows clear and accurate delineation of the bony injury. Although part of the joint surface is intact, the anterior two‐thirds are severely displaced inferiorly.

Figure 2.40 (a and b) AP and lateral X‐rays of severe ankle fracture. On the AP view, in addition to fractures of the fibular shaft and medial malleolus, the space between the distal tibia and the fibula is widened, indicating disruption of the distal tibiofibular joint. The lateral view reveals a displaced fragment of bone from the posterior aspect of the distal tibia, known as the third malleolus (green), and also posterior subluxation of the talus (articular surface of tibia in orange and talus in white).

Figure 2.41 (a) Lisfranc injury. The index (second) tarsometatarsal joint (TMTJ) is subluxed laterally by only 2 or 3 mm. This is shown by the step (orange) on the medial side of the index TMTJ. Although the

residual

displacement is minimal, it would have been severe as the injury occurred. Afterwards the bones have returned to a relatively normal position, disguising the fact that there is significant damage to the surrounding soft tissues. (b and c) Standard views of normal foot for comparison. By using both views, it can be seen that each metatarsal base aligns exactly with its respective tarsal bone. The exception is the styloid process of the little toe metatarsal because this is not part of the articular surface. In particular, a step where the medial border of the index metatarsal lines up with the intermediate cuneiform is abnormal.

Figure 2.42 (a, b and c) Assessing the lateral c‐spine film. (b) Line 1 follows the anterior cortex of the vertebral bodies, although not including C1 due to the different anatomical arrangement at this level. Line 2 follows the posterior cortex of the vertebral bodies, also extending up along the posterior aspect of the peg of C2. Line 3 is called the spinolaminar line because it runs along the bases of the spinous processes, where these join the laminae. All three lines should be smooth curves with no step or abrupt change in curvature. The space between the anterior arch of C1 and the peg of C2 (green) should measure 2 mm or less at its narrowest point in an adult. (c) Look for even spacing between the adjacent vertebrae at the discs, facet joints and spinous processes. The spaces between the latter (orange) are occupied by the interspinous ligaments. The prevertebral soft tissue shadow (green) should also be assessed.

Figure 2.43 Normal cervical spine, AP view: Straight alignment and spacing of the spinous processes (orange) should be checked. There should be no abrupt alteration of either. Also the lateral borders of the vertebrae should align with one another.

Figure 2.44 Normal through‐mouth view of C1 and C2. In addition to looking for fracture lines, check symmetrical spacing of the peg of C2 with the lateral masses of C1 (green). Also the lateral sides of the lateral masses of C1 must align with those of C2 (white lines). A step of 2 mm or more is abnormal.

Figure 2.45 (a and b) A patient with severe lower c‐spine subluxation from a high‐force traffic injury. Assessing the adequacy of the first film reveals that it demonstrates the vertebrae down to C6 only. A second lateral image performed as a ‘swimmer’s view’ shows the cervicothoracic junction more fully. Alignment at C6/7 is grossly abnormal. A combination of the two views shows that all three of the lines discussed in Figure 2.42b are abnormal and that the bodies of C6 and C7 are separated. Also the regular spacing between the spinous processes (orange) changes at the injured level (red).

Figure 2.46 Fracture of the body of C6 with anterior wedging plus separation of the spinous processes of C5 and C6, indicating rupture of the interspinous and supraspinus ligaments, which usually hold these together. Vertebral body fracture (green). Enlarged space between spinous processes (orange). Although this patient has prominent osteophytes, these should be ignored when following the line along the anterior aspect of the vertebral bodies. Following the lines shown in Figure 2.42b shows an abrupt change in angulation of the three lines.

Figure 2.47 (a and b) Fracture of the base of the peg of C2. The posterior cortex of the peg is displaced backwards relative to the posterior cortex of its vertebral body. C1 has displaced backwards along with the peg, and therefore the spinolaminar line shows abrupt posterior displacement at this level.

Figure 2.48 (a, b and c) Unilateral fracture/subluxation of C6/7. The lateral X‐ray (a) shows subtle alteration of alignment and prevertebral soft tissue swelling (green) at the level of injury. The AP film (b) shows a change in alignment of the spinous processes (orange). Above C7, these are displaced to the right rather than continuing in the midline. They are not clearly visible because they are projected over the other lateral bony structures. A sagittal CT reconstruction through the right‐sided facet joints.

Figure 2.49 A child’s elbow is identical in shape to an adult’s, but a lot of the bone consists of cartilage which has not yet ossified (orange). Cartilage has the same X‐ray density as the surrounding soft tissues making it essentially invisible on plain films. It can be shown using ultrasound or MRI however. Also note the appearances of the growth plates (green), with their smooth undulations and corticated outline.

Figure 2.50 Normal synchondroses in a child (green). The temporary localised bone thickening is part of the normal growth process but can be mistaken for healing fractures.

Figure 2.51 (a and b) The base of the little toe metacarpal is a common site for injuries and the growth plate here can be mistaken for a fracture. However, (a) the growth plate (yellow) always has a longitudinal orientation, whereas (b) a fracture tends to run transversely (orange). Also note the smooth rounded appearance of the margins of the growth plate compared with the sharp, uncorticated edges of the fracture.

Figure 2.52 A buckle or torus fracture of the distal radial metaphysis in a child. Signs: The dorsal, medial and lateral sides of the bone have buckled slightly at the fracture site, deforming the normally smooth curve of the cortex. The lack of sharp fracture margins, which would be seen in an adult, reflects the less brittle nature of the paediatric skeleton.

Figure 2.53 Salter–Harris growth plate fracture classification. Purple line represents the growth plate.

Figure 2.54 Salter–Harris II fracture of the distal tibia in an adolescent. The fracture line (orange) extends partially along the growth plate and then superiorly across a corner of the metaphysis.

Figure 2.55 Slipped upper left femoral epiphysis: A 13‐year‐old boy with left hip pain following a minor hip injury. In this condition, the proximal femoral epiphysis slips

posteriorly

at the growth plate. The displacement is therefore difficult to see on an AP film and is best seen on a lateral view of the upper femur. This is achieved by asking the patient to rotate both knees outwards, which externally rotates the femurs. On the normal, right side, a line drawn up through the centre of the femoral neck extends through the centre of the femoral epiphysis, but on the left the femoral head does not lie centrally on the neck and therefore has slipped.

Figure 2.56 (a and b) Supracondylar fracture of the humerus. The fracture line is visible on the AP and lateral views (orange), and the lateral also shows the typical posterior angulation of the distal fragment.

Figure 2.57 In this second patient with a less displaced supracondylar fracture, the anterior humeral line sign helps confirm the diagnosis. A line is drawn down the anterior cortex of the humeral shaft. When this is extended distally, it should normally pass through the middle third of the capitellum ossification centre (blue). However, in this patient, posterior angulation at the fracture site has shifted the capitellum backwards, causing the line to pass anterior to the capitellum.

Figure 2.58 Diagrammatic representation of metaphyseal fracture. The injury occurs immediately adjacent to the growth plate and extends transversely across the bone, separating a disc‐shaped fragment. On an X‐ray, this fragment may have the appearance of a ‘bucket handle’ or ‘corner’ depending on the angle of the X‐ray.

Figure 2.59 AP X‐ray of the distal tibia of a 2‐month‐old child showing a metaphyseal fracture caused by child abuse. The fracture runs just proximal to the growth plate, with the separated fragment of metaphysis giving the impression of a ‘bucket handle’ (yellow). (The distal tibial epiphysis is not visible at this age as its ossification centre has not yet appeared.)

Figure 2.60 AP X‐ray of the knee of an infant. There is a ‘corner’ fracture of the medial aspect of the distal femoral metaphysis (yellow). This type of injury is caused by traction and twisting forces, and so is frequently associated with child abuse. However, in this case, it was the result of a difficult delivery. This emphasises the importance of correlating the history and other information fully.

Figure 2.61 Chest X‐ray of a 2‐month‐old child. There are healing fractures of the right 4th and 11th ribs posteriorly, caused by child abuse. These are visible because callus produces subtle focal thickening of the ribs at the fracture sites (orange).

Chapter 03

Figure 3.1 Features of OA with marginal osteophytes (purple) and supero‐lateral joint space narrowing (green). The adjacent subchondral bone of the acetabulum shows areas of increased density (sclerosis) relative to normal bone and rounded areas of reduced density due to the presence of a subchondral cyst (blue).

Figure 3.2 Osteoarthritis (OA) of the knee. Moderately severe OA changes are present in the medial compartment in the form of joint space narrowing (green) and marginal osteophytes (purple).

Figure 3.3 Osteoarthritis (OA) of the first carpometacarpal joint. Typical OA changes with prominent osteophytes (purple), joint space narrowing (green) and minor subchondral sclerosis (yellow) on both sides of the thumb carpometacarpal joint.

Figure 3.4 Rheumatoid arthritis. There are extensive erosions (orange) visible particularly in the metacarpal heads of the thumb, index and middle fingers on the right and middle finger on the left, together with scaphoid bone in the left wrist and ulnar styloid on the right seen

en face

. There is severe joint space narrowing in the right first and second MCP joints (green).

Figure 3.5 Severe established rheumatoid arthritis. There is evidence of a severe symmetrical destructive erosive polyarthropathy with almost complete fusion of the carpal joints bilaterally (green). The left wrist has been surgically fused. Further changes are seen more distally with periarticular osteopenia, erosive damage and deformity particularly affecting the right third MCP and proximal interphalangeal (PIP) joints where there is early subluxation.

Figure 3.6 Atlanto‐axial subluxation. Lateral radiograph of cervical spine in flexed position of a patient with established RA, demonstrating atlanto‐axial subluxation with an anterior atlanto‐dental interval of 7mm (yellow) (normal 2mm). This is measured (arrow) between the anterior arch of C1 (orange) and odontoid peg of C2 (green)

Figure 3.7 (a) Gout affecting left great toe. There is soft tissue swelling (yellow) and severe erosive changes (purple) which are characteristically wide based and ‘punched out’, located just away from the interphalangeal joint margin.

Figure 3.7 (b) Tophaceous gout great toe. There is a destructive arthropathy affecting the great toe MTP and interphalangeal (IP) joints, with severe erosive damage shown as loss of clarity of bone margins (orange), marked joint space loss (green), soft tissue swelling and tophaceous deposits in the soft tissues with punctate calcification (pink) adjacent to the IP joint.

Figure 3.8 Calcium pyrophosphate arthropathy of the hands and wrists. There is chondrocalcinosis in the triangular fibrocartilage at the ulna–carpal compartments of both wrists (pink), joint space loss (green) and osteophyte formation at the MCPs (purple) and a background of changes of osteoarthritis affecting a number of PIP, DIP and first carpometacarpal (CMC) joints (blue).