Hook of hamate fractures are rare. They occur from the hamate fracturing after blunt trauma, falls, and in sports player (e.g. golf, baseball, racquet sports) from a direct blow while swinging. Stress fractures have also been reported.
It may result in Guyon's canal syndrome.
The hook of the hamate has its own ossification center, which may fail to fuse with body of the hamate, creating an ossicle. This ossicle is reffered to as an os hamuli proprium or unfused hamulus
In some instances, this can be difficult to distinguish from a fracture of the hook, but is sugge...
Systemic lupus erythematosus (SLE) is a complex autoimmune disease with multisystem involvement. It is also sometimes classified as a vasculitis.
There is an overall increased female predilection. In adults, women are affected 9-13 times more than males. In children, this ratio i...
Avulsion fracture of the 5th metatarsal styloid, also known as a pseudo-Jones fracture or a dancer fracture, is one of the more common foot avulsion injuries and accounts for over 90% of fractures of the base of the 5th metatarsal.
Despite what should be a simple entity, controversy exists, as ...
Haemochromatosis is a systemic disease which affects many organs systems, including the joints, characterised by haemosiderin and calcium pyrophosphate deposition.
For a general discussion, and for links to other system specific manifestations, please refer to the article on haemochromatosis.
Shoulder arthrography is an imaging technique used to evaluate the glenohumeral joint to evaluate the joint components. Glenohumeral joint injection is usually performed under fluoroscopic guidance although the use of US has also been reported 1. An alternative to direct arthrography (where cont...
Indirect arthrography is an MRI technique to produce arthrographic images without the need to perform a direct joint injection.
A standard dose of a gadolinium-containing contrast agent is injected intravenously and imaging of the shoulder performed after a delay of typically between 5 and 15 ...
A Morel-Lavallée lesion is a closed degloving injury associated with trauma which then evolves to form a haemolymphatic mass. MRI and ultrasound are useful modalities for evaluation.
The lesions classically occur over the greater trochanter of the femur 1. Morel-Lavallée lesions, s...
The patella (plural: patellae) is the largest sesamoid bone in the human body. It lies within the quadriceps tendon / patellar ligament and forms part of the knee joint.
The patella is triangular in shape with a superior base and inferior apex. The posterior surface ...
A rocker bottom foot (also known as a congenital vertical talus) is a congenital anomaly of the foot. It is characterised by a prominent calcaneus/heel and a convex rounded sole.
It results from a dorsal and lateral dislocation of the talonavicular joint.
Köhler disease is an eponymous term referring to childhood-onset osteonecrosis of the navicular bone in the foot. Mueller Weiss syndrome is the adult counterpart of navicular bone osteonecrosis 4,5 .
It typically presents in the paediatric population (4-6 years of age) and there i...
Chondrosarcomas of the base of the skull are rare compared with other skull base tumours but are an important differential diagnosis as surgical resection and management are affected by the preoperative diagnosis.
Chondrosarcomas of the base of the skull make up only a small fract...
Sever disease refers to a calcaneal apophysitis, an inflammation of the apophysis of the heel.
It typically presents in active young children and adolescents, especially those who enjoy jumping and running sports.
Patients tend to present with posterior he...
Mueller Weiss syndrome refers to a spontaneous adult onset osteonecrosis of the tarsal navicular. This syndrome is multifactorial and related to chronic loading on a suboptimally ossified navicular bone which is susceptible to central osteonecrosis due to its centripetal blood supply. It is dist...
Cervical degenerative disease can be graded using a very old but reliable classification given by Kellgren et al. It is based on findings on a lateral cervical spine radiograph although it can also be applied to MRI evaluation of spine.
The key parameters are osteophyte formation, intervertebra...
Anterior cruciate ligament (ACL) tears are the most common knee ligament injury encountered in radiology and orthopaedic practice.
The ACL is the most commonly disrupted ligament of the knee, especially in athletes who participate in sports that involve rapid starting, stopping, and ...
Focal periphyseal oedema zones, also known as FOPE zones, are regions of bone marrow oedema seen on MRI that are principally located at the physes about the knee. They are thought to represent potentially painful manifestations of physiologic physeal fusion 1.
FOPE zones are seen ...
Langerhans cell histiocytosis (LCH) is a rare multi-system disease with a wide and heterogeneous clinical spectrum and variable extent of involvement.
Langerhans cell histiocytosis was previously known as histiocytosis X. The newer term is preferred as it's more descriptive of its...
Lipomatosis is a condition where there is diffuse excessive fat deposition within the body. This can especially affect certain regions.
neck and upper region of trunk
lipomatous hypertrophy of the interatrial septum
lipomatous metaplasia of th...
The arcuate sign is often a subtle but important finding on knee x-rays and represents an avulsion fracture of the proximal fibula at the site of insertion of the arcuate ligament complex, and is usually associated with cruciate ligament injury (~90% of cases) 2. The fracture fragment is attache...
Bone age assessment is used to radiologically assess the biological and structural maturity of immature patients from the hand and wrist x-ray appearances. It forms an important part of the diagnostic and management pathway in children with growth and endocrine disorders. It is helpful in the di...
The olecranon is a large bony prominence at the proximal end of the ulna. It is palpable at the posterior aspect of the elbow.
proximal end of the ulna
articulates with the olecranon fossa of the humerus
deep nutrient branch of the ulnar artery
The term deep vein thrombosis (DVT) is practically a synonym for those that occur in the lower limbs. However, it can also be used for those that occur in the upper limbs and neck veins. Other types of venous thrombosis, such as intra-abdominal and intracranial, are discussed in separate article...
Erosive arthritis has a broad differential, including:
clinically an acute inflammatory attacks (swelling, erythema, pain) in postmenopausal woman
typically includes the DIPs, PIPs 1st CMC joint 6, but not the metacarpophalangeal (MCP) joints and large joints
Interparietal hernias are a general category of ventral abdominal wall hernia, defined by occurrence of the hernia sac lies between the layers of the anterior abdominal wall. They are commonly incisional hernias and most Spigelian hernias are of this type.
Seronegative spondyloarthritides, also known as spondyloarthropathies or spondyloarthritis, are a group of musculoskeletal syndromes linked by common clinical features and common immunopathologic mechanisms. The subtypes of spondyloarthritis are usually distinguished on the basis of the patient’...
Pseudohypoparathyroidism (PHP) is a condition where there is end-organ resistance to parathyroid hormone (PTH).
There are several recognised subtypes which include:
type I: abnormal cAMP response to PTH stimulation
type Ia (Albright hereditary osteodystrophy (AHO)): has c...
Degenerative disc disease (DDD) is an exceedingly common entity in the spine, encountered with increasing frequency throughout life and becoming almost universal in late adulthood to a varying degree. It is related to a combination of biomechanical stresses and genetic predisposition which alter...
Brachymetatarsia (a.k.a. congenital short metatarsus) is a rare condition that develops from early closure of the growth plate.
Females are almost exclusively affected 1.
It typically involves the fourth ray or, less frequently, more than one metatarsal bon...
Abdominal hernias (herniae also used) may be congenital or acquired and come with varying eponyms. They are distinguished primarily based on location and content. 75-80% of all hernias are inguinal.
Content of the hernia is variable, and may include:
small bowel loops
mobile colon segments (s...
Kikuchi-Fujimoto disease, also known as subacute necrotising lymphadenitis or subacute necrotising histiocytosis, is an idiopathic disease characterised usually by cervical lymph node enlargement (80%).
It typically affects young women.
It usually presents ...
Levator ani syndrome (LAS) is a musculoskeletal pain syndrome involving the pelvic floor, thought to be caused by spasm or scarring of the levator ani muscles.
Levator ani syndrome is characterised by recurrent pain, pressure or discomfort in the region of the rectum, sac...
Atlanto-occipital dissociation injuries are severe and include both atlanto-occipital dislocations and atlanto-occipital subluxations.
The tectorial membrane and alar ligaments provide most of the stability to the atlanto-occipital joint, and injury to these ligaments results in inst...
The coccyx (plural: coccyges) is the series of rudimentary vertebrae forming the caudal termination of the vertebral column and is positioned inferior to the apex of the sacrum. The coccyx is one leg of the tripod formed in conjunction with the ischial tuberosities for support in a seated positi...
Tophi (plural of tophus) appear as lumps on affected joints due to deposits of monosodium urate (MSU) crystals in patients with longstanding high levels of serum uric acid (hyperuricaemia).
Tophi are a pathognomonic feature of gout.
History and etymology
Tophus means "stone" in Latin.
The levator palpebrae superioris muscle is a small muscle of the superior orbit that elevates and retracts the upper eyelid. It is not part of the extra-ocular muscles; it does not insert on the globe and therefore does not produce eye movements. It is mostly composed of skeletal muscle but ther...
Avulsion injuries or fractures occur where a portion of cortical bone is ripped from the rest of the bone by the attached tendon, are common among those who participate in sports, and there are numerous sites at which these occur. Being familiar with them is important as chronic injuries can app...
Tibial plateau fractures were originally termed a bumper or fender fracture but only 25% of tibial plateau fractures result from impact with automobile bumpers.
The most common mechanism of injury involves axial loading, e.g. fall from a significant height. In younger patients, the m...
Schatzker classification system is one method of classifying tibial plateau fractures.
Increase in type number denotes increasing severity, reflecting an increase in energy imparted to the bone at the time of injury and also an increasingly worse prognosis 1. The most common fracture of the tib...
Clinodactyly is a descriptive term that refers to a radial angulation at an interphalangeal joint in the radio-ulnar or palmar planes. It typically affects the 5th finger.
The estimated incidence is highly variable dependent on sampling and has been reported to range between 1-18...
Slipped upper femoral epiphysis (SUFE), also known as a slipped capital femoral epiphysis (SCFE), is a relatively common condition affecting the physis of the proximal femur in adolescents. It is one of commonest hip abnormalities in adolescence and is bilateral in ~20% of cases.
The genitofemoral nerve is a branch of the lumbar plexus arising within the substance of the psoas major muscle from the union of anterior rami of L1 and L2 spinal nerves. The nerve descends in the retroperitoneum to give off genital and femoral terminal branches supplying the skin over the ante...
Indirect inguinal hernias are the most common type of abdominal hernias.
It is five times more common than a direct inguinal hernia, and is seven times more frequent in males, due to the persistence of the processus vaginalis during testicular descent.
In children, the vast majo...
Companion shadows are smooth, homogeneous, radiopaque shadows running parallel along the bones. In a study of 700 chest radiographs, Ben Felson found that 75% had companion shadows on the lower ribs 3.
They appear secondary to soft tissues and intercostal muscles running ...
Die-punch fractures result from an axial loading force on the distal radius. It is an intra-articular fracture of the lunate fossa of the distal radius 1. It is by definition depressed or impacted and is named after the machining technique of shearing a shape, depression or hole in a material wi...
Cervical ribs are supernumerary or accessory ribs arising from the seventh cervical vertebra. They occur in ~0.5% of the population, are usually bilateral, but often asymmetric 2, and are more common in females.
Although cervical ribs are usually asymptomatic, they are the most important anato...
Costal cartilage fractures are fractures of the cartilage connecting the ribs anteriorly to the sternum.
There is little published data on costal cartilage fractures. Most reported cases are in males and resulted from blunt trauma or a fall 1,2.
In young ch...
Gout is a crystal arthropathy due to deposition of monosodium urate crystals in and around the joints.
Typically occurs in those above 40 years. There is a strong male predilection of 20:1.
Acute gouty arthritis presents with a monoarticular red, inflamed, ...
The accessory soleus muscle is an anatomical variant characterised by an additional distinct muscle encountered along a normal soleus muscle. It is uncommon with a prevalence of ~3% (range 0.7-5.5%).
origin: fibula, soleal line of the tibia, or the anterior surface of the soleus muscle...
Tibial tuberosity avulsion fractures are uncommon and usually associated with sports activities that require jumping. Avulsion occurs with the violent active extension of the knee or passive flexion against contracted quadriceps muscles.
Although an acute injury, tibial tuberosity avulsion is m...
Pipkin classification is the most commonly used classification for femoral head fractures, which are uncommon but are associated with hip dislocations.
type I: fracture distal to the fovea capitis, a small fracture not involving the weightbearing surface
type II: fracture proxi...
Extensor pollicis brevis (EPB) is one of the muscles of the deep layer of the posterior compartment of the forearm, inserting into the base of the proximal phalynx of the thumb. Along with extensor pollicis longus, it is responsible for extension of the thumb. Along with abductor pollicis longus...
Condylar hyperplasia is a rare pathology of the mandible, which refers to an asymmetrical, non-neoplastic growth of a mandibular condyle.
Mandibular condylar hyperplasia usually occurs unilaterally. It affects males and females equally and is usually encountered between 10-30 ye...
Pisiform fractures are an uncommon type of fracture involving the carpal bones.
They are only thought to account for ~0.2% of all carpal fractures. Approximately 50% occur in association with other carpal fractures.
Very rarely the pisiform may be dislocated without fracture and ...
Cellulitis (more specifically referred to as superficial cellulitis) is an acute infection of the dermis and subcutaneous tissues. It results in pain, erythema, oedema, and warmth. Since the epidermis is not involved, cellulitis is not transmitted by person-to-person contact.
Pectus excavatum (or funnel chest) is a congenital chest wall deformity characterised by concave depression of the sternum, resulting in cosmetic and radiographic alterations.
It is the most common chest wall deformity, accounting for approximately 90% of cases, occurs in up to 1 ...
The gastrocnemius muscle is one of the calf muscles (triceps sure) in the superficial posterior compartment of the leg which sits superificial to the much larger soleus muscle. It gives the calf its distinctive two-headed appearance and is a primary plantarflexor.
origin: superior to a...
Fibrous cortical defects (FCD) are benign bony lesions and are a type of fibroxanthoma, histologically identical to the larger non-ossifying fibroma (NOF).
Fibrous cortical defects typically occur in children (usually 2-15 years), and indeed are one of the most common benign bony ...
Facioscapulohumeral muscular dystrophy (FSHD) is a form of muscular dystrophy characterised by extremely variable degrees of facial, scapular and lower limb muscle involvement.
It is considered one of the more common hereditary muscular disorders with a prevalence of ~1 in 8,000.
Os acromiale is an anatomical variant and represents an unfused accessory centre of ossification of the acromion of the scapula.
Os acromiale are relatively common, seen in ~8% (range 1-15%) of the population 1,2 and may be bilateral in 60% of individuals 5.
The term amputation refers to the disconnection of all or part of a limb from the body. Specifically amputation is defined as removal of the structure through a bone. This is in contrast to disarticulation, which is removal of the structure through a joint.
When due to trauma, traumatic amputat...
Epiphyseal spur refers to a spur seen in skeletally mature individuals arising at the level of closed epiphyseal line. It may be seen in any epiphysis.
Greater trochanteric fractures generally result from forceful muscle contraction of a fixed limb, which usually occurs in those who are young and physically active. It can also be caused by direct trauma.
Generally, isolated trochanteric fractures are seen more so in young, active...
The foot series is comprised of a dorsoplantar (DP), medial oblique, and a lateral projection. The series is often utilised in emergency departments after trauma or sports related injuries 2,4.
See: approach to foot series.
Foot radiographs are performed for a variety of indicatio...
Arthrogryposis (multiplex congenita) is a clinical or imaging descriptor that denotes congenital non-progressive joint contractures involving two or more body regions.
It is thought to occur in approximately 1:3000-10,000 live births 6,8.
It can result from a number o...
Flexor digitorum superficialis (FDS) is a muscle in the second (intermediate) layer of the anterior compartment of the forearm that splits into four tendons, passes under the flexor retinaculum and through the carpal tunnel, to insert into the middle phalanx of the 2nd-5th digits.
Hajdu-Cheney syndrome is a very rare connective tissue disorder with only 50 cases reported in the literature 2.
It is mostly diagnosed in adulthood or adolescence with the presence of a positive family history. There has been no link between severity of disease and age o...
Mazabraud syndrome is a rare syndrome consisting of:
fibrous dysplasia: usually polyostotic 2
multiple soft tissue myxomas (intramuscular myxomas): typically in large muscle groups
It is very rare, with only 81 cases in the global literature reported to 2012 13. It is most frequ...
Geographic appearance is a term used in imaging, and other clinical fields (e.g. histopathology) to describe lesions with a well-circumscribed margins with adjacent tissues. The term derives from the somewhat similar appearance of the outline of countries on a map or the clear demarcation forme...
An os peroneum is a small accessory bone located at the lateral plantar aspect of the cuboid within the substance of the peroneus longus tendon as it arches around the cuboid. It is a very common anatomical variant, seen in up to 26% of feet 1.
It should not be mistaken ...
A geographic skull is a radiographic appearance which is seen in eosinophilic granuloma (EG) and characterised by destructive lytic bone lesions, the edges of which may be bevelled, scalloped or confluent.
The Lodwick classification is a system for describing the margins of a lucent/lytic bone lesion. The terms used in the description suggest the level of concern for an aggressive, and possibly malignant, process.
type 1: geographic
1A: thin, sclerotic margin
1B: distinct, well-...
Clavicle tumours may be malignant or benign.
osteoma: uncommon, sclerotic, hamartomatous surface lesion
enchondroma: rare, geographic, intramed...
Hanging and strangulation are injuries involving constricting pressure applied to the neck.
In America hangings are the second most common form of suicide after firearm use. In other parts of the world due to the relative difficulty in accessing firearms, hangings are the most com...
Ossification centres of the pectoral girdle can be divided into each of the three bones that form it: clavicle, scapula and proximal humerus.
Ossification centres of the clavicle
lateral end: 5 weeks in utero
medial end: 15 years
Ossification centres of the scapula
body: 8 weeks in utero
A pilon fracture is a type of fracture involving the distal tibia. These are considered to represent 1-10% of all lower limb fractures 6.
Typically occurs as a result of an axial loading injury which drives the talus into the tibial plafond.
Several classification s...
Trimalleolar fractures refer to a three-part fracture of the ankle. The fractures involve the medial malleolus, the posterior aspect of the tibial plafond (referred to as the posterior malleolus) and the lateral malleolus. Having three parts, this is a more unstable fracture and may be associate...
The clavicle (or informally collar bone) is the only bone connecting the pectoral girdle to the axial skeleton and is the only long bone that lies horizontally in human skeleton.
The clavicle is roughly "S-shaped" with a flattened, concave, lateral one-third and a thi...
Conventional chondrosarcoma also known as central chondrosarcoma is the most common subtype of chondrosarcoma and may be low, intermediate or high grade (see chondrosarcoma grading).
They typically occur in the 4th and 5th decades with a slight male predominance 1.5-2:1.
The interossei muscles, as a group consist of four palmar (1st is often rudimentary) and four dorsal muscles. Collectively the interossei contribute to abduction and adduction of the fingers and also contribute to flexion of the metacarpophalangeal joints (MCPJ) and extension of the interphalan...
A mnemonic to remember the structures passing through the lesser sciatic foramen is:
P: pudendal nerve
I: internal pudendal artery and vein
N: nerve to obturator internus
TO: tendon of obturator internus
A mnemonic to remember the structures passing below the piriformis muscle in the greater sciatic foramen is:
PIN PINS or SNIP NIP
P: posterior cutaneous nerve of thigh
I: inferior gluteal artery, vein and nerve
N: nerve to quadratus femoris
P: pudendal nerve
I: internal pudendal ...
Posteromedial corner injury of the knee is a readily identifiable but frequently underappreciated on imaging. Importantly, it can result in increased stress on the cruciate ligaments and can result in anteromedial rotatory instability of the knee.
These injuries are frequ...
The double PCL sign appears on sagittal MRI images of the knee when a bucket-handle meniscal tear (medial meniscus in 80% of cases) flips towards the centre of the joint so that it comes to lie anteroinferior to the posterior cruciate ligament (PCL) mimicking a second smaller PCL.
A double PCL ...
Bucket-handle meniscal tears are a type of displaced longitudinal meniscal tear where the inner part is displaced centrally. They are more commonly occur in the medial meniscus and are often associated with anterior cruciate ligament tears.
Bucket-hand tears can man...
Haematometrocolpos refers to a blood-filled distended uterus and vagina usually due to an anatomical mechanical obstruction precluding the evacuation of the menstrual blood.
The estimated incidence in teenagers is at ~1 in 1000-2000 5.
imperforate hymen: in ~2...
Peroneus brevis tendon tears can present with lateral ankle pain with or without a history of trauma, worsening with activity. They are usually diagnosed with ultrasound or MRI and management is typically conservative.
Little epidemiological information available but patients typi...
Lateral epicondylitis, also known as tennis elbow, is an overuse syndrome of the common extensor tendon and predominantly affects the extensor carpi radialis brevis (ECRB) tendon.
Lateral epicondylitis occurs with a frequency seven to ten times that of medial epicondylitis. As wit...
Spondylodiscitis is characterised by infection involving the intervertebral disc and adjacent vertebrae.
Spondylodiscitis has a bimodal age distribution, which many authors consider essentially as separate entities:
older population ~50 years
Psoas muscle abscess and fluid collections are located in the retrofascial space rather than in the retroperitoneal space because the psoas muscles are located in the iliopsoas compartment posterior to the transversalis fascia, which is the posterior boundary of the retroperitoneum.
Intra-articular loose bodies can result from a variety of pathological processes.
Use of the term "loose" is frowned upon by some because the fragments do not necessarily move around in the joint - the term intra-articular body or fragment is a safer alternative.
Fibrous dysplasia (FD) is a non-neoplastic tumour-like congenital process, manifested as a localised defect in osteoblastic differentiation and maturation, with the replacement of normal bone with large fibrous stroma and islands of immature woven bone. Fibrous dysplasia has a varied radiographi...
Melorheostosis, also known as Leri disease, is an uncommon mesenchymal dysplasia manifesting as regions of sclerosing bone with a characteristic dripping wax appearance or flowing candle wax appearance.
Although changes occur in early childhood, age at presentation is often later...