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Osteitis condensans ilii

Sclerosis of iliac side of SI joint, which is otherwise pristine.
Usually females after several births, but men can have too.
Usually bilateral, triangle shaped (base inferiorly)
Can present with pain, often incidental finding.

Causes of secondary DJD


Localized thickening of periosteum

Brodie's abscess
Osteoid osteoma
Healed stress fracture

Wormian bones

Cleidocranial dysostosis
Osteogenesis imperfecta
Down syndrome

Permeative pattern

Lymphoma Leukemia
Multiple myeloma

Expansile lesions of bone

Multiple myeloma
Aneurysmal bone cyst.
Fibrous displasia
Brown tumor

Pelvic lesions think of

Solitary plasmacytoma

Spine lesions think of


Malignant lesions multiple sites

Metastatic diesease
Multiple myeloma
Ewings (rare)
Osteosarcoma (rare)

Causes of avascular necrosis

Sickle cell
Caisson's disease

Round cell lesions

Multiple myeloma - 50s
Ewing's - teens early 20s
Histiocytosis - infant child
Leukemis - 5 to 15
Reticular cell sarcoma - mid 30s

Expansile rib lesions

Fibrous displasia
Eosinophilic granuloma

Lytic lesions in childern

Eosinophilic granuloma

Blastic lesions in children

only Medulloblastoma

Lytic lesions in adults

Multiple myeloma.
Primary tumor.
Mets - lung, renal, thyroid.

Blastic lesions in adults

Mets - breast, prostate, colon, lymphoma

Benign lesions without sclerotic margin

Giant cell tumor
Brown tumor
Paget's in lytic phase

Differential of focal periostitis

Stress fracture
Osteoid osteoma
Periosteal osteosarcoma

Differential of lesion with appearance of sequestrum

Osteoid osteoma
Eosinophic granuloma (Langerhans cell histiocytosis) "button sequestrum"

Differential of chest wall mass with rib destruction

Ewing sarcoma
PNET (Askin tumor)
Soft tissue sarcoma.


Calcium pyrophosphate deposition disease.

Rare under age 30, predominantly in elderly.
Possibly enzyme mutation regulating pyrophsphate.

Cartilage narrowing, sclerosis subchondral cysts, osteos
patellofemoral predominant
chondrocalcinosis of menisci (not required)
Hand wrist
TFCC chondrocalcinosis posible
Hook osteophytes heads of metacarpals, 2 and 3 predom.
scaphlunate advanced collapse common
Other joints less common, but will also be symmetric

Differential of hypodense wedge lesion in kidney

Acute renal infarction
I atrogenic (catheters)
Arterial thrombosis
Acute renal vein thrombosis


Renal tuberculosis


Rare, benign tumor of brown fat which is indistinguishable from liposarcoma on imaging
Follows fat signal on MRI and density on CT, BUT unlike lipoma there is enhancement due to metabolic activity. Also high activity on FDG-PET.
Slow growing.
Highly vascular

Malignant Fibrous Histiocytoma

Most common soft tissue sarcoma of older adults.
Contains both fibroblastlike and histiocytelike cells in varying proportions.
Distant metastasis most commonly occurs to the lung (90%), bone (8%), and liver (1%).
Peak incidence in the fifth and sixth decades, but an age range of 10-90 years.
Most commonly in the extremities (70-75%, with lower extremities accounting for 59% of cases), followed by the retroperitoneum. Arises in deep fascia or skeletal muscle.
Most common clinical presentation is an enlarging painless soft-tissue mass in the thigh, typically 5-10 cm in diameter. Two thirds of tumors are intramuscular.
Associations to associated with hematopoietic diseases such as non-Hodgkin lymphoma, Hodgkin lymphoma, multiple myeloma, and malignant histiocytosis.
Retroperitoneal MFH usually presents with constitutional symptoms, including fever, malaise, and weight loss. The tumor is often larger than 10 cm in diameter at presentation and may cause displacement of the bowel, kidney, ureter, and/or bladder. May occur after radiation or shrapnel injury.
Muscle density on CT. Can have hypodence regions.
Calcification 5-20% any pattern. Also heterotopic bone.
Heterogeneous on MRI, T1<T2
Enhances, hypervascular and high uptake of FDG and on MDP and gallium scans.

Tibialis Anterior tear

•Characteristic findings of Anterior Tibial Tendon tears include tendon thickening (>5mm) and signal abnormalities of the tendon within 3cm of the distal point of insertion.
•Most people have dual insertions of the anterior tibial tendon on the first metatarsal and medial cuneiform.
•Patients often present with slight foot drop preceded by a history of pain and swelling over dorsomedial midfoot.
•More common scenario is a patient between the ages of 60 and 70 who reports chronic symptoms that accompany swelling at the dorsomedial aspect of the midfoot, possibly in combination with an acute exacerbation of pain. This type of tear is a result of hypoxic or mucoid degeneration
•Acute tears of the ATT are very rare, may occur at any age, and are the result of massive trauma associated with fractures or soft-tissue lacerations.

Discoid Meniscus

The meniscus is thickened and has lost it's C shape. Likely due to failure to resorb the central tissue.
More often lateral.
More prone to tears.
Look for >13 mm transverse diameter or
Shows in more than 3 consective slices.


• Very rare lucent bubbly expansile bone lesion
• Mixed areas of lucency and sclerosis
• Most commonly found in the anterior tibial diaphysis (90%).
• Often multi-focal with a soft tissue component.
•Adamantinomas are malignant (15% at time of diagnosis)
• Mainly known for being locally aggressive and recurrent.
High T1, low T2, enhances, does not fat suppress.
giant cell tumor,
fibrous dysplasia (most similar on imaging),
simple bone cyst,
aneurysmal bone cyst,
osteofibrous dysplasia of the tibia,
eosinophilic granuloma,
chondromyxoid fibroma, and

Synovial sarcoma

Sarcoma of mesenchymal origin occurring in para-articular regions of extremities

Slow growing palpable soft tissue mass with progressive pain
Metastases in 80% on presentation
Size less than 5 cm, young age (15 years or younger) have favorable prognosis
Treatment: Surgical resection with wide margins
Local recurrence in 20-25%, less with pre-radiation

60% in lower extremity, knee and foot
within 5 cm of joint or intra-articular

Soft tissue mass close to joint
Amorphous calcifications: 25-30%
Bone invasion: 10-20%
Periosteal reaction, invasion of cortex, massive bone destruction rare
Juxta-articular osteoporosis

CT: avid enhancing
T1: Heterogeneous low signal, septated
T2: Heterogeneous high signal
US: again, heterogeneous
Angio: vascular

Soft Tissue Chondrosarcoma
Myositis Ossificans
Pigmented Villonodular Synovitis (PVNS)
Parosteal Osteosarcoma
Malignant Fibrous Histiocytoma (MFH)


Proliferation of hemorrhagic synovium

Radiograph: Large effusion ± associated erosions & subchondral cysts
MR: large effusion with synovial proliferation, low signal on all sequences & blooms on gradient echo
PVNS (intraarticular): 80% occur in knee
Knee > ankle > hip > shoulder > elbow
Hand & wrist (65-89%): Volar aspect of digits
May be focal nodular mass
May be diffuse, with villonodular proliferation of entire synovium & in all potential joint recesses
Makes large well defined subchondral cysts

supraspinatus outlet

Space formed by the acromion, coracoacromial arch, and acromioclavicular joint on the upper rim and the humeral head and glenoid below.
Accommodates passage and excursion of the supraspinatus tendon.
Abnormalities of the supraspinatus outlet have been identified as a cause of impingement syndrome and rotator cuff tendonitis.

Suprospinatus and infraspinatus atrophy

These muscles are more prone to atrophy than farry degeneration. The suprascapular nerve supplies both and is most susceptible to injury in the suprascapular notch. Any pathology there will result in atrophy such as traction, hematoma, mass, irradiation etc.

Residual red marrow

Common in proximal femur and humerus
Also common at the distal femora especially in adolescents and menstruating women.
May be confused with a tumor

Brown tumor

No actually a neoplasm.
Fibrotic proliferation associated with any cause of severe hyperparathyroidism. Term brown is from brown coloration of gros specimen due to hemorrhagic products in the tissue (from microbleeds).
Imaging appearance is variable, from lytic to blastic.
Due to fibrous and hemorrhagic makup, hypointense on both T1 and T2 sequences.
To diagnose a brown tumor, need to find other evidence of hyperparathyroidism such as subperiosteal resorption, labs etc.
Can be mutifocal.
Most common locations are facial and hand bones. Can also be in spinous process.
Differential: Giant cell tumor can look very similar, but when in spine, usually occurs in the vertebral body, NOT the spinoud process.

Bipartite patella

Secondary ossification center results in non-fusion of part of the patella.

Most commonly in the upper outer segment (insertion of vastus lateralis)

1- inferior pole (least common, can mimck Sinding-Larsen-Johansson syndrome)
2- lateral margin
3- superolateral

Male:female 9:1

Almost half of cases are bilateral.

Commonly demonstrates activity on bone scan even when asymptomatic

Spinoglenoid notch

The suprascapular nerve passes through this to get from the supraspinous muscle to the infraspinous. Compression of the nerve in this notch would result in atrophy of only the infraspinatus.

Quadrilateral space.

Bounded by:
above/superior: the Subscapularis and Teres minor.
below/inferior: the Teres major
medially: the long head of the Triceps brachii
laterally: the surgical neck of the humerus

The axillary nerve, and the posterior humeral circumflex artery, pass through the quadrilateral space to reach the teres major and deltoid muscles. A mass in this area would result in atrophy of these two muscles.


Rheumatoid arthritis
Metabolic diseases

Pubic ramus muscles

Gracilis - anterior medial
Obturator externus - at the obturator foramen
Adductors - between the first two, Magnus is Medial
Obturator internus - on the posterior surface

Obturator internus and adductor magnus also partially on the ischial ramus

Anterior superior iliac spine important insertions

Sartorius and inguinal ligament

Anterior inferior iliac spine important insertions

Straight head of the rectus femoris superiorly
Ilio-femoral ligament inferiorly

Iliac wing fossa insertion

Iliacus. Lower bowndary is the arcuate line

Ischium important insertions

Semimebranosus from upper part
Semitendinosus and long head of rectus femoris from lower part

Also part of adductor magnus and obturator internus anteriorly.

Greater trochanter important insertions

Obturator internus at the very tip
Pyriformis just below that
Gluteus medius on an oblique ridge on the lateral surface

Gluteus minimis at the lower part and
Vastus lateral just below that, more on the shaft

Lesser trochanter important insertions

The psoas major is the only one

Posterior part of femur important insertions

Quadratus femoris on the quadrate tubercle
Gluteus maximus

Lateral femoral epicondyle important insertions

Lateral head of gastrocnemius
Tendinous insertion of adductor magnus

Medial femoral epicondylw important insertions

Medial head of gastrocnemius

Important tibial insertions

Sartorius anteriorly
Semimembranosus on medial condile posteriorly
Popliteus on metaphysis posteriorly
Flexor digitorum longus shaft posteriorly

Lesser tubercle insertion


Intertubercular groove

All the asuctors: Pectoralis major, Teres Major

Medial humeral epicondyle insertions

Common origin of flexors:
Flexor carpi radialis
Apmaris longus
Flexor digitorum
Flexor carpi ulnaris

Pronator teres just above those

Lateral humeral epicondyle insertions

Common origin of extensors:
Extensor carpi radialis
Extensor digitorum
Extensor carpi ulnaris
Extensor digiti minimi

Greater tuberosity insertions

Posterior to anterior
Teres minor

Koracoid process insertions

Has fibers from
pectoralis minor
short head of biceps brachii

coracoclavicular ligament
coracoacromial ligament
coracohumeral ligament


Humerus shaft insertions

Brachialis anteriorly inferior
Deltoid on deltoid tubercle

Perilunate dislocation

Perilunate dislocation is accompanied by fracture in 75%. It is 2-3 time more common than lunate dislocation.
Often associated with scaphoid waist fracture because a scaphopid waist fracture is often associated with disruption of the radioscaphocapitate ligament. Scaphocapitate syndrome = transscaphoid perilunate fracture dislocation with a transcapitate fracture.

Lunate fracture

Often associated with Kienbochs osteomalacia

Freiberg disease

avascular necrosis of the metatarsal head (usually 2nd, but 3rd or 4th can also be involved)
Usual patient is young female with unfusued growth plates.
Predisposition when 2nd metatarsal is longer than 1st (which is actually the majority) and women who frequently wear high heals. 10% bilateral.

This thing is a relative of all the other avascular necroses including femoral and humeral head, Kienochs (lunate) and Kohler (tarsal navicular).
Like all the others is an evolvling process often presenting initially with vague pain in the affected region but normal radiographs, progressing to eventual collapse of the epiphysis and sclerosis. Leads to severe early DJD later in life.
Like the others nuclear scintigraphy and MRI have findings earlier than radiographs (edema, tracer takeup). Early on, area may actually be photopenic on nucs studies because the area is avascular and the tracer cant get there. For that reason delayed images are important. Also pinhole is preferred method as it increases resolution and can provide magnification.

Some cases resolve spontaneously (minority). Conservative therapy works (decreased weight bearing, orthotics to relieve pressure). However most present late in disease and require surgery.

Contents of carpal tunnel

Tendons of flexor digitorum profundus and superficialis
Tendon on flexr carpi radialis
tendon of flexor hallucis longus
Median nerve

Contents of tarsal canal

posterior Tibial tendon
flexor Digitorum longus
Artery-posterior tibial
Nerve-posterior tibial nerve
flexor Hallucis longus

nerve injured in clavicle fracture

Axillary nerve
Located anterior
Cutaneous branch innervates skin over scapula-injury results in pain over this area.

Kümmell's disease

delayed post-traumatic collapse of a vertebral body.
Disk space is preserved

Chronic recurrent multifocal osteomyelitis

most common nonneoplastic process involving the clavicle in patients less than 20 years of age.
Female predominance
Thought to have autoimmunie mechanism-associated with psoriasis and IBD
Likes women, tubular bones and clavicles, more in metaphyses, more in lower extremities.
Tubular bone lesions can heal well. Clavicles ones can presist for years and can cause thoracic outlet obstruction.
Clinically insidious onset of pain and swelling, can last for years.
Self limiting, but anti-inflammatories help.

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