All Cases

Fibrous dysplasia (Rind sign)
Classically, fibrous dysplasia lesions are intramedullary, expansile, and well defined lucent lesion in the diaphysis or metaphysic ("long lesion in long bone"). Although endosteal scalloping may be present, a smooth cortical contour is always maintained (absence of periosteal reaction). Lesions show varying degrees of hazy density with a ground-glass quality, although some may appear almost completely radiolucent or sclerotic. The lesion may be surrounded by a layer of thick, sclerotic reactive bone termed a rind. The classic rind is most commonly seen in proximal femur.

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Erosive (inflammatory) osteoarthritis
Erosive osteoarthritis is typically bilateral and symmetrical, and it occurs in the interphalangeal, particularly distal interphalangeal, joints of the hands. The disease most commonly occurs in postmenopausal women, and it may be hereditary. The erosions are centrally located in contrast to the marginal erosions in rheumatoid arthritis. Joints assume a gull-wing configuration, with central erosions flanked by raised lips of bone.

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Tuft fracture in the ring finger - Bone sarcoidosis
Skeletal involvement is seen in approximately 5% - 10% of patients with sarcoidosis. The phalanges in the hands and feet are most frequently affected. Radiologic features are characterized by cystic or lacelike appearance which is bilateral in distribution, usually at the ends in small bones (hands and feet). The articular spaces are usually intact, unless extensive lesions (punched-out lesions) develop. Calcification is absent. A subcutaneous soft-tissue mass or tenosynovitis may also be present.

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Absent semimembranosus muscle
Semimembranosus muscle may be reduced or absent, quite large or double in which case arising mainly from the sacrotuberous ligament giving a slip to the femur or adductor magnus.

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Insufficiency fracture of sacrum and iliac bone
Insufficiency fracture is a subgroup of stress fracture caused by the effect of normal or physiologic stress upon weakened bone.

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Haglund syndrome
Represent painful condition caused by mechanically induced retrocalcaneal bursitis, superficial Achilles bursitis and Achilles tendonopathy by exostosis at posterosuperior calcaneus (Haglund's deformity). Exostosis at posterosuperior calcaneus can compress the retrocalcaneal structures during dorsal flexion.

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Plantar Fibromatosis (Ledderhose disease) case 2
Plantar fibromatosis (Ledderhose disease) occurs most frequently between the ages of 30 and 50 years, with bilateral involvement seen in 20%–50% of cases. These lesions are located in the plantar subcutaneous tissues of the foot, which are generally associated with the superficial surface of the medial portion of the plantar aponeurosis. Plantar fibromatosis is often asymptomatic until the lesion enlarges and causes mass effect or invades adjacent muscles or neurovascular structures.
The typical MR imaging appearance of plantar fibromatosis on T1-weighted and T2-weighted images is heterogeneous mass with an overall signal intensity equal to or slightly greater than that of adjacent muscle. The enhancement with gadolinium contrast material is variable, with marked enhancement seen in approximately 50% of lesions. The uniqueness of these signal intensity characteristics and the consistency of the location and morphology exhibited by plantar fibromatosis enable diagnoses to be made with reasonable confidence. Differential includes clear-cell sarcoma, callus, scar, and the subcalcaneal hypointense foci can also be enhanced. The majority of plantar fibromas show marked enhancement when gadolinium is administered, and administration of this contrast agent may be useful in evaluation of the extent of infiltration or in detection of small lesions, which may be overlooked on unenhanced images.

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Galeazzi fracture/dislocation of the left forearm
Galeazzi fractures are isolated fractures of the junction of the distal third and middle third of the radius with associated subluxation or dislocation of the DRUJ.

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Melorheostosis
Melorheostosis is a rare nonhereditary sclerosing mesenchymal dysplasia of bone originally described in 1922 by Leri and Joanny. It is usually incidentally discovered in asymptomatic adults. The common reference to this abnormality as having a "flowing candle wax" appearance. One or multiple adjacent bones are often affected, often in a sclerotomal distribution. Nucleide scintigraphy cases of melorheostosis demonstrate a region of increased nucleide uptake. MR imaging demonstrate regions of decreased signal intensity on all pulse sequences.

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Glenoid hypoplasia/dysplasia
Glenoid dysplasia is a rare developmental disorder that was initially described by Valentine in 1931. The basic radiographic findings in glenoid hypoplasia is underdevelopment of the inferior aspect of the scapular neck and glenoid rim. In the more severe forms, the inferior portion of the glenoid appears confluent with the lateral scapular border.

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Superior Peroneal Retinaculum Injury with Peroneus Longus Subluxation
The peroneus longus and brevis tendons function primarily as evertors of the foot and dynamic stabilizers of the lateral ankle. The major stabilizing structure preventing peroneal subluxation is the superior peroneal retinaculum, which converts the retromalleolar groove into a fibroosseous tunnel. Superior peroneal retinaculum (SPR) injuries are graded with Oden's classification system (see below).

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Primary lymphoma of bone
Primary lymphoma of the bone accounts for approximately 3% of malignant bone neoplasms and comprises less than 5% of all extranodal non-Hodgkin's lymphomas.
Diagnosis of primary bone lymphoma includes initial involvement of a single bone (most commonly a long bone)with no evidence of disease elsewhere for at least 6 months after diagnosis.
On conventional radiography, primary lymphomas of bone are characterized as "mottled" or "moth-eaten" radiolucencies, corresponding to regions of marrow and cortical replacement by lymphoma cells. Periosteal reaction has been reported in about 60% of cases. It is dark on T1, bright on T2 and enchances.

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Posterior cruciate ligament (PCL) tear
The posterior cruciate ligament (PCL) is described as the primary restraint to posterior tibial translation relative to the femur. Injury of the PCL occurs less often than injury to the ACL and makes up 2%-23% of all knee injuries. In 30% of these cases, the PCL injury is isolated.
A torn PCL typically becomes abnormally enlarged whether the tear occurred proximally or distally. With use of sagittal T2-weighted images, a 7-mm or greater anteroposterior measurement of the vertical portion of the PCL can be considered evidence of a torn PCL with a high degree of certainty. Additionally torn PCL, the ligament has abnormally increased intrasubstance signal intensity on proton-density images (increased relative to the signal intensity on T2-weighted images).
Bony contusion is often associated finding with PCL tears. A contusion involving the anterior proximal tibia is a known common finding related to a direct blow. Hyperextension injury resulting in kissing contusions with focal bone marrow edema on the antero-inferior femoral condyle and proximal anterior tibia also may be seen on MR images.

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Dislocation long head of the biceps brachii tendon
All biceps tendon dislocations are associated with tears of the ligamentous pulley. The transverse ligament overlying the bicipital groove is not considered a crucial stabilizing structure unless the medial coracohumeral ligament is torn. In a shallow bicipital groove, the possibility of subluxation of a tendon is potentially greater. If the tendon of the subscapularis is intact then the biceps tendon is seen lying anterior to it (extraarticular). If, as is common, the subscapularis tendon is also deficient then the tendon of the long head of biceps can prolapse into the glenohumeral joint (intraarticular).
Diagnosis is best made on axial MRI images, where the bicipital groove is seen to be empty, and the tendon can be identified medially. If the tendon cannot be identified then a complete tear of the tendon should be sought.

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Necrotizing fasciitis
Necrotizing fasciitis is a progressive, rapidly spreading, inflammatory infection located in the deep fascia, with secondary necrosis of the subcutaneous tissues.
Necrotizing fasciitis can occur after trauma or around foreign bodies in surgical wounds, or it can be idiopathic, as in scrotal or penile necrotizing fasciitis.
In cases of massive fluid collections along fasciae seen on CT or sonography necrotizing fasciitis can be suspected. MR imaging with its characteristic findings of thickening and fluid collections along deep fascial sheaths is probably the best radiologic tool for diagnosing necrotizing fasciitis. This method is limited because of its suboptimal specificity. If MR imaging does not exclude the presence of necrotiting fasciitis, a biopsy should be performed.

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Osteoid osteoma in the scaphoid
Osteoid osteoma is a benign tumor consisting of a central core of vascular osteoid tissue (the nidus) surrounded by a peripheral zone of sclerotic bone.
Osteoid osteoma usually occurs in the second and third decade of life.
Localization in the hand occurs with an incidence of only about 8% of all reported cases. The phalanges are the most frequent sites for osteoid osteoma in the hand, followed by the carpal bones. The metacarpals are the least common sites for osteoid osteoma. The most frequently involved carpal bone is the scaphoid.

See more about osteoid osteoma on this site:

Case 1
Case 2

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Fabella syndrome
The syndrome is most common in early adolescence (it may be seen in all ages) and most likely is the result of repetitive friction of the fabella over the posterolateral femoral condyle.
Radiographically fabella may be big, demonstrates irregular shape and abnormal density. This finding may be associated with chondral or subchondral change in posterior portion of lateral femoral condyle. Irregular appereance of fabela may be confused with foreign body. Abnormality in posterior portion of femoral condyle may look like osteochondral defect or osteochondritis dissecans.

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Carpometacarpal dislocations and fractures
Dislocations of the carpometacarpal (CMC) joints are rare injuries which may occur with or without fracture. Fractures in this area of the hand are hard to diagnose as the radiographic evidence is often subtle. The key to radiographic diagnosis lies in often called a "broken zigzag line" or "broken parallel M line sign". However, a true lateral roentgenogram is needed for accurate diagnosis.

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Rupture of soleus and medial head of gastrocnemius
This condition usually occurs in the middle-aged, patient engaged in strenuous physical activity. A sudden pain is felt in the calf, and the patients often report an audible or palpable "pop" in the medial aspect of the posterior calf. Although these clinical findings are believed to be characteristic of a tear of the medial head of the gastrocnemius. Similar clinical findings is seen in patients with plantaris and soleus tear.

Magnetic resonance imaging and ultrasonography have been used as the primary imaging techniques for evaluation of patients with this clinical diagnosis. MR imaging findings include edematous changes at the myotendinous junction with a feathery pattern, intramuscular hematoma, perifascial fluid collections, and complete rupture with retraction of the tendon. The importance of imaging patients with this condition is to rule out more serious conditions, such as deep venous thrombosis.

Please see: Plantaris tendon tear on this website.

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Nail patella syndrome
Nail patella syndrome, also known as hereditary osteoonychodysplasia, Fong disease, Turner-Kieser syndrome, and Osterreicher-Turner syndrome, is an autosomal dominant disorder with a constellation of clinical findings affecting the bones and nails. It affects approximately 1 in 50,000 live births.
Characteristic imaging findings include those associated with the patellar changes and iliac horns. The iliac horns have been shown to consist of cortex and medulla that blend in with the normal iliac cortex at the attachment of the gluteus medius muscle. On nuclear medicine studies, these have demonstrated bilateral increased uptake with an appearance of bony projections extending from the midsacroiliac regions. The patellae are usually hypoplastic or aplastic producing instability and pain in the knee. A combination of patellar hypoplasia and hypoplasia of the lateral femoral condyle produces a situation conducive of recurrent patellar subluxation and dislocation.

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Cone-shaped epiphyses
Cone-shaped epiphyses may occur in normal children and are unrelated to any skeletal dysplasia or arthropathy.
Coned epiphyses can be result of premature closure of the central portion of the physis, following which the peripheral portion of the physis continue to grow.

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Glenolabral articular disruption (GLAD) lesion
The GLAD lesion as described by Neviaser is a superficial tear of the anteroinferior labrum in combination with an articular cartilage lesion of the anterior inferior quadrant of the glenoid. The injury is thought to result from glenohumeral impaction while the arm is abducted and externally rotated.

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Osteosarcoma conventional
Osteosarcoma is the most common malignant primary bone tumor. It tends to occur in children and young adults typically 10-25 or 30 years of age. Osteosarcomas also tend to occur in patients in the sixth decade, likely related to malignant degeneration of Paget’s disease. The most common of osteosarcoma is the Conventional Osteosarcoma which accounts for 75% of cases. The distal femur and proximal tibia are the bones most commonly involved, followed by the humerus and iliac wing. Conventional osteosarcoma is typically located around the knee (commonly arise in the metadiaphysis) and is a very aggressive lesion associated with a soft tissue mass, cortical destruction, a permeative pattern of bone change and wide zone of transition. Periosteal reaction typically presents with a Codman’s triangle or sunburst pattern. At least 90% of conventional osteosarcomas produce osteoid matrix in variable quantities which alters their radiographic appearance.

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Osteosarcoma of the Jaw (Gnathic Osteosarcoma)
Gnathic Osteosarcoma of the mandible and maxilla constitute 6%-9% of all osteosarcomas. It is considered a distinct category because of its predilection to affect patients in the fourth decade. It has been reported with pre - existing conditions including radiation therapy, Paget's disease and fibrous dysplasia.
Lesions affect the alveolar ridge, maxillary antrum, and body of the mandible. At histologic analysis, the lesions are often predominantly chondroblastic. The radiologic appearance of gnathic osteosarcoma is similar to that of conventional osteosarcoma, with evidence of osteoid matrix, aggressive periosteal reaction in mandibular lesions, and soft-tissue cxtension. CT is the optimal modality for detecting areas of mineralized osteoid and periosteal reaction. MR imaging shows both intramedullary involvement and soft tissue mass which are advocated for staging workup.

Thanks to Dr. Shafi for providing this case.

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Unicameral bone cyst (UBC) or Simple bone cyst
Unicameral bone cyst present in the 1st and 2nd decades of life. Very rarely can be seen in older age like in our case. Majority of unicameral bone cysts occur in the proximal humerus and proximal femur (94%). Typically it is centrally located in metaphysis. It often leads to thinning of adjacent cortex of bone such that fracture may occur. Such a fracture is often associated with a fracture fragment which settles dependently within the cystic space. This has been called the "fallen fragment" sign. Usually UBC does not demostrate septation or loculation. Zone of transition is narrow with thin rim of non reactive bone. Without fracture periosteal reaction is not present.

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Osteoporosis circumscripta (Paget's disease)
Paget's disease can be divided into three phases of increasing clinical and radiographic severity: 1) initial resorptive/osteolytic phase, 2) mid-phase, mixed, osteoblastic/osteoclastic hyperplasia and 3) late sclerotic phase.
The initial phase is characterized by increased osteoclastic activity that produces a radiologic picture of advancing, metaphyseal to diaphyseal V-shaped cutting zone in long bones on conventional radiograph ("Candle flame" or "blade of grass" pattern).

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Neuropathic osteoarthropathy (Charcot's joint)
Neuropathic arthropathy was first time described in 1869 in patients with syphilis. Since that time, conditions other than syphilis have been found to cause a "Charcot's joint." The radiographic changes include destruction of articular surfaces, opaque subchondral bones, joint debris, deformity, and dislocation. Radiography may be the only imaging required. It poses a special problem in imaging when it is associated with a soft tissue infection. Probably radionucleide scanning, 111In–labeled leukocytes has the highest sensitivity and specificity.

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Osseous Hemangioma (Knee)
The majority of hemangiomas that involve bone are discovered incidentally in asymptomatic patients. Men are affected twice as often as women, and lesions are usually discovered in the 4th 5th decades of life. Soft-tissue components may also be associated with these lesions. Osseous hemangioma is particularly common in the spine and calvaria and less frequently affects long bones such as the tibia, femur, and humerus.
Osseous hemangiomas in long bones may have radiating trabecular thickening on radiographs. Another common pattern is a bubbly bone lysis that creates a honeycomb, latticelike, or "hole-within-hole" appearance. These lytic areas are invariably multifocal and usually metaphyseal or epiphyseal. Bone lysis can have linear and circular components on radiographs, suggestive of a vascular lesion, with linear and circular elements representing vascular channels seen longitudinally and en face, respectively. However, these serpentine vascular channels are recognized more easily with CT and MR imaging.

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Avulsion of the triceps brachii tendon
Disruption of the triceps tendon is a rare injury comprising approximately 2% of all tendon injuries and less than 1% of all tendon ruptures related to the upper extremity. The most common mechanism of injury resulting in avulsion of the triceps tendon has been reported to be a fall on the outstretched hand with the elbow in mid flexion, with or without a concomitant direct blow to the posterior aspect of the elbow.
The triceps brachii muscle is chief extensor of forearm, lies in the posterior compartment of the arm and is composed of three heads. Disruption of the triceps tendon is a rare injury comprising approximately 2% of all tendon injuries and less than 1% of all tendon ruptures related to the upper extremity. Diagnosis is usually made on clinical basis. The pathognomonic features are inability or weakness of extension of the elbow and a palpable gap in the substance of the muscle. In cases of doubt, diagnosis using MRI or ultrasound is of great use. Furthermore, MRI has been proved to be useful in preoperative planning because it shows whether rupture is complete or partial.

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Osteomalacia
Osteomalacia is a metabolic bone disease characterized with lack of available calcium or phosphorus (or both) for mineralization of newly formed osteoid. Osteomalacia (adults) and rickets (children) are essentially the same process characterized by an abnormally high ratio of osteoid (inadequately mineralized bone matrix) to mineralized bone.

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Soft Tissue Hemangioma (Gastrocnemius)
Soft-tissue hemangiomas is the most frequent tumor of infancy and childhood. It is one of the most common soft-tissue tumors, constituting 7% of all benign tumors. Soft-tissue hemangiomas are more common in women and may dramatically increase in size during pregnancy. They are usually intramuscular, although synovial hemangiomas (less than 1% of hemangiomas) also occur.
Classification is based on the histologic appearance, and the tumors are categorized as follows: capillary, cavernous, arteriovenous, venous, and mixed.

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Os subfibulare
Ossification in lateral submalleolar area or in between lateral malleous and talus has been reported to be a normal variant - os subfibulare. The etiology of these ossifications/calcifications is unclear (unfused epiphyseal ossification center, supernumerary ossicles or traumatic origin).

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Diffuse idiopathic skeletal hyperostosis (DISH)
Diffuse idiopathic skeletal hyperostosis (DISH) is disorder of unknown cause characterized by excessive bone fomation at skeletal sites subject to normal or abnormal stresses, generally where tendons and ligaments attach to bone (enthesopathy).

Three criteria are required to diagnosis spinal involvement in DISH:

1. Flowing ossification of the anterolateral aspect of at least four contiguous vertebral bodies.
2. Relative preservation of the disc height in the involved segments and absence of radiographic changes associated with disc degenerative disorder.
3. Absence of sacroilitis and facet ankylosis.

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Chronic osteomyelitis (sequestrum/involucrum)
Osteomyelitis is an infectious process involving all bone components but primarily the bone marrow and can be subdivided into acute, subacute, and chronic stages.
Cierny and Mader proposed an anatomic classification of osteomyelitis:
Type 1 - Endosteal or medullary lesion
Type 2 - Superficial osteomyelitis limited to the surface
Type 3 - Localized, well-marked legion with sequestration and cavity formation
Type 4 - Diffuse osteomyelitis lesions
Preoperative radiological assessment has two main goals:
- to evaluate bone involvement (i.e. extent of active intramedullary infection or abscess superimposed on areas of necrosis, sequestrum and fibrosis);
- to identify soft-tissue involvement (i.e. areas of cellulitis, abscess, and sinus tracts).
Conventional radiography usually is the initial imaging examination. MRI is probably the best tool evaluate caracteristic finding in osteomyelitis (see below).

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Chronic Lateral Collateral Ligament (LCL) tear
A chronic LCL tear appears as a thickened low T1/T2-weighted signal ligament.

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Partial tear of Achilles tendon
Differentiation between partial tear and severe chronic Achilles tendinosis may be difficult apart from clinical history. However, acute partial tears are often associated with subcutaneous edema, hemorrhage within the Kager fat pad, and intratendinous hemorrhage at MR imaging, whereas chronic tendinosis does not usually demonstrate increased subcutaneous or intratendinous signal intensity on T2-weighted images.

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Cortical desmoid
Cortical desmoid is a benign shallow cortical irregularity seen in older children or adolescents. It is recognised at specific metaphyseal sites, the most common being the medial posterior aspect of the distal femoral metaphysis at the insertion of the adductor magnus aponeurosis.

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Cleidocranial dysplasia
Cleidocranial dysplasia (cleido = collar bone, + cranial = head, + dysplasia = abnormal forming), also known as Scheuthauer-Marie-Sainton or Marie-Sainton syndrome, is a rare autosomal dominant dysplasia with an estimated incidence of 1:1,000,000. Prominent features include a large head with delayed suture closure, persistent metopic suture, Wormian bones (tiny separate bones within the skull sutures, particularly the lambdoid), hypertelorism, a small face, a cleft mandible, dental dysplasia, hypoplasia or aplasia of the clavicles, hypoplastic scapula with a small glenoid, a cleft sternum, coxa vara or valga, a narrow pelvis, delayed pubic ossification, and several varieties of spinal abnormalities. These patients have a normal life expectancy. Several dysplastic disorders (Pyknodysostosis, Congenital pseudoarthrosis of the clavicle, Yunis-Varon syndrome, Scapulo-iliac dysostosis atc.) may share similar osseous abnormalities.

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Subtalar or peritalar dislocation
Subtalar dislocation is the simultaneous dislocation of the distal articulations of the talus at both the talocalcaneal and talonavicular joints (perhaps more appropriately called peritalar dislocation). With this injury the tibiotalar joint is undisturbed. Subtalar dislocation can occur in any direction but more commonly medialy (80%) and laterally (rarely anterior or posterior). It typically is caused by falls from a height, MVCs, and severe twisting injuries such as in basketball players who land on an inverted and plantar-flexed foot. Inversion injuries result in medial dislocations and eversion injuries result in lateral dislocations.

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Achilles Tendon Rupture
Achilles tendon injuries may be classified as noninsertional or insertional. The former group includes a rupture 2-6 cm above the insertion of the tendon on the calcaneus. The latter group includes insertional Achilles tear, which may be associated with Haglund deformity of the calcaneus. Majority of individuals who sustain Achilles tendon injury are men. The diagnsosis can often be made by physical examination. However, up to 25% of patients with partial or complete Achilles tear may be misdiagnosed based on physical exam findings alone. MR imaging findings confirm the diagnosis particularly in questionable cases.

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Osteopetrosis (Albers-Schoenberg disease)
Osteopetrosis is a rare disorder caused by osteoclast dysfunction with resultant failure of cartilage and bone matrix resorption.. It presents in one of three forms: osteopetrosis tarda, osteopetrosis congenita and "marble bone" disease.
The radiographic findings are similar in all forms (less severe in osteopetrosis tarda). The bones are diffusely sclerotic, with thickened cortex, obliteration of the medullary cavity, and pathologic fractures. The vertebral endplates become accentuated, especially with advancing age . A "bone within bone" appearance or radiolucent bands in the ends of the diaphyses are sometimes seen. Abnormal modeling of metaphysic such as "Erlenmeyer flask deformity" also may be seen.

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Bone metastasis from renal cell carcinoma
The most commonly affected sites from renal cell carcinoma are the pelvis and ribs and the spine. Other common sites included long bones and the skull. Bone lesions associated with renal cell carcinoma are typically osteolytic and are generally very aggressive.
Monitoring patients with renal cell carcinoma for bone metastasis by either bone scans or plain X-ray films is an important aspect of patient care.

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Ulnar/Ulnocarpal impaction syndrome
Ulnocarpal impaction syndrome is a condition of chronic ulnar wrist pain that is caused by impaction of the distal ulna against the proximal lunate and triquetrum. The most common predisposing factors include congenital positive ulnar variance, malunion of the distal radius, premature physeal closure of the distal radius, and previous radial head resection. The increased mechanical load on the triangular fibrocartilage complex and the underlying proximal ulnar-sided pole of the lunate leads to triangular fibrocartilage complex lesions and chondromalacia of the lunate bone and distal ulnar head. In advanced stages, osteoarthritis of the distal radioulnar and ulnocarpal joints appears.

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Trevor's disease
Also known as Dysplasia Epiphysealis Hemimelica. A rare congenital bone developmental disorder characterised by asymmetrical limb deformity due to localised overgrowth of cartilage, usually involving the lower extremities. It is thought to be a variant of osteochondroma arising within a joint.

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Hamatolunate Impaction Syndrome
Hamatolunate impingement is cause of ulnar-sided wrist pain. This syndrome is associated with anatomic variant (type II lunate) which has been defined as a lunate that has an “extra” articulation medially with the hamate bone. Type II lunate causes alteration of normal uniform loading, and the altered biomechanics leads to chondromalacia and osteoarthritis. The chondromalacia is secondary to impingement and abrasion of the hamate and lunate.
MRI demonstrates subchondral edema or sclerosis (advanced disease) of the proximal hamate or medial lunate facet (in advanced disease)

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Lateral collateral ligament (LCL) tear
The lateral collateral ligament (LCL) arises from the lateral femoral condyle and inserts on the lateral aspect of the middle third of the fibular head, sometimes joining the biceps femoris tendon. This ligament has a posterior and oblique course and is seldom seen entirely on one coronal image. The LCL is 5-7 cm long, extracapsular, and free from meniscal attachments.
The location of the injury relative to the lateral collateral ligament can be proximal, mid substance, or at the fibular insertion. MRI appearance of an LCL tear depends less on the degree of tearing. Most commonly an acute LCL tear is seen as a serpiginous or lax ligament with discontinuous fibers (or avulsed fibular head), often without significant thickening of the ligament.

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Medial collateral ligament (MCL) tear
The MCL is a ligament measuring approximately 8-11 cm long by 10-15 mm wide. The MCL arises 5 cm above the joint from the medial femoral epicondyle and inserts 6-7 cm below the joint on the medial tibial metaphysis.
Medial collateral ligament (MCL) injuries are common and usually partial. Any injury involving a valgus force is likely to result in injury to the MCL. Isolated tears of the MCL are treated conservatively and imaging is rarely required. However, a torn MCL is often seen on MRI as part of a more complex injury. The ligament usually tears near the femoral insertion. Minor bony oedema may be seen in the adjacent condyle at the site of the avulsion. In minor injuries the tear may be confined to the deep layers and is seen on MRI as high signal on T2 weighted or short tau inversion recovery (STIR) images deep to the superficial fibers.

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Intramuscular ganglion in infraspinatus muscle
The intramuscular ganglion (cyst) typically is located within the sheath or substance of muscles of the rotator cuff. Usually, it is not palpable or visible at arthroscopy. These ganglions like paralabral cysts are associated rotator cuff tear which allows fluid from the glenohumeral joint to leak out into the substance of muscles (periarticular tissues).

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Gout
Gout is asymmetric polyarticular disease of the appendicular skeleton, characterized by soft tissue masses, eccentric osseous erosions, bony proliferation, preservation of joint space, and absence of osteoporosis. Disease rather involves lower extremities, often seen in feet, knees, hands, wrists and elbows. Involvement of the spine, hips, shoulders, and sacroiliac, sternoclavicular, and acromioclavicular joints is unusual. Podagra, or pain in the first metatarsophalangeal joint, is the classic presentation of gout. The symptoms of gout suddenly appear at night and occur in men with hyperuricemia who are aged 30-60 years.

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