Haglund Syndrome - MSK Radiology Imaging Findings: • The Haglund Deformity (enlarged superior

Posterior Ankle Impingement (Os Trigonum) Syndrome - MSK Radiology Imaging Findings: • Os trigonum which has marrow signal alteration with T2-hyperintense and T1-hypointense signal; consistent with marrow edema/contusion. • Arrows showing posterolateral capsular thickening and fluid-signal consistent with synovitis. • "Edema-like" marrow signal of the posterolateral talus and calcaneus adjacent to the os trigonum. Case description: • Usually presents with localized severe pain at the back of the ankle, worse upon plantar flexion. • Ballet dancer or other athletes with plantar flexion. • MRI: Posterolateral capsular thickening/synovitis; Predisposing factors such as Stieda process, os trigonum, abnormal morphology calcaneal tuberosity; Tenosynovitis flexor hallucis longus Differential diagnosis for similar location of pain: • Posterior syndesmotic ligament tear: no impingement findings and torn ligament on MRI. • Achilles tendinopathy: thickening and abnormal signal of the achilles tendon. • Posterior talar dome osteochondral lesion: pain limits plantar flexion but no symptoms of impingement. Dr. Donald von Borstel @DrvonBorstel #Posterior #Ankle #Impingement #Os #Trigonum #OsTrigonum #Syndrome #clinical #mri #clinical #Radiology #diagnosis #msk

Osgood-Schlatter Disease - MSK Radiology Imaging Findings: • Infrapatellar fat-pad edema with loss of the patellar tendon sharp posterior margin. There is also fragmentation and mild bone marrow edema of the tibial tuberosity. • T2-hyperintense fluid-signal within the infrapatellar bursa consistent with bursitis. • Thickening and intrinsic intermediate signal of the distal patella tendon. Case description: • Active adolescents typically 10-15 year-olds. • Tibial tuberosity pain and swelling exacerbated with activity. • Isolated apophysis "fragmentation" DOES NOT OSD in all cases; possible secondary ossification centers. Eval clinical presentation & look for secondary findings! • MRI is more sensitive & specific: - Hoffa fat pad and subcutaneous soft-tissue swelling - Patellar tendon thickening/edema-like signal - Infrapatellar bursitis - Marrow edema of tibial tuberosity Differential diagnosis: • Sinding-Larsen-Johansson disease (similar condition but at the inferior pole patella) • Patellar tendon tear (similar symptoms, absence of marrow edema and bony fragmentation) Dr. Donald von Borstel @DrvonBorstel #Osgood #Schlatter #Disease #Knee #patella #clinical #mri #clinical #Radiology #diagnosis #msk

Plantar fasciitis - MSK Radiology Imaging Findings: • Thickening of the plantar fascia central band (measuring 9mm) with intrinsic T 2-hyperintense signal and perifascial "edema-like" signal. • Linear T2-hyperintense intrinsic fluid-like signal on the Sagittal STIR is consistent with a small interstitial tear of the central fascicle. Case description: • Most commonly involves central band of the fascia (superficial to flexor digitorum brevis). • Plain film: Not specific. Heel spur often seen in asymptomatic patients. Can see fascial thickening. • Ultrasound: >4.5mm thickness and hypoechoic fascia. • MRI: T1/PD intermediate signal, T2 hyperintense signal, STIR is most sensitive to edema. Perifascial edema and reactive marrow edema of the calcaneus can also be seen. Differential diagnosis: • Plantar fibromatosis: Nodular thickening of fascia and usually more distal. • Plantar fascia tear: Discontinuity of the fascia usually due to injury or from steroid injection. • Plantar heel pad fibrosis: Within the subcutaneous fat in the heel pad, elderly, diabetics. Dr. Donald von Borstel @DrvonBorstel #Heel #Plantar #fasciitis #clinical #mri #clinical #Radiology #diagnosis #msk

Tenosynovitis of the peroneal tendons due to hypertrophic peroneal tubercle Imaging Findings: • Large volume ofT2-hyperintense fluid signal within the tendon sheath of the peroneal tendons. • Marked marrow edema of the calcaneus with a hypertrophic peroneal tubercle and vertical non-displaced fracture of the tubercle on the Coronal PD fat saturated sequence. • The thickened peroneus brevis lies superior and the peroneus longus inferior to the peroneal tubercle. Case description: • Enlarged peroneal tubercle can impinge the peroneal tendons and result in stenosis tenosynovitis due to chronic friction and increased tension on the tendons. - Thickened tendons with fluid-signal in the sheath. • Can result in bone marrow edema of the calcaneus at the tubercle. +/- adventitial bursitis adjacent to the peroneal tubercle. +/- thickening of the inferior peroneal retinaculum. Differential diagnosis for similar location of pain: • Peroneal tendon subluxation/dislocation or tear. • Talar osteochondral lesions. • Calcaneal stress fracture. Dr. Donald von Borstel @DrvonBorstel #hypertrophic #peroneal #tendons #tubercle #clinical #mri #clinical #Radiology #diagnosis #msk

Achilles Tendon Tear on POCUS (Labeled) A 35yo male presents with ankle pain. Achilles tendon tear is seen on POCUS. Usually caused by jumping/sprinting/agility activities (eccentric loading and explosive plyometric contractions). Dr. Meghan Herbst @EUSmkh #Achilles #Tendon #Tear #POCUS #Labeled #clinical #ultrasound #msk #radiology #orthopedics

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Hydroxyapatite Deposition Disease (HADD) - MSK Radiology Imaging Findings: • Ovoid hypointense structures along the bursal surface of the superior cuff footprint attachment consistent with Calcium Hydroxyapatite deposits. • Fluid-like signal seen within the deltoid muscle fibers and soft-tissues adjacent to the Calcium Hydroxyapatite deposits consistent with myositis. • T2-hyperintense fluid-signal is seen within the subacromial/subdeltoid bursa consistent with bursitis. Case description: • Hydroxyapatite Deposition Disease is a broad spectrum of musculoskeletal pathology due to crystal deposition. • This is generally monoarticular with inhomogeneous calcifications which are generally round/ovoid and faint on radiograph. • MRI shows globular low-signal on all sequences with surrounding hyperintense signal of the soft-tissues. - Deposits may show blooming on gradient-echo imaging with abnormal signal in the adjacent cuff. - Limits evaluation of cuff pathology (i.e. lower specificity of tear diagnosis) • Milwaukee shoulder: - Generally elderly women with severe destructive arthropathy of the shoulder with hydroxyapatite deposition in the synovial fluid. • Treatment for HADD: generally conservative. They may be needled, lavaged, and aspirated with variable results. Differential diagnosis: • Dystrophic calcifications from other systemic disorders: Progressive systemic sclerosis, hyperparathyroidism, etc. • Tendinopathy or tenosynovitis: Differentiate low-signal normal tendon from globular low-signal Hydroxyapatite deposits. Dr. Donald von Borstel @DrvonBorstel #HADD #Hydroxyapatite #Deposition #Disease #clinical #mri #clinical #Radiology #diagnosis #msk

Medial Meniscus Bucket Handle Tear - MSK Radiology Imaging Findings: • Truncation of the medial meniscus on the coronal sequence. • Mesial displacement of the meniscal fragment into the intercondylar notch. The "double PCL sign" is seen on the Sagittal with the displaced meniscal fragment parallel to the PCL. • The displaced fragment is also seen on the axial with visualization of the anterior and posterior attachment points. Case description: • Bucket Handle Tear is an extensive vertical longitudinal meniscus tear with mesial displacement of the free edge fragment toward (or into) the intercondylar notch. • Usually maintains anterior/posterior attachments. • Displaced fragment usually DOES NOT spontaneously reduce. • Repair if tear in peripheral red zone of the vascular meniscal tissue (3-5 mm from periphery). Differential diagnosis: • Displaced flap tear of meniscus: not attached to anterior/posterior meniscus. • Intra-articular body: Chondral/osteochondral fragment may migrate to intercondylar notch. • Meniscofemoral ligament: extends from posterior horn lateral meniscus to intercondylar notch. Dr. Donald von Borstel @DrvonBorstel #Medial #Meniscus #BucketHandle #Tear #knee #mri #clinical #Radiology #diagnosis #msk

Morel-Lavallée Lesion - MSK Radiology Imaging Findings: • Large, smoothly marginated, well-circumscribed mass along the medial myofascial planes of the thigh within the subcutaneous tissues. • Well defined acute angle at the margin of the lesion shear plane of the myofascial tissues. • Low-intensity peripheral pseudocapsule surrounding the lesion. • Nodules within the collection are of similar signal intensity to the subcutaneous fat (following fat-signal on all sequences.) Case description: • Closed degloving injury due to abrupt, posttraumatic separation of the skin and subcutaneous fat from the underlying fascia. • Commonly in the peritrochanteric area. • Appearance changes depending on chronicity but usually has components of fat nodules, blood products, and lymph: - Acute/subacute: Irregular complex margins and internal heterogeneous signal. - Chronic: Elongated and smooth margins with decreased heterogeneity. • If a fibrous pseudocapsule is present; almost certain it will recur with conservative treatment alone. These usually require surgical debridement and resection. Differential diagnosis: • Abscess: Absence of symptoms of and/or clinical concern for infection. Also, no internal air density or avid rim enhancement. • Neoplasm: Will have avid internal enhancement. • Fat necrosis: Usually smaller and ill-defined with heterogeneous attenuation on CT. Dr. Donald von Borstel @DrvonBorstel #Morel #Lavallée #Lavallee #Lesion #clinical #mri #clinical #Radiology #diagnosis #msk

$Freiberg Infraction - MSK Radiology Imaging Findings: • Sclerosis of the 2nd MT head with flattening of$

Freiberg Infraction - MSK Radiology Imaging Findings: • Sclerosis of the 2nd MT head with flattening of the articular surface and concavity of the metatarsal head. Widening of the MTP joint space. • T1-hypointense signal with flattening and concavity of the metatarsal head articular surface. • Hyperintense subchondral edema-like signal of the 2nd MT head. Case description: • Controversy: Subchondral fracture and/or osteonecrosis of metatarsal head. • Most common location 2nd MT head, less likely 3rd MT head. • Predisposing factors include: Short 1st MT, hallux valgus, and high-heels. • Pain worsens with weight-bearing. • Flattened MT head in isolation NOT DIAGNOSTIC. Look for secondary signs. • Unstable 2nd MTP joint can mimic Freiberg infraction. Differential diagnosis for similar location of pain: • Plantar plate injury: Dorsal MTP subluxation, torn plantar plate, subchondral bone edema. • Intermetatarsal bursitis: T2-hyperintense fluid-collection between metatarsal heads. • Morton Neuroma: Enhancing fusiform mass between MT heads. Dr. Donald von Borstel @DrvonBorstel #Freiberg #Infraction #foot #clinical #mri #clinical #Radiology #diagnosis #msk

Pes Anserine Bursitis - MSK Radiology Imaging Findings: • T2-hyperintense fluid-like signal along the medial aspect of the knee; below the level of the joint line. • The signal lies deep to the pes anserine tendons; Sartorius, Gracilis, Semitendinosus. Case description: • Well-defined fluid collection between the pes anserine tendons and the medial tibia. • Typically 2-cm below the joint line. • Other imaging findings may include bursal wall thickening, adjacent soft-tissue inflammation, and post-contrast enhancement. • BE SURE to exclude connection to meniscus and possible parameniscal cyst. Differential diagnosis for similar location of pain: • Popliteal Cyst (Baker Cyst): found superior and medial between medial gastrocnemius and semimembranosus. • Tenosynovitis of the pes anserine tendons: fluid WITHIN the tendon sheath not deep to them. • Parameniscal cyst: connection to meniscus. • Semimembranosus-Tibial Collateral Ligament bursitis: location, location, location. Dr. Donald von Borstel @DrvonBorstel #Pes #Anserine #PesAnserine #Bursitis #knee #clinical #mri #clinical #Radiology #diagnosis #msk