Musculoskeletal Ultrasound Deep-Dive
A region-by-region field guide to diagnostic MSK ultrasound. For each joint: the standard scanning protocol (patient position and probe), the structures you assess, and the common pathologies with the sonographic signs that clinch them — plus the measurement cut-offs that turn a grey-scale picture into a report. Pick a region on the left. Start with General MSK Principles if you are new to the probe.
Representative teaching values — follow local protocols and correlate clinically. Frequencies, presets, depths and measurement thresholds (median-nerve CSA, plantar-fascia and tendon thickness, Graf angles, etc.) are typical adult reference points drawn from the literature below; they vary with habitus, transducer, machine, patient age and your department’s / accrediting body’s reference set. Cut-offs are diagnostic aids, never standalone diagnoses — always integrate history, examination, comparison with the asymptomatic contralateral side, and correlation with radiographs, MRI or electrophysiology where indicated. MSK ultrasound is profoundly operator-dependent; nothing here replaces supervised, hands-on training.
General MSK Principles
Master these before any joint. Almost every MSK error is either an anisotropy artefact mistaken for pathology or a missed dynamic finding. Get the machine, the plane and the manoeuvre right and the pathology declares itself.
High-frequency linear array, typically 10–18 MHz (small “hockey-stick” for fingers, superficial nerves). Drop to a 5–9 MHz linear or small-footprint probe for deep structures (hip, gluteal tendons, obese thigh).
MSK/superficial preset. Focal zone at the depth of interest; enough gain to see the tendon fibrils; harmonics/compound imaging on. Copious gel or a stand-off for very superficial targets.
Scan every structure in two orthogonal planes (long axis and short axis), always compare with the contralateral asymptomatic side, and add dynamic assessment (move the joint / contract the muscle) whenever a tear, impingement, subluxation or snapping is possible.
- Tendon: tightly packed hyperechoic parallel fibrils — “fibrillar” long axis, “broom-end” short axis.
- Muscle: hypoechoic bulk with hyperechoic perimysial striations (“starry sky” / “veins-on-a-leaf”).
- Nerve: hypoechoic fascicles in hyperechoic connective tissue — “honeycomb” short axis, “fascicular” long axis. Less anisotropic than tendon.
- Ligament: compact fibrillar band bridging two bones, slightly more compact than tendon.
- Bursa: thin (<2 mm) hypo/anechoic sliver; a normal bursa is barely visible.
- Bone/cartilage: bright continuous cortex with posterior shadow; hyaline cartilage is a thin anechoic rim over the cortex.
Core pitfallAnisotropy — the #1 error Free
Tendons (and ligaments) are highly reflective only when the beam strikes them at 90°. Tilt off perpendicular by even a few degrees and the structure turns artefactually hypoechoic (dark) — mimicking a tear or tendinopathy.
Keep the beam perpendicular to the fibres: “toggle / heel-toe” the probe until the tendon lights up brightly. The artefact appears and disappears with small tilts; true pathology stays dark in both planes and through the toggle.
- Curved insertions (supraspinatus footprint, biceps as it dives, rotator-cuff curve over the humeral head).
- Test: if darkening resolves on toggling perpendicular → artefact. If it persists in two planes → real.
TechniqueColour / power Doppler — hyperaemia Free
Low wall filter, low pulse-repetition frequency (PRF) / high sensitivity, small box over the target, minimal probe pressure (pressure squeezes out low-velocity flow — a classic false-negative). Power Doppler is more sensitive for slow flow than colour.
Intratendinous / peritendinous or synovial flow = active hyperaemia (neovascularity in tendinopathy, active synovitis in inflammatory arthritis). Grades disease activity and guides where to inject.
Shoulder
The commonest MSK ultrasound request. A systematic cuff protocol covers the biceps long head, subscapularis, supraspinatus, infraspinatus and the subacromial–subdeltoid (SASD) bursa, finished with a dynamic impingement manoeuvre.
Seated on a rotating stool, examiner behind or to the side. Modified Crass (“hand-in-back-pocket”: palm on iliac crest, elbow back) to roll supraspinatus out from under the acromion.
High-frequency linear (10–15 MHz). Anatomical landmarks in fixed sequence: biceps groove → subscapularis (external rotation) → supraspinatus (modified Crass) → infraspinatus/teres minor (hand on opposite shoulder).
Passive/active abduction under direct vision for subacromial impingement and bursal bunching; internal/external rotation to check biceps stability in the groove.
- Long head of biceps (LHB) tendon in the bicipital groove — long & short axis
- Subscapularis (with external rotation to spread it out)
- Supraspinatus (modified Crass) — the critical zone
- Infraspinatus & teres minor posteriorly
- Subacromial–subdeltoid (SASD) bursa
- Acromioclavicular joint & greater tuberosity cortex
- Posterior glenohumeral joint recess (effusion)
TearRotator cuff tear — full vs partial Free
Supraspinatus is torn most often (critical zone ~1 cm from footprint). Scan in both planes; confirm any hypoechoic defect is not anisotropy by toggling perpendicular.
Full-thickness: defect spanning bursal to articular surface. Partial: hypoechoic/anechoic defect touching only one surface (articular-sided commonest) or intrasubstance.
- Focal non-visualisation / hypoechoic or anechoic defect reproducible in two orthogonal planes.
- Cortical irregularity / pitting of the greater tuberosity underlying the defect — a strong secondary sign of a chronic tear.
- Concave “compressibility” of the deltoid into the defect on probe pressure; cartilage-interface (“naked tuberosity”) sign; retraction of the torn stump.
- Fluid in both the SASD bursa and the joint suggests a full-thickness communicating tear.
BursaSubacromial–subdeltoid bursitis Free
Normal bursa is a thin (<2 mm) hypoechoic line with the peribursal fat. Distension by anechoic fluid or hypoechoic thickening = bursitis.
Bursal bunching / “hitching” as fluid and bursa pile up at the acromion during abduction = subacromial impingement.
- Fluid/thickening >2 mm; power-Doppler flow in an inflamed bursa.
- Impingement demonstrated dynamically, not just measured.
CalcificCalcific tendinopathy Pro
Hyperechoic focus within the tendon (most often supraspinatus). Dense calcium shadows; softer “toothpaste” calcium may not shadow — important for barbotage planning.
LHB dislocation/subluxation (medial out of the groove, often with subscapularis tear) is assessed dynamically in rotation; effusion tracks in the biceps sheath.
Elbow
Four quadrants — lateral (common extensor), medial (common flexor), anterior (distal biceps), posterior (triceps) — plus the ulnar nerve in the cubital tunnel with a dynamic subluxation check.
Seated, elbow on the couch. Lateral: elbow flexed, hand pronated/thumb-up. Medial: forearm supinated, elbow extended. Anterior biceps: elbow extended, supinated. Ulnar nerve: elbow flexed then extended for the dynamic test.
High-frequency linear (12–18 MHz). Anchor the proximal end on the epicondyle and fan through the tendon origin in long and short axis.
- Common extensor origin (lateral epicondyle)
- Common flexor origin (medial epicondyle)
- Lateral collateral / RCL complex
- Ulnar collateral ligament (UCL)
- Distal biceps tendon & bicipitoradial bursa
- Triceps insertion (olecranon)
- Ulnar nerve in the cubital tunnel
- Anterior/posterior joint recesses (effusion, loose bodies)
TendonLateral epicondylosis — “tennis elbow” Free
Common extensor origin (ECRB deepest and most affected). A degenerative tendinosis, not true inflammation.
Medial epicondylosis = same findings at the common flexor origin; assess the UCL alongside.
- Tendon hypoechoic swelling / loss of fibrillar pattern at the origin.
- Neovascular flow on power Doppler = active disease.
- Intrasubstance anechoic clefts (partial tears); cortical irregularity / enthesophyte at the epicondyle; calcification.
TearDistal biceps & triceps Pro
Assess from anterior and medial (and a posterior/pronated “cobra” view of the radial tuberosity). Retraction, wavy discontinuous tendon and a fluid gap indicate full rupture; dynamic pronation–supination confirms non-movement.
Olecranon insertion — hypoechoic gap, avulsed osseous fleck, fluid; often after a fall on the outstretched hand.
NerveUlnar nerve — cubital tunnel & subluxation Free
Nerve enlarged & hypoechoic (loss of fascicular pattern) at/just proximal to the cubital tunnel; measure cross-sectional area and compare with the contralateral side.
Scan in short axis over the medial epicondyle during flexion: watch for the nerve subluxing / dislocating anteriorly over the epicondyle (± snapping triceps). A static image misses it entirely.
Wrist & Hand
Carpal tunnel is the marquee study; the wrist and hand also excel for tenosynovitis, ganglia, trigger finger and — with power Doppler — inflammatory-arthritis synovitis and erosions.
Seated across the couch, hand supinated on a pad for the volar wrist (carpal tunnel), pronated for dorsal tendons, ulnar-deviated for De Quervain. Fingers semi-flexed for trigger-finger dynamic testing.
Very high-frequency linear or hockey-stick (15–22 MHz) with generous gel/stand-off — everything is superficial. Light touch to preserve Doppler flow.
- Median nerve at the carpal tunnel inlet (pisiform) & outlet
- Flexor tendons within the tunnel
- First dorsal compartment (APL, EPB) — De Quervain
- A1 pulley & flexor tendon (trigger finger)
- Extensor tendon compartments (dorsal)
- Radiocarpal / intercarpal / MCP & PCP joint recesses
- TFCC region (ulnar side) & distal radioulnar joint
- Ganglia (dorsal & volar)
NerveCarpal tunnel syndrome Free
Median-nerve cross-sectional area (CSA) traced inside the hyperechoic rim at the tunnel inlet (pisiform level). A widely used cut-off is > 9–10 mm² (~9 mm² gives the best odds ratio; departments use 10–11 mm² for higher specificity).
Flattening ratio (width÷height) of the nerve at the distal tunnel is increased (e.g. ~3.3 vs ~2.1 in controls). Wrist-to-forearm ratio > 1.4 is highly sensitive and habitus-independent.
- Swollen hypoechoic median nerve proximal to / at the inlet with the “notch sign” (abrupt calibre change at the flexor retinaculum).
- Palmar bowing of the flexor retinaculum; increased intraneural power-Doppler flow in significant cases.
- Always exclude a space-occupying cause (ganglion, anomalous muscle, tenosynovitis).
TenosynovitisDe Quervain & trigger finger Free
First dorsal compartment (APL/EPB): tendon-sheath thickening, hypoechoic halo of fluid, retinacular thickening, Doppler hyperaemia; look for an intercompartmental septum. Radial styloid tenderness clinically.
Thickened, hypoechoic A1 pulley with a swollen underlying flexor tendon. Dynamic flexion–extension shows the tendon catching/snapping under the pulley.
ArthritisSynovitis, erosions, effusion & ganglia Pro
Grey-scale synovial hypertrophy (hypoechoic, non-compressible, poorly displaceable) with power-Doppler signal grades active synovitis (EULAR–OMERACT scoring). Erosions = cortical breaks seen in two planes, typically at MCP/PCP and ulnar styloid.
Well-defined an-/hypoechoic lobulated cyst, often dorsal (scapholunate) with a stalk; posterior enhancement, no internal Doppler.
Hip & Thigh
Deeper than the distal limbs — often needs a lower-frequency or curvilinear probe. Greater trochanteric pain, hip effusion, snapping hip and hamstring/quadriceps injury dominate; paediatric DDH uses the Graf technique.
Anterior hip/effusion: supine, hip neutral, probe along the femoral neck. Greater trochanter: lateral decubitus, affected side up. Snapping hip: dynamic supine (iliopsoas: hip flexed-abducted-externally-rotated → extended) or standing (IT band). Hamstrings: prone.
Linear 9–12 MHz for gluteal tendons/anterior recess in slim patients; curvilinear 3.5–6 MHz for deep hip and larger habitus. Infant hip: high-frequency linear.
- Anterior hip joint recess (femoral head–neck junction)
- Gluteus medius & minimus tendons (trochanteric facets)
- Greater trochanteric & iliopsoas bursae
- Iliopsoas tendon (dynamic snapping)
- Iliotibial band over the trochanter (dynamic)
- Hamstring origin (ischial tuberosity)
- Rectus femoris / quadriceps
- Infant hip: femoral head, bony & cartilaginous roof, labrum (Graf)
GTPSGreater trochanteric pain syndrome Free
Mostly gluteus medius/minimus tendinopathy or tears at the trochanteric facets rather than isolated “trochanteric bursitis.”
Trochanteric bursal fluid/thickening may coexist; a normal bursa is barely visible.
- Tendon thickening/hypoechogenicity, insertional cortical irregularity/enthesophyte, calcification, partial or full-thickness gluteal tears with retraction.
- Peritendinous/bursal fluid and Doppler hyperaemia.
EffusionHip joint effusion / synovitis Free
Anterior recess along the femoral neck (probe parallel to the neck). Measure the bone-to-capsule distance and compare with the other hip.
Capsular distension > ~7 mm, or > ~1–2 mm asymmetry vs the normal side, suggests an effusion — useful in a child with an irritable hip; ultrasound guides aspiration.
DynamicSnapping hip & muscle injury Pro
Internal: iliopsoas tendon snapping over the iliopectineal eminence/femoral head on FABER→extension — watch live. External: IT band flicking over the greater trochanter (lateral, standing).
Grade muscle strains (fibre disruption, haematoma, retraction). Proximal hamstring avulsion off the ischial tuberosity is a surgical trigger.
PaediatricDDH — Graf technique (brief) Pro
Standard coronal plane in the lateral decubitus infant. Draw the baseline (along the ilium), the bony-roof (alpha) line and the cartilage-roof (beta) line.
Alpha = bony-roof coverage: normal (mature, type I) is ≥ 60°. Beta = cartilage roof (higher with subluxation). Lower alpha + higher beta = dysplasia; type/subtype guides Pavlik harness vs monitoring.
Knee & Lower Leg
Ultrasound excels at the extensor mechanism, effusion, popliteal (Baker) cysts, collateral ligaments and calf-muscle tears; the cruciates and menisci remain an MRI job.
Anterior extensor mechanism & suprapatellar recess: supine, knee flexed ~20–30° over a bolster. Baker cyst & posterior structures: prone, knee extended. Collaterals: slight valgus/varus stress. Calf: prone, foot over the couch edge for dynamic dorsiflexion.
High-frequency linear 9–15 MHz; a stand-off or heavy gel helps for the very superficial patellar tendon.
- Quadriceps tendon (suprapatellar)
- Patellar tendon (infrapatellar)
- Suprapatellar recess (effusion)
- Medial (MCL) & lateral (LCL) collateral ligaments
- Popliteal fossa — Baker cyst (gastroc–semimembranosus)
- Medial gastrocnemius & plantaris (tennis leg)
- Prepatellar / pes anserine bursae
TendonPatellar/quadriceps tendinopathy — “jumper’s knee” Free
Classically the proximal patellar tendon at the inferior pole of the patella (jumper’s knee); quadriceps tendinopathy affects the superior patellar pole.
Anechoic gap, fibre discontinuity and retraction; a complete quadriceps/patellar tendon rupture disrupts the extensor mechanism (surgical).
- Focal hypoechoic swelling and loss of the fibrillar pattern; neovascular Doppler flow correlates with symptoms.
- Intratendinous calcification / enthesophyte; keep the beam perpendicular to avoid anisotropy at the curved insertion.
FluidEffusion & Baker cyst Free
Anechoic distension of the suprapatellar recess; complex/echogenic fluid ± Doppler suggests haemarthrosis or infection. Compressible, displaceable fluid vs non-compressible synovial hypertrophy.
Well-defined fluid collection with a neck between the medial gastrocnemius and semimembranosus tendons — the diagnostic location. A ruptured cyst tracks fluid down the calf and mimics DVT (scan the veins too).
TearCollaterals & calf (“tennis leg”) Pro
Ligament thickening/hypoechogenicity (sprain) or fibre discontinuity with fluid (tear); dynamic valgus/varus stress adds sensitivity. Pellegrini-Stieda calcification at the proximal MCL is chronic.
Tear at the medial gastrocnemius musculotendinous junction, often with a fluid/haematoma cleft between the gastrocnemius and soleus; ± plantaris involvement. Exclude DVT.
Ankle & Foot
Achilles and plantar fascia headline; the tibialis posterior and peroneals (with a dynamic subluxation check), Morton neuroma and gout crystal signs round out a high-yield foot study.
Achilles: prone, feet over the couch edge, dynamic dorsiflexion. Plantar fascia: prone, ankle dorsiflexed. Tib post/peroneals: supine/lateral with the malleolus up; peroneal subluxation tested with active eversion/dorsiflexion. Morton neuroma: supine, sole up, Mulder manoeuvre.
High-frequency linear 12–18 MHz; stand-off/gel for the superficial plantar fascia and interdigital spaces.
- Achilles tendon & retrocalcaneal / Kager’s fat
- Plantar fascia (calcaneal origin)
- Tibialis posterior tendon (behind medial malleolus)
- Peroneus longus/brevis (behind lateral malleolus)
- Superior peroneal retinaculum (dynamic)
- Anterior tibiotalar / other joint recesses
- Intermetatarsal spaces (Morton neuroma)
- 1st MTP joint & cartilage (gout)
AchillesAchilles tendinopathy & tear Free
Mid-portion fusiform thickening: an AP diameter > 6 mm is commonly treated as abnormal in suspected mid-portion tendinopathy (the tendon is normally ovoid/flat). Hypoechoic swelling, neovascular Doppler; insertional disease adds calcification & retrocalcaneal bursitis (measure insertional carefully — insertional thickness overlaps normals).
Hypoechoic/anechoic gap with fibre discontinuity. Dynamic passive dorsiflexion opens the gap (widening = full tear) and assesses tendon-end apposition for treatment planning.
- Full tear: complete discontinuity, refractile stump edges, gap that enlarges on dorsiflexion, retracted stumps ± posterior acoustic features.
- Partial tear: focal intrasubstance defect touching one surface.
FasciaPlantar fasciitis Free
Proximal plantar-fascia thickness at the calcaneal origin > 4 mm is the accepted diagnostic threshold (normal heels ~2–3 mm; controls up to ~3.8 mm).
Hypoechogenicity and loss of the fibrillar pattern at the origin; peri-fascial fluid; hyperaemia on power Doppler; ± calcaneal spur.
TendonsTibialis posterior & peroneal subluxation Pro
Tenosynovitis (halo of fluid, Doppler), tendinosis (thickening/hypoechoic) or tear — a driver of acquired flat foot. Scan to the navicular insertion.
With active eversion/dorsiflexion, watch the peroneal tendons flick anteriorly over the lateral malleolus when the superior peroneal retinaculum is torn/lax — a purely dynamic diagnosis.
ForefootMorton neuroma Pro
Well-defined hypoechoic ovoid mass in the intermetatarsal space (commonest 3rd web space), plantar to the transverse metatarsal ligament; not a true neoplasm (perineural fibrosis).
Medio-lateral squeeze of the metatarsal heads displaces the neuroma plantar-ward with a palpable/visible click under live scanning.
CrystalGout & effusion Free
A hyperechoic band of urate crystal on top of the hyaline cartilage surface, parallel to the bright bony cortex (e.g. over the 1st metatarsal head) — highly specific for gout (OMERACT elementary lesion). Distinguish from CPPD, which deposits within cartilage/fibrocartilage.
Tophus = heterogeneous hypo/hyperechoic aggregate with a hypoechoic rim; “wet clumps of snow” hyperechoic aggregates in joint fluid; erosions at the joint margin. Doppler shows active inflammation.
- Joint effusion: anechoic/complex distension of the recess (1st MTP, tibiotalar) — ultrasound guides diagnostic aspiration for crystal analysis.
Go deeper with High Yield Ultrasound Pro
The Free cards above cover the core protocol and the marquee pathology for every region. Pro unlocks the full clinical deep-dive:
- Annotated probe-position photos & labelled reference images (normal + pathology) for every view
- Step-by-step ultrasound-guided injection & aspiration technique (subacromial, GTPS, ganglion, calcific barbotage)
- Full measurement tables with local-reference worksheets and structured reporting templates
- Complete dynamic-manoeuvre video library (ulnar-nerve & peroneal subluxation, snapping hip, Mulder, dorsiflexion tear gap)
- Region self-test question banks with worked sonographic-sign reasoning
References & further reading
- Jacobson JA. Fundamentals of Musculoskeletal Ultrasound. 3rd ed. Elsevier, 2018.
- ESSR (European Society of Musculoskeletal Radiology). Musculoskeletal Ultrasound Technical Guidelines: I. Shoulder. essr.org.
- ESSR. Musculoskeletal Ultrasound Technical Guidelines: II. Elbow; III. Wrist & Hand; IV. Hip; V. Knee; VI. Ankle. essr.org.
- Klauser AS, et al. Clinical indications for musculoskeletal ultrasound updated in 2017 by ESSR consensus. Eur Radiol. 2018.
- Radiopaedia.org — Rotator cuff tear (ultrasound); Anisotropy (artefact); Median nerve / carpal tunnel syndrome; Plantar fasciitis; Achilles tendinopathy; Gout (double contour sign); Developmental dysplasia of the hip.
- Cardinal E, et al. US of the rotator cuff. RadioGraphics.
- Linehan V, et al. Ultrasound parameters to identify and diagnose carpal tunnel syndrome: a review. Australas J Ultrasound Med. 2020.
- Fowler JR, et al. Diagnostic accuracy of ultrasonography for carpal tunnel syndrome (CSA cut-offs; wrist-to-forearm ratio >1.4). Systematic reviews / meta-analyses.
- Cartwright MS, et al. Cross-sectional area reference values for nerve ultrasonography. Muscle Nerve.
- Beggs I. Sonography of common peripheral nerve entrapments including ulnar nerve at the elbow.
- Long G, et al. Sonography of greater trochanteric pain syndrome and gluteal tendinopathy. AJR.
- Graf R. Hip Sonography: Diagnosis and Management of Infant Hip Dysplasia. Springer. (Alpha angle ≥60° = mature/type I).
- Radiology Assistant (radiologyassistant.nl) — Developmental Dysplasia of the Hip: Ultrasound (Graf method).
- Grassi W, et al. Sonographic imaging of tendons. Arthritis Rheum.
- Ozcakar L, et al. EURO-MUSCULUS/USPRM basic scanning protocols. Eur J Phys Rehabil Med.
- McAlindon T, et al. American College of Rheumatology report on reasonable use of musculoskeletal ultrasonography.
- Backhaus M, et al. Guidelines for musculoskeletal ultrasound in rheumatology. Ann Rheum Dis. (EULAR).
- D’Agostino MA, Terslev L, et al. OMERACT ultrasound definitions of synovitis and scoring (EULAR–OMERACT combined score).
- Gutierrez M, Terslev L, et al. OMERACT ultrasound elementary lesions in gout: double contour sign, tophus, aggregates, erosion. J Rheumatol. 2015.
- Chiavaras MM, Jacobson JA, et al. Sonography of the plantar fascia (thickness >4 mm threshold). AJR / RadioGraphics.
- Pang BSF, Ying M. Sonographic measurement of Achilles tendon thickness. J Clin Ultrasound.
- De Maeseneer M, et al. Sonography of the peroneal tendons and dynamic subluxation assessment.
- Bianchi S, Martinoli C. Ultrasound of the Musculoskeletal System. Springer.
- Torriani M, et al. Sonography of Morton neuroma and the Mulder manoeuvre.
Measurement cut-offs cited (median-nerve CSA >9–10 mm², plantar fascia >4 mm, Achilles AP >6 mm, Graf alpha ≥60°, double contour sign) are literature reference points; confirm against local protocols and correlate clinically.