At the Bedside

  • Probe choice
  • Linear high-frequency probe: default for tendons, ligaments, superficial bone, soft tissue, foreign bodies, small joints.
  • Curvilinear probe: deeper structures, obese patients, hip effusion, large hematoma.
  • Image optimization
  • Use generous gel; keep probe perpendicular to tendon/fiber.
  • Adjust depth so the target fills the screen.
  • Put the focal zone at the target.
  • Use compound imaging/harmonics cautiously; they may obscure subtle foreign bodies or tendon fibrils.
  • Scanning principles
  • Scan in two orthogonal planes.
  • Compare with the contralateral normal side.
  • Use dynamic maneuvers: active/passive ROM, compression, resisted motion.
  • Follow the structure from normal → abnormal → normal.
  • Key sonographic concepts
  • Tendons: fibrillar, hyperechoic linear fibers. Rupture = discontinuity, retraction, hypoechoic gap/hematoma.
  • Muscle: “starry night” appearance in short axis; tears show fiber disruption and hematoma.
  • Ligaments: compact hyperechoic bands connecting bone to bone; sprain/tear = thickening, hypoechoic edema, discontinuity.
  • Nerves: honeycomb short-axis pattern; avoid injecting directly into nerve.
  • Fluid: usually anechoic/hypoechoic; may be complex if blood, pus, or debris.
  • Bone cortex: bright hyperechoic line with posterior acoustic shadowing.
  • Common ED applications
  • Achilles/patellar/quadriceps tendon rupture.
  • Shoulder dislocation confirmation/reduction.
  • Joint effusion detection and arthrocentesis guidance.
  • Abscess vs cellulitis.
  • Foreign body localization.
  • Fracture screening in select settings.
  • Pitfalls
  • Anisotropy: tendons and ligaments appear falsely dark if the beam is not perpendicular. Heel-toe the probe before diagnosing a tear.
  • Over-compression: can collapse vessels or small fluid collections.
  • Mistaking growth plates for fractures in pediatrics.
  • Missing deeper injury because a superficial abnormality was found.
  • Disposition
  • Ultrasound supports, but does not replace, clinical decision-making.
  • Suspected complete tendon rupture, septic arthritis, compartment syndrome, neurovascular compromise, or unstable fracture needs urgent specialty involvement.
A Classic Presentation
A 42-year-old recreational basketball player presents with posterior ankle pain after feeling a “pop.” Exam shows weak plantarflexion and an abnormal Thompson test. Bedside linear-probe ultrasound of the Achilles shows loss of normal fibrillar tendon continuity with a hypoechoic gap and proximal retraction compared with the normal side. The patient is splinted in plantarflexion, given analgesia, made non-weight-bearing, and referred urgently to orthopedics.

Study Directive

  • Practice identifying tendon, muscle, bone cortex, nerve, vessel, and fluid on 5 normal volunteers or patients.
  • From memory, draw the normal sonographic appearance of tendon in long and short axis.
  • Perform a two-plane scan of Achilles, patellar tendon, quadriceps tendon, and shoulder joint.
  • Deliberately create and correct anisotropy on a tendon to understand the artifact.
  • Review your department’s workflow for saving MSK clips and documenting dynamic findings.