MSK: Fractures for the ABR Core Exam Part 3
Review of fractures for the ABR Core examination. Make sure to also check out the free downloadable study guide on this topic available at www.theradiologyreview.com.
Show Notes/Study Guide:
Bilateral calcaneal fractures = Casanova fracture. Next step on board exams? Plain films of the spine to look for compression and/or burst fractures from axial loading. Results from? Jumping from a height and landing feet first.
If Bohler’s angle is <20 degrees, you should worry about which type of fracture? Calcaneal fracture
Bohler’s angle is a line between the anterior and posterior boarders of the calcaneus on the lateral view
Non-avulsed fracture of the base of the 5th metatarsal = Jones fracture
Treat with a cast
Avulsion fracture of the base of the 5th metatarsal = more common than Jones fracture, classic history is acute 5th metatarsal fracture in a dancer. If the fracture extends to the articular surface it is an avulsion fracture, if the fracture does not extend to the articular surface it is a Jones fracture. Jones fractures are typically horizontal in orientation and are prone to non-union (50%) whereas avulsion fractures heal better.
5th metatarsal stress fractures are difficult to heal and are high-risk to progress to a complete fracture
Most common fracture associated with a LisFranc injury? Base of 2nd metatarsal fracture (Fleck Sign)
You see a small fleck of bone in the widened space between the base of the 1st and 2nd metatarsals as the 1stmetatarsal goes medial and the 2nd-5th metatarsals go lateral
Most common site of stress fracture in young athletes? Tibial stress fracture
Tibial stress fractures most common on compressive side (posteromedial tibia)
If stress fracture on tensile side (midshaft anterior) these have worse healing
Compressive side stress fractures heal well as bones are constantly in opposition
Tensile side stress fractures have more difficulty to heal.
Femoral stress fractures tend to be compressive in youth (heal well) and tensile in older adults (don’t heal well).
Older woman with sudden pain after arising from a seated position? SONK = spontaneous osteonecrosis of the knee—a misnomer as this is really an insufficiency fracture most commonly of the medial femoral condyle NOT osteonecrosis. Usually unilateral and no history of trauma but is often associated with a meniscal injury (can happen in younger people after meniscal surgery)
Runners running on hard surfaces are prone to which location of stress fracture in the foot? Navicular stress fracture. Analogous to the scaphoid the navicular bone is at high risk of AVN with a displaced fracture
Navicular osteonecrosis = Kohler’s disease
Metatarsal stress fractures = March fracture—think military recruits marching all day
The most commonly fractured tarsal bone = calcaneal bone, stress fractures tend to be intra-articular (75%). The stress fracture line runs perpendicular to the trabecular lines
High risk locations for stress fractures to progress to complete/displaced fractures? Tensile side of femoral neck, transverse patellar fractures (longitudinal patellar fracture is lower risk), anterior tibial midshaft fracture, 5th metatarsal fracture, talus fracture, navicular fracture, sesamoid great toe fracture
What is the name for lucent bands that traverse bones at right angles to the cortex? Looser zones. When you see these think insufficiency fractures associated with osteomalacia or Rickets
Most common location for fractures in setting of osteoporosis? Spine, then hip, then wrist
Insufficiency fracture of soft bone in femur or tibia in patient with Paget’s disease = banana fracture
Warning signs for pathologic fractures:
Avulsion of the lesser trochanter (pathologic fracture present); any lesion with >50% or >3 cm of cortex missing, any vertebral lesion encompassing >50% of vertebral body, any femoral neck lesion are at risk to develop pathologic fracture
Secondary signs of ACL injury = deep notch sign, bone contusions, segond fractures (You’re going to need a segond ACL if you have a segond fracture)
Avulsion fracture of the proximal fibula = arcuate sign. This is avulsion at the insertion of the arcuate ligament complex (fibular collateral ligament, biceps femoris tendon, or both) and is (90%) associated with cruciate ligament injury.
