Sports Medicine: Just the Facts

CHAPTER 18 • DIAGNOSTIC IMAGING 109

Complex acute fractures should be evaluated with CT

if further imaging is needed.

• The choice of imaging modality also depends on the
  level of patient’s activity. In the case of an elite athlete
  where the decision of return to play is important, one
  may choose to obtain advanced imaging (usually
  MRI) immediately after obtaining radiographs.

TISSUE OF INTEREST

• Boneis the fundamental scaffolding of the muscu-
  loskeletal system, and plays a central role in diagnos-
  tic imaging. With MRI, marrow edema in context of
  an injury indicates at a minimum trabecular trauma
  and contusion. Specific patterns of marrow edema
  may prompt a closer search for injury to specific soft
  tissue structures. In the knee, e.g., marrow edema in
  the posterior tibia and the lateral femoral condyle at
  the sulcus terminalis has a high association with an
  acute anterior cruciate ligament tear.


• Cartilageoutlines the bony surfaces of the joints. As
  a shock absorber it is prone to wear and tear as well as
  acute injuries. Acute chondral fractures, often with an
  adjacent bone fragment (osteochondral fracture), are
  common in sports medicine. Cartilage is not directly
  visible with plain radiography; however, an initial
  evaluation of cartilage thickness may be performed
  with plain radiography to assess joint space narrow-
  ing. MRI, on the other hand, not only demonstrates
  acute injuries to the osteochondral unit, but also
  nicely shows intrinsic signal abnormalities of carti-
  lage owing to wear and tear (chondromalacia). MRI
  can also evaluate the cartilage for focal areas of thin-
  ning, fissuring, and ulceration. One of the more
  common areas of interest for cartilage evaluation is
  the anterior knee for chondromalacia patellae.


• Joint stabilizing ligaments and tendons and the
  dynamic muscle and tendon units are prone to
  injuries. Certain sports are associated with specific
  injury patterns. The examples are innumerable,
  including jumper’s knee (patellar tendon), tennis leg
  (plantaris tendon and/or gastrocnemius muscle), and
  tennis or golfers’ elbow (collateral ligament). If plain
  films are normal, MRI will provide the necessary soft
  tissue contrast for diagnosis. The spectrum of findings
  range from mild edema to hematoma, partial tear, and
  complete disruption. Ultrasound is gaining popularity
  for evaluation of the more superficial tendons and
  muscles, especially around the elbow and ankle.


• Bursaeare fluid filled structures with synovial linings
  that act as cushions at foci of increased motion or fric-
  tion. They are classically found between bones and
  tendons or muscles and skin, but can form anywhere

protection is needed. Inherent to their function, bursae

are prone to inflammation, especially in cases with

overuse. MRI is excellent for demonstrating inflamed

and fluid filled bursal structures. Ultrasound is suit-

able for detecting superficial fluid collections and

possibly hyperemia in an inflamed superficial bursa.

Ultrasound may also provide guidance for therapeutic

injections.

ACUTE INJURY VS. OVERUSE

• Plain radiography is usually used to evaluate for acute
  fracture. With chronic complaints or overuse, plain
  films provide an effective screening tool for arthritis,
  inflammatory processes, and musculoskeletal tumors.
  Plain films may be helpful in demonstrating acute or
  chronic joint effusions (e.g., knee and elbow) by
  demonstrating a soft tissue density displacing normal
  fat planes. In cases of chronic injuries, calcifications
  are easily seen with radiography. Plain films are also
  used to evaluate for periosteal new bone formation,
  abnormal bone sclerosis and callus formation.


• If plain films are deemed to be normal and symptoms
  warrant, MRI is usually the next modality undertaken.
  With chronic or overuse disorders, stress reaction or
  fracture will appear on MRI as edema in bone
  marrow, possibly with immature periosteal new bone
  formation. Focal abnormalities are also evident in
  muscles, tendons, and ligaments. When the suspicion
  of an acute fracture is high and plain films are normal,
  MRI will detect radiographically occult fractures in
  weight-bearing bones such the tibial plateau and prox-
  imal femur. Early diagnosis is important to avoid
  fragment displacement with activity.


• If a patient’s symptoms persist after adequate conser-
  vative treatment or seem out of proportion to the clin-
  ical setting, additional imaging is warranted. It is not
  uncommon for bone and soft tissue tumors to be ini-
  tially diagnosed as a hematoma or muscle strain. Any
  palpable mass diagnosed as a hematoma should be
  followed clinically to maturation or resolution.

CHRONIC SEQUELA TO TRAUMA

• Areas of prior hemorrhage, hematoma, or inflamma-
  tion may undergo transformation into mature bone.
  This phenomenon is called heterotopic ossification or
  myositis ossificans. The former name is preferred,
  since this is not an inflammatory process of the mus-
  cles. Plain radiography and possibly CT play a crucial
  role in recognizing this entity. The finding of peripheral
  calcification around a soft tissue mass is the hallmark