Sports Medicine: Just the Facts

2002 a). More commonly the test elicits pain

(Richmond, 1996).

• Cysts at or below the joint line may be palpable, and
  are highly correlated with meniscal tears, most com-
  monly lateral (Greis et al, 2002a).


• No clinical examination finding is consistently pre-
  dictive of meniscus tear; however, the combination of
  several positive tests, from the following list is highly
  predictive of meniscus tear: joint line tenderness, pain
  on forced flexion, positive McMurray test, and a
  block to extension.


• Sensitivity of thorough examination reaches 95%, and
  specificity 72% (Greis et al, 2002a).


• Confounding diagnoses include fibrotic plica, fat pad
  impingement, chondral lesions, and synovitis (Greis
  et al, 2002a).

IMAGING

• Diagnostic studies should begin with plain radiography.
  Radiographs are assessed for associated skeletal injury,
  loose bodies, and presence of degenerative changes.


• Radiographs should include a 45° flexed knee PA
  weight-bearing view for individuals who may have
  knee arthrosis. Flexion weight-bearing views allow
  evaluation of the posterior tibiofemoral contact
  region, which is most frequently involved in early
  degenerative arthritis. Identification of arthrosis may
  have significant influence on treatment planning.


• Arthrograms are generally reserved for individuals for
  whom magnetic resonance imaging(MRI) is not pos-
  sible. This includes individuals with metal implants
  (pacemaker, aneurysm clips, foreign body, and the
  like), individuals too large for the MRI equipment, or
  individuals with severe claustrophobia.


• MRI is the diagnostic modality of choice to evaluate
  the menisci.


• Accuracy of modern MRI scans in detection of
  meniscus tears approaches 95% (Greis et al, 2002a).


• MRI studies have shown that the meniscal substance
  is not always homogeneous.


• Abnormal signal has been found in up to 30% of
  asymptomatic patients without any history of knee
  injury (Rath and Richmond, 2000).


• Normal anatomic structures adjacent to the meniscus,
  such as the intermeniscal ligament, and hiatus for the
  popliteus tendon, can be a source of confusion in
  interpretation of MRI scans (Greis et al, 2002a).
  •False positive results occur more frequently than false
  negative results, which emphasize the need for clini-
  cal correlation.


• Routine preoperative MRI scan does not significantly
  improve diagnostic accuracy over clinical examination

alone (Miller, 1996). Each has accuracy in competi-

tive athletes of approximately 90% (Muellner et al,

1997).

• MRI does provide information regarding the extent of
  the tear, and identification of occult chondral and
  osseous injuries.


• Judicious use of MRI is recommended, particularly in
  patients in whom arthroscopic surgery is anticipated.

MRI INTERPRETATION

• Meniscal signals as shown by MRI have been classi-
  fied into four grades.


• Grade 0 signal: Uniformly low signal intensity
  (normal meniscus).
  •Grade I signal: Irregular increases in intrameniscal
  signal.


• Grade II signal: Linear increases in intrameniscal
  signal, not communicating with the superior or infe-
  rior meniscal surface.


• Grade III signal: Abnormal increased signal extends
  to one meniscal surface.


• Grades I and II have no surgical significance. Grade
  III signal is visible arthroscopically and represents a
  meniscus tear.

MENISCUS TEAR PATTERNS

• Meniscus injuries are commonly classified by the
  description of the pattern of tear.
  •Patterns of tear include vertical longitudinal, oblique
  (flap, parrot-beak), horizontal, radial (transverse), and
  complex.
  •Vertical and oblique patterns constitute approximately
  80% of tears (Greis et al, 2002a).


• Complex, degenerative tears increase in frequency
  with age (>40).
  •A complete, displaced vertical tear is termed a bucket
  handle tear, and is the pattern often associated with
  mechanical block to motion.


• Radial tears disrupt the circumferential fibers of the
  meniscus, and when they extend to the periphery,
  result in loss of the load bearing function of the
  meniscus.

TREATMENT

•Treatment of meniscal injury is influenced by patient

factors, as well as the nature of the meniscal pathol-

ogy. Patient factors include the chronicity of symp-

toms, tolerance for activity modification following

346 SECTION 4 • MUSCULOSKELETAL PROBLEMS IN THE ATHLETE