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How does McCormack load sharing classification determine level of spine fixation?

Asked by Anonymous 

McCormack load sharing classification takes into account, 3 different factors: 
  1. Apposition
  2. Comminution
  3. Deformity correction
Score1point2 points3 points
Comminution/Sagittal collapse30%30-60%>60%
Apposition of fragments1 mm2 mm> 2 mm
Deformity (kyphosis) correction</= 3 degrees4-9 degrees>/= 10 degrees
Total3 points6 points9 points
Source: McCormack T, Karaikovic E, Gaines RW. The load sharing classification of spine fractures

  1. Score <6: Short segment posterior stabilization
  2. Score >6 without translation: Anterior instrument and strut graft
  3. Score >6 with fracture dislocation: Staged surgery; posterior short segment posterior stabilization followed by anterior column support OR Long segment posterior stabilization
Long-Segment Posterior Fixation (LSPF) at least two levels above and below the fractured vertebra allows for a stronger construct, though limits flexibility at the fractured level and is more extensile and may be associated with higher intraoperative blood loss and length of operation. Short-segment fixation has largely replaced long-fixation in the management of burst fractures. However, instrument failure and recurrence of kyphosis are reported if short-segment posterior fixation.