title: Chronic exertional compartment syndrome: the controversial "fifth" compartment of the leg.
abstract: BACKGROUND
  The existence of a "fifth" compartment in the leg capable of developing distinct chronic exertional compartment syndrome remains a subject of controversy.
  
  
  OBJECTIVE
  Specific pressure recordings and dissection will confirm or disprove the existence of a fifth compartment.
  
  
  METHODS
  Empirical anatomic study.
  
  
  METHODS
  Radiopaque dye was injected directly into the tibialis posterior muscle of 25 embalmed cadaveric legs while intracompartmental pressure was monitored. Radiographs demonstrated dye distribution, and dissection-documented fascial and epimysial layers.
  
  
  RESULTS
  Evidence was found that the fibular origin of the flexor digitorum longus muscle, when present, could create subcompartments within the deep posterior compartment. The nature of this attachment varied from being absent, to small (<8 cm), to extensive (>8 cm). The attachment partially covered the tibialis posterior muscle in the majority of the 14 legs that developed high pressures, and it was limited or absent in the 11 legs that did not. Radiographs demonstrated that the dye was confined to the tibialis posterior muscle in four legs.
  
  
  CONCLUSIONS
  No consistent fifth compartment exists in the leg; however, subcompartments within the deep posterior compartment created by the fibular origin of the flexor digitorum longus muscle may develop pressures congruent with chronic exertional compartment syndrome.
  
  
  CONCLUSIONS
  Potential deep posterior subcompartments demand accurate pressure investigation. A modified technique to decompress the entire deep posterior compartment, including the tibialis posterior muscle, is necessary for successful treatment of chronic exertional compartment syndrome.
authors.affiliation: Department of Anatomy, University of Dublin, Trinity College, Dublin, Ireland.
authors.forename: Matthew
authors.initials: M
authors.lastname: Hislop
authors.forename: Paul
authors.initials: P
authors.lastname: Tierney
authors.forename: Pairic
authors.initials: P
authors.lastname: Murray
authors.forename: Moira
authors.initials: M
authors.lastname: O'Brien
authors.forename: Nick
authors.initials: N
authors.lastname: Mahony
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D003161:Compartment Syndromes / Q000503:physiopathology*; D005260:Female; D005456:Fluorescent Dyes; D006801:Humans; D007866:Leg / Q000033:anatomy & histology; D008297:Male; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000473:pathology*; D011312:Pressure
chemical_list: D005456:Fluorescent Dyes