PURPOSE: Up to date, some approaches retarding the flow of cerebrospinal fluid (CSF) could be regarded as direct applications of the fluid mechanics (Poiseuille's law). However, there is a lack of the research on the efficacy of subfascial drainage for management of CSF leak after spine surgery based on the law. This is a prospective and comparative study on subfascial drainage for CSF.METHODS: Every four months in the three years from January 2010 to December 2012, the patients were enrolled respectively in Group A, Group B and Group C, in which, the drainage tube was discontinued within postoperative 3-4 days, 5-6 days, 7-10 days. Results and complications of postoperative CSF leak were investigated, and mean wound healing time (MWHT) of the three groups was compared.RESULTS: A total of 108 cases (Group A/B/C:35/32/41) of CSF leak following posterior spine surgery were admitted to Tianjin Union Medicine Center, and 92 cases have been followed up for more than 1 year (follow-up rate of 85.2%). Preoperative demographics were similar among the 3 groups. In Group A, 7 patients developed CSF leak through the wound (CSFLW), of which 5 cases had to undergo reoperation. One case in Group A was confirmed to have pseudomeningocele at the 1st month after surgery. The MWHT was (16.6±3.6) days. In Group B, 3 patients developed CSFLWand cured by reoperation, in which 1 case of superficial infection recovered well after reoperation. MWHT was (11.4±2.2) days. In Group C, CSFLWwas not found and MWHT was (10.1±2.9) days. The differences of MWHT among Groups A, B and C were statistically significant.CONCLUSION: Postoperative subfascial drainage, which is used to decrease the subfascial space pressure (P₂), would help wound healing. When it is placed for more than 7 days, the wound resistance (Rw) would be strong enough to withstand the subarachnoid pressure (P₁). Meanwhile, the power trans- duction in a sequence of Rw > P₂ > P₁ will indirectly retard CSF leak at the durotomy site and accordingly facilitate the healing of damaged spinal dura mater.