STUDY DESIGN: Prospective propensity score-matched study.
OBJECTIVE: To compare the outcomes of minimal invasive surgery (MIS) and 
conventional open surgery for spinal metastasis patients.
SUMMARY OF BACKGROUND DATA: There is lack of knowledge on whether MIS is 
comparable to conventional open surgery in treating spinal metastasis.
METHODS: Patients with spinal metastasis requiring surgery from January 2008 to 
December 2010 in two spine centers were recruited. The demographic, 
preoperative, operative, perioperative and postoperative data were collected and 
analyzed. Thirty MIS patients were matched with 30 open surgery patients using 
propensity score matching technique with a match tolerance of 0.02 based on the 
covariate age, tumor type, Tokuhashi score, and Tomita score.
RESULTS: Both groups had significant improvements in Eastern Cooperative 
Oncology Group (ECOG), Karnofsky scores, visual analogue scale (VAS) for pain 
and neurological status postoperatively. However, the difference comparing the 
MIS and open surgery group was not statistically significant. MIS group had 
significantly longer instrumented segments (5.5 ± 3.1) compared with open group 
(3.8 ± 1.7). Open group had significantly longer decompressed segment 
(1.8 ± 0.8) than MIS group (1.0 ± 1.0). Open group had significantly more blood 
loss (2062.1 ± 1148.0 mL) compared with MIS group (1156.0 ± 572.3 mL). More 
patients in the open group (76.7%) needed blood transfusions (with higher 
average units of blood transfused) compared with MIS group (40.0%). Fluoroscopy 
time was significantly longer in MIS group (116.1 ± 63.3 s) compared with open 
group (69.9 ± 42.6 s). Open group required longer hospitalization (21.1 ± 10.8 
days) compared with MIS group (11.0 ± 5.0 days).
CONCLUSION: This study demonstrated that MIS resulted in comparable outcome to 
open surgery for patients with spinal metastasis but has the advantage of less 
blood loss, blood transfusions, and shorter hospital stay.
LEVEL OF EVIDENCE: 3.