OBJECTIVES:To define the incidence of sacral U-type insufficiency fracture and describe management of a consecutive series of patients with this injury. DESIGN:Retrospective analysis. SETTING:Single Level II trauma center. PATIENTS/PARTICIPANTS:Sixteen adult patients with sacral U-type insufficiency fractures treated over a 36-month period. INTERVENTION:Patients were indicated for percutaneous screw fixation of the posterior pelvis if they had posterior pelvic pain that prohibited mobilization. MAIN OUTCOME MEASUREMENTS:Visual analog scale for pain, distance ambulated on postoperative day 1, and change in sacral kyphosis. RESULTS:The sacral U-type insufficiency fracture incidence was 16.7% (19/114); average patient age was 75 years. Delayed surgery was performed after primary nonoperative treatment had failed in 62.5% (10/16) at an average 83 days postinjury. Acute surgery was performed in 37.5% (6/16) at an average 5 days postinjury. Distance ambulated on postoperative day 1 was 114.4 feet 95% confidence interval (CI) (50.6, 178.2) and 88.7 feet 95% CI (2.8, 174.6) in the delayed and acute surgery groups, respectively, P = 0.18. Change in visual analog scale for pain was −3.2 95% CI (−5.0, −1.4) and −3.7 95% CI (−7.0, −0.4) in the delayed and acute surgery groups, respectively, P = 0.15. Change in sacral kyphosis from presentation to surgery was 12.3 degrees 95% CI (6.7, 17.9) and 0.3 degrees 95% CI (−0.2, 0.9) in the delayed and acute surgery groups, respectively, P < 0.01. Minimum follow-up was 12 months. CONCLUSIONS:Treatment of sacral U-type insufficiency fractures by percutaneous screw fixation permits early mobilization, provides rapid pain relief, and prevents progressive deformity. LEVEL OF EVIDENCE:Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.