Fragility fractures of the pelvis always produce some degree of instability and may progress to fractures with increased instability (such as widening of fracture lines or secondary fractures; Fig.
5) when patients are forced to mobilize with full weight bearing [
57,
94,
95]. Even after unilateral dorsal fracture fixation a progression from a uni- to a bilateral fracture has been reported [
59]. Such increased instability may lead to longstanding courses of pain at mobilization and finally to bedridden patients. In patients treated non-surgically, the time to improvement of symptoms and full mobilization varies from 4 weeks to 3.3 months [
21,
37,
96]. A complete resolution of pain and regain of independence was evident after 9 months in only 85 % [
36]. Data concerning required time of bed rest with conservative treatment vary widely in the literature between 12 days and 8 weeks [
25,
36,
97]. Immobilization, particularly in the elderly, leads to a high number of complications such as deep venous thrombosis, pulmonary embolism, decline of muscle strength, risk of pneumonia, pressure ulcers, or psychological changes [
48], occurring in 20–52 % of patients suffering from a FFP [
98‐
100]. The mean duration of hospital admission was reported to be 10–45 days [
23,
99,
100] with significant longer stays in patients with a combined anterior and posterior pelvic ring injury [
23]. Thereby, the early in-hospital mortality rate was 3–10 % [
8,
23,
100,
101]. The high impact of FFP on the survival is evident considering the 1-year mortality of 11–19 % [
8,
97,
101‐
103]. Patients with a FFP aged more than 90 years even showed a 1-year mortality of 39 % [
102]. The overall 5-year mortality reached 54 %, increasing with age and dementia [
8]; after 10 years the overall mortality rate reached 94 % which was statistically significantly higher than observed in an age-matched population [
100]. In addition to the high mortality rate, the functional status also decreases after such an injury. One year after the fracture, only 16 % of the patients were able to mobilize without walking aids and only 18 % were able to live independently [
101], half of patients lost their pre-traumatic autonomy [
99].
Rare complications of FFP include massive hemorrhage [
104] due to injury of the inferior epigastric artery [
105‐
107], an avulsion of the corona mortis [
108], or an injury to the obturator, the pudendal, or the internal iliac artery [
107]. Bleeding after an isolated FFS was described due to an injury of the superior gluteal artery [
108]. The occurrence of an infected hematoma of the psoas muscle as consequence of a FFS was reported [
109]. Further, an intrapelvic abscess formation was described after a displaced fracture of the pubic rami due to a bladder puncture [
110,
111].