Objective: To conduct a systematic review on the effect of posterior tilt on reoperations, patient reported outcome measures (PROM) and functional outcome following osteosynthesis of undisplaced FNFs (uFNF). Material and methods: A search string was developed with the aid of a scientific librarian and the search was performed in PubMed, CINAHL and Embase. The studies were screened independently by two authors using Covidence. Data were extracted by two authors and quality assessment was performed using Robins-I tool. The meta-analyses were performed in STATA IC 16 using Risk Ratio as the primary effect estimate. Results: In total, 617 studies were screened and ten studies were included with a total of 3,131 patients. The mean age ranged from 68.3 to 85.0 years and the prevalence of posterior tilt ≥20° in the studies ranged from 4.5% to 27.6%. There were 10.3% reoperations when posterior tilt was <20° whereas there were 24.5% when posterior tilt was ≥20° The meta-analysis therefore demonstrated an overall risk ratio of 0.11 (95% confidence interval; 0.04–0.18). Only one study investigated functional outcome, using ADL as measurement, but found no significant difference. No studies investigated PROM. In general, the studies were assessed to be of poor quality mainly due possible bias and confounding. Conclusion: A posterior tilt ≥20° leads to a higher risk of reoperations in uFNF. Even though the studies were of poor quality, the results suggest that we should include the measurement of posterior tilt in national guidelines.