Background <p>Acetabular fractures, though rare, present significant challenges due to complex anatomy and patient comorbidities, particularly in the elderly. While open reduction and internal fixation remain standard for most fractures, they are associated with high perioperative morbidity, especially in the elderly. Minimally invasive screw fixation may allow early mobilization while avoiding the morbidity of open reduction. The aim of this study was to compare clinical outcomes between operative minimally invasive fixation and conservative treatment in geriatric patients with non- or minimally displaced acetabular fractures.</p> Materials and methods <p>This retrospective cohort study included geriatric patients with non- or minimally displaced acetabular fractures treated between 2015 and 2023 at a level I trauma center. Patients underwent either minimally invasive screw fixation or conservative treatment. The primary outcome was in-hospital mobility loss, defined as the difference between pre-injury Charité Mobility Index (CHARMI) and the best CHARMI score achieved during hospitalization. Secondary exploratory outcomes included in-hospital medical complications, loss of autonomy, length of hospital stay, conversion to surgery, and one-year mortality. Group comparisons were performed using Fisher’s exact test and Welch’s t-test. Multivariable regression analyses were performed using predefined clinically relevant covariates.</p> Results <p>A total of 151 patients were included, comprising 92 operatively treated and 59 conservatively treated patients. Baseline characteristics were comparable between groups. In unadjusted analysis, operatively treated patients showed less in-hospital mobility loss than conservatively treated patients (CHARMI difference 2.53 ± 1.73 vs. 3.44 ± 1.57; mean difference − 0.91, 95% CI − 1.45 to − 0.37; <i>p</i> = 0.0011). However, after adjustment for baseline mobility and other clinically relevant confounders, treatment modality was not independently associated with mobility loss (β − 0.07, 95% CI − 0.59 to 0.44; <i>p</i> = 0.780). Secondary exploratory analyses showed lower one-year mortality in the operative group in unadjusted analysis (10.9% vs. 30.5%; OR 0.28, 95% CI 0.12–0.66; <i>p</i> = 0.0046), but this association was not confirmed after multivariable adjustment. Treatment modality was also not independently associated with loss of autonomy, medical complications, or length of hospital stay.</p> Conclusion <p>In this retrospective cohort, minimally invasive screw fixation was associated with less in-hospital mobility loss in unadjusted analysis, but this association was not confirmed after adjustment for baseline mobility and other confounders. Mortality and other secondary outcomes should be interpreted as exploratory. Minimally invasive fixation may be considered in selected patients who fail to mobilize adequately under conservative treatment, but no causal conclusion regarding superiority over conservative management can be drawn.</p>