Aims: The treatment of ankle fractures and fracture-dislocations involving the posterior malleolus (PM) has undergone considerable changes over the past decade. The aim of our study was to identify risk factors related to the occurrence of complications in surgically treated ankle fractures with PM involvement. Patients and methods: We retrospectively analyzed 300 patients at a mean age of 57 years with 300 ankle fractures involving the PM treated surgically at our institution over a 12-year period. The following relevant comorbidities were noted: arterial hypertension (43.7%; n = 131), diabetes mellitus (DM) (14.0%; n = 42), thereof insulin-dependent (3.7%; n = 11), peripheral vascular disease (0.7%; n = 2), osteoporosis (12.0%; n = 36), dementia (1.0%; n = 3), and rheumatoid arthritis (2.0%; n = 6). Furthermore, nicotine consumption was recorded in 7.3% (n = 22) and alcohol abuse in 4.0% (n = 12). Results: Complications occurred in 41 patients (13.7%). A total of 20 (6.7%) revision surgeries had to be performed. Patients with DM (p < 0.001), peripheral vascular disease (p = 0.003) and arterial hypertension (p = 0.001) had a significantly increased risk of delayed wound healing. Alcohol abuse was associated with a significantly higher overall complication rate (OR 3.40; 95% CI 0.97–11.83; p = 0.043), increased rates of wound healing problems (OR 11.32; 95% CI 1.94–65.60; p = 0.001) and malalignment requiring revision (p = 0.033). The presence of an open fracture was associated with an increased rate of infection and wound necrosis requiring revision (OR 14.25; 95% CI 2.39–84.84; p < 0.001). Multivariate analysis identified BMI (p = 0.028), insulin-dependent DM (p = 0.003), and staged fixation (p = 0.043) as independent risk factors for delayed wound healing. Compared to the traditional lateral approach, using the posterolateral approach for fibular fixation did not lead to increased complication rates. Conclusions: Significant risk factors for the occurrence of complications following PM fracture treatment were identified. An individually tailored treatment regimen that incorporates all risk factors is important for a good outcome.