BackgroundTo investigate the radiologic and prognostic outcomes after using arthroscopic-assisted reduction and internal fixation (ARIF) in complex tibial plateau fractures with mid- to long-term follow-up.MethodsThis retrospective study reviewed complex tibial plateau fractures that underwent ARIF from 1999 to 2019. Radiologic outcomes, including tibial plateau angle (TPA), posterior slope angle (PSA), Kellgren–Lawrence classification and Rasmussen radiologic assessment, were measured and evaluated. The prognosis and complications were assessed by the Rasmussen clinical assessment with a minimum follow-up of 2 years.ResultsNinety-two consecutive patients (mean age: 46.9 years) with a mean follow-up of 74.8 months (24–180) were included in our series. Using AO classification, there were 20 type C1 fractures, 21 type C2 fractures, and 51 type C3 fractures. All the fractures achieved solid union. TPA was maintained well on average at the last follow-up and showed no significant difference compared to postoperatively (p= 0.208). In the sagittal plane, the mean PSA increased from 9.3 ± 2.9° to 9.6 ± 3.1° (p= 0.092). A statistically significant increase in PSA was also noted in the C3 group (p= 0.044). Superficial or deep infection was noted in 4 cases (4.3%), and total knee arthroplasty (TKA) was performed in 2 cases (2.2%) due to grade 4 osteoarthritis (OA). Ninety (97.8%) and 89 (96.7%) patients had good or excellent results in the Rasmussen radiologic assessment and Rasmussen clinical assessment, respectively.ConclusionsThe complex tibial plateau fracture could be treated successfully using arthroscopy-assisted reduction and internal fixation. Most patients achieve excellent and good clinical outcomes with low complication rates. In our experience, a higher incidence of increased slope was noted, especially in type C3 fractures. Reduction of the posterior fragment should be done cautiously during the operation.Levels of evidenceLevel III.