PurposeThe objective of this study was to investigate the effect of proximal fibular and/or posterolateral joint facet (PJF) fractures on early functional recovery after Schatzker type VI tibial plateau fractures (TPFs).MethodsSeventy-nine patients with Schatzker type VI TPFs sustained from November 2016 to February 2021 were divided into three groups according to the integrity of the proximal fibula and PJF (groups A, B, and C). Details including demographics, duration of surgery, and complications were recorded. The Western Ontario and McMaster Universities Osteoarthritis index (WOMAC) score, Hospital for Special Surgery (HSS) score, lateral knee pain and lateral hamstring tightness were ascertained at the final follow-up. The HSS and WOMAC scores have high reliability in evaluating knee function and osteoarthritis.ResultsThere was a significant difference in the HSS score between groups A and C (P< 0.001) and between groups B and C (P= 0.036). The hospital stay was significantly different between groups A and C (P= 0.038) and between groups B and C (P= 0.013). There was a significant difference in lateral knee pain and lateral hamstring tightness between groups A and C (P< 0.001) and between groups B and C (P< 0.001).ConclusionOur study demonstrates that proximal fibular and PJF fractures do not increase the time from injury to surgery, the incidence of complications, or the duration of surgery for Schatzker type VI TPFs. However, fractures of the proximal fibula significantly increase the hospital stay, reduce knee function, and cause lateral knee pain and lateral hamstring tightness. Combined proximal fibular fracture is more decisive than PJF involvement for prognosis.