Posterolateral Tibial Plateau Fractures in Adult Anterior Cruciate Ligament Avulsion Effect on Postoperative Knee Function

Background: The impact of posterior lateral tibial plateau fractures (PLTPFs) on knee joint stability after anterior cruciate ligament (ACL) reconstruction has garnered widespread attention. However, limited literature exists on the co-occurrence of ACL tibial avulsion fractures (ACLAFs) and PLTPFs. The objective of this study is to investigate the prevalence of PLTPFs in adult ACLAF patients and assess the impact of concurrent PLTPFs on postoperative knee function. Methods: This retrospective study analyzed adults, who underwent arthroscopic surgery for ACLAF at our institution between January 2016 and January 2022. Demographic and preoperative/postoperative imaging data were collected, focusing on meniscus and ligament injuries, Segond fractures, PLTPFs, and tibial plateau slope. Patients were grouped into isolated ACLAF (I-ACLAF) and ACLAF with concurrent PLTPFs (ACLAF-PLTPF). The ACLAF-PLTPF group was further divided into Group A (PLTPFs not exceeding the anterior edge of the lateral meniscus posterior horn) and Group B (PLTPFs exceeding this edge). Clinical outcomes were evaluated using International Knee Documentation Committee and Tegner scores. The study also examined the morphology of PLTPFs and their specific affected areas. Statistical analysis was performed using the Mann-Whitney U tests for continuous variables and Fisher's exact tests for categorical variables. Results: The study included 62 patients with a mean follow-up of 41 +/- 17 months. Among these, 71.0% (44/62) patients with ACLAF also had PLTPFs. The ACLAF-PLTPF group showed a significantly steeper lateral tibial plateau slope than the I-ACLAF group (10.86 degrees +/- 5.47 degrees vs. 7.17 degrees +/- 3.68 degrees, p = 0.011). Segond fractures were present in 22.7% of the ACLAF-PLTPF group, compared to none in the I-ACLAF group (p = 0.027). IKDC and Tegner scores were lower in the ACLAF-PLTPF group (80.7 +/- 5.2 and 4, respectively) than in the I-ACLAF group (87.4 +/- 6.4 and 4.5, respectively), with statistical significance (p < 0.001 and p = 0.008, respectively). Older age correlated with a greater extent of concurrent PLTPFs (p = 0.038). Additionally, Patients in Group B exhibited a significantly higher incidence of meniscal injury (22.2% vs. 53.8%, p = 0.036) and poorer postoperative knee joint function compared to those in Group A (IKDC 82.3 +/- 2.8 vs. 78.5 +/- 5.6, p = 0.013). More extensive PLTPFs were linked to increased fracture collapse and a higher rate of lateral meniscus injuries. Conclusion: PLTPFs demonstrated a high prevalence in adults with ACLAF. Additionally, the ACLAF-PLTPF cohort frequently showed reduced postoperative knee function. Simultaneous management of severe concomitant PLTPFs may improve long-term outcomes in patients with ACLAF.