Periprosthetic tibial fractures after unicompartmental knee arthroplasty (UKA) are rare but devastating events. Given the relative infrequency of these injuries, treatment strategies are not well defined. The goal of this retrospective case series is to report the findings for a series of patients who underwent open reduction and internal fixation (ORIF) of periprosthetic fracture after UKA, including radiographic alignment, Knee Society Score (KSS), and failure rate. Patients were identified by the International Classification of Diseases code for periprosthetic tibial plateau fractures. Electronic medical records and radiographs were retrospectively reviewed. Fracture patterns and coronal and sagittal alignment of UKA components were measured on radiographs. Clinical outcomes, including range of motion assessment, visual analog scale pain score, and KSS, were collected at final follow-up. Eight patients satisfied the inclusion criteria for this study. Fractures occurred at a median of 14 days (range, 5–52 days) after UKA, and all showed a vertical shear pattern that exited at the meta-diaphyseal junction. Of the 8 fractures, 7 (87.5%) healed to radiographic and clinical union after the initial ORIF. One patient required reoperation for hardware failure. Mean visual analog scale pain score and KSS at final follow-up were 3 and 85±14, respectively. Periprosthetic tibial plateau fractures after UKA commonly occur as a vertical shear fracture exiting at the metadiaphyseal junction. The use of ORIF with a 3.5-mm plate in buttress mode is a reliable method for treatment of these fractures. Restoration of alignment and motion is achievable, but residual pain may affect patient-reported outcome scores. [Orthopedics. 20XX;XX(X):xx–xx.]

单髁膝关节置换术 (UKA) 后的假体周围胫骨骨折是罕见但具有破坏性的事件。鉴于这些损伤的发生频率相对较低，治疗策略尚不明确。本回顾性病例系列的目的是报告一系列在 UKA 后接受切开复位内固定 (ORIF) 的假体周围骨折患者的结果，包括影像学对线、膝关节协会评分 (KSS) 和失败率。患者由国际疾病分类确定假体周围胫骨平台骨折的代码。电子病历和射线照片进行了回顾性审查。在 X 光片上测量 UKA 组件的骨折模式以及冠状和矢状位对齐。在最终随访时收集临床结果，包括运动评估范围、视觉模拟量表疼痛评分和 KSS。八名患者符合本研究的纳入标准。骨折发生在 UKA 后 14 天（范围为 5-52 天）的中位数，并且均显示在干骺连接处退出的垂直剪切模式。在 8 例骨折中，7 例（87.5%）在初始 ORIF 后愈合至影像学和临床愈合。一名患者因硬件故障需要再次手术。最终随访时的平均视觉模拟量表疼痛评分和 KSS 分别为 3 和 85±14。UKA 后的胫骨平台假体周围骨折通常发生在干骺端交界处的垂直剪切骨折。在支撑模式下使用带有 3.5 毫米钢板的 ORIF 是治疗这些骨折的可靠方法。可以实现对线和运动的恢复，但残余疼痛可能会影响患者报告的结果评分。[骨科。20XX;XX(X):xx–xx.]