The coronoid process, a major osseous stabilizer of the ulnohumeral joint, provides resistance against varus stress of the elbow joint [[1], [2], [3], [4]]. In 2003, O'Driscoll et al. [4] first described varus posteromedial rotatory instability (VPMRI), which involves anteromedial facet (AMF) fracture and lateral collateral ligament (LCL) injury. They proposed a new classification system of coronoid fractures based on the location and size of the fracture fragment [4]. O'Driscoll type 2 coronoid fracture, which involves the anteromedial facet, has three subtypes: anteromedial subtype I involves the rim; subtype II, the rim and tip; and subtype III, the rim and sublime tubercle. VPMRI occurs as a result of axial loading with varus force and internal rotation of the forearm. The varus force causes disruption of the LCL complex and further progression of the injury can damage medial collateral ligament (MCL) [5]. If VPMRI was not recognized or managed inappropriately, gravitational varus stress upon the elbow joint would result in subluxation of the trochlea and persistent instability can lead to development of chondral damage and early posttraumatic arthritis [6,7].

Despite a comprehensive classification system and knowledge regarding the injury mechanism, standard guidelines for treatment have not yet been established. To date, it has been widely accepted that VPMRI injuries can be treated with AMF fracture fixation alone, LCL repair alone, or both of these techniques, depending on the fragment size and displacement, as well as instability [3,8]. Although good clinical and functional results have been reported in cases with VPMRI, several studies have reported high complication and reoperation rates after surgical treatment [3,[9], [10], [11]]. On the other hand, satisfactory outcomes have been reported with conservative treatment in selected cases of VPMRI [[12], [13], [14]].

In 2021, Lanzerath et al. [15] reported a systematic review for the treatments, outcomes, and complications of AMF fracture including 10 studies (128 cases). They reported satisfactory clinical outcomes after operative treatment for AMF fractures, while the complication rate requiring reoperation was 7.8%. However, they enrolled several studies that include the cases with other injury mechanisms such as terrible triad injury or olecranon fracture dislocation [16,17]. The results from a systematic review reported by Lanzerath et al. [15] might be confused for outcomes after treatment of AMF fractures. Therefore, the purpose of this study is to report on a systematic review of the outcomes and complications after treatment for AMF fracture.