## 1 Introduction  
Ankle fractures represent the fourth most frequent injury treated by orthopedic surgeons, with an annual incidence of approximately 187 cases per 100,000 individuals [1, 2] constituting the second most common lower limb fractures after proximal femoral fractures. The distribution is bimodal, with a peak in young adult males and another in elderly women with an average incidence age of 45 years [3]. The term \"posterior malleolus\" was introduced in 1911 by [PERSON] [4] and it was [PERSON] in 1932 who began discussing trimalleolar fractures [5]. Trimalleolar fractures constitute 10-15% of all malleolar fractures and are associated with a worse prognosis and a higher risk of post-traumatic osteoarthritis compared to bimalleolar fractures [6]. In ankle fractures, involvement of the posterior malleolus ranges from 7 to 44% [3, 7] and is usually due to rotational trauma with detachment of a fragment due to the force exerted by the posterior-inferior tibiofibrular ligament (PITFL). The size of the fractured fragment varies widely, from a small extra-articularfragment to one involving up to 40% of the tibial articular surface. Anatomical reduction in the case of an unstable joint is necessary to achieve satisfactory functional outcomes. The first studies reporting posterior malleolus osteosynthesis with screws date back to 1922 [8], when conservative approaches were more prevalent. However, over the years, inferior outcomes were observed with non-surgical treatment for larger fragments [9], establishing a critical threshold for surgical synthesis. For many decades, a posterior malleolus fracture involving more than 33% and later 25% of the articular surface indicated surgery [6, 10, 11], especially if accompanied by a step-off \(\geq\)2 mm in lateral X-rays [12, 13]. The introduction of CT scans provided three-dimensional information (Figure 1) not only about fragment size and composition but also about the involvement of the fibular notch, tibial plafond impaction, intercalary fragments, and syndesmosis instability [14, 15, 16, 17, 18]. These factors became considerations for the correct treatment of these fractures, altering the goals of surgical intervention. The revised objectives are as follows [19, 20]:  
1. Restoration of the correct articular surface of the ankle joint. 2. PITFL reinsertion and restitution of syndesmotic stability. 3. Reconstruction of the correct anatomy of the fibular notch, facilitating the reduction of the distal fibula. Based on these considerations, CT-guided classifications were formulated, with notable ones being [PERSON]'s and especially [PERSON]'s [21]. [PERSON]'s 2015 classification takes into account the three-dimensional aspects of the posterior fragment, including size, shape, fragment position, and integrity of the fibular notch [16, 18, 20, 22, 23, 24]. Historically, posterior malleolus fractures were primarily treated with percutaneous anteroposterior screw fixation [25, 26]. The rationale behind this technique is a minimally invasive treatment and the reduction of the posterior malleolus fracture through ligamentotaxis, an indirect reduction technique of a fracture fragment by acting on intact ligaments attached to the bony fragment. After fixing the lateral and medial malleoli, with the patient in a supine position, the posterior malleolus is synthesized using one or two screws, sized 3.5 mm/4.0 mm, from anterior to posterior percutaneousously (Figure 2). Figure 1: CT scan images of posterior malleolus fracture with plafond impaction (**a**), complex fracture margin, (**b**) and intercalary fragments (**c**). This technique faces challenges in achieving adequate reduction, especially for ligamentotaxis, and has limitations in addressing interposed fragments [27; 28; 29]. Percutaneous approaches may also risk damage to the anterior tibial artery or nerve. The posterior approach has gained preference due to its ability to address fragment size, shape, and fracture line obliquity.