2.1

Patients with ankle fracture were screened to identify candidates meeting inclusion criteria of (1) ankle fracture involving the PM, (2) aged 18 years and above, (3) PMF was surgically fixed through APSF-LMA, APSF-DA or PPF-PLA，(4) underwent pre- and post-operative X-rays and CT examination of the ankle, including a three-dimensional CT reconstruction of Bartoníček-Rammelt type 4, (5) a minimum follow-up of 2 years postoperatively. The exclusion criteria included patients aged less than 18 years, those with pathological fractures, open fractures of Gustilo-Anderson type III, concomitant severe neurovascular injury, preexisting ankle arthritis, and those lost to follow-up.

2.2

Data for this retrospective study were retrieved from the medical records of patients with PMFs who had undergone surgical operation using one of these three approaches at our trauma center from 2019 to 2023. The study was conducted in accordance with the standards of the Declaration of Helsinki and approved by the Ethics Committee of Funing People’s Hospital (Ethics approval number: 2024–13). Patient signed informed consents were obtained accordingly for the publication of data and images included in this article.

PMFs were identified based on preoperative radiographic films and CT scans and classified according to the Bartoníček-Rammelt classification system . After screening, we identified 65 patients with PMFs treated with fixation. Among them, 58 patients who met the inclusive criterion were involved in this study. Twenty-two of them were treated using an APSF-LMA approach, 15 were treated with the APSF-DA approach, and the rest 21 patients were treated with the PPF-PLA approach. All patients were operated on by the same surgical team using the Ankle Joint Internal Fixation System (Kanghui, Changzhou, China).

2.3

Introduction to the method of reduction and fixation via the lateral malleolus incision window for the treatment of displaced Bartoníček-Rammelt type 4 PMFs. In the past, the reduction and fixation of fibular fractures and the recovery of ligament tension during ankle dorsiflexion were used to move and reduce the PMF fragment. Using ankle dorsiflexion and folding a towel under the heel (to prevent sagging of the posterior foot) helped to lock in the anatomical reduction of the PMF fragment. However, in unusual situations, these techniques cannot lead to acceptable clinical and radiographic alignment.

The author recommended introducing a king tong clamp around the joint. The patient was placed in a supine position and the fibula was exposed through a traditional incision on the lateral side. First, the fractured end of the lateral malleolus was fully exposed through the traditional lateral incision. At the same time, the anterior and posterior soft tissues and blood vessels and nerves of the ankle were not interfered. One end of the C-type king tong clamp had a ball tooth that entered the central body of the PMF through the gap between the peroneals and the flexor hallucis longus, while the other end had a ball tooth that was located on the anterior medial tibial ridge of the ankle joint. During the clamping process, a rotational force was applied towards the proximal end to complete the anatomical reduction and compression fixation of the PMF fragment. The anatomical reduction of the PMF fragment was confirmed by internal rotation fluoroscopy of the ankle joint.

Once anatomical reduction of displaced PMF fragment confirmed, a longitudinal incision of approximately 5 mm was made at the junction of the distal anterior epiphyseal plate of the tibia. After blunt dissection with vascular forceps, a protective sleeve was inserted until the bone surface was reached. Based on the characteristics of the three-dimensional CT fracture fragment, 1–2 1.0 mm Kirschner wires were drilled vertically into the fracture surface at slightly different levels and angles, and the reduction of the PMF and the position of the guide wire were confirmed by fluoroscopy again. Once confirmed to be in good condition, a 4.5 mm hollow screw was screwed in along the guide pin and finally confirmed through fluoroscopy ( Fig. 1 ).

Preoperative anteroposterior (a) and lateral (b) plain radiographs and the three-dimensional reconstruction CT scan (c) were taken for a 55-year-old woman who sustained an ankle fracture involving the posterior malleolus in the left side. She experienced the percutaneous anterior to posterior screw fixation via lateral malleolus incision window approach. The intraoperative photograph shows that the forceps was used to reduce posterior malleolus fragment via lateral malleolus incision window (d, e). Satisfactory reduction was confirmed on the plain radiographs (f-i) during surgery. Bony union was noted on the plain radiographs (j, k) at the 3-month follow-up.

Finally, the anatomical reduction and fixation of the internal ankle fracture fragment was completed according to the procedure, and the stability of the ankle joint was checked. If necessary, inferior tibiofibular ligament was repaired.

2.4

Active flexion and extension exercise of knees and toes were started at the first day after surgery and ankles were fixed with braces and were immobilized for 2 weeks. Then passive flexion and extension training of the ankles was started under the guidance of a rehabilitation physician. Active flexion and extension exercise of the ankles were started 4 weeks post-surgery. Patients without tibiofibular fixation began partial weight-bearing at 6 weeks and full weight-bearing at 8 weeks post-operatively. Patients who underwent tibiofibular fixation with syndesmosis screws started weight-bearing at 12 weeks after the syndesmosis screws were removed. Patients who underwent tibiofibular fixation with suture buttons started weight bearing 8 weeks after surgery. The follow-up duration of all patients was between 1.2 and 3.5 years.

2.5

Assessments were mainly based on clinical and radiographic outcomes. Comparisons of clinical outcome were conducted between groups in terms of operative time, postoperative articular surface flatness, loss of fracture reduction, postoperative complications, and union time. Radiographic imaging and functional examinations of the ankle were evaluated at 4, 8, and 12-week, 6-month, and 1 year and 2-year follow-up using the Olerud-Molander Ankle Score (OMAS), EuroQol-5 Dimensions (EQ-5D), American Orthopedic Foot and Ankle Society (AOFAS) score and Kellgren-Lawrence (KL) osteoarthritis classification , respectively.

2.6

Continuous variables were presented in the form of the mean ± standard deviation (SD). Categorical variables were represented by absolute and relative frequencies. A one-way ANOVA test was used to compare the OMAS, EQ-5D and AOFAS scores of different types, followed by Tukey’s multiple comparisons test. Association between the mechanism of injury and classification or severity of osteoarthritis was investigated with Fisher’s exact test. All analyses were performed using GraphPad Prism, version 10.0 (GraphPad, Inc., San Diego, CA), with a P value less than 0.05 set as statistically significant.