A Minimally Invasive Fixation Versus Double Plating of Associated Posterior Malleolus and Fibula Fractures—A Comparative Human Cadaveric Biomechanical Study

Background and Objectives: Ankle fractures are common and occur in up to 25% of cases with posterior malleolus (PM) involvement. The gold standard for their treatment considers posterior approaches and plating of both the PM and fibula. However, in elderly and comorbid patients, this strategy remains controversial. The objective of this biomechanical study was to compare a minimally invasive fixation—utilizing a fibula nail and percutaneous anteroposterior (AP) screws—versus double plating. Materials and Methods: An oblique fibula fracture associated with a Haraguchi type 1 PM fracture was reproduced in sixteen human cadaveric specimens randomized to two groups. Eight specimens were treated with a fibula nail plus two AP screws fixing the PM, while the remaining eight specimens underwent double plating. Biomechanical testing was performed under destructive complex cyclic loading applying a staircase protocol. Interfragmentary movements were captured via motion tracking. Results: Initial axial stiffness was similar between nailing (1125.9 ± 341.7 N/mm) and double plating (742.9 ± 600.1 N/mm) (p = 0.129). During cyclic testing, interfragmentary fibula displacement was higher for double plating versus nailing (p = 0.057), whereas PM displacement and syndesmosis diastasis remained comparable between the two techniques (p ≥ 0.197). Conclusions: The minimally invasive fixation of associated PM and fibula fractures utilizing a fibula nail and two anteroposterior screws demonstrated non-inferiority to double plating and presents a viable option in cases where delicate soft tissue management is required.