Does indirect reduction during minimally invasive percutaneous plate osteosynthesis for distal fibular fractures compromise mortise alignment and lead to post-traumatic osteoarthritis? A comparative study of long-term radiographic and functional outc

To evaluate radiological parameters and functional outcomes, and to compare joint degeneration progression at a minimum 2-year follow-up between minimally invasive percutaneous plate osteosynthesis (MIPPO) and traditional open reduction and internal fixation (ORIF) for distal fibular fractures. This retrospective cohort study reviewed 174 adult patients with displaced Danis–Weber type B and C distal fibular fractures managed between 2017 and 2024. Sixty-three patients underwent MIPPO utilizing a bridging approach, while 111 underwent traditional ORIF. Clinical, radiographic, and functional outcomes—measured by the medial clear space (MCS), tibiofibular clear space (TFCS), tibiofibular overlap (TFO), talocrural angle (TCA), Olerud–Molander Ankle Score (OMAS), American Orthopaedic Foot and Ankle Society score (AOFAS), and Visual Analogue Scale (VAS)—were assessed. Post-traumatic osteoarthritis (PTOA) progression was evaluated using the Kellgren–Lawrence (KL) grading system over a minimum two-year follow-up period. Baseline demographics and injury characteristics were comparable between groups. Radiographically, post-reduction parameters remained within normal physiological range; however, the MIPPO group demonstrated a significantly narrower MCS (3.35 ± 0.88 vs. 3.72 ± 0.97, p = 0.014). TFCS, TFO, and TCA were comparable. Functionally, MIPPO yielded significantly higher AOFAS scores (80.78 ± 7.83 vs. 77.32 ± 7.01, p = 0.003), which multivariable linear regression controlling strictly for baseline confounders confirmed as an independent association (β = 4.03, p < 0.001). OMAS and VAS scores did not differ significantly. MIPPO exhibited a lower, non-statistically significant wound complication rate (4.8% vs. 9.9%, p = 0.230). At final follow-up, overall OA progression rates (△KL ≥ 1) were comparable (61.9% in MIPPO vs. 67.6% in ORIF, p = 0.556). Multivariable logistic regression adjusted strictly for preoperative baseline confounders confirmed that the MIPPO technique did not increase the risk of joint degeneration and was independently associated with a reduced likelihood of substantial PTOA progression (△KL > 1) compared with ORIF (adjusted OR = 0.35, 95% CI 0.12–0.97, p = 0.043). The MIPPO technique demonstrated generally comparable clinical and radiographic outcomes to ORIF for distal fibular fractures at a minimum 2-year follow-up, with small differences in the AOFAS score and medial clear space. Crucially, despite reliance on indirect reduction, MIPPO demonstrates comparable joint degeneration progression to ORIF at a minimum 2-year follow-up, allaying literature concerns regarding non-anatomical alignment and accelerated PTOA.