Longitudinal 3D Shape and Alignment Analysis of Post-traumatic Osteoarthritis After Tibial Plafond Fractures
Andrew C Peterson1, Jordan S Langford1,2, Jacob C Benna3
1Department of Mechanical Engineering, University of Utah, Salt Lake City, UT, USA.
Background:
This study aimed to characterize longitudinal 3-dimensional morphologic, alignment, and radiographic changes of the ankle and hindfoot following surgical fixation of tibial plafond fractures and to identify structural features associated with post-traumatic osteoarthritis (PTOA) severity.
Methods:
Thirty-two patients with surgically treated pilon fractures from 3 institutions underwent weightbearing computed tomography (WBCT) at 6, 12, and 18 months post-operatively. At 18 months, patients were grouped into low-grade and high-grade PTOA groups. Statistical shape modeling was used to quantify morphologic and alignment variation across the tibia, fibula, talus, and calcaneus. Joint distances at the talocrural and subtalar joints were calculated using correspondence-based metrics. Radiographic parameters were automatically derived from 3-dimensional bone models using a MATLAB toolbox. Cross-sectional and longitudinal statistical differences were assessed.
Results:
Patients who developed high-grade PTOA demonstrated progressive flattening of the calcaneal pitch, posterior and inferior translation of the tibia and fibula, and narrowing of the central tibiotalar joint. In contrast, the low-grade group exhibited greater valgus hindfoot alignment, mild widening of the medial and posterior tibiotalar joint, and greater alignment variation over time. Radiographically, the high-grade group displayed a significant increase in tibiocalcaneal angle over time (P = .03) and a trend toward a more varus hindfoot configuration.
Conclusion:
Distinct longitudinal alignment and morphologic trajectories differentiate low-grade and high-grade PTOA development following pilon fracture fixation. Preservation of coronal alignment and subtalar adaptability may provide a protective mechanism against rapid PTOA progression. These findings highlight the clinical potential of WBCT and shape-based 3-dimensional analysis for early detection of malalignment patterns associated with post-traumatic degeneration.
Level Of Evidence:
Level III, prognostic study.
