Clinical outcomes of osteosynthesis of well-fixed periprosthetic proximal tibial fractures (Felix type 2A) after total knee arthroplasty.

Aims: This study aimed to evaluate the clinical and radiologic outcomes of well-fixed periprosthetic tibial fractures after TKA.

Patients And Methods: The medical records of patients who presented with Felix type 2A periprosthetic tibial fractures after TKA between March 2015 and February 2020 were retrospectively obtained from 5 institutions. Data on injury mechanism, fracture pattern including open fractures and Felix classification, and surgical method were recorded. Functional outcomes including range of motion (ROM) and Knee Society Score (KSS) at postoperative 1 year were reviewed. The need for reoperation was also reviewed. Radiologic findings included union time and mechanical proximal tibial angle (MPTA) at the last radiologic follow-up.

Results: Eighteen patients (13 women, 5 men; average age, 73.9 years) were included. The average follow-up duration was 20.8 months. The fractures resulted from high-energy (11 cases) and low-energy (7 cases) injuries. Two cases involved open fractures. Anatomical locking plates were used in all cases: single plate (4 cases) and dual plates (14 cases). The average number of proximal screws was 7.1 (range, 4-9). All patients achieved bone union at an average of 18.6 weeks without secondary intervention. No infection occurred; however, 1 patient with skin necrosis required local flap. Implant removal was performed in 5 cases: 1 case, skin defect and 4 cases, discomfort due to plate prominence. The average ROM and KSS were 120.3° and 85.9, respectively. The mean MPTA was 87.8°; the MPTA was higher in the single-plate group (94.0° vs. 88.1°, p=0.013). Three cases involved values beyond the normal MPTA range (85-90°): 104° and 96° with a single plate and 92° with dual plates. The malalignment rate was higher in the single-plate group (p=0.043).

Conclusion: Felix type 2A periprosthetic tibial fractures treated with minimally invasive osteosynthesis showed excellent clinical outcomes, and tibial alignment was well maintained in the dual-plate group.