Evaluation of predisposing factors and comparison of treatment strategies for Su type 2 femur periprosthetic fractures.

Abstract

This study aimed to evaluate the predisposing factors for Su type 2 femur periprosthetic fractures. Moreover, we compared the mid- and short-term outcomes of patients who had undergone single-plate and double-plate fixation for Su type 2 fractures. A retrospective review was conducted on 3817 patients who had undergone knee replacement surgery at our hospital between January 2009 and December 2022. Of these, 39 patients (Group 1: fracture group) developed periprosthetic femoral Su type 2 fractures. A control group of 40 patients (Group 2: non-fracture group) without fractures was selected using propensity score matching for comparison. To minimize potential confounding, propensity score matching (PSM) was conducted using age, sex, body mass index, and comorbidities. Preoperative Kellgren-Lawrence grading, postoperative hip-knee-ankle (HKA) angles, weight-bearing line (WBL) ratios, femoral component angulation in anteroposterior and lateral views, and femoral notch status were evaluated. Body mass index, vitamin D levels, calcium levels, bone mineral density, and comorbid conditions were recorded and compared. No statistically significant differences in femoral notching, HKA angle, and femoral component angulation in the coronal plane were observed between the fracture (Group 1) and nonfracture (Group 2, control group) groups (p > 0.05). However, statistically significant differences in WBL ratio and femoral component angulation in the sagittal plane were observed between the two groups (p < 0.05). Vitamin D and calcium levels also significantly differed between the two groups (p < 0.05). Five patients who underwent single-plate fixation experienced refractures after a mean of 19 ± 8.1 (12-33) months, whereas no refractures occurred in patients with double-plate fixation. Perioperative and postoperative calcium and vitamin D supplementation and close follow-up of high-risk patients (those with low femoral component sagittal plane angulation and WBL ratio) may help prevent fractures. Double-plate fixation is more advantageous than single-plate fixation for Su type 2 periprosthetic stable fractures. Level III, retrospective comparative study.