ABSTRACT
Objective:To investigate the effect of Notch on periprosthetic fracture (PPF) of the femoral prosthesis after primary total knee arthroplasty.Methods:A total of 34 patients diagnosed with femoral PPF at Xi'an Honghui Hospital were retrospectively collected from January 2013 to December 2020. There were 4 males and 30 females with a mean age of 69.2±7.2 years (range, 55-84 years). A total of 102 patients without PPF were matched by gender and age as the control group in a ratio of 1∶3. There were 12 males and 90 females with a mean age of 69.2±7.2 years (range, 55-84 years). The main observation indexes included patients' general information and factors such as coronal alignment, prosthesis design and Notch conditions. Then, subgroup analysis was performed with the depth and Tayside classification of Notch to analyze their effects on PPF.Results:The PPF and control groups were comparable in terms of baseline information such as gender, age, body mass index (BMI), and surgical side. There was no significant difference between the two groups in coronal alignment (χ 2=1.019, P=0.601) and prosthesis design (χ 2=1.545, P=0.214). There was no statistical difference in Notch between the PPF and control groups (χ 2=3.548, P=0.060). The mean length of Notch in the PPF group was 4.5±2.7 mm, compared with 4.9±2.8 mm in the control group, with no significant difference between the two groups ( t=0.732, P=0.465). Further subgroup analysis using a Notch depth of 3 mm as a cut-off and Tayside classification revealed a statistical difference between the two groups (χ 2=11.262, P=0.004; χ 2=14.601, P=0.003). Compared with patients without Notch, the risk of PPF was higher when the depth of Notch exceeded 3 mm, with an odds ratio ( OR) of 4.88 (95% CI: 1.76, 13.51). The incidence of PPF was higher when Notch depth reached Tayside grade 3 or 4. Compared with patients without Notch, the risk of PPF would be 6.99-fold (95% CI: 1.85, 26.32) higher when Notch depth reached grade 3. In female patients, there was a significant difference in Notch status between the PPF and control groups (χ 2=3.956, P=0.047), with a higher risk of PPF in female patients with Notch, OR 2.33 (95% CI: 1.01, 5.43). In patients who underwent right-sided TKA, the risk of PPF was higher in patients with Notch compared to those without Notch (χ 2=5.502, P=0.019), with an OR of 3.58 (95% CI: 1.19, 10.75). Conclusion:The Notch has no significant effect on the femoral PPF after primary total knee arthroplasty. However, the risk of PPF will increase significantly when the Notch depth exceeds 3 mm or is above Tayside grade 3.