Safe femoral condyle range for the reverse Rigidfix femoral fixation device in anterior cruciate ligament reconstruction

Abstract

Background: To determine the characteristics of cross-pin protrusion in patients treated with the reverse Rigidfix femoral fixation device for femoral tunnel preparation through the anteromedial portal in ACLR, analyse the reasons for this outcome, and identify safety hazards of this surgical technique for improvement. Methods: A retrospective analysis of patients who underwent ACLR using this technology at our hospital in 2018 was conducted. Patients with and without cross-pin protrusion were included in the case and control groups, respectively. The sex, age and imaging characteristics of the patients with cross-pin protrusion were identified, and the reasons for cross-pin protrusion were analysed. Results: There were 64 and 212 patients in the case and control groups, respectively. The proportion of cross-pin protrusion cases was 23.19% (64/276). There was a significant difference in the ratio of males to females (P <0.001, χ2=185.184), the mediolateral femoral condyle diameter (case group, 70.59 ±2.51 mm; control group, 82.65±4.16 mm; P <0.001, t=28.424), and the anteroposterior diameter of the lateral femoral condyle (case group, 58.34±2.89 mm; control group, 66.38±3.53 mm; P <0.001, t=16.615). The cross-pins did not penetrate the lateral femoral condyle cortex in patients with a mediolateral femoral condyle diameter ≥76 mm, but the cross-pins definitely penetrated the cortex when the diameter was ≤70 mm. The cross-pins did not penetrate when the anteroposterior lateral femoral condyle diameter was ≥66 mm, but the cross-pins definitely penetrated it when the diameter was ≤59 mm. Conclusion: The patients with cross-pin protrusion after reverse Rigidfix femoral fixation treatment to prepare the femoral tunnel through the anteromedial portal in ACLR were mainly females with small femoral condyles. For patients with a mediolateral femoral condyle diameter ≥76 mm and an anteroposterior lateral femoral condyle diameter ≥ 66 mm, there is no risk of cross-pin protrusion, so this technique can be used with confidence.