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

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.

Interference Screw Versus Suture Anchors for Femoral Fixation in Medial Patellofemoral Ligament Reconstruction: A Biomechanical Study

Background: Femoral-sided graft fixation in medial patellofemoral ligament (MPFL) reconstruction is commonly performed using an interference screw (IS). However, the IS method is associated with several clinical disadvantages that may be ameliorated by the use of suture anchors (SAs) for femoral fixation. Purpose: To compare the load to failure and stiffness of SAs versus an IS for the femoral fixation of a semitendinosus autograft in MPFL reconstruction. Study Design: Controlled laboratory study. Methods: Based on a priori power analysis, a total of 6 matched pairs of cadaveric knees were included. Specimens in each pair were randomly assigned to receive either SA or IS fixation. After an appropriate reconstruction procedure, the looped end of the MPFL graft was pulled laterally at a rate of 6 mm/s until construct failure. The best-fit slope of the load-displacement curve was then used to calculate the stiffness (N/mm) in a post hoc fashion. A paired t test was used to compare the mean load to failure and the mean stiffness between groups. Results: No significant difference in load to failure was observed between the IS and the SA fixation groups (294.0 ± 61.1 vs 250.0 ± 55.9; P = .352), although the mean stiffness was significantly higher in IS specimens (34.5 ± 9.6 vs 14.7 ± 1.2; P = .004). All IS reconstructions failed by graft pullout from the femoral tunnel, whereas 5 of the 6 SA reconstructions failed by anchor pullout. Conclusion: In this biomechanical study using a cadaveric model of MPFL reconstruction, SA femoral fixation was not significantly different from IS fixation in terms of load to failure. The mean load-to-failure values for both reconstruction techniques were greater than the literature-reported values for the native MPFL. Clinical Relevance: These results suggest that SAs are a biomechanically viable alternative for femoral-sided graft fixation in MPFL reconstruction.

Safe Femoral Fixation Depth and Orientation for Lateral Extra-Articular Tenodesis in Anterior Cruciate Ligament Reconstruction

Background: Patients who undergo anterior cruciate ligament (ACL) reconstruction (ACLR) can have a persistent postoperative pivot shift. Performing lateral extra-articular tenodesis (LET) concurrently has been proposed to address this; however, LET femoral fixation may interfere with the ACLR femoral tunnel, which could damage the ACL graft or its fixation. Purpose: To evaluate the safe maximum implant or tunnel depth for a modified Lemaire LET when combined with ACLR anteromedial portal femoral tunnel drilling and to validate the safe LET drilling angles to avoid conflict with the ACLR femoral tunnel. Study Design: Descriptive laboratory study. Methods: Twelve fresh-frozen cadaveric knees were used. With each knee at 120° of flexion, an ACLR femoral tunnel in the anteromedial bundle position was created arthroscopically via the anteromedial portal using a 5-mm offset guide, a guide wire, and an 8-mm reamer, which was left in situ. A modified Lemaire LET was performed using a 1 cm-wide iliotibial band strip harvested with the distal attachment intact, to be fixed in the femur. The desired LET fixation point was identified with an external aperture 10 mm proximal and 5 mm posterior to the fibular collateral ligament’s femoral attachment, and a 2.4-mm guide wire was drilled, aiming at 0°, 10°, 20°, or 30° anteriorly in the axial plane and at 0°, 10°, or 20° proximally in the coronal plane (12 different drilling angle combinations). The relationship between the LET drilling guide wire and the ACLR femoral tunnel reamer was recorded for each combination. When a collision with the femoral tunnel was recorded, the LET wire depth was measured. Results: Collision with the ACLR femoral tunnel occurred at a mean LET wire depth of 23.6 mm (range, 15-33 mm). No correlation existed between LET wire depth and LET drilling orientation ( r = 0.066; P = .67). Drilling angle in the axial plane was significantly associated with the occurrence of tunnel conflict ( P < .001). However, no such association was detected when comparing the drilling angle in the coronal plane ( P = .267). Conclusion: Conflict of LET femoral fixation with the ACLR femoral tunnel using anteromedial portal drilling occurred at a mean depth of 23.6 mm but also at a depth as little as 15 mm, which is shorter than most implants. When longer implants or tunnels are used, the orientation should be directed at least 30° anteriorly in the axial plane to minimize the risk of tunnel conflict, bearing in mind the risk of joint violation. Clinical Relevance: This study provides important information for surgeons performing LET in combination with ACLR anteromedial portal femoral tunnel drilling regarding safe femoral implant or tunnel length and orientation.