The Effects of Inaccurate Femoral Tunnel Placement During Medial Patellofemoral Ligament Reconstruction on Midterm Clinical Outcomes in Treatment of Recurrent Patellar Dislocation

Abstract

Background:There is a lack of evidence and continuous debate on whether femoral tunnel displacement substantially influences the clinical efficacy of medial patellofemoral ligament reconstruction (MPFL-R) in addressing recurrent patellar dislocation.Purpose:To investigate possible associations between inaccurate femoral tunnel placement during MPFL-R and clinical outcomes, with a specific focus on proximal tunnel malpositioning.Study Design:Cohort study; Level of evidence, 3.Methods:Patients who were diagnosed with recurrent patellar dislocation and underwent MPFL-R were retrospectively analyzed. A true lateral view on 3-dimensional computed tomography was obtained, and the distance from the center of the femoral tunnel to the Schöttle point (DF-to-S) was measured. Accordingly, femoral tunnels were divided into the suboptimal group (DF-to-S > 10 mm) and the optimal group (DF-to-S≤ 10 mm). Patient data were collected and pathoanatomic risk factors were evaluated. Clinical assessments included patient-reported outcome measures, including the International Knee Documentation Committee (IKDC), Kujala, Lysholm, and Tegner scores; subjective satisfaction; and postoperative complications. A subgroup analysis was performed between proximally malpositioned tunnels and tunnels lying in other directions.Results:A total of 112 patients (112 knees) were included, with 34 in the suboptimal group and 78 in the optimal group. Patient characteristics and pathoanatomic abnormalities were comparable between the 2 arms, with mean follow-ups of 52.90 ± 23.80 months and 60.14 ± 27.88 months in the suboptimal and optimal groups, respectively ( P = .259). At the final follow-up, inferior IKDC (76.3 ± 12.8 vs 85.9 ± 6.3; P < .001), Kujala (87.7 ± 9.3 vs 93.8 ± 4.9; P = .001), and Lysholm (87.0 ± 11.8 vs 94.5 ± 5.3; P = .001) scores and subjective satisfaction (8.2 ± 1.4 vs 9.3 ± 0.9; P < .001) were observed in the suboptimal group compared with the optimal group. Lower proportions of patients met the minimal clinically important difference for the IKDC (82.4% vs 100.0%; P = .001) and Lysholm (79.4% vs 98.7%; P = .001) scores in the suboptimal group compared with the optimal group. Subgroup analysis demonstrated that the final IKDC ( P = .002), Kujala ( P = .001), and Lysholm ( P = .001) scores and subjective satisfaction ( P = .031) were statistically worse in the proximally located group, with insignificant improvements compared with preoperative levels. The suboptimal group showed a higher rate of overall complications, and anterior knee pain was more often reported in the proximally located subgroup.Conclusion:Inaccurate femoral tunnel positioning was associated with inferior midterm subjective functional scores and a higher rate of postoperative complications after MPFL-R. Proximal displacement in particular was associated with adverse clinical outcomes.