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

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.