Robot-Assisted Individualized Medial Patellofemoral Ligament Reconstruction in Skeletally Immature Patients With Recurrent Patellar Dislocation: A Single-Center Retrospective Study

Background: The surgical treatment of patellar instability in children and adolescents can be challenging, as successful surgical techniques used in adults may pose a risk to the open growth plate when applied in this younger population. Purpose: To review a series of adolescent patients with recurrent patellar dislocation who underwent robot-assisted individualized medial patellofemoral ligament (MPFL) reconstruction. Study Design: Case series; Level of evidence: 4. Methods: This retrospective clinical study included 76 patients with recurrent patellar dislocation who underwent MPFL reconstruction by a robot-assisted technique or adductor magnus sling technique from June 2018 to August 2022. All patients were divided into the robot-assisted group (42 patients) or the adductor magnus sling group (34 patients). In both groups, a semitendinosus autograft was used for the MPFL reconstruction. In the robot-assisted group, the graft was fixed to the femur using an interference screw. In the adductor magnus sling group, the graft was loped around the adductor magnus. During the surgery, the distance between Schoettle point and the medial distal femoral physis, along with the simulated angle range of the bone tunnel and the optimal angle, was recorded in the robot-assisted group using an intraoperative 3-dimensional navigation system. The clinical results were evaluated using preoperative and postoperative functional scores and imaging. Results: All patients returned for follow-up at a mean of 39.7 ± 9.8 months after surgery. The mean age of the patients was 13.3 years (range, 10-16 years). The Schoettle points were all located below the medial distal femoral physis, with a mean distance of 6.48 ± 1.78 mm from Schoettle points to the medial distal femoral physis. The angle range of the bone tunnel was achieved by targeting a mean of 8.6° to 23.4° anteriorly and 10.9° to 17.8° distally, with the optimal angles being 14.6° anteriorly and 13.5° distally. No patients experienced recurrent patellar instability after surgery; however, the functional scores in the robot-assisted group were slightly higher than those in the traditional adductor magnus sling group (International Knee Documentation Committee score: 93.2 ± 6.2 vs 86.1 ± 7.9; Lysholm score: 90.0 ± 8.1 vs 85.9 ± 7.3; Kujala score: 87.8 ± 6.8 vs 83.0 ± 8.8; all P < .05) at the last follow-up. All the patients had normal patellar tracking, except for 3 patients (8.8%) in the adductor magnus sling group. None of the patients exhibited subsequent growth deformity or any evidence of physeal invasion. Conclusion: The intraoperative robotic navigation system confirmed that the Schoettle point can be safely positioned in patients with open epiphyses. The robot-assisted design of individualized anatomic reconstruction of the MPFL using a forward distal oblique bone tunnel is safe and effective, demonstrating good clinical outcomes.